THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS

June 8, 1984 Paper 109

CAMBRIAN OF AND GREENLAND PART I, PTYCHAGNOSTIDAE'

R. A. ROBISON Department of Geology, University of Kansas Lawrence, Kansas 66045

Abstract—Representatives of the family Ptychagnostidae are described or further documented from open-shelf lithofacies in North America and Greenland. These include 21 distributed among the genera Lejopyge, Onymagnostus, and . Seventeen of the 21 species have intercontinental distributions and are important for global biostratigraphy. New species from western North America include Lejopyge acantha, Lejopyge rigbyi, Ptychagnostus hintzei, and Ptychagnostus michaeli. A new geographic subspecies, Lejopyge laevigata rubyensis, also is described. Five successive interval-zones based on agnostoids are defined for the middle part of the System. The base of each zone is defined by a biohorizon corresponding to the first appearance of a single species selected for its abundance and wide geographic distribution within the interval. In ascending order, the species and corresponding zone names are Ptychagnostus praecurrens, P. gibbus, P. atavus, P. punc- tuosus, and Lejopyge laevigata. The upper boundary of each zone is defined by the lower boundary of the one overlying it. Additional widespread agnostoid species are present in each zone. These together with the name species give each zone a distinctive character. As defined here, the Lejopyge laevigata Zone is stratigraphically equivalent to the uppermost Bolaspidella Zone and much of the Cedaria Zone as traditionally used in North America. An informal lower subzone probably has close temporal correlation with the Zone of Solenopleura brachymetopa as commonly used in Scandinavia, and an informal upper subzone probably correlates closely with the Zone of Lejopyge laevigata as used in Scandinavia. These correlations further support the idea that, in reference to the standard of northwestern , much of the Cedaria Zone of North America is Middle rather than Late Cambrian in age. Also, the lower part of the Dresbachian Stage in North America is Middle Cambrian in age.

I Manuscript received January 15, 1984.

2 The University of Kansas Paleontological Contributions—Paper 109

ABUNDANCE, WIDE geographic distribution, and documented similar Middle Cambrian ag- rapid evolution make agnostoid some nostoid successions elsewhere in the world. of the best indices for global correlation of Shergold (1981) has drawn attention to the Cambrian strata. The value of agnostoids for potential importance of agnostoids in Upper regional biostratigraphy was well demonstrated Cambrian biostratigraphy. by A. H. Westergard (1946) in his monograph This is the first of a planned series of papers on the Middle Cambrian agnostoids of Sweden. documenting the diverse Cambrian agnostoid Subsequent studies (e.g., Pokrovskaya, 1958; fauna of North America and Greenland. New Opik, 1961a, 1979; Robison, 1964, 1976, 1982; information about North American agnostoids Ergaliev, 1980; Egorova and others, 1982) have is based on several hundred collections of

/Wellsville rMountains

_JiVasatch Mountains

Toana Range n

nN ‘t . Deep Creek 1 --Mountains t UTAH I' , Dugway Range fi . _ ,-40° LAKE t Ruby Mountains i 1 L__L northern L.' •--_, I i Toiyabe Fish Springs Range 4 ,-- ,% 1 Drum Mountains 1 !`... Range northern f I ks 71. Egan Range I 7 I Eureka 4 northern 1 _, i'- mining district' Schell Creek 1 House Range Canyon Range Range

39° southern White Pine Range'. I Ft southern Snake Range

southern Schell Creek Range southern Egan Ranges

38°-n .- 38° 0 < < > I 1— I D Z

j 0 .kilometers 100 I

\.

Fig. I. Map of parts of Nevada and Utah showing outcrops of Cambrian rocks (black) in mountains or ranges mentioned in this paper (after Palmer, 1971).

Robison—Cambrian Agnostida, Part I, Ptychagnostidae 3

Peary Land Cambrian fossils that I have assembled during Nyeboe Land nvggliT more than two decades. Most of these collec- tions are from thick, generally well-exposed 84/1/6, stud ylif area stratigraphic sections in the Great Basin of Nevada and Utah (Fig. 1). Other significant ( -r) GREENLAND information has come from about 50 collections <<` of Cambrian fossils from Peary Land in central North Greenland (Fig. 2). These were mostly "CD collected by John S. Peel of the Geological -7 -0 Survey of Greenland. The Survey generously \ -0 made them available for this study. A major purpose of this paper is to provide revised or new systematic descriptions for spe- cies of one agnostoid family, the Ptychag- nostidae. It is treated first because several of its species have been used by researchers around the world as zonal indices in Middle Cambrian rocks. Another purpose is to begin a global zonation based on agnostoids from the middle part of the Cambrian System. Fig. 2. Map of Henson Gletscher region, central North Faunas in terranes exotic that were accreted Greenland, indicating collecting localities (black dot, For- to North America after the Cambrian Period mation 2, Bronlund Fjord Group; black square, Formation are not included in this study. These are mainly TI, Tavsens Iskappe Group; black stars, Formation T2, the so-called "Atlantic province" faunas in Tavsens Iskappe Group). Margins of permanent i cc caps arc indicated by broken lines. such places as the Carolina slate belt (Secor and others, 1983) and the Avalonian terranes in LITHOFACIES AND BIOFACIES parts of New England and eastern Canada. The most diverse and best documented of these Similarities in patterns of lithofacies and faunas are in southeastern Newfoundland biofacies indicate that Greenland and most of (Hutchinson, 1962). North America were united in a single con- Acknowledgments. —I am indebted to several tinent during Cambrian time. Thick and friends who have generously contributed speci- widespread carbonate deposits support paleo- mens and information used in this study. Some magnetic evidence that the continent was in also have guided me to important localities and equatorial latitudes (e.g., Bambach and others, others have arranged for the loan of specimens 1980). Lithofacies show that the craton was from institutional collections. These include F. encircled by a broad marine shelf with shallow- J. Collier, W. H. Fritz, Lloyd Gunther, Metta water, carbonate platform deposits of variable Gunther, Val Gunther, L. F. Hintze, C. H. extent (Palmer, 1973; Robison, 1976). The Kindle, L. B. McCollum, M. B. McCollum, platform carbonates were flanked by lagoonal A. R. Palmer, J. S. Peel, R. L. Randolph, M. muds and nearshore sands on one side and by N. Rees, J. K. Rigby, A. J. Rowell, D. K. outer-shelf muds on the other side. Strickland, M. E. Taylor, and W. W. White. Two almost mutually exclusive biofacies are The manuscript has been improved by the common in Middle Cambrian rocks of North reviews of Virginia Ashlock, J. B. Jago, Rolf America. Evidently the faunas were separated Ludvigsen, and A. J. Rowell. Margery Rowell by salinity and temperature barriers on the translated much of the Russian literature that is shallow carbonate platforms. An inner, re- cited. The illustrations were prepared by R. B. stricted-shelf biofacies is found in limestone, Williams, photographs were printed by Eileen shale, and sandstone. Generally it is char- Williams, and manuscript was typed by Jane acterized by sparse, low-diversity, endemic, Priesner. The research was supported most polymeroid faunules. Agnostoids are almost recently by National Science Foundation grants unknown in this inner biofacies. An outer, EAR-8024066 and EAR-8218322. For all of open-shelf biofacies found mostly in limestone this help and support I am most grateful. and shale is characterized by common to abun-

4 The University of Kansas Paleontological Contributions—Paper 109 dant, high-diversity, mixed polymeroid and open-shelf biofacies are widely distributed agnostoid faunas. Fossils are usually most around the continent, but most lack interconti- abundant near the seaward margin of the car- nental distribution. Agnostoid taxa also are bonate lithofacies. Polymeroid genera in the widely distributed around the continent, but

NEVADA UTAH _ northern s. Egan & central Deep Creek, Agnostoid Eureka northern Snake s. Schell Cr. House Fish Sp., & Zones mining Egan Schell Creek Range mtns. district Range Range ranges Range Drum 7 1 2 3 4 5 6 • CO Orr Formation 2 oc < Zi3 o a) 0 Q) C in 7) ...= ..= --o E o c D t 76 a) E 8 o o E E 's _o TD Q) u) E (21 ô a a) _a a IL Tts c a) _c E E ,._ a) ce .a. Weeks as a) '5 a co _J co ci. z) '5 u) Limestone a 8 CO z E -rE) o_ E" o) CO ca a ca -3 2 7 0 2 C C .6 (11 0 0 tt 7E1 L1J 0 E E 6 Is. men,. E A mem. u_ u_ Trippe Limestone Q) es Q) a) Il a_ c c co c o 75 6 0 0 o a) Secret c c Ta Marjum 0 ra 8 'i a) .?. Canyon E -_7.1 .c) _c Formation > c c) E u) 0o .—0 Z c Shale E a) co z u_ u) c 7'1 _< Q c E ca 0 E 0 a) a l.'2 'a CC >, Ts c c .c Q) IL CO co FL 2 112 8 a) < '8 3 CD 6'o O cs_ Q) atavus Geddes u) Wheeler Wheeler W Limestone Formation Formation _i 0 gibbus 0 .,= Swasey Swasey •a Limestone Limestone a) a) a) co c c c C C o o o E "V) 'j.). rn a) E '8 a) o o E E E Q)0 E -1' ai Z '5 zi Li a u_ c c c CI o O o o o ›, >, -o -o c c c as as ra as as ô '5 o o o -0 -0 a) a) o LI EL z z z

Fig. 3. Correlation chart for some Cambrian units in Nevada and Utah. Sources for stratigraphie nomenclature are: I, Nolan, Merriam, and Williams, 1956; 2, Fritz, 1968; 3, Drewes, 1967; 4, Drewes and Pahncr, 1957; 5, Kellogg, 1963; 6 and 7, Hintze and Robison, 1975. Dashed lines indicate uncertain chronocorrelation fi)r some boundaries.

Robison—Cambrian Agnostida, Part I, Ptychagnostidae 5 most of the genera and many species have Individual species are not necessarily restricted intercontinental distributions. Regional ag- to any one zone. nostoid subfacies within the open-shelf biofacies Brief discussions of each zone follow. Strat- (Jago, 1973; Robison, 1975) indicate influences igraphie distributions of North American from other ecological controls that are difficult ptychagnostid species are shown in Figure 4. to identify. Distributions in North Greenland are shown in Fossils recorded here are from several for- Figure 5. Detailed discussions of biostratigra- mations representing open-shelf environments. phy and intercontinental stratigraphie cor- A correlation of relevant stratigraphic units in relations are deferred pending review or Nevada and Utah is shown in Figure 3. Gen- description of other important agnostoid taxa. eral discussions of geologic setting and stratig- raphy have been given by Palmer (1971), Ptychagnostus praecurrens Interval-zone Hintze (1973), Hintze and Robison (1975), and Lower and upper boundaries of the P. Stewart (1980). Agnostoid-bearing sections in praecurrens Zone are defined by the first appear- North Greenland have been divided into un- ances of P. praecurrens and P. gibbus, respectively. named formations that have been discussed by Diversity of agnostoid species is low in the Peel (1979, 1982), Palmer and Peel (1979), and zone. In North America, P. praecurrens (= P. Ineson and Peel (1980). burgessensis) is known only from 21 m of the Stephen Formation in British Columbia, where BIOSTRATIGRAPHY it is associated with columbiensis and Peronopsis mantis (Fritz, 1971). Representatives Most agnostoid trilobites were probably of the zone are not known from Greenland. In pelagic (Robison, 1972b), whereas most poly- parts of Europe, , and , Peronopsis meroid trilobites were probably benthic. Signif- fallax is associated with P. praecurrens in the icantly different observed geographic and zone. Partly because of the few agnostoid spe- stratigraphie distribution patterns are in accord cies and partly because of significant areal with these inferred environmental adaptations. restriction of favorable biofacies, this biozone is Therefore, it is desirable to establish separate much less widely identifiable than others de- sets of agnostoid and polymeroid zones (Robi- scribed here. son, 1976). Biozonal divisions of Cambrian strata gen- Ptychagnostus gibbus Interval-zone erally have been intended only for regional, or at most continental application. Now sufficient Lower and upper boundaries of the P. gibbus data on widespread agnostoid faunas are avail- Zone are defined by the first appearances of P. able to make possible a global agnostoid zona- gibbus and P. atavus, respectively. Globally, the tion of open-shelf lithofacies in the middle part base of the zone commonly coincides with an of the Cambrian System. A succession of five unconformity or an abrupt lithofacies change, interval-zones here are defined. Preliminary possibly related to a eustatic rise in sea level. descriptions of the lowest three zones were Twenty-two agnostoid species from the P. previously published (Robison, 1982:132-133). gibbus Zone in several countries have been listed The base of each zone is defined by a bio- by Rowell, Robison, and Strickland (1982, horizon corresponding to the first appearance of table 1). Among the more widespread and a single species selected for its abundance and common of these are Onymagnostus seminula, wide geographic distribution. In ascending Peronopsis fallax, Peronopsis scutalis, Ptychagnostus order, these species and corresponding zone gibbus, Ptychagnostus intermedius, and Tomagnostus names are Ptychagnostus praecurrens, P. gibbus, P. lissas. atavus, P. punctuosus, and Lejopyge laangata. The In western North America, the P. gibbus upper boundary of each zone is defined by the Zone commonly includes Doryagnostus wasatchen- lower boundary of the one overlying it. Addi- sis, Onymagnostus seminula, Peronopsis amplaxis tional widespread agnostoid species are present (lower part), Peronopsis fallax, Peronopsis gaspensis in each zone. These together with the name (lower part), Peronopsis interstricta, Peronopsis species give each zone a distinctive character. montis (lower part), Peronopsis segmenta (middle

6 The University of Kansas Paleontological Contributions—Paper 109

Formation Wheeler Marjurn Weeks Agnostoid gib- laevigata praecurrens atavus punctuosus Zone bus lower upper

P. praecurrens= O. seminula =I= P. intermedius P gibbus P. atavus P. germanus P. occulta tus P. &finis P. michaeli P. punctuosus L. lundgreni P akanthodes I O. hybridus I L. rigbyi I P. acidusus I L. calva P. hintzei L. acantha P. aculeatus

L. I. rub yensis I -? L armata MIN

Fig. 4. Composite stratigraphie ranges of species of Lejopyge, Ortymagnostus, and Ptychagnostus known from western North America. Thicknesses of formations in the House Range, Utah, arc used as a standard.

and upper parts), Ptychagnostus gibbus, and gaspensis, Peronopsis interstricta, Ptychagnostus gib- Ptychagnostus intermedius (Robison, 1978, 1982). bus, Ptychagnostus intermedius, and Tomagnostus This assemblage is widespread in basal parts of sp. the Geddes, Lincoln Peak, and Wheeler forma- The P. gibbus Zone as defined here probably tions of Nevada and Utah (Fig. 3). The zone is is a close temporal correlative of the Zone of P. especially well developed in the basal 70 m of gibbus as used by Westergard (1946) in Sweden. the Wheeler Formation in the Drum Moun- tains of west-central Utah (Fig. 1; for discus- Ptychagnostus atavus Interval-zone sion and illustrations, see Rowell, Robison, Lower and upper boundaries of the P. atavus and Strickland, 1982). Characteristic species of Zone are defined by the first appearances of P. the zone also are present in the "black band" of atavus and P. punctuosus, respectively. From the Eldon Formation in British Columbia (see analysis by Rowell, Robison, and Strickland Fritz, 1971, fig. 2) and the basal Meagher (1982), chronocorrelation of the lower bound- Formation in Montana. ary of this zone appears to be as precise as for Faunas of the P. gibbus Zone are known any known in the Cambrian System. from only isolated localities in eastern North Thirty-five agnostoid species from the P. America. Some of the best preserved specimens atavus Zone in several countries have been listed are from the Taconic sequence of eastern New by Rowell, Robison, and Strickland (1982, York (Rasetti, 1967; Bird and Rasetti, 1968). table 2). Among the more widespread and Other well-preserved specimens are in C. H. common of these are Hypagnostus parvifrons, Kindle collections 362, 378, 380, 409, and 420 Peronopsis . fa//ax, Peronopsis ferox, Peronopsis from boulders of Cow Head Conglomerate in scutalis, Ptychagnostus atavus, Ptychagnostus ger- western Newfoundland (see Kindle, 1981, manus, Ptychagnostus occultatus, Tomagnostus fissus, 1982). and Tomagnostus perrugatus. In North Greenland, faunas of the P. gibbus In western North America, the P. atavus Zone are present in the upper half of Formation Zone commonly includes Baltagnostus eurypyx 2 of the Brotilund Fjord Group (Fig. 5). Among (upper part), Hypagnostus parvifrons, Peronopsis the agnostoid species are On_ymagnostus seminula, fat/ax (lower part), Peronopsis ferox (upper part), Peronopsis amp/axis, Peronopsis fa//ax, Peronopsis Peronopsis interstricta, Peronopsis segmenta, Ptychag-

Robison—Cambrian Agnostida, Part I, Ptychagnostidae 7

Group BrOnlund Fjord Tavsens lskappe Formation 2 I 3 4 Ti T2 T3 Agnostoid gib- punc- I laevigata i 1 i Zone bus tuosusi upper 1 O. seminula wm P. intermedius iin P. gibbus III= O. hybridus M P. occultatus Mi L. laevigata L. armata

Fig. 5. Observed stratigraphie ranges of species of 1.6opyge, Onymagnoslus, and hychapiostus in Peary Land, central North Greenland.

nostus atavus, Ptychagnostus germanus, and Ptychag- Among the more widespread and common of nostus occultatus (upper part). These species are these are Cotalagnostus lens, Doryagnostus tncertu,s, especially common in the middle and upper Coniagnostus nathorsti (upper part), Hypagnostus Wheeler and lower Marjum formations of west- mammillatus, Hypagnostus parv:frons, Iniospheniscus central Utah. Some also are present in parts of ta/is, Lejopyge lundgreni, Onymagnostus hybridus, the Geddes, Lincoln Peak, and equivalent units Peronopsis ferox, Pseudoperonopsis perplexus, Pty- in Nevada. chagnostus acidusus, Plychagnostus affinis, Ptychag- Agnostoids of the P. atavus Zone are rare in nostus atavus (lower part), Ptychagnostus germanus, eastern North America. A few specimens are Ptychagnostus occulta/us, Ptychagnostus puncluosus, present in boulders of Cow Head Conglomer- and Tomagnostus perrugatus. As agnostoid faunas ate in western Newfoundland (Kindle, 1981, become better documented, subdivision of this 1982). Also, some agnostoids in conglomeratic interval probably will be warranted. boulders of the Levis Formation of southeastern In western North America, the P. punctuosus Quebec (Rasetti, 1948) may represent the zone. Zone contains Baltagnostus euryp_yx, Cotalagnostus Agnostoid trilobites of the P. atavus Zone are laevus, Hypagnostus parvifrons, Iniospheniscus tails, not known from Greenland. Lithofacies (In- Lejopyge lundgreni, Lejopyge rigbyi, Onymagnostus eson and Peel, 1980) of the biochron indicate hybridus, Peronopsis ferox, Peronopsis? incertus, Pero- restricted-shelf conditions that probably were nopsis interstricta, Peronopsis segmenta, Pseudo- unfavorable for agnostoids. peronopsis perplexus, Ptychagnostus affini s, Pty- As defined here, the P. atavus Zone probably chagnostus akanthodes, Ptychagnostus atavus, Ply- has close temporal correlation with West- chagnostus german us, Ptychagnostus michaeli, ergArd's (1946) Zone of Tomagnostus fissus and Ptychagnostus occultatus, Ptychagnostus punctuosus, Ptychagnostus atavus as well as his Zone of Hypag- and Utagnostus trispinulus. Agnostoids of this nostus parvifrons in Sweden. P. atavus and H. zone are common in the Marjum Formation of parvifrons first appear at nearly the same strat- the House Range in western Utah. Generally, igraphie horizons in both Sweden and Utah. they are sparse in coeval parts of the Lincoln According to WestergArd's range charts (1946: Peak, Patterson Pass, and Secret Canyon for- 98-103), the Zone of H. parvifrons in Sweden mations in Nevada. does not include a single distinctive species. Only a single locality in the eastern part of Evidently, identification of that zone was based Cambrian North America has yielded a di- on local abundance of H. parvifrons. verse, well-preserved fauna of the P. punctuosus Zone. This is the Stockport Station locality of Ptychagnostus punctuosus Interval-zone Rasetti (1967) and Bird and Rasetti (1968) in Lower and upper boundaries of the P. the Taconic sequence of eastern New York. puncluosus Zone are defined by the first appear- From three meters of exposed strata at that ances of P. punctuosus and Ldopyge laevigata, locality Rasetti described 21 species of tri- respectively. Globally, more than 60 agnostoid lobites, including 7 agnostoids. species have been reported from this interval. In North Greenland, rich faunas of the P.

8 The University of Kansas Paleontological Contributions—Paper 109 punctuosus Zone are present in the middle part of clusus, Lejopyge acantha, Lejopyge lundgreni, Formation Ti of the Tavsens Iskappe Group. Peronopsis ferox, Ptychagnostus aculeatus, Ptychag- Agnostoid species include Baltagnostus euryp_yx, nostus hintzei, and Utagnostus trispinulus. In more Hypagnostus parvifrons, Onymagnostus hybridus, seaward lithofacies of central Nevada, L. calva is Peronopsis ferox, and Ptychagnostus occultatus. replaced by L. laevigata rubyensis. Landward, in As defined here, the P. punctuosus Zone shallower water carbonates, agnostoids gener- probably has close temporal correlation with ally become less common and mainly include WestergArd's (1946) Zone of Ptychagnostus punc- species of Baltagnostus, Kormagnostus, and Per- tuosus as well as his Zone of Ptychagnostus onopsis. The best North American reference lundgreni and Goniagnostus nathorsti. section for the lower subzone is the upper Marjum and lower Weeks formations in the Lejopyge laevigata Interval-zone vicinity of Marjum Pass in the House Range, Utah (Fig. 1). Elsewhere in western North The lower boundary of the L. laevigata Zone America, Palmer (1968) has described Phalag- is defined by the first appearance of L. laevigata. nostus bituberculatus in association with L. calva Pending further study, the upper boundary is and P. aculeatus in Alaska. provisionally defined by the first appearance of Because of areal reduction of favorable Aspidagnostus. Globally, more than 50 agnostoid lithofacies, the upper L. laevi gala subzone in species have been described from this interval; Nevada and Utah is known from fewer lo- however, many of these are in need of further calities than the lower subzone. Among the documentation, and several synonyms appear more commonly encountered agnostoids are to be included. Acmarhachis sp., Agnostascus sp., Clavagnostus sul- Such species as Lejopyge armata, L. laevigata, catus (s. 1.), Connagnostus sp., Kormagnostus sim- and Diplagnostus planicauda (s. I.) are widespread plex, Lejopyge armata, and Triadaspis bigeneris. and range throughout most of the L. laevigata Although the section is not well exposed, the Zone. Several other widespread species seem to best known North American development of be mostly confined to either lower or upper the upper subzone is in the upper shale member parts of the zone. Therefore, I provisionally of the Lincoln Peak Formation near Cleve divide the zone into informal lower and upper Creek in the northern Schell Creek Range, subzones. With further documentation, these Nevada (Fig. 1). One collection from this sec- probably will warrant definition as formal tion also contains probable representatives of L. Among other widespread species in the zones. laevigata rubyensis. lower subzone are neglectus, Clavagnostus repandus (s. 1.), Goniagnostus nathorsti, Lejopyge The Lejopyge laevigata Zone in North Green- calva, Lejopyge lundgreni, Peronopsis ferox, Phalag- land is represented by only faunas of the upper nostus bituberculatus, and Ptychagnostus aculeatus. subzone, which range throughout Formation Other widespread species in the upper subzone T2 of the Tavsens Iskappe Group. Among include Agnostus pi siformis, Clavagnostus sulcatus diverse trilobite faunas in several collections are (s. 1.), Goniagnostus spiniger, Hypagnostus sulcifer, Acmarhachis sp., Agnostus aff. A. pisiformis, Con- Kormagnostus simplex, Oidalagnostus 1rispinife7, and nagnostus sp., Diplagnostus planicauda (s. I.), Triadaspis bigeneris. Representatives of Ac- Hypagnostus sulcifer, Kormagnostus simplex, Lejo- marhachis (= Cyclagnostus), Agnostascus, and Con- pyge armata, Lejopyge laevigata, Oidalagnostus tri- nagnostus are widespread in the upper subzone, spinifer, and Triadaspis bigeneris. The many but taxonomic concepts need review. species of associated polymeroid trilobites in- The lower L. laevigata subzone is strat- clude representatives of Bolaspidella, Cedaria, igraphically equivalent to the L. calva Zone as and Elrathia. used regionally in parts of Nevada and Utah As defined here, the Lejopyge laevigata Zone is (e.g., Robison, 1964, 1976). There L. calva is stratigraphically equivalent to the uppermost present in great abundance at many localities. Bolaspidella Zone and much of the Cedaria Zone Less common associated agnostoids include as traditionally used in North America (e.g., Agnostus aff. A. neglectus, Baltagnostus eurypyx, Lochman-Balk and Wilson, 1958; Robison, Clavagnostus repandus (s. I.), Diplagnostus plani- 1964). Also, the lower subzone probably has cauda (s. 1.), Hypagnostus sp., Kormagnostus se- close temporal correlation with WestergArd's Robison—Cambrian Agnostida, Part I, Ptychagnostidae 9

(1946) Zone of Solenopleura brachymetopa in Swe- ard of northwestern Europe, much of the den, and the upper subzone probably correlates Cedaria Zone of North America is Middle rather closely with his Zone of Lejopyge laevigata. These than Late Cambrian in age. Also, the lower correlations support the conclusion of Daily part of the Dresbachian Stage in North Amer- and Jago (1975) that, in reference to the stand- ica is Middle Cambrian in age.

SYSTEMATIC PALEONTOLOGY

Depositories. —Materials used in this study Phylum ARTHROPODA Siebold are identified by either specimen or collection and Stannius, 1845 numbers that may be combined with depository Class TRILOBITA Walch, 1771 abbreviations. These are: Geological Survey of Order AGNOSTIDA Kobayashi, 1935

Canada, GSC; Geological Survey of Greenland [num. transi Nil/ORE, 1959, p. 0172, ex suborder Agnostida (Gronlands Geologiskc Undersogelse), GGU; KOBAYASHI 935, p. 811 Geologisk Museum (formerly Mineralogisk Diagnosis. —Trilobites having basal lobes on U. S. Geo- Museum), Copenhagen, MGUH; cephalon, no articulating half ring on anterior col- logical Survey—Cambrian and thoracic segment, and no overlap between S. National Museum of lections, CO; U. cephalon and thorax; labrum having unusually and University of Natural History, USNM; long anterior and posterior wings; thorax hav- Kansas Museum of Invertebrate Paleontology, ing two segments. KUMIP. Remarks. —The order Agnostida includes Material identified by three-digit numbers small, eyeless, isopygous trilobites that lack only is from my research collections. These are facial sutures and possess only two thoracic at the University of Kansas, where a locality segments in the holaspid stage. Development of description for each collection is listed in the a unique hinge line without overlap between locality tile of the Museum of Invertebrate the cephalon and thorax (Robison, 1964:515) Paleontology. was accompanied by transformation of the oc- Materials identified by initials and numbers cipital ring into a lateral pair of triangular basal were collected by M. N. Rees (MNR), A. J. lobes and by loss of the articulating half ring on Rowell and M. N. Rees (RR), and D. K. the anterior thoracic segment. The labrUm, Strickland (DKS). These collections are in the with two pairs of long, slender wings, resembles University of Kansas Museum of Invertebrate a long-legged stool (Robison, 1972a). All evi- Paleontology, where localities are recorded. dence of segmentation is effaced from pleural The C. H. Kindle collections from the Cow regions of the pygidium. Head Conglomerate of western Newfinindland, From a review of morphologic, paleoeco- cited herein, have been accessioned by the logic, and biogeographic evidence, I previously Geological Survey of Canada in Ottawa concluded that most agnostoids were probably (Kindle, 1982). adapted for a pelagic lifestyle (Robison, 19726). 7ermino1ogy.—Many morphological terms Recently, Fortey and Barnes (1977:306) noted used in this paper are defined in the Treatise on that Early Ordovician agnostoids in Spits- Invertebrate Paleontology (Harrington, Moore, bergen "seem to be related in occurrence to and Stubblefield, 1959). Other terms have been benthic communities..., and, therefore, a pe- defined by Robison (1964, 1982) or Opik lagic habitat does not seem probable for t his (1967). group..." Those Spitsbergen agnostoids were 10 The University of Kansas Paleontological Contributions—Paper 109 subsequently assigned by Fortey (1980) to one nodes, tubercles, spines, genal scrobicules, and new species of Micragnostus and two new sub- surface granulation is variable. species of Arthrorhachis danica (Poulsen). Al- Several genera have been defined using one though the three taxa of Spitsbergen agnostoids or more characters derived during evolution of seem to be related in occurrence to benthic the ptychagnostid complex. Lejopyge Corda (in communities, numerous agnostoid species are Hawle and Corda, 1847) was defined prior to not. Many agnostoid species, including several Ptychagnostus and traditionally has included spe- discussed here, have intercontinental distribu- cies characterized by extreme effacement of tions and each is associated with multiple poly- dorsal furrows. Other commonly used names meroid assemblages. Moreover, instances of are Triplagnostus Howell (1935) and Goniagnostus positive correlation between agnostoid species Howell (1935). Concepts of these genera, par- and matrix lithology may be reflecting such ticularly that of Goniagnostus, have been factors as water chemistry, nutrients, or tem- modified by subsequent authors. In 1979, dpik perature in the general habitat rather than a divided ptychagnostid species among 10 pre- relationship between an agnostoid species and a viously defined or new genera. At the same substrate condition. time, he further modified the concepts of some previously defined genera. Goniagnostus was re- Family PTYCHAGNOSTIDAE Kobayashi, vised to include species with a medial spine on 1939 the posterior glabella and Lejopyge was revised j noon. trans!. herein, ex Ptychagnostinae KOBAYASHI, 1939, p 151 to include some species with well-developed (tor nomenclatural history, see Ôpik, 1967, p. 90)1 dorsal furrows. Diagnosis. —Agnostoids having preglabellar Although the complex of ptychagnostid spe- median furrow. Cephalic axis conical; un- cies could be consolidated under one generic equally divided by transglabellar (F3) furrow, name (Lejopyge having priority), I prefer to length of posteroglabella about twice that of assign major evolutionary lineages to separate anteroglabella. Pygidial axis subconical with genera. Some generic diagnoses are difficult to slight lateral constriction at M2, not reaching write, however, because homeomorphy is com- posterior border furrow; divided by two trans- mon. axial furrows (F1, F2). Border furrows of ex- As defined here, the Ptychagnostidae is a oskeleton narrow. Cephalic border narrow, monophyletic family that includes Ptychagnostus pygidial border usually of moderate width. praecurrens and all of its descendant species (Fig. Furrows on cephalic and pygidial acrolobes 6). The family is divided into genera represent- secondarily effaced in some lineages, resulting ing inferred monophyletic subgroups. As re- in multiple smooth homeomorphs. vised here, Ptychagnostus is paraphyletic and Discussion. —Except in secondarily effaced Onymagnostus, Lejopyge, Goniagnostus, and Myr- species, representatives of the Ptychagnostidae mecomimus are holophyletic, each repre- typically possess a preglabellar median furrow senting a phyletic branch arising from a that is fairly uniform in depth and width different species of Ptychagnostus. In general, throughout its course. The cephalic and these taxonomic subdivisions parallel those of pygidial axes are typically conical; however, dpik (1979); however, I prefer to recognize lateral sides of the posteroglabella are sub- fewer genera. parallel in early species of Ptychagnostus Jaekel Representatives of Doryagnostus are close (1909) and Onymagnostus Opik (1979), and the homeomorphs of some ptychagnostids (Robi- pygidial axis is considerably modified in Myr- son, 1978). Much of the similarity in morphol- mecominzus dpik (1979). A postaxial median ogy was inherited from two similar species of' furrow is present in the ancestral species, Peronopsis that independently evolved a pre- Ptychagnostus praecurrens (WestergArd), and is glabellar median furrow. Peronopsis brighamensis retained in many later species. In some groups, (Resser) appears to be the immediate ancestor particularly in Onymagnostus and in those species of Ptychagnostus praecurrens (WestergArd), and with pronounced effacement of other furrows, Peronopsis gaspensis Rasetti of Doryagnostus the postaxial median furrow may disappear, at wasatchensis Robison. Axial shape in early spe- least during the holaspid period. Evolution of cies of Ptychagnostus and Doryagnostus is quite Robison—Cambrian Agnostida, Part I, Ptychagnostidae 11

similar, but other inherited characters are diag- Cambrian (Ptychagnostus praecurrens Zone) to the nostic. On the pygidium, P. praecurrens has two top of the Middle Cambrian (top of L6opyge moderately developed transaxial furrows (FI, laevigata Zone). Geographically, Ptychagnostus, F2), a small median tubercle on the second Onymagnostus, and Lejopyge are cosmopolitan in axial segment (M2), and a smooth border. In open-shelf lithofacies. Goniagnostus (sensu 45pik, contrast, the pygidium in D. wasatchensis has 1979) is common in parts of Europe, Asia, and nearly effaced transaxial furrows, a median Australia, but in North America is known from node on the second segment, and a pair of short only an Avalonian terrane in New Brunswick posterolateral spines on the border. (Howell, 1935). Myrmecomimus is a highly The Ptychagnostidae have an observed evolved genus that seems to be endemic to stratigraphic range from the lower Middle Australia.

0. Cr, ru o_ PTYCHAGNOSTUS arma ta CE

a:1'D aculeatus acantha laeogata o • hintzet• ca,!

It elegans o ti re) o o acidusus

o akanthodes rigbyi o_

\punctuosus michaeh • , tundgreni afhnis // LEJOPYGE

a)

intermedius

ONYMAGNOS TUS

praecurrens

-0 5 a) CE c 00 ON PER ONOPSIS o 0) u_ brighamensis

Fig. 6. Diagram of inferred phylogeny of some genera and species of Ptychagnostidae. Except for L6apyge elegans (open dot), all species are known from North America or North America and Greenland. Solid dots are at observed first appearances of species within interval zones. Dashed lines indicate uncertain relationship.

1 2 The University of Kansas Paleontological Contributions - Paper 109

Genus PTYCHAGNOSTUS Jaekel nostus but he incorrectly stated that it was established by subsequent designation of Ptychagnostus JAEKEL, 1909, p. 400 and 401; Vogdes (1925). KOBAYASHI, 1939, p. 152-153; SHIMER and Diagnosis. -Ptychagnostids having elongate SHROCK, 1944, p. 600; WESTERGÂRD, 1946, basal lobes. Axis moderately separated from p. 67-69; PAI,MER, 1954, p. 60; 1968, p. anterior and posterior borders. Postaxial me- B28; SNAJDR,' 1958, p. 70; HOWELL, 1959, dian furrow present. p. 0178; POKROVSKAYA in Tchernysheva, Description. -Anteroglabella commonly sub- 1960, p. 58; 6E1K, 1961a, p. 76-77; 1979, triangular, entire or with rare anteromedian p. 88-89; ROBISON, 1964, p. 522-523; 1982, cleft. Posteroglabella variable in form, ante- p. 135-136; Lu and others, 1965, p. 37; rolateral sides subparallel to anteriorly con- RUSHTON, 1966, p. 35; 1978, p. 261; 1979, vergent, back end rounded and constricted p. 53; JAG°, 1976a, p. 150-152; YIN, 1978, between basal lobes; median node variable in p. 387. position and probably not homologous in some Triplagnostus HOWELL, 1935, p. 14; 1959, p. species. Basal lobes elongate, entire or divided. 0179; KOBAYASHI, 1939, p. 145-148; LER - Genae smooth to strongly scrobiculate or MONTOVA, 1940, p. 127; SHIMER and coarsely granulose, or both. Cephalic border SHROCK, 1944, p. 600; POKROVSKAYA in may possess pair of posterolateral spines. p. 58; bEIK, 1979, p. Tchernysheva, 1960, Thorax unmodified or with median spine on 115-117. posterior segment. Pygidial axis moderately WHITEHOUSE, p. Solenagnostus 1936, 86. separated from posterior border furrow; M2 LERMONTOVA, 1940, p. 127; Pentagnostus commonly hexagonal, rarely pentagonal or 0185-0186; 6pik, HOWELL, 1959, p. subrectangular. Median node, tubercle, or p. p. 139-140. 1967, 77-78; 1979, spine on posterior part of M2; secondary me- Huarpagnostus RUSCONI, 1950, p. 92. dian nodes may be midway along or at tip of RUSCONI, 1951, p. 13-14. Canotagnostus posteroaxis. Pleural fields commonly smooth, tilEtx, 1979, p. 105. Zeteagnostus rarely granulose. Postaxial median furrow usu- bEIN, 1979, p. 128-129. Aotagnostus ally present throughout ontogeny, rarely be- species. -Agnostus punctuosus Angelin, coming effaced in late holaspides. Pygidial 1851:8; by original designation. border slightly wider than cephalic border, Apparently because of an error in type smooth or with pair of posterolateral swellings assembly, Jaekel's (1909) short original descrip- or spines. tion of Ptychagnostus (top, p. 401) is separated Remarks. -Development of nodes, tuber- from the brief generic discussion and the desig- cles, spines, genal scrobicules, and surface nation of "A. punctuosus Angelin" as "typus" granulation is highly variable within Ptychag- (top, p. 400). The discussion and type species nostus. designation are included in a section on the The origin, some aspects of evolution, and family , but the generic description synonyms of Ptychagnostus have been recently is misplaced in a section on the new family discussed (Robison, 1982:135-136). As revised Leiagnostidae. Jaekel's inclusion of an illustra- here, the concept of Ptychagnostus is restricted by tion of "Ptychagnostus reticulatus" with those of reassignment of some species to Onymagnostus other agnostoids indicates that he considered (as revised herein), Goniagnostus (sensu 6pik, Ptychagnostus a member of that family rather 1979), and Lejopyge (as revised herein). than of the Leiagnostidae. Vogdes (1917:44) Occurrence. -Ptychagnostus has been reported continued the error by listing Ptychagnostus as a from all continents except Africa. In North member of the Leiagnostidae and he incorrectly America it ranges through nearly the upper listed "A. reticulatus Ang." as the type of two-thirds of the Middle Cambrian (P. prae- Ptychagnostus. Although the species name was currens Zone through lower L. laevigata sub- misspelled, Vogdes (1925:111) subsequently zone). The ancestral species is P. praecurrens and listed A. punctuosus as the "genotype" of the youngest species probably is P. aculeatus. Ptychagnostus. In 1959, Howell (p. 0179) also Ptychagnostus? serus bpik (1967), from the lower listed A. punctuosus as the type species of Ptychag- Upper Cambrian of Australia, is based on a Robison—Cambrian Agno.slida, Part I, Ptychagnostidae 13 single juvenile cephalon that probably repre- original species description, bpik (1979) noted sents Glyptagnostus. that, on the single cephalon known at the time, the anterior glabella is blunt and sulcate. Speci- PTYCHAGNOSTUS ACIDUSUS (ipik mens from Nevada (Fig. 7,1) have a nonsulcate Figure 7 and more pointed anterior glabella; however, similar variation in shape of the anterior Ptychagnostus (Acidusus) acidusus 6P1K, 1979:100- glabella is common in populations of P. atavus. 101, pl. 46, figs. 2-4. Surface granules and punctae on illustrated Diagnosis. —Cephalon subquadrate. Axis Australian specimens of P. acidusus are weak moderately tapered forward. F1 undeveloped, and may represent only secondary effects of F2 moderately developed adjacent to axial fur- preservation or weathering. rows. Median node behind midpoint of post- 6pik (1979:99-100) designated P. acidusus eroglabella. Basal lobes elongate and entire. as the type species of a new subgenus Ptychag- Scrobicules well developed on late holaspid nostus (Acidusus), the distinguishing character genae, but depth irregular along individual being "its terminal pygidial axial node." In my furrows; weak, longitudinally directed, sub- opinion, the taxonomic importance attributed crescentic pair usually opposite F2. Postero- to that node is unwarranted, and I prefer not to lateral border lacking spines, but fulcral points recognize the subgenus. A terminal node is not prominent. Thorax nonspinose; anterior seg- evident front illustrations of many of the speci- ment having weak, median axial node. mens that bpik assigned to his new subgenus. Pygidium semicircular. Axial Fi deepest about Moreover, a similar node is present on speci- midway between sagittal line and axial furrows. mens of various species of Ptychagnostus (e.g., P. M2 well defined, hexagonal; large, reclined, incautus, P. michaeli) that otherwise arc quite median tubercle at posterior margin. Post- d Ire re n t from P. acidus us . eroaxis ogival; bearing terminal, secondary P. acidusus shares many features with P. node. Postaxial median furrow shallow. Border atavus, from which it appears to have directly lacking spines. evolved. Differences are minor and mainly Discussion. —Previously, I suggested that P. consist of a more constant presence of genal acidusus was probably a synonym of P. atavus scrobicules and presence of a terminal axial (Robison, 1982). Upon further study, I here node. Lower convexity observed in P. acidusus is tentatively recognize P. atavus and P. acidusus as probably due to partial flattening in shaly lime- separate species; however, the differences are stone, which also may cause reduction in width minor and of questionable taxonomic value. P. and minor changes in shape of the axis. acidusus is known from few specimens and its Occurrence. —Rare specimens of P. acidusus range of morphologic variation is yet to be have been collected in Australia (Queensland) determined. The species is characterized by the and the United States (Nevada). In addition to combination of genal scrobicules of irregular the specimens described by bpik (1979), three depth, elongate and entire basal lobes, lack of cephala and one pygidium are in collection 168 spines, and a large median tubercle and a from 303 in above the base of the Secret terminal node on the pygidial axis. In the Canyon Formation in the northern Egan

Fig. 7. Ptychagnostus acidusus Ùpik. /, Cephalon, KUMIP 204201, X 8; 2, pygidium, KUNIIP 204202, x 9; both preserved in argillaceous limestone of collection 168, Secret Canyon Formation, northern Egan Range, Nevada.

14 The University of Kansas Paleontological Contributions-Paper 109

Range, Nevada. All known specimens are asso- prominent granules of uneven size, well-devel- ciated with faunas of the P. punctuosus Zone. oped genal scrobicules, and spines on the cephalic border and pygidial axis. Representa- PTYCHAGNOSTUS ACULEATUS tives somewhat resemble those of P. punctuosus, (Angelin) but can be readily distinguished by the pres- Figure 8 ence of spines on the cephalon and pygidium. bpik (1979:144) stated that Agnostus acu- Agnostus aculeatus ANGELIN, 1851, p. 8, pl. 6, fig. leatus Angelin "has a cephalon of Goniagnostus 12; BROGGER, 1878, p. 71, pl. 5, figs. 5a, b; and is a separate genus; it is discussed in TULLBERG, 1880, p. 23, pl. 1, figs. 11a, b; connection with Onymagnostus." Neither his dis- GR6NWALL, 1902, p. 197; STRAND, 1929, p. cussion of Onymagnostus nor Goniagnostus further 345, pl. 1, fig. 7. mentions aculeatus and his notion of a "separate Ptychagnostus aculeatus (Angelin) JAEKEL, 1909, genus" remains unexplained. Although P. acu- p. 400; Lu and others, 1965, p. 37, pl. 3, leatus is a highly evolved species, I find no figs. 11, 12; KHAIRULLINA, 1970, p. 7, pl. 1, compelling reason for excluding it from Ptychag- figs. 4, 5; 1973, p. 34, pl. 1, figs. 5-7; nostus. ROBISON, 1978, fig. 2B; XIANG and others, Specimens of P. aculeatus have a relatively 1981, pl. 7, figs. 6,7; KINDLE, 1982, pl. 1.2, thin exoskeleton, which seems to correlate with figs. 16, 19, 23. an unusually large holaspid size and probable Goniagnostus aculeatus (Angelin) KOBAYASHI, retention of a pelagic mode of life. Because of 1939, p. 154. the thin exoskeleton, most specimens from Ne- Ptychagnostus (Ptychagnostus) aculeatus (Angel in) vada and Utah are flattened and deformed. WESTERGÂRD, 1946, p. 79-80, pl. 12, figs. Nevertheless, except for longer cephalic border 8-11; 6P1K, 1961a, p. 80-81, pl. 21, figs. 3, spines, morphologic details closely resemble 4a, b; PALMER, 1968, p. B28, pl. 6, fig. 20; those of specimens previously assigned to the YANG, 1982, pl. 1, figs. 16, 17. species from other continents. Diagnosis.-Mature holaspides relatively The pattern of ramified genal rugae on large, maximum length of complete exoskel- holaspid cephala of P. aculeatus is closely similar eton probably ranging to 20 mm. Exoskeletal to the pattern of intestinal diverticula in larvae surface mostly covered with prominent, dense of the recent xyphosuran Limulus polyphemus granules of uneven size. (see Robison, 1978, fig. 2). This resemblance Cephalon subquadrate to subcircular in supports bpik's (1961b) interpretation of the dorsal view, convexity decreasing from moder- ramified rugae of agnostoids as a surface ex- ate to low during holaspid ontogeny. Fi weak pression of the internal alimentary system. The and F2 moderately developed. Median node surface granules may have served an auxiliary behind midpoint of posteroglabella. Basal lobes respiratory function. elongate and usually divided. Genal scrobicules Occurrence. -Geographically, P. aculeatus is well developed, outlining rugae with as many widespread; however, at most localities the as three orders of branching. Border lacking number of specimens tends to be relatively low. granules, posterolateral spines short to long and In North America, rare specimens have been slender. previously documented from east-central Thorax unknown except anterior segment Alaska (Palmer, 1968) and western Newfound- (Fig. 8,4), which is weakly granulose. land (Kindle, 1981, 1982). Specimens com- Pygidium generally subquadrate with low pared with P. aculeatus also have been reported convexity. During holaspid ontogeny, Ml be- from the District of Mackenzie (Fritz, 1981: coming transversely tripartite and postaxial 153). Within the conterminous United States, median furrow disappearing. Median spine on P. aculeatus here is described and illustrated for M2 unusually large, with base extending well the first time from Nevada and Utah. From back onto posteroaxis; length undetermined Nevada are more than 30 specimens in collec- because of difficulty in preparation. Border tions 155 and 156 from 1.5 and 3.0 m, respec- granulose, lacking spines. tively, above the base of member B, Emigrant Discussion. -P. aculeatus is characterized by Springs limestone, in the southern Schell

Robison—Cambrian Agnostida, Part I, Ptychagnostidae 15

5 6 7

Fig. 8. Ptychagnostus aculeatu.s (Angelin); 3 is from collection 751, Weeks Limestone, House Range, Utah; all others are froni collection 156, Emigrant Springs Limestone, southern Schell Creek Range, Nevada. 1,7, Late holaspid cephala, KUM 11' 204203 and 204204, both x 5; 2, early holaspid cephalon, KUMIP 204205, x 15; 3, flattened, intermediate holaspid pygidium, KUMIP 204206, X 5; 4, anterior thoracic segment, KUMIP 204207, x 5; .5,6, flattened, late holaspid pygidia, KUMIP 204208 and 204209, both X 5.

Creek Range (for lists of associated taxa, see mark, Norway, the Soviet Union, and Sweden Clark and Robison, 1969). A single cephalon of (see synonomy). Additionally, the species has P. aculeatus (KUMIP 147589) is in collection been reported in faunal lists for Australia DKS78-139g from the highest beds containing (Opik, 1979:5), New Zealand (Cooper, 1979: Lejopyge calva in the Lincoln Peak Formation of 54), and the Salair region of the Soviet Union the southern Snake Range. From Utah are. (Poletaeva, 1969:27). about 40 specimens in collections 749, 751, and Stratigraphically, the reported range of P. 828 from 24 to about 45 m above the base of the aculeatus is the upper two-thirds of the L. Weeks Limestone in the central House Range. laevigata Zone; however, most occurrences ap- Outside North America, P. aculeatus has pear to correlate with the upper half of the been described from Australia, China, Den- lower subzone.

16 The University of Kansas Paleontological Contributions—Paper 109

PTYCHAGNOSTUS AFFINIS (Brogger) romedially in some; median node usually ante- Figure 9 rior from posteroglabellar midpoint. Basal lobes elongate, entire or divided. Genae usually Agnostus punctuosus Angelin var. affinis BROGGER, with well-developed scrobicules. Dorsal surface 1878, p. 68, 5, 2a, pl. figs. b. lacking granules. Angelin var. bipunctata ?Agnostus punctuosus Thorax relatively unmodified and non- BROGGER, 1878, 68, 5, p. pl. fig. 2e. spinose. Agnostus intermedius THORSLUND (not Tullberg) Pygidium low to moderately convex, com- in Asklund and Thorslund, 1935, p. 106, monly subquadrate, without border spines. pl. 1, figs. 5-7. Axis moderately well defined, constricted at Ptychagnostus punctuosus affinis (Brogger) KOBA- hexagonal M2. Median structure on M2 vary- YASHI, 1939, p. 152-153; 6P1K, 1979, p. ing from low, weak tubercle at posterior edge 8; 40, figs. 2-7. 91-92, pl. 39, fig. pl. (common) to low, ill-defined, longitudinal ridge ?Ptychagnostus punctuosus bipunctata (Brogger) (rare). Posteroaxis centrally depressed, in some KOBAYASHI, 1939, p. 152-153. having secondary median node at midlength, Ptychagnostus (Ptychagnostus) punctuosus a nts and in some having as many as five pairs of (Brogger) WESTERGARD, 1946, p. 79, pl. 11, characteristic, tiny, lateral pits. Postaxial me- figs. 26-33; PALMER, 1968, p. B28, pl. 4, dian furrow usually present, but disappearing figs. 26, 27. on some late holaspides. Surface of pleural Diagnosis. —Cephalon moderately to highly fields covered with weak granules. convex, subcircular to subquadrate in dorsal Discussion. —In his monograph on Swedish view; posterolateral borders smooth. Axis well agnostoids, WestergArd (1946:79) concluded defined, tapering anteriorly, weakly cleft ante- that "a practically continuous evolutional se-

Fig. 9. Plychagnostus affinis Brogger; 1-6 arc from collection 394, 7,8 from collection 772; all Marjum Formation, House Range, Utah. 1,4,6,7, Holaspid cephala of various sizes, KUMIP 204211-204214; x8.0, 10.0, 9.0, 6.5, respectively. 2,3,5,8, Holaspid pygidia of various sizes, KUMIP 204215-204218; x 8, 8, 10, 7, respectively. Robison—Cambrian Agnostida, Part I, Ptychagnostidae 17

ries" is formed by taxa that here are designated affinis are in collections (337, 393, 394, 396, as Ptychagnostus atavus, P. affinis, and P. punc- 772) ranging from 15 to about 185 in above the tuosus. Morphologies and lowest stratigraphic base of the Marjum Formation. appearances of these same taxa in Nevada and Stratigraphically, P. affinis ranges through Utah (Fig. 4) support WestergArd's conclusion approximately the lower half of the P. punctuosus concerning phylogeny. Although variation is Zone. evident, generally P. affinis differs from P. atavus by having a more constant development of PTYCHAGNOSTUS AKANTHODES genal scrobicules, lower pygidial convexity, a Robison centrally depressed posteroaxis, and weak gran- Figure lo ules on pleural fields of the pygidium. P. punc- tuosus primarily differs from P. affinis by the Ptychagnostus akanthodes ROBISON, 1964, p. 523, pl. presence of granules on the cephalon, and by 79, figs. 1-7. addition and enlargement of granules on the Aotagnostus akanthodes (Robison) 6iuk, 1979, p. pygidium. Also, within this series of three 129. species the primary median structure on the Diagnosis. —Cephalon subcircular, of mod- pygidial M2 changes from a moderately large, erate convexity, with unusually large post- subcircular tubercle to a low, ill-defined, longi- erolateral border spines. Axis moderately tudinal ridge. tapered, anteroglabella usually ending in WestergArd (1946:79) noted that the me- rounded point. Fl weak, F2 moderately devel- dian posteroglabellar node of P. affinis is situ- oped. Median node behind posteroglabellar ated slightly more forward than that of P. midpoint. Basal lobes elongate and varying atavus. Without comment, he also illustrated from entire to strongly divided. Genal scrob- (pl. 11, fig. 30) an unusual cephalon of P. affinis icules well developed, outlining rugae with up with two median nodes. The nodal position on to three orders of branching. most specimens of P. atavus corresponds to that Thorax having median spine on posterior of the posterior node on WestergArd's binodal segment. specimen, whereas the nodal position on most Pygidium semicircular, of moderate con- specimens of P. a//mis corresponds to that of the vexity, with pair of medium-sized spines on anterior node on his binodal specimen. There- posterolateral borders. Axis slightly constricted fore, I suggest that the glabellar nodes on most at M2; median spine on M2 long, reflexed specimens of P. atavus and P. affinis are probably upward and backward to point over posterior not homologous, and the change in position border; posteroaxis ogival. Postaxial median probably does not represent evolutionary mi- furrow weak to moderately developed. gration. Rather, the posterior node was proba- Dorsal surface generally smooth but may bly suppressed and an anterior, latent node was have either scattered weak granules or pits. developed during the transition from P. atavus Discussion.—P. akanthodes is a rare species to P. affinis. that closely resembles P. occultatus, from which Occurrence. —P. affinis has been documented it probably evolved. It can be differentiated from Sweden, Norway, Denmark, Alaska, and from P. occultatus, however, by the presence of Australia (see synonymy). Previous assignment border spines on the pygidium, and it has to P. affinis of specimens from Wales (Koba- larger spines on the cephalon and pygidial axis. yashi, 1939:153) is questionable (Lake, 1906, The spines of P. spinosus Ergaliev (1980:71, pl. caption pl. 1; WestergArd, 1946:78; see P. 1, figs. 23, 24) are similar in number and punctuosus, herein). position to those in P. akanthodes, but appear to For the first time, specimens of P. affinis are be considerably less robust. Further study may illustrated herein from Nevada and Utah. In show these species to be synonyms. P. akanthodes the northern Egan Range, Nevada, the species also resembles P. aculeatus but differs from that is rare in collections 167 and 169 from 301 and species by lacking well-developed granules on 317 m, respectively, above the base of the the dorsal surface and by the presence of border Secret Canyon Formation. In the central spines on the pygidium.

House Range, Utah, numerous specimens of P. bpik (1979:129) reassigned P. akanthodrs- to

18 The University of Kansas Paleontological Contributions-Paper 109

Fig. 10. Plychagnostus akanthodes Robi- son. /. Cephalon, USNM 374581, X8; 2, pygidiurn, USNM 374582, x 5; 3, pygidium, USNM 374583, X6; all paratypes from collection 3309-CO, Marjum Formation, House Range, Utah. 2a a new genus Aotagnostus, which I consider to be fig. 6; pl. 11, figs. 1-3; pl. 13, fig. 13; pl. 51, a junior synonym of Ptychagnostus. Moreover, in fig. 11; pl. 55, figs. 16, 18, 20, 21; pl. 64; my opinion, P. akanthodes does not appear to be KINDLE, 1982, pl. 1.2, fig. 2. closely related to Australian species that Opik Ptychagnostus alarms coartatus 6Pix, 1979, p. assigned to Aotagnostus. The Australian species 94-95, pl. 42, figs. 5, 6. lack well-developed genal scrobicules and de- Ptychagnostus mesostatus dPix, 1979, p. 97-98, pl. tails of axial structure are different, particularly 40, fig. 8; pl. 41, figs. 6, 7. that of the posteroaxis of the pygidium. ?Ptychagnostus (Acidusus) navus 6P1K, 1979, p. Occurrence. -More than 30 specimens are in 101-102, pl. 46, fig. 1. collections 3309-CO and 765, both from 134 m not Ptychagnostus atavus (Tullberg) ERGALIEV, above the base of the Marjum Formation, 1980, p. 67-69, pl. 1, figs. 13-17. central House Range, Utah. The observed Ptychagnostus intermedius Tullberg ERGALIEV, occurrence is within the lower half of the 1980, p. 69-70, pl. 1, figs. 18-20. Ptychagnostus punctuosus Zone (Fig. 4). Ptychagnostus karatauensis ERGALIEV, 1980, p. 72, pl. 1, figs. 21, 22. Ptychagnostus (Pt.) atavus (Tullberg) 1982, PTYCHAGNOSTUS ATAVUS (Tullberg) YANG, pl. 1, fig. 18. Figurt It Lectotype. -In 1946, WestergArd (p. 130, pl. Agnostus atavus TULLBERG, 1880, p. 14, pl. 1, 11, fig. 8) designated one of Tullberg's syntypes figs. la-d. of P. atavus as lectotype of the species. Recently, Plychagno.slus atavus (Tullberg) JAEKEL, 1909, p. Ergaliev (1980:69) stated that a different speci- 400; OPIK, 1979, p. 93-94, pl. 29, fig. 7; pl. men illustrated by WestergArd (1946, pl. 11, 42, figs. 7, 8; pl. 43, figs. 1-4; XIANG and fig. 14) must be taken as the lectotype of P. others, 1981, pl. 7, fig. 5; ROBISON, 1982, p. atavus. Ergaliev's proposed change in lectotype 136-139, pl. 1, figs. 1-9 (see for additional is invalid for two reasons. According to Article synonymy); ROWELL, Rostsorsi, and 74(a)(i) of the International Code of Zoological STRICKLAND, 1982, p. 161-182; EGOROVA, Nomenclature (1961), "the first published desig- PEGEL, and TCHERNYSHEVA in Egorova and nation of a lectotype fixes the status of the others, 1982, p. 63-64, pl. 6, fig. 7; pl. 7, specimen." Moreover, Article 74(a) indicates Robison—Cambrian Agnostida, Part I, Ptychagnostidae 1 9

••.\

Nti • t a lb id

4a 5 4b 6

Fig. li Plychagnostus alavus (Tullberg). I, Enrolled specimen, KUMIP 204219, X9, collection 114 from middle Wheeler Formation, House Range, Utah; la, cephalon; lb, anterior cephalon (above) and posterior pygidiutn (below); le, left- lateral view; Id, thorax; le, pygidium. 2,3, Cephalon and pygidium, KUMIP 204220 and 204221, both X 9, collection 775 from lower Marjum Formation, House Range, Utah. 4,5, Cephalon and pygidium, KUMIP 204222 and 204223, x 9 and 8, collection 789 from middle Geddes Limestone, Eureka mining district, Nevada. 6, Complete specimen from shale matrix with ventral cone-in-cone encrustation of calcite, KUMIP 204224, X 9, collection 114 from middle Whceler Formation, House Range, Utah.

that a lectotype must be chosen from one of the Discussion.—P. atavus, an immediate de- syntypes. The specimen chosen by Ergaliev is scendant of P. intermedius, has been more fully from Jiimtland and is not one of Tullberg's diagnosed and discussed by Robison (1982: syntypes, which are from Scania. 136-139). A companion paper (Rowell, Robi- Diagnosis.—Ptychagnostus lacking spines, son, and Strickland, 1982) includes a discrimi- coarse surface granulation, and secondary me- nant function analysis of its morphological dian node on posteroaxis of pygidium; basal variation, a cladistic analysis of its phylogeny, a lobes elongate, entire or divided; median node summary of' its biogeography, and an evalua- usually behind posteroglabellar midpoint; tion of its use in biostratigraphy. pygidial M2 hexagonal in outline, having P. atavus (Tullberg) and P. intermedius prominent median tubercle at rear margin; (Tullberg) were considered by Westergâ'rd holaspid genae smooth to moderately scrobicu- (1946:76-77) to be synonyms. Reasons for rec- late. ognizing the validity of both species were ide- 20 The University of Kansas Paleontological Contributions—Paper 109

pendently reached and almost simultaneously ularly in Scandinavia, has much potential value published by bpik (1979), Ergaliev (1980), and for refinement of global correlation. Robison (1982). As shown by some of Ptychagnostus mesostatus Opik (1979:97-98, Tullberg's (1880) syntypes that were subse- pl. 40, fig. 8; pl. 41, figs. 6, 7) is based on one quently illustrated by WestergArd (1946, pl. 11, complete exoskeleton and one pygidium, both figs. 8-10, 19-21), P. atavus and P. intermedius poorly preserved and each from a different most obviously differ in characters of the locality. The distinguishing characters cited by pygidial axis. P. atavus has a prominent median dpik are parallel flanks of the posterior tubercle that displaces the F2 backward in a glabella, arcuate genal scrobicules, and a gran- broad V, and the M2 segment is hexagonal in ular pygidial surface. In my opinion, P. meso- outline. In comparison, P. intermedius usually status is a synonym of P. atavus, which com- has a small median node instead of a tubercle, monly has a pair of arcuate genal scrobicules. the F2 is only slightly indented, and the M2 is The posterior glabella of the specimen 6pik pentagonal. On the cephalon, the median node assigned to P. mesostatus (pl. 41, figs. 6, 7) is in P. atavus is usually situated behind the post- practically identical in shape to that of speci- eroglabellar midpoint, whereas in P. intermedius mens he assigned to P. atavus (pl. 43, figs. 1, 3). it is near the midpoint. Genal scrobicules are A granular pygidial surface is evident on only a present on syntypes of both species. latex cast of one of dpik's specimens and is As indicated by both descriptions and illus- probably of secondary origin, perhaps from trations, Ergaliev (1980) appears to have misi- weathering processes. dentified specimens of P. atavus as P. intermedius, The single known specimen of P. (Acidusus) and vice versa. Such identification would cause navus Opik (1979:101-102, pl. 46, fig. 1) differs P. atavus to precede P. intermedius in strat- from typical representatives of P. atavus only in igraphic position, which is the order deter- the absence of a postaxial median furrow. Both mined by Tullberg (1880, table on p. 10). in ontogenetic and phylogenetic successions, However, WestergArd (1946:77) reported that members of several species of Ptychagnostus ex- Tullberg's "type specimens of atavus were col- hibit a trend toward effacement of the postaxial lected from a loose stinkstone lens" that was median furrow. Therefore, I consider absence incorrectly believed to originate below strata of that furrow by itself to be an inadequate containing P. gibbus. Further studies have pro- character for assigning a single specimen to a duced much evidence to prove the first strat- new species. P. navus is probably a synonym of igraphic appearance of P. atavus to be well P. atavus. above the first appearance of P. gibbus. Without Specimens of P. atavus that I illustrated in mention of WestergArd's correction, Ergaliev 1982 are all from the lower and middle parts of (1980:69) cited Tullberg's table as agreeing its stratigraphie range in Utah. Additional with the vertical distribution of species recently specimens illustrated herein were selected to identified in the Lesser Karatau Range of Ka- show more fully the range of morphologic zakhstan. Correction of Ergaliev's taxonomic variation within the species. Also, they are from identifications also requires stratigraphie rever- the middle and upper parts of its stratigraphie sal of his zonal names (Ergaliev, 1980:36) that range in either Nevada or Utah. are based on P. atavus and P. intermedius. Occurrence.—P. atavus is a common species Because most previous workers have not that has been described from Sweden, Norway, recognized the morphological differences be- Denmark, Canada, United States, Australia, tween P. atavus and P. intermedius, precise strat- China, and the Soviet Union. Many collections igraphie ranges of these species are not known with P. atavus from Nevada and Utah were in most parts of the world. Moreover, from recently listed (Robison, 1982:139). Additional available illustrations, I suggest that some spec- collections from the same states are 789 and 790 imens from the P. gibbus Zone of Scandinavia from the middle Geddes Limestone, Eureka and the Soviet Union that have been identified mining district, Nevada; 822 from an unnamed as P. praecurrens may actually represent P. inter- formation in the Toana Range, Nevada; and medius. Further biostratigraphic documentation 389, 393, 396, 701, 775. 796 from the upper of representatives of all of these species, partie- Wheeler and lower Marjurn formations in the Robison—Cambrian Agnostida, Part I, Ptychagnostidae 2 1

House Range, Utah. In Nevada and Utah, P. PTYCHAGNOSTUS GERMANUS Opik atavus has an observed range through the P. Figure 12 atavus Zone and about the lowest quarter of the P. punctuosus Zone. Ptychagnostus (Acidusus) germanus 6P1K, 1979, p. In western Newfoundland, a few specimens 102-103, pl. 47, figs. 1-6. of P. atavus are in C. H. Kindle collections 448 Ptychagnostus (Acidusus) retrotextus 6PIK, 1979, p. and 619 from boulders in the Cow Head Con- 102, pl. 46, fig. 5. glomerate. ?Ptychagnostus sp. indet. B (aff. atavus) 6PIK,

5 6 7 8

Fig. 12. Ptychagnostus germanus (5pik. Complete specimens, all preserved in calcareous shale, and all front die House Range, Utah. 1-4, Specimens with weak genal scrobieules from high in stratigraphie range; all from collection 716, about 300 m above base of Marjum Formation; KUMIP 204225-204228; x 8, 8, 8, and 6.5, respectively. 5-8, Specimens with smooth genae from low in stratigraphie range, all x 10; .5,6, from collection 819, about 60 m above base of Wheeler Formation, KUMIP 204229 and 204230; 7,8, from collection 115, about 15 m below top of Wheeler Formation, KUMIP 204231 and 204232.

22 The University of Kansas Paleontological Contributions-Paper 109

1979, P. 49-50, pl. 49, figs. 1-4. those from Australia, show progressive devel- Ptychagnostus sp. RITTERBUSH, 1983, figs. lc,d. opment of weak genal scrobicules from lower to higher parts of their stratigraphie range (see Diagnosis. -Cephalon having pair of short Fig. 12). Utah specimens also show a slight posterolateral border spines. Basal lobes elon- reduction in size of the M2 tubercle and slight gate, entire or divided. Glabella commonly increase in distance between the end of the pointed at anterior end, median node behind pygidial axis and the posterior border. A sec- posteroglabellar midpoint. Genae smooth to ondary median node near the posterior end of weakly scrobiculate. Thorax having small me- the pygidial axis is rare in specimens of P. dian node on anterior segment and median from Utah. spine, usually of moderate length, on posterior germanus Two specimens identified as Ptychagnostus segment. Pygidium having prominent post- sp. were recently illustrated from the Wheeler eromedian tubercle on M2. Posteroaxis weakly Formation of the House Range, Utah (Ritter- ogival. Pleural fields usually divided by narrow, bush, 1983). Both appear to represent P. ger- shallow, postaxial median furrow. Pygidial One retains a poorly preserved labrum border lacking spines. manus. beneath the front part of the posteroglabella. Discussion. -P. germanus is morphologically Occurrence. -In addition to specimens re- intermediate between P. atavus, which lacks ported from Australia, more than 200 speci- spines, and P. occultatus, which is characterized mens of P. germanus are in collections 115, 348, cephalic spines and single median by a pair of 716, 819, and possibly 796, which range from spines on the posterior thoracic segment and about 60 m above the base of the Wheeler the pygidial M2. P. germanus mainly differs Formation to about 300 m above the base of the P. occultatus by having a prominent post- from Marjum Formation in the central House tubercle on the pygidial M2 rather eromedian Range, Utah. Observed biostratigraphic range than a spine. The recognition of separate spe- of the species is from low in the P. atavus Zone to cies is supported by the overlap of stratigraphie the upper part of the P. punctuosus Zone. ranges for the three species (Fig. 4) but lack of species association within most collections. PTYCHAGNOSTUS GIBBUS (Linnarsson) bpik (1979:102) described a new species, P. Figure 13 (Acidusus) retrotextus, based on a single, partially Agnostus gibbus LINNARSSON, 1869, p. 81, pl. 2, flattened specimen from strata of the upper P. figs. 52, 53. punctuosus Zone as used herein. The "blunt and Tri plagnostus gibbus (Linnarsson) HOWELL, sulcate glabellar front" mentioned by bpik 1935, figs. 5, 6; ERGALIEV, 1980, p. 72-73, appears to be a secondary feature resulting pl. 1, figs. 11, 12; EGOROVA, PEGEL, and from compaction. Otherwise, the specimen dif- TCHERNYSHEVA in Egorova and others, fers from his definition of P. germanu.s, from 1982, p. 64, pl. 1, fig. 1; pl. 2, fig. 2; pl. 3, older strata, only by the presence of weak genal fig. 4a; pl. 52, figs. 3, 4. scrobicules. Because genal scrobicules comprise Ptychagnostus gibbus (Linnarsson) ROBISON, a variable character within several species of 1982, p. 139-143, pl. 2, figs. 1-13 (see for Ptychagnostus, commonly becoming better devel- additional synonymy); ROWELL, ROBISON, oped during the history of a species, I consider and STRICKLAND, 1982, p. 161-182. P. germanus and P. retrotextus to be synonyms Ptychagnostus cf. P. gibbus (I.innarsson) KINDLE, representing early and late members, respec- 1982, pl. 1.1, figs. 13, ?18. tively, of a single species. In accord with the first reviser principle (ICZN, Art. 24), I select Diagnosis. -Ptychagnostus characterized by P. germanus as the senior subjective synonym. short to moderately long spines on post- Disarticulated cephala and pygidia that erolateral borders of cephalon, posterior seg- bpik (1979:98-99, pl. 49, figs. 1-4) referred to ment of thorax, and M2 of pygidium; middle Ptychagnostus sp. indet. B (aff. atavus) likely half of glabella nearly parallel sided, posterior represent P. germanus; however, reassignment half of posteroglabella tumid; median node cannot be confirmed without knowledge of behind posteroglabellar midpoint; basal lobes thoracic morphology. elongate, entire or divided; genae usually Specimens of P. germanus from Utah, like smooth, rarely with weak scrobicules. Robison—Cambrian Agnostida, Part I, Ptychagnostidae 23

Fig. 13. Ptychagnostus gibbus (Linnarsson); 1,2,4,5 from upper 3 m, Formation 2, Bronlund Fjord Group, North Greenland; 3 from lower Wheeler Formation, House Range, Utah. I, Cephalon, MGUH 16.265 from GGU 271492, X 10. 2, Partly exfoliated cephalon, MGUH 16.266 from GGU 271428, X 9. .3, Exoskeleton, KUMIP 204233 from 157, x 10. 4, Pygidium, MGUH 16.267 from GGU 271428, X 9. Pygidium, MGUH 16.268 from GGU 271489, X 9.

Discussion.—P. gibbus has been more fully In much of the world, P. gibbus is not known diagnosed and discussed by Robison (1982: to have given rise to descendant species, and it 139-143). A companion paper (Rowell, Robi- rarely ranges above the zone that bears its son, and Strickland, 1982) includes a discrimi- name. In Australia, however, it ranges into the nant function analysis of its morphological P. punctuosus Zone and is the apparent ancestral variation, a cladistic analysis of its phylogeny, a source of several species characterized by summary of its biogeography, and an evalua- modification or further development of spines tion of its use in biostratigraphy. (Opik, 1979). Previously illustrated specimens (Robison, Occurrence.—P. gibbus is a common and 1982, pl. 2) are representative of populations of widespread species that has been reported from P. gibbus in the Great Basin. Specimens illus- all continents except Africa and South Amer- trated herein are mostly from North Greenland ica. Many collections with P. gibbus were re- and are representative of collections from that cently listed from Nevada and Utah (Robison, region. In the Great Basin, cephalic spines of P. 1982:142-143). In western Newfoundland, rare gibbus usually are of moderate length; however, specimens of P. gibbus are in C. H. Kindle in rare collections from low in its stratigraphie collection 362 from a boulder of' Cow Head range, the spines may be very short (see Robi- Conglomerate. In Greenland, P. gibbus is rare son, 1982, pl. 2, fig. 8). In available collections to common in collections GGU-271411, from Greenland, the opposite is observed; most 271428, 271488, 271489, and 271492 from the specimens of P. gibbus possess very short spines upper half of Formation 2 of the Bronlund whereas only rare specimens possess spines of Fjord Group. P. gibbus disappears just below moderate length. the first appearance of P atavus in strata of' 2 4 The University of Kansas Paleontological Contributions—Paper 109

North America and northwestern Europe; how- spines. Basal lobes elongate and entire. ever, in Siberia (Savitsky, 1976) and Australia Pygidium having short axis and wide anterior (6pik, 1979) it ranges into the P. atavus Zone. borders; anterior border furrows terminating against lateral border furrows, lateral furrows extending to anterior margin. PTYCHAGNOSTUS HINTZEI, n. sp. Description. —Ptychagnostus of relatively small Figure 14 size; length of largest cephalon or pygidium not Etymology. —The species name honors Prof. exceeding 3 mm, maximum length of complete Lehi F. Hintze of Brigham Young University holaspid probably less than 7 mm. for his many contributions to our understand- Cephalon moderately to highly convex, ing of the geology and paleontology of the length slightly greater than width. Axis mark- Great Basin. edly tapering, constricted at F3, anteroglabella Holotype. —Pygidium (Fig. 14,8), USNM pointed. Fl and F2 undeveloped. Median node 374590. slightly posterior from midpoint of post- Diagnosis—Small Ptychagnostus lacking eroglabella. Basal lobes elongate, entire. Basal

Fig. 14. Ptychagnostus hintzei, n. sp.; / is from collection 821, Marium Formation, House Range, Utah; 2-8 are from collection 2523-CO, Emigrant Springs Limestone, southern Schell Creek Range, Nevada; all x 10. 1, Silicified cephalon, KUMIP 204210. 2,3,5,7, Cephala, USNM 374584-374587. 4,6, Pygidia, USNM 374588, 374589. 8, Holotype pygiditini, USNM 374590.

Robison-Cambrian Agnostida, Part I, Ptychagnostidae 25

furrow geniculate, deep posteriorly, shallow Peak Formation, northern Schell Creek Range. near intersections with axial furrow. Genae In Utah, about 40 cephala and pygidia are in smooth to weakly scrobiculate on late collections 733, 747, 782, 817, and 821 from an holaspides. Posterior border lacking spines. interval ranging from 18 in below the top of the Thorax unknown. Marjum Formation to about 30 m above the Pygidium moderately to highly convex, base of the Weeks Limestone in the central having wide (exsag.) anterior border. Lateral House Range. border furrows continuing to anterior margin and anterior border furrows terminating PTYCHAGNOSTUS INTERMEDIUS against lateral furrows. Axis moderately con- (Tullberg) stricted at M2; MI transversely wider than Figute 15 remainder of' axis and sagittally constricted; Agnostus intermedius TULLBERG, 1880, p. 17, pl. M2 bearing moderate-sized, low, median tu- 1, figs. 4a,b; LINNARSSON, 1883, p. 32; bercle near posterior edge. Posteroaxis ogival, GR6NWALL, 1902, p. 52; STRAND, 1929, p. tip well separated from posterior border furrow. 344. Postaxial median furrow well developed. Ptychagnostus intermedius (Tullberg) JAEKEI., Border lacking spines. 1909, p. 400; KOBAYASHI, 1939, p. 152; Discussion. -P. hintzei is most similar to P. ROBISON, 1982, p. 143-145, pl. 3, figs. 1-9; cassis bpik (1961a:77-80, pl. 20, figs. 4-13); ROWELL, ROBISON, and STRICKLAND, 1982, however, it lacks spines on the posterior p. 161-182. cephalic border, whereas P. cassis has a pair of not Ptychagnostus intermedius (Tullberg) ERGA- short spines. P. hintzei also resembles Lejopyge LIEV, 1980, p. 69-70, pl. 1, figs. 18-20. lundgreni (see Figs. 27, 28) and L. rigbyi (see Fig. Ptychagnostus (Ptychagnostus) atavus (Tullberg) 29) in axial shape, but it has elongate basal WESTERGARD (in part), 1946, pl. 11, figs. lobes, the anterior border of the pygidium is 19-23 (not figs. 8-18, 24, 25). wider (exsag.), and the anterior border furrows Ptychagnostus atavus (Tullberg) ERGALIEV, 1980, of the pygidium terminate against the lateral p. 67-69, pl. 1, figs. 13-17. border furrows. Ptychagnostus richmondensis (Walcott) PALMER (in The ancestry of P. hintzei is unclear, but part), 1954, pl. 13, fig. 5 (not fig. 4). similarity to P. intermedius (Robison, 1982, pl. Ptychagnostus sinicus Lu, 1957, p. 259, pl. 137, 3; also Fig. 15, herein) in general axial shape, figs. 17-19; Lu and others, 1965, p. 37, pl. as well as course and depth of basal furrows, 3, figs. 16-18. may indicate a close phyletic relationship. The Ptychagnostus idmon Om, 1979, p. 95-96, pl. 43, two species, however, are stratigraphically well figs. 5-8. separated, and morphologically intermediate Ptychagnostus scarifatus Om, 1979, p. 96-97, pl. species are not known. Pygidia of P. hintzei 44, figs. 1-5; pl. 58, fig. 2. differ from those of P. intermedius by having a Ptychagnostus sp. aff. scarifatus 6P1K, 1979, p. 97, more angular F2 and the lateral border furrows pl. 44, fig. 6. continue to the anterior margin. Occurrence. -P. hintzei is a relatively rare Lectotype.-Ergaliev (1980, p. 69) selected as species in the Lejopyge calva Zone of Nevada and a lectotype of P. intermedius a syntype cephalon Utah. All known specimens are preserved in illustrated by WestergArd (1946, pl. 11, fig. 19). coquinas dominated by L. calva. In Nevada, This has priority over the subsequent designa- about 30 cephala and pygidia are in collections tion of a different lectotype (Robison, 1982:43). 2523-CO and 155 from the uppermost part of Diagnosis. -Ptychagnostus without spines or member A and the basal 1.5 m of member B, surface granulation. Cephalon moderately con- Emigrant Springs Limestone, southern Schell vex; axis usually having fairly even forward Creek Range. Two cephala are in collection taper; basal lobes elongate, entire or divided; 820 from about 10 m above the base of member median node near midpoint of posteroglabella; A, Emigrant Springs Limestone, southern genae smooth (rare) to moderately scrobiculate Egan Range. Two pygidia are in collection (common), pair of crescentic scrobicules com- Illa from between 3 and 10 m above the top of monly developed near anterior end of glabella. the middle limestone member of the Lincoln Anterior basal furrow effaced on some late 26 The University of Kansas Paleontological Contributions—Paper 109

2

Fig. 15. Specimens of Ptychagnostus intermedius showing some features of either ?. atavus or P. idmon; all from upper 3 m in type section of Formation 2, Bronlund Fjord Group, North Greenland. 1-3, Ccphala, MGUH 16.269-16.271 from GGU 271489; X9, 9, 10, respectively. 4,5, Pygidia, MGUH 16.272 and 16.273 from GGU 271489, both x 9. 6, 7, Cephalon and pygidium, MGUH 16.274 and 16.275 from GGU 271492, x9 and 10.

holaspides, resulting in confluence of anterior 143-145). A discriminant function analysis of basal lobes and adjacent areas of glabella. its morphologic variation and a cladistic analy- Pygidium moderately to highly convex; axial sis of its phylogeny have been given by Rowell, Fi deflected forward, being broadly rounded Robison, and Strickland (1982). Reasons for or forming obtuse medial angle; F2 nearly recognition of P. intermedius and P. atavus as straight, in some slightly indented by median separate species are given in the discussion of P. node; M2 usually pentagonal in outline, rarely atavus. Further study has provided additional becoming subrectangular by straightening of information about P. intermedius and requires Fl or rarely hexagonal by bending of F2; some modification of previous work. posteroaxis weakly ogival; postaxial median P. intermedius can be differentiated from furrow usually present. most other species of Ptychagnostus by the pen- Discussion.—P. intermedius has been recently tagonal shape of its pygidial M2, a median diagnosed and discussed by Robison (1982: node near the posteroglabellar midpoint, a

Robison—Cambrian Agnostida, Part I, Ptychagnostidae 27 median node rather than a tubercle on the course near junctions with the glabellar F3 (Fig. pygidial M2, and a lack of exoskeletal spines. P. 15,1-3). By the late holaspid stage, this results intermedius differs from P. praecurrens, its imme- in a marked difference in axial width near the diate ancestor, by having a more broadly and F3, with the front of the posteroglabella being evenly tapered cephalic axis, more elongate abruptly wider than the anteroglabella. Con- basal lobes, a median node that is more cen- fluence of the basal lobes and adjacent glabella trally positioned on the posteroglabella, and a by effacement of the anterior part of the basal node rather than small tubercle on the pygidial furrows is also observed in some late holaspides M2. of P. intermedius. Rare specimens of P. inter- Generally, P. intermedius is one of the most medius also possess a secondary median node on common agnostoid species in collections from the posteroaxis (Fig. 15,4). Therefore, speci- the P. gibbus Zone in North America and mens that Opik assigned to P. idmon appear to Greenland. In most collections, particularly in represent the late stages of an evolutionary western North America, morphologic vari- continuum from P. intermedius. In the absence of ability is relatively low (for representative speci- stable differential characters, I here consider P. mens, see Robison, 1982, pl. 3). Collections idmon to be a junior subjective synonym of P. from North Greenland are more variable, how- intermedius. ever, and include specimens (Fig. 15) with Ptychagnostus scari fatus Opik (1979:96-97, pl. characters that are transitional to those of P. 44, figs. 1-5; pl. 58, fig. 2) and P. sp. all. atavus. scarifatus bpik (1979:97, pl. 44, fig. 6) also From cladistic analysis, Rowell, Robison, appear to be synonyms of P. intermedius. The and Strickland (1982) concluded that P. inter- only reported specimens of P. scarifatus and P. medius is the immediate ancestor of P. atavus. sp. aff. scarifatus are associated with specimens That conclusion is supported by the subsequent assigned to P. idmon in Opik's collection M176. discovery in Greenland of specimens high in Specimens with an irregular axial furrow and the stratigraphie range of P. intermedius that narrow anteroglabella were assigned by Opik possess characters transitional between P. inter- (1979, pl. 43, figs. 6, 8) to P. idmon, whereas medius and P. atavus (Fig. 15,6, 7). The median specimens with a more regular axial furrow and node on the posteroglabella is behind the mid- without significant difference in glabellar width point, as in P. atavus. On the pygidium, the near the F3 were assigned to P. scarifatus. From median node is slightly more enlarged than is Opik's illustrations, the morphologic differ- usual in P. intermedius, but the course of the ences appear to be gradational within a single, second transaxial furrow (F2) is displaced only variable, species population. slightly to the rear. Hence, the pygidial M2 With expressed reservation, dpik (1979:95, remains more pentagonal than hexagonal. Be- pl. 41, fig. 8) assigned a single Australian cause I judge the total morphological aspect of specimen to Ptychagnostus intermedius. Subse- these specimens to be closer to P. intermedius, quently, I (Robison, 1982:139) reassigned that they are arbitrarily assigned to that species. specimen to P. atavus,. however, I now consider bpik (1979:95-96, pl. 43, figs. 5-8) named a its specific assignment to be uncertain. The new species, Ptychagnostus idmon, which first specimen is flattened in siltstone and some axial appears in the P. atavus Zone of Australia. He features appear to have been altered. The post- distinguished the species "by the change of eroglabellar node is centrally located, as in P. direction of the axial furrows in their passage intermedius. The pygidial M2 is hexagonal, as in from the slender frontal lobe to the flanks of the P. atavus; however, a prominent tubercle is not stout posterior glabellar lobe; and by the struc- evident from Opik's illustration. ture of the double basal lobes, whose anterior Occurrence.—P. intermedius is presently known part is almost confluent with the glabella. The from Norway, Sweden, Soviet Union, China, pygidial axial node is low and short, and the Australia, Greenland, Canada (British Colum- node on the posterior axial lobe is placed well to bia), and the United States (Montana, Nevada, the rear." During the ontogeny of some speci- Utah). Its distribution in western North Amer- mens of P. intermedius in Greenland (common, ica was recently summarized (Robison, 1982). GGU 271428 and 271489) and western North In North Greenland, many specimens are in America (rare) the axial furrow also changes GGU collections 218614, 271411, 271428, 28 The University of Kansas Paleontological Contributions—Paper 109

271489, and 271492 from the upper half of terior to imaginary line drawn laterally from tip Formation 2 of the Bronlund Fjord Group. P. of axis. intermedius is a common species in the P. gibbus Discussion. —P. michaeli appears to be most Zone. Its only documented occurrence in the P. similar to P. cassis bpik (1961:77, pl. 20, figs. atavus Zone is in Australia ( = P. idmon bpik, 4-13) from Australia; however, P. cassis lacks 1979; = P. scarifatus bpik, 1979) where it seem- pygidial border spines and has a more anterior ingly survived longer than elsewhere in the secondary node on the pygiclium. The thorax of world. P. cassis is unknown. 6pik (1979:105, pl. 48. figs. 5, 6) assigned a PTYCHAGNOSTUS MICHAEL!, n. sp. cephalon and pygidium from different localities Figure 16 in Australia to Ptychagnostus (Acidusus) sp. nov. Both were reported to be from the P. punctuosus ?Ptychagnostus (Acidusus) sp. nov. 61=1K (in part), Zone. bpik noted that the "shields may or may 1979:105, pl. 48, fig. 6 (not fig. 5). not be conspecific; the 'sp. nov.' in the title Etymology. —The species is named after refers to the pygidium." From the illustrations, Michael B. McCollum, who made numerous the pygidium agrees closely in all characters contributions to this study. with P. michaeli, and here is questionably reas- Holotype. —Complete holaspid exoskeleton signed to this new taxon. The cephalon lacks of intermediate size, KUMIP 204283 from border spines and may represent P. atavus; collection 397, 15 m above base of Marjum however, its taxonomic assignment remains Formation, House Range, Utah (Fig. 16,10). uncertain. Diagnosis.—Ptychagnostus having pair of Among agnostoid species in western North spines on posterolateral cephalon, one median America, P. michaeli closely resembles Lejopyge spine on posterior thoracic segment, and pair of lundgreni, with which it is commonly associated. posterolateral spines on pygidium. Cephalic Nevertheless, P. michaeli clearly differs from L. axis evenly tapered. Basal lobes intermediate to lundgreni by having more elongate basal lobes elongate, entire or weakly divided. Genal and by the presence of border and thoracic scrobicules weak or absent. Pygidial M2 having spines. Disarticulated cephala also may be dif- median tubercle. ficult to distinguish from those of associated P. Description. —Cephalon low to moderate in occultants; however, P. occultatus commonly has convexity; subcircular to subquadrate in out- longer basal lobes and its genal scrobicules are line, length approximately equals width. Axis usually better developed. Pygidia of P. michaeli rather evenly tapered to acute point. F3 can be easily distinguished from those of P. straight, of moderate depth; F2 weak and Fl occultatus by their lack of a median axial spine undeveloped. Median node behind midpoint of and presence of border spines. posteroglabella. Basal lobes intermediate to Occurrence. —P. michaeli is presently known elongate, entire or weakly divided. Preglabellar from the United States (Nevada and Utah) and median furrow deep. Genae smooth to weakly questionably from Australia. In Nevada, sev- scrobiculate. Border having pair of postero- eral specimens have been collected (105) from lateral spines of short to moderate length. the upper Geddes Limestone in the Eureka Thorax poorly preserved on known speci- mining district. In Utah, numerous specimens mens. Posterior segment having median spine. are in collections (397, 738-740, 759, 831) Pygidium low to moderate in convexity, ranging from 15 to about 240 m above the base semicircular in outline. Mi sagittally con- of the Marjum Formation in the House Range. stricted, forming yoked lateral swellings. M2 The species has an observed range through having slight transverse constriction; median about the lower two-thirds of the P. punctuosus tubercle small, posteriorly deflects F2. Post- Zone. eroaxis slightly ogival on early holaspides, be- coming moderately ogival on late holaspides; PTYCHAGNOSTUS OCCULTATUS Opik secondary node rare on posterior tip. Postaxial Figures 17, 18 median furrow well developed throughout

ontogeny. Border having pair of short to mod- Ptychagnostus (Acz'dusus) occultatus 61, 1h, 1979, p. erately long, slender, posterolateral spines pos- 103-104, pl. 48, figs. 1, 2. 7

Fig. 16. Ptychagnoslus michadi, n. sp.; 6 and 8 from upper Geddes Limestone, Eureka mining district, Nevada, all others from Marjum Formation, House Range, Utah. 1,2, Cephala, KUMIP 204274 and 204275 from 397, both X9. 3,4, Pygidia, KUMIP 204276 and 204277 from 397, x 9 and 10. 5, Pygidium, KUMIP 204278 from 759, x 10. 6,8, Pygidium and complete dorsal exoskeleton, KUMIP 204279 and 204280 from 105, X8 and 10. 7, Pygidium, KUMIP 20428. 1 from 740, x8. 9, Complete dorsal exoskeleton, KUMIP 204282 from 831, x 10. 10, Latex cast of holotype exoskeleton, KUMIP 204283 from 397, x 10. 30 The University of Kansas Paleontological Contributions—Paper 109

Ptychagnostus (Acidusus) sp. aft. . occultatus 6PIK, characters of P. occultatus are the tapered mid 1979, P. 104-105, pl. 48, fig. 3. glabella, elongate and divided basal lobes, and Ptychagnostus richmondensis (Walcott) ROBISON (in the presence of spines on the posterolateral part), 1964, p. 523-524, pl. 79, figs. 12, cephalic borders, axis of the second thoracic 16-22 (not fig. 15). segment, and axis of the pygidial M2. Genal scrobicules commonly are well developed but Diagnosis. —Cephalon subcircular to sub- may be weak or absent, particularly during quadrate, length approximately equaling early Spines width, convexity moderate. Axis well defined; phylogeny. are absent on the border and granules not developed middle half of glabella moderately tapered for- pygidial are ward, front of glabella sharply to bluntly on the dorsal surface. Collapse of the ex- pointed. Fl undeveloped; F2 weakly to moder- oskeleton along the axial furrow during com- ately developed adjacent to axial furrows; F3 paction in fine-grained matrix seems to have narrow (sag.), shallowing medially. Median secondarily decreased the axial width in many node slightly posterior from posteroglabellar specimens. midpoint. Basal lobes elongate and divided. A morphological series from P. atavus to P. Genae weakly to strongly scrobiculate, rarely germanus to P. occultatus to P. akanthodes appears smooth; depth along individual scrobicules to represent a single lineage that evolved by the commonly irregular, giving dimpled aspect. successive addition of new spines. This inter- Posterolateral border spines well developed. pretation is supported by the stratigraphie first Thorax having strong median spine on pos- appearance of each species in the same order terior segment, anterior segment commonly (Fig. 4). P. atavus lacks spines; P. germanus has a having median node. pair of posterolateral cephalic spines and a Pygidium semicircular to subquadrate, median spine on the posterior thoracic seg- length about equal to or slightly less than width, ment; P. occultatus has in addition a median convexity moderate. Axis well defined. MI spine on pygidial M2; P. akanthodes shows also a normally wide (trans.) and unequally tripartite. pair of posterolateral spines on the pygidial Fl deep abaxially, shallowing medially. M2 border. slightly constricted, hexagonal, and having The holotype of P. occultatus from Australia moderate to long median spine with base has a secondary median node at the tip of deeply indenting F2. Posteroaxis variable in the pygidial axis (6pik, 1979, pl. 48, fig. 1). width, weakly ogival (common) to lanceolate Only a few specimens from North America and (rare); secondary median node may be present Greenland (e.g., Fig. 17 ,3,8) show a secondary at or near posterior end. Postaxial median node on the pygidium, and these are well furrow dividing pleural fields. Border lacking forward from the tip of the axis. Whether this spines. variation in position represents development of Ontogeny. —Numerous silicified specimens of different latent nodes (see discussion of P. P. occultatus in collection 337 provide informa- affinis) or node migration is unknown. How- tion about ontogeny of the species (Fig. 18). ever, because the nodes are rare, they are not Meraspides do not appear to possess genal accorded taxonomic significance at this time. scrobicules or spines; however, absence of those Opik (1979:104) noted that genal scrob- features may be the result of inadequate preser- icules on Australian specimens of P. occulatus vation. Among readily observed holaspid begin adaxially as "dimples." Similar dimples changes are the development and general in- are present on some specimens from Utah; crease in length of the characteristic spines, and however, that feature is variable within single increase in relative size of the posteroaxis. Late populations (compare Fig. 18,1-12) and is lack- in the holaspid period, a pair of short spines ing on many specimens (Fig. 17). Opik also develops at fulcral points on rear pleural mar- described the pygidial M1 as being bipartite, gins of the posterior thoracic segment (compare but the Ml changes from undivided to tripar- Fig. 18,14,15). A secondary median node is tite during holaspid ontogeny, and definition of present on the posteroaxis of only rare late lateral divisions may be variable among instars holaspides (Fig. 18,25). of similar size. Discussion. —Among important differential A reappraisal of P. richmondenso has led me Robison—Cambrian Agnostida, Part 1, Ptychagnostidae 3 1

to the conclusion that it is an unrecognizable most specimens from Utah that I formerly species (see separate discussion). Moreover, assigned to that species (e.g., Robison, 1964,

Fig. 17. Ptythagnoslus occulialus ejpik from various lithologies, stratigraphie horizons, and localities. 1,3, CephaIon and pygidium in lime mudstone, KUM1P 204234 and 204235 from 159, about 300m above base of Marjum Formation, House Range, Utah; x6 and 10. 2,4, Cephalon and pygidium in calcareous shale, MGUH 16.276 and 16.277 from GGU 218644, 80m above base of Formation TI, Tavsens Iskappe Group, North Greenland; x8 and 9. 5, Pygidium in lime mudstone, KUM1P 204236 from 759, about 250 m above base of Marjum Formation, House Range, Utah; X 7. 6, Exoskeleton from shale, ventral surface encrusted with cone-in-cone calcite; KUMIP 204237 from 115, upper 30 m of Wheeler Formation, House Range, Utah; X 10. 7-9, Exoskeletons in lime mudstone, KUMIP 204238-204240 from 737, 397, and 758, respectively; about 40, 135, and 245m above base of Marjum Formation, House Range, Utah; X9, 6, and 8, respectively.

32 The University of Kansas Paleontological Contributions-Paper 109

(it fA 2 3 4 0 0 47, 5 6

Fig. 18. Ontogeny of Ptychagnostus occultatus Opik; silicified specimens from lime mudstone, collection 337, about 15 m above base of Marjum Formation, House Range, Utah; all X 8. 1-3, Meraspid cephala, KUMIP 204241-204243. 4-12, Holaspid cephala, KUMIP 204244-204252. 13, Anterior thoracic segment of late holaspid, KUMIP 204253. 14,1.5, Posterior thoracic segments of late holaspides, KUMIP 204254 and 204255. 16-19, Meraspid pygidia, KUMIP 204256-204259. 20-26, Holaspid pygidia, KUMIP 201260-204266.

1976, 1982) probably are not conspecific with the lower shale member of the Lincoln Peak the type, and few, if any, were coeval with it. Formation in the southernmost White Pine Therefore, most specimens that I formerly as- Range (349), an undetermined level in the signed to P. richmondensis are here reassigned to lower shale member of the Lincoln Peak For- P. occultatus. Other specimens, more recently mation in the southern Ruby Mountains (350), collected from Nevada and Utah, together with and 317 m above the base of the Secret Canyon a few specimens from North Greenland, are Formation in the northern Egan Range (169). also assigned to this species. In Utah, numerous specimens are in collections Occurrence.-P. occultatus is presently known (113, 115, 159, 337, 347, 349, 350, 391, 393, from Australia, the United States (Nevada, 395, 397, 737, 739, 740, 758, 759, 772, 796, Utah), Greenland, and possibly Canada (Dis- 3293-CO, 3296-CO, 3298-CO, 3302-CO, trict of Mackenzie). Australian occurrences 3303-CO, 3306-CO, 3326-CO, 3430 to 3432- have recently been documented by bpik CO) ranging from 30 m below the top of the (1979). In Nevada, a few specimens are in Wheeler Formation to about 330 in above the collections from about 60 m above the base of base of the Marjum Formation in the central

Robison-Cambrian Agnostida, Part I, Ptychagnostidae 33

House Range. In North Greenland, a few glabella. Basal lobes slightly elongate, anteri- specimens are in collections GGU 218626, orly ill-defined. Pygidial M2 having median 218644, and 218647 from 75 to 85 m above the tubercle of small to medium size. Spines lack- base of Formation Tl of the Tavsens Iskappe ing. Group. Fritz (1981) has reported the occur- Discussion. -The species concept of Robison rence of P. richmondensis?, which may represent (1982:145-148) is followed here. P. occultatus as used herein, from 52 m above the P. praecurrens is the oldest species of Ptychag- base of the Rockslide Formation in the Mac- nostus. It appears to have evolved directly from kenzie Mountains, District of Mackenzie, Can- Peronopsis brighamensis, the major difference be- ada. ing development of a preglabellar median fur- P. occultatus has a total observed strat- row in P. praecurrens (Robison, 1978:2-3). igraphic range from the uppermost P. atavus Occurrence. -In North America, P. praecur- Zone through the lower two-thirds of the P. rens is known from 21 m of the Stephen Forma- punctuosus Zone. In the Great Basin, the species tion at the famous Burgess quarry locality in is most common in the P. punctuosus Zone, and British Columbia. There it is one of the most all specimens known from Greenland are from abundant fossils (Fritz, 1971:1166). Elsewhere that zone. the species is known from Australia, Sweden, the Soviet Union, and possibly Norway and PTYCHAGNOSTUS PRAECURRENS Antarctica (see Robison, 1982:148). It ranges (Westergird) through the P. praecurrens Zone, and in Aus- Figure 19 tralia, Sweden, and the Soviet Union it ranges into the P. gibbus Zone. Agnostus gibbus praecurrens WESTERGÂRD, 1936, p. 29, pl. 1, figs. 19-23. PTYCHAGNOSTUS PUNCTUOSUS Ptychagnostus praecurrens (WestergArd) RASETTI, (Angelin) 1967, p. 28; ROBISON, 1982, p. 145-148, pl. Figure 20 4, figs. 7-10 (see for additional synonymy). Agnostus punctuosus ANGELIN, 1851, p. 8, pl. 6, Diagnosis. -Cephalon having smooth fig. 11; BROGGER, 1875, p. 576, pl. 25, fig. genae. Glabella elongate, sides nearly parallel; 2; 1878, p. 67, pl. 6, figs. 12a, b; Tuu.- median node behind midpoint of postero- BERG, 1880, p. 17, pl. 1, figs. 5a-d; LIN- NARSSON, 1883, p. 32; KOKEN, 1896, p. 349; MATTHEW, 1896, p. 232, pl. 16, figs. I la, b; GRGINWALL, 1902, p. 55; LAKE, 1906, p. 4-6, pl. 1, figs. 4-6; ILLING, 1916, p. 409, pl. 29, figs. 2, 3; NICHOLAS, 1916, p. 452-453; STRAND, 1929, p. 344.

Agnostus laevigatus terranovicus MATTHEW (?part), 1896, p. 233-234 [see note by Hutchinson, 1962, p. 84]. Agnostus punctuosus var. MATTHEW, 1897, p. 172, pl. 1, fig. 3. Agnostus scutalis SALTER (part) in Hicks, 1872, p. 175, pl. 5, fig. 9 (10?). Agnostus scarabaeodes SALTER in Hicks, 1872, p. 175, pl. 5, fig. 8; SALTER, 1873, p. 4. Ptychagnostus punctuosus (Angelin) JAEKEL, 1909, p. 400; KOBAYASHI, 1939, p. 153; SHIMER and SHROCK, 1944, p. 600, pl. 251, fig. 20; Fig. 19. Pochagnostus prarcurrens (Westergird); complete HUTCHINSON, 1962, p. 84, pl. 9, figs. 9-19; exoskeletons flattened in shale; Stephen Formation, British RASETTI, 1967, p. 28, pl. 9, figs. 28-30; Columbia, Canada; both X 10. /, GSC 65861 from GSC ALLEN, JACKSON, and RUSHTON, 1981, pl. collection 75000. 2, GSC 65863 from GSC collection 81235. 16, fig. 1. 34 The University of Kansas Paleontological Contributions—Paper 109

Ptychagnostus (Ptychagnostus) punctuosus (Angelin) Ptychagnostus punctuosus fermexilis OPIK, 1979, p. WESTERGÂRD, 1946, p. 78-79, pl. 11, figs. 92, pl. 41, figs. 1-5. 34, 35; pl. 12, figs. 1-7. Ptychagnostus punctuosus punctuosus (Angelin) Diagnosis. —Holaspides consistently possess- bP1K, 1979, p. 89-91, pl. 38, fig. 1; pl. 39, ing genal scrobicules and lacking spines. Sev- figs. 1-7, 9, 10; pl. 40, fig. 1. eral other features change during ontogeny. On

Fig. 20. Ptychagnostus punctuosus (Angelin); 3 is x 10, all others are x 8. 1,2, Complete and partial dorsal exoskeletons, KUMIP 204267 and 204268 from 347, about 60 m above base of Marjum Formation, House Range, Utah. 3,4, Cephala, KUMIP 204269 and 204270 from 398, about 145m above base of Marjum Formation, House Range, Utah. 5, Pygidium, KUMIP 204271 from 398. 6, Dorsal exoskeleton and cephalon, KUMIP 204272 and 204273 from 105, upper Geddes Limestone, Eureka mining district, Nevada. Robison—Cambrian Agnostida, Part I, Ptychagnostidae 35

late holaspides, granules are prominent on I find no reason to continue recognition of this genae and on pleural fields of pygidium, weak subspecies. on cephalic and pygidial axes, and apparently Occurrence. —Geographically, P. punctuosus is absent on thoracic segments. Meraspides com- widely distributed. Representatives have been monly have acutely pointed glabella and described and illustrated from Sweden, Nor- pygidial axis, well-defined postaxial median way, Denmark, England, Wales, Canada (east- furrow, and granules may be lacking. During ern Newfoundland), United States (New York), holaspid ontogeny, anteroglabella may become and Australia. Additionally, the species has bluntly rounded in front and rarely may be been reported in faunal lists for New Bruns- weakly cleft, pygidial M2 becomes slightly con- wick, Canada (Howell in Hayes and Howell, stricted, and posteroaxis may become moder- 1937:89), New Zealand (Benson, 1956:287), ately to bluntly pointed. Postaxial median and the Siberian platform of the Soviet Union furrow effaced on largest holaspides. Basal (Demokidov, Pisarchik , and Tchernysheva, lobes elongate and usually divided. Median 1966:55). node anterior from posteroglabellar midpoint, For the first time, specimens of P. punctuosus between F2. Primary median tubercle on are illustrated herein from Nevada and Utah. pygidial M2 generally low, elongate, and About 20 specimens are in collections 105 and poorly defined; moderately indents F2. Post- 804 from the upper 4 m of the Geddes Lime- eroaxis centrally depressed, may have weak stone, Eureka mining district, Nevada. Several secondary median node at midlength, and may other specimens are in collections 347, 396, and have slightly concave flanks on large holaspides. 398, ranging from 27 to about 140 m above the Convexity of cephalon moderate to high, of base of the Marjum Formation, central House pygidium low to moderate. Range, Utah. Discussion. —Holaspides of P. punctuosus, the Stratigraphically, P. punctuosus is restricted type species of Ptychagnostus, are most easily to the interval-zone that bears its name. differentiated by the combination of prominent Among fossils described from Nyeboc genal scrobicules, abundant granules on sur- Land, western North Greenland, are a ceph- faces of both cephalon and pygidium, and the alon and a pygidium that Poulsen (1969:4-5, absence of spines. fig. 4A,B) assigned to P. punctuosus. The The recognition of subspecies of P. punc- scrobiculate cephalon is poorly preserved, but tuosus has been a common practice. By far the appears to lack granules on the dorsal surface. subspecies most commonly referred to are P. It probably does not represent P. punctuosus, punctuosus punctuosus and P. punctuosus affinis. In and I consider its placement within Ptychagnostus a few places, these taxa have been reported in to be indeterminate. The pygidium also ap- association, but usually only one taxon is pres- pears to lack granules that are typical of P. ent. According to WestergArd (1946:79), "in- punctuosus. On the basis of its axial shape and termediate links exist." Nevertheless, in most strong median tubercle that deeply indents the collections, specimens can easily be assigned to F2, I suggest an assignment to Onymagnostus one taxon or the other, and I here prefer to hybridus rather than P. punctuosus. Hence, P. assign them species rank rather than sub- punctuosus is not known with certainty from species. P. affinis most noticeably differs from P. Greenland. puncluosus by lacking granules on the cephalic surface, and granules on the pygidial surface PTYCHAGNOSTUS RICHMONDENSIS are usually more weakly developed. (Walcott) dpik (1979) described a new subspecies, P. Discussion. —Although I (Robison, 1964: punctuosus fermexilis, which he differentiated pri- 524) previously followed Palmer's (1954:61-62) marily "by the slenderness of its glabella and appraisal of P. richmondensis, further collecting by the prominence of the central node on the and review has led me to the conclusion that the second lobe of the pygidial axis." These and species is unrecognizable. From the Eureka other differences discussed by 6pik are all mining district, Nevada, Walcott (1884:24-25, minor and fall within the range of variation pl. 9, fig. 10) originally described a single seen in large populations of P. punctuosus. Thus, cephalon as Agnostus richmondensis, which he

36 The University of Kansas Paleontological Contributions -Paper 109 illustrated by a line drawing. The cephalon was Genus LEJOPYGE Corda reported to be from the upper portion of the Lejopyge CORDA in Hawle and Corda, 1847, p. "Prospect Mountain limestone," a rock unit 51; KOBAYASHI, 1937, p. 437-447; 1939, p. that was later reassigned to the Geddes Lime- 131-132; LERMONTOVA, 1940, p. 130; stone (see Nolan, Merriam, and Williams, WESTERGARD, 1946, p. 87; POKROVSKAYA, in Walcott's de- 1956:9). Features mentioned 1958, p. 72-76; in Tcherneysheva, 1960, p. scription or shown by his figure indicate that 60; HOWELL, 1959, p. 0178; ROBISON, the cephalon probably represents Ptychagnostus; p19 . 6124 ,. p. 521; PALMER, 1968, p. 27; DAILY that he gave no indica- however, it is important and JAGo, 1975, p. 527-550; JAGo, 1976b, tion of the presence of posterolateral border spines. Miagnostus JAEKEL, 1909, p. 401. In 1954, Palmer (p. 61) reported that Wal- Phoidagnostus WHITEHOUSE, 1936, p. 93; KOBA - cott's original specimen could not be located YASHI, 1939, p. 135-136; LERMONTOVA, among collections of the U. S. National Mu- 1940, p. 130; WESTERGÂRD, 1946, p. 91; seum. From more recent U. S. Geological IVSHIN, 1953, p. 24-25; PoKRovskAYA, Geddes Limestone Survey collections from the 1958, p. 37-38; in Tcherneysheva, 1960, p. of the Eureka district, Palmer described and 60; HOWELL, 1959, p. 0181. illustrated specimens that he thought to be Leiopyge Hawle and Corda 0pix, 1961a, p. 85; The single conspecific with P. richmondensis. 1979, p. 157-159. illustrated cephalon from collection 965-CO has Pseudophalacroma POKROVSKAYA, 1958, p. 79; border spines a pair of stout posterolateral 6Pik, 1961a, p. 90-92; 1967, p. 77; 1979, from whereas the single illustrated pygidium p. 163. collection 901-00 lacks axial and border spines. Review of the available U. S. Geo- Type species.-Battus laevigatus Dalman, logical Survey collections as well as additional 1828:136; by monotypy. collecting by me has shown that the Geddes Diagnosis. -Early species with little efface- Limestone of the Eureka district contains ment of dorsal furrows on acrolobes, later faunas of the P. gibbus to lower P. punctuosus species having those furrows effaced in varying zones. Among those faunas, I have been unable degrees. Cephalic axis strongly but somewhat to find an agnostoid species with a combination irregularly tapered, acutely pointed at front. of spines on the cephalon and pygidium like Basal lobes simple. Pygidial F2 shallower than Palmer described as P. richmondensis. Moreover, Fl. Postaxial median furrow present through- I conclude that the pygidium illustrated by out ontogeny. Palmer probably represents P. intermedius Discussion. -Part of the preceding diagnosis whereas the cephalon represents an undeter- necessarily pertains only to early species of mined species of Ptychagnostus, but not P. inter- Lejopyge that lack much effacement of furrows medius. Based on features shown in Walcott's on the acrolobes. Effacement of furrows was (1884) original illustration, P. richmondensis may common in subsequent lineages, resulting in be a junior synonym of P. atavus, which is smooth homeomorphs that may be difficult to present in the Geddes Limestone (Robison, distinguish. Development of spines was another 1982); however, details are inadequate for con- common evolutionary trend. In one lineage, fident identification. the pygidial border became unusually wide. Specimens from Utah that I (Robison, In most species of Lejopyge, the pygidial axis 1964:523-524, pl. 79, figs. 12, 15-22) pre- has a weak median node near the posterior viously assigned to P. richmondensis are from margin of the M2; however, one new species, strata younger than the Geddes Limestone. L. rigbyi, possesses a median spine on the M2. One of the illustrated specimens (pl. 79, fig. 15) Daily and Jago (1975:530, table 1) have dis- has been reassigned to P. atavus (Robison, cussed and tabulated the variable presence or 1982:137). The other illustrated specimens are absence of weak secondary median nodes on here reassigned to P. occultatus bpik. the MI and M3 of pygidia representing di- Robison—Cambrian Agnostida, Part I, Ptychagnostidae 37

fferent effaced species of Lejopyge. Because of species of Lejopyge. Indeed, Opik (1979:159) apparent random variability in development of later speculated that a lineage including a new secondary nodes, I accord them no taxonomic species, L. praecox, "maintained its continuity value. in the species of the genus Pseudophalacroma." Most authors have assigned only highly Pygidial borders in L. praecox and L. multifora effaced ptychagnostid species to Lejopyge. As the Opik (1979) are transitional in width between number of assigned species has increased, rare those in species previously assigned to either specimens showing vestigial features of the axis Lejopyge or Pseudophalacroma. Therefore, I find suggest that more than one phyletic lineage are no justification for continuing to recognize represented. In 1979, bpik significantly revised Pseudophalacroma as a separate genus, and I the generic concept to include species with consider it to be a junior synonym of Lejopyge. ordinary ptychagnostid dorsal furrows. In gen- A thorough review of the and eral, I accept Opik's revision because it adds biostratigraphic significance of several effaced ancestral species that unite polyphyletic lin- species of Lejopyge has been given by Daily and eages to form an enlarged liolophyletic genus. Jago (1975). A revision of the generic concept Two new species and one new subspecies are and a description of three new species were added here, necessitating further slight given by 6pik (1979). Based on further review modification of the generic concept. As here as well as study of many additional collections, defined, Lejopyge includes L. lundgreni and all of the following previously described species are its inferred descendant species (Fig. 6). here included in Lejopyge: L. laevigata (Dalman, Early species of Lejopyge are characterized 1828), L. armata (Linnarsson, 1869), L. elegans by a slightly shortened axis with a strong (Tullberg, 1880), L. lundreni (Tullberg, 1880), anterior taper to the cephalon, simple basal L. dubium (Whitehouse, 1936), L. crebrum (Pok- lobes, and a relatively shallow F2 on the rovskaya, 1958), L. calva (Robison, 1964), L. pygidium. The simple condition of the basal multifora (bpik, 1979), and L. praecox (Opik, lobes is a derived character that is home- 1979). The holotype and only illustrated speci- omorphic with the condition in some species of men of L. cosfordae (bpik, 1979) is an early Onymagnostus; however, other axial features are holaspid and the name may be a synonym of L. rather different in the two genera. praecox. Three new taxa, L. acantha, L. rigbyi, Phoidagnostus limbatus Whitehouse is the type and L. laevigata rubyensis, are described here. species of Phoidagnostus Whitehouse (1936). Four taxa, Agnostus laevigatus var. forfex Bregger Opik (1961a:54, 86; 1967:76) concluded that (1878), L. exilis Whitehouse (1936), L. em- the type specimens of P. limbatus are com- pozadense Rusconi (1954), and L. eosa Yang pressed representatives of either Lejopyge (1982), are considered to be indeterminate. laevigata or L. armata. Therefore, Phoidagnostus is With regard to spelling of the generic name, a subjective junior synonym of Lejopyge. bpik (1979:157-158) used Leiopyge rather than Pseudophalacroma was erected by Pokrov- Lejopyge because "(1) the word is classical Greek skaya (1958) to include a single new species, P. in Latin translation, and (2) 'i' (iota) cannot be crebra, from Yakutia in the Soviet Union. dpik expressed by T which is unknown in Latin and (1961a) subsequently reassigned Phalacroma? Greek alphabets." bpik's emendation is an dubium Whitehouse (1936) to Pseudophalacroma, invalid change in spelling (nomen vanum) be- and he corrected the name of the type species to cause ICZN Article 11(b)(i) specifically states P. crebrum. Pokrovskaya indicated that P. that the letter 'j,' which is common in neo- crebrum lacks a glabellar node and basal lobes; Latin, "may be used in zoological names." however, judging from her illustrations of type Occurrence.—Lejopyge is a geographically specimens, absence of those features may be widespread genus in open-shelf lithofacies, hav- due to poor preservation rather than an original ing been reported from all continents except condition. Otherwise, except for an unusually Africa. It has an observed stratigraphic range wide pygidial border, both P. crebrum and P. from near the base of the Ptychagnostus punctuosus dubium agree in all essential features with some Zone to the top of the Lejopyge laevigata Zone.

3 8 The University of Kansas Paleontological Contributions—Paper 109

LEJOPYGE ACANTHA, n. sp. furrows of ptychagnostid type. Pygidium lack- Figure 21 ing spines; border of moderate and uniform width posteriorly, narrowing anterolaterally. Holotype.—Cephalon (Fig. 21, 1), KUMIP Furrows of pygidial acrolobe mostly effaced 204324. except distally shallowing axial furrows along Description.—Lejopyge having paired spines sides of MI. On internal mold, cephalon may of moderate size on posterolateral borders of retain weak, anteriorly shallowing vestiges of cephalon and posterior pleural bands of poste- axial furrows immediately in front of basal rior thoracic segment. Furrows of cephalic ac- lobes; pygidium may retain vestiges of axial rolobe usually effaced except those outlining furrows to back of M2 as well as abaxial basal lobes. Thorax having normally developed vestiges of Fl. Surface of acrolobes lacking

- .e, %, • - ,, N• 'Ai. , 4 - ' n -4 , ' . , , • • - '• •' '',4, "';

‘ . 4V .. $14, ' ..

7a 8a 7b 8b

Fig. 21. Lejopyge acantha, n. sp. 1-3,5,6 from locality 816, about 20 m above base of Weeks Limestone, House Range, Utah; 4,7,8 from locality 1 1 la, about 8 m above middle limestone member of Lincoln Peak Formation, northern Schell Creek Range, Nevada. 1, Holotype cephalon in limestone, KUMIP 204324, x8. 2, Cephalon, KUMIP 204325, X8. 3, Thorax with broken pleural spines on posterior segment, KUMIP 204326, x 8. 4, Silicified posterior thoracic segment with pleural spines, KUMIP 189183, x 10. 5,6, Pygidia with muscle markings on anterior axial region. KUMIP 204327 and 204328, both X8. 7,8, Silicified cephalon and pygidium, KUMIP 189182 and 189184, both XII). Robison—Cambrian Agnostida, Part I, Ptychagnostidae 39

punctae. abundant in collections 380, 732-734, and 816 Discussion.—L. acantha closely resembles L. from the upper meter of the Marjum Forma- multifora (Opik, 1979:162-163, pl. 65, figs. 3,4) tion to about 20 m above the base of the Weeks in spine morphology. They are the only species Limestone in the central House Range. Bio- of L6opyge with one pair of spines on the stratigraphically, the observed range of L. cephalon, one on the thorax, and none on the acantha is in the middle of the lower L. laevigata pygidium. L. acantha differs from L. multifora by subzone (Fig. 4). lacking punctate acrolobe surfaces; also, its pygidial border is only about half as wide. LEJOPYGE ARMATA (Linnarsson) acantha also closely resembles L. calva, L. Figure 22 which is its inferred ancestor. L. acantha pri- marily differs from L. calva by the presence of Agnostus laevigatus var. armata LINNARSSON, 1869, spines, but it also has slightly less effaced p. 82, pl. 2, figs. 58, 59; WALLERIUS, 1895, anterior axial furrows on the pygidium. p. 37. Occurrence.—L. acantha is presently known Lejopyge laevigatus armatus (Linnarsson) KOBA- from only Nevada and Utah. In Nevada, it is YASHI, 1939, p. 131-132. abundant in collection 378 from 6 in above the Lejopyge armata (Linnarsson) LERMONTOVA, base of the upper shale member of the Lincoln 1940, p. 130, pl. 36, figs. I 1 a-c; DEMOK- Peak Formation in the northern Schell Creek WON', PISARCHIK, and TCHERNYSHEVA, Range. It is also present in collection 155 from 1966, p. 56; ERGALIEV, 1980, p. 77-79, pl. 1.5 m above the base of member B of the 2, figs. Il, 13-17; YANG, 1982, p. 301, pl. 1, Emigrant Springs Formation in the southern fig. 9. Schell Creek Range. In Utah, it is rare to Lejopyge laevigata armata (Linnarsson) WEST-

Fig. 22. Lejopyge annals (1.innarsson). 1, Cephalon, USNM 374591 from USNM 8m; from unknown horizon in Lincoln Peak Formation, Snake Range, Nevada; x 6. 2, Cephalon, MGUH 16.278 from GGU 225544; 90 in above base of Formation T2, Tavsens Iskappe Group, North Greenland; x 8. 3,4 Cephalon and pygidium, KUM I P 204312 and 204313 from RR79- I8A; about 45 in above middle limestone member, Lincoln Peak Formation, Ruby Mountains, Nevada; both X8. 40 The University of Kansas Paleontological Contributions-Paper 109

ERGÂRD, 1946, p. 89, pl. 13, figs. 28-36; Lu Daily and Jago (1975:529-532) presented a and others, 1965, p. 34, pl. 3, fig. 1; DAILY, detailed and cogent argument for concluding 1966, p. 95-96; KOBAYASHI, 1971, p. 176; that L. cos bpik (1967) is a junior synonym of Lu and others, 1974, p. 79, pl. 1, fig. 11; L. laevigata armata (= L. armata herein). I concur DAILY and JAGo, 1975, p. 528-532, pl. 62, with that synonymy. figs. 10-18; JAGo, 1976b, p. 13, pl. 2, figs. Occurrence.-L. armata has previously been 3-8; YANG, 1978, p. 23, pl. 1, figs. 19, 20. described from Sweden, the Soviet Union, Lejopyge laevigata (Dalman) WESTERGÂRD (in China, and Australia. part), 1946, pl. 13, fig. 25. L. armata is here reported for the first time Lejopyge laevigata perrugata WESTERGÂRD, 1946, from three localities in Nevada. A few speci- p. 89-90, pl. 14, figs. 1, 2; DAILY and JAGo, mens are in collection RR79-18A from about 1975, pl. 63, figs. 1-3. 45 m above the base of the upper shale member

Leiopyge laevigata armata (Linnarsson) 61, 1K, of the Lincoln Peak Formation in the southern 1961a, p. 87, pl. 21, fig. 10a, b; pl. 22, figs. Ruby Mountains. More than 200 specimens 1-4. are in collections DKS76-124v, 124z, 124-210, Leiopyge cos Ofqx, 1967, p.93-94, pl. 57, figs. 5, 124aa, and 124bb ranging from 36 to 78 m 6. above the base of the upper shale member of the Leiopyge armata (Linnarsson) OPix, 1979, p. Lincoln Peak Formation in the northern Schell 161-162, pl. 64, figs. 5, 6. Creek Range. Four specimens are in USNM collection 8m, which according to the label was Diagnosis. -Furrows of acrolobes usually collected in 1900 by F. B. Weeks from "4 miles effaced except basal furrows and distally shal- northeast of Osceola, Nevada" in the southern lowing axial furrows along most of postero- Snake Range. I have attempted to visit locality glabella and anteroaxis. Paired spines, variable 8m for additional collecting, but extensive out- in length, present on posterolateral borders of crops of Prospect Mountain Quartzite of Early both cephalon and pygidium. Genae usually Cambrian age in the area four miles northeast smooth, rarely with weak to moderately deep Osceola indicates an error in the recorded scrobicules. Pygidial acrolobe commonly hav- of locality description. ing slight indentations adjacent to bases of L. armata also is here reported for the first border spines. time from North Greenland. Two cephala are Discussion.-L. armata is the only species of in GGU 225544 and a few poorly preserved Lejopyge to possess border spines on both the specimens are in GGU 271414 from 90 and 12 cephalon and pygidium. In degree of efface- m, respectively, above the base of Formation ment of dorsal furrows, L. armata closely resem- T2 of the Tavsens Iskappe Group. bles L. laevigata, its inferred ancestor. Reasons From worldwide reports, L. armata ranges for recognizing L. armata and L. laevigata as throughout most of the L. laevigata Zone as separate species, and for including rare speci- defined herein; however, it usually is most mens with genal scrobicules in L. armata, are common in the upper subzone. According to given in the discussion of L. laevigata. Westergaxd (1946:89), L. armata is very rare in Yang (1982:30, pl. 1, figs. 10, 11) has the Solenopleura brachymetopa Zone ( = lower L. described some pygidia from the Zhejiang laevigata subzone, herein) in Sweden. In North Province of China under the name "Lejopyge America and Greenland, L. armata has been armata forma trigonospinosa, forma nov." These observed in association with only faunas of the pygidia are unusual in having border spines upper L. laevigata subzone. with exceptionally large bases that are much closer together than in typical representatives of LEJOPYGE CALVA Robison L. armata. According to ICZN Article 45(e)(ii), Figures 23, 24 the form name is to be regarded as of in- frasubspecific rank and provisions of the Code Lejopyge calva ROBISON, 1964, p. 521, pl. 83, do not apply to it (Article 45e). On the basis of figs. 1-4; PALMER, 1968, p. 827-828, pl. 6, available information, I am uncertain whether figs. 15-18; DAILY and JAGo, 1975, pl. 63, or not these specimens represent L. armata or a figs. 7-10; ERGALIEV, 1980, p. 79-80, pl. 2, new species. fig. 12. Robison—Cambrian Agnostida, Part I, Ptychagnostidae 4 1

Diagnosis. —Exoskeleton nonspinose. Fur- outlining basal lobes on cephalon and axial rows of acrolobes usually effaced except those furrows adjacent to MI on pygidium. Genae

9 8b

Fig. 23. 1,6opur calva Robison from Nevada and Utah; all preserved in limestone. /, Cephalon, KUM IP 204314 from 156; 3 m above base, member B, Emigrant Springs Limestone, southern Schell Creek Range, Nevada; X 8. 2,5, Cephala, KUMIP 204315 and 204316 from 376; 2.4 ni above middle limestone member, Lincoln Peak fOrmation, northern Schell Creek Range, Nevada; both x 7. 3, Pygidium, KUMIP 204317 from 155; 1.5 m above base, member B, Emigrant Springs Limestone, southern Schell Creek Range; X 7. 4, Silicified pygidium, KUMIP 204318 from 821; near top of Marjum Formation, House Range, Utah; x 7. 6, Pygidium, KUMIP 204320 from 376, x 8. 7, Cephalon with weak genal scrobicules, KUMIP 204321 from 751; about 43 m above base of Weeks Limestone, House Range; x 7. 8, Small cephalon with moderately deep genal scrobicules, KUMIP 204319 from 156, x 10. 9, Cephalon with moderately deep genal scrobicules, KUMIP 204322 from 154; top bed, member A, Emigrant Springs Limestone, southern Schell Creek Range; X8. 42 The University of Kansas Paleontological Contributions—Paper 109

armata and L. laevigata, I consider these scrobicules to represent minor intraspecific variation rather than a character of taxonomic significance. Acrolobe shape in large popula- tions of L. calva is also variable. Subcircular (e.g., Fig. 23,1-3) and slightly elongate (e.g., Fig. 23,5, 6) end members of a morphologic continuum may represent sexual dimorphism, but proof is lacking. At several localities in Nevada and Utah specimens of L. calva commonly show similar patterns of dark markings (Fig. 24). These markings are similar to those discussed by Harrington (1959:094-097). Most axial mark- ings may represent patterns from muscle inser- tions on parietal surfaces. Weak, irregular lines on genae may represent parietal attachment of mesenteries that separated underlying alimen- tary diverticula. Representatives of L. calva closely resemble those of L. laevigata, differing primarily in the more complete effacement of axial furrows in L. calva. Occurrence.—L. calva has been described from the United States (Alaska, Nevada, Utah) Fig. 24. Lgopyge calva Robison with dark markings on and the Soviet Union (Kazakhstan). cephala and pygidia; KUMIP 204323 from 155; 1.5 m above base, member B, Emigrant Springs Limestone, In addition to localities recorded in previous southern Schell Creek Range, Nevada; X 10. literature, L. calva is here reported from several new localities in the Great Basin. Additional collections from Nevada are from the northern usually smooth, very rarely with weak to mod- Schell Creek Range (111a and 376 from 2 to 8 erately deep scrobicules. Pygidial border of m above base of upper shale member, Lincoln uniform and moderate width posteriorly, nar- Peak Formation), southern Schell Creek Range rowing anterolaterally. (154-156 from top bed of member A and basal 3 Discussion.—L. calva is one of the most m of member B, Emigrant Springs Limestone), common fossils in upper Middle Cambrian and southern Egan Range (820 from about 10 rocks of the Great Basin. At many localities, m above base of member A, Emigrant Springs coquinas of disarticulated sclerites comprise Limestone). All additional collections from thin to moderately thick, laterally extensive Utah are from the central House Range. These limestone beds. include collections 728-731, 733, 734, 746-751, Illustrated type specimens of L. calva (Robi- 766-769, 776-778, 813-815, 821, 826, and 828 son, 1964, pl. 83, figs. 1-4) are mostly exfoli- ranging from 34 m below the top of the Mar- ated internal molds. Additional specimens jum Formation to about 30 m above the base of illustrated here are not exfoliated and were the Weeks Limestone. selected to demonstrate minor observed varia- Biostratigraphically, L. calva is restricted to tion in morphology. In general, vestiges of axial the lower subzone of the L. laevigata Zone. furrows are slightly longer on internal molds than on dorsal surfaces of the cephalon and LEJOPYGE LAEVIGATA (Dalman) pygidium. Figure 25 Genal surfaces in L. calva are usually smooth, but weak (Fig. 23,7) to moderately Battus laevigatus DALMAN, 1828, p. 136-137; deep (Fig. 23,8,9) scrobicules are rarely devel- HISINGER, 1837, p. 20, pl. 4, fig. 7. oped (less than 0.1 percent of cephala). As in L. Lejopyge laangata (Dalman) CORDA in Hawle and

Robison-Cambrian Agnostida, Part I, Ptychagnostidae 43

Corda, 1847, p. 51, pl. 3, fig. 25; WEST- 1880, p. 27, pl. 2, fig. 17; WALLERIUS, 1895, ERGARD, 1946, p. 87-89, pl. 13, figs. 18-24, p. 35; not MATTHEW, 1896, p. 233; KOKEN, 26, ?27 (not 25); pl. 16, fig. 9; POKROV- 1896, p. 347, fig. 242; GR6NWALL, 1902, p. SKAYA, 1958, p. 76-78, pl. 5, figs. 16, 17; 60; STRAND, 1929, p. 346. POLETAEVA in Khalfin, 1960, p. 163, pl. 18, ?Agnostus laevigatu.s. (Dalman) var. MATTHEW, figs. 3a, b; DAILY, 1966, p. 95; HUCKE and 1897, p. 173, pl. 1, fig. 7. VOIGHT, 1967, p. 48, pl. 5, fig. 6; MARTINS- ?Phoidagnostus limbatus WHITEHOUSE, 1936, p. SON, 1968, p. 149, fig. 9A; PALMER, 1968, 93-94, pl. 9, figs. 10, 11. p. B28, pl. 6, fig. 19; KHAIRULLINA, 1970, Lejopyge laevtgata rugifesa WESTERGÂRD, 1946, p. p. 16, pl. 1, fig. 15; 1973, p. 50, pl. 3, figs. 90, pl. 14, fig. 3; DAILY and JAGO, 1975, 11-14; HILL, PLAYFORD, and Woons, 1971, P. 529, pl. 63, fig. 6. p. cm. 20, pl. 10, figs. 5, 6; DAILY and Leiopyge laevigata (Dalman) 61 , ii;, 1961a, p. JAGo, 1975, p. 527-550, pl. 62, figs. 1-9 (not 85-87, pl. 21, figs. 5-9; 1979, p. 161, pl. 64, 10); not POULSEN and ANDERSON, 1975, p. figs. 1-3. 2075-2076, pl. 2, figs. 1-9; JAGo, 197613, p. ?Lejopyge cf. laevigata (Dalman) YANG, 1982, p. 12, pl. 2, figs. 1, 2; YANG, 1978, p. 22-23, 301, pl. 1, figs. 12, 13. pl. 1, fig. 17; ERGALIEV, 1980, p. 77, pl. 3, figs. 1-9; EGOROVA, PEGEL, and TCHER- Diagnosis. -Exoskeleton nonspinose. Fur- NYSHEVA in Egorova and others, 1982, p. rows of acrolobes usually effaced except basal 74, pl. 25, fig. 1; pl. 28, figs. 2-5; pl. 46, fig. furrows and distally shallowing axial furrows 6. along most of posteroglabella and anteroaxis. Agnostus laangatus (Dalman) ANGELIN, 1851, p. Genae usually smooth, rarely with weak to 6, pl. 6, fig. 3; LINNARSSON, 1869, p. 82; moderately deep scrobicules. Pygidial border of 1873, p. 246; BROGGER, 1876, p. 194, pl. 8, uniform and moderate width posteriorly, nar- fig. 1; 1878, p. 74, pl. 5, fig. 6; TULLBERG, rowing anterolaterally.

la

3a 4a 3b 4b

Fig. 25. Lejopyge laevigala (Dalman); all from Formation T2, Tavsens Iskappe Group, North Greenland. 1,2, Cephalon and pygidium, MGUH 16.279 and 16.280 from GGU 225546, both x 10. 3, Mostly exfoliated pygidium, MGUH 16.281 from GGU 225552, x9. 4, Mostly exfoliated pygidium MGUH 16.282 from GGU 225561, X 7. 44 The University of Kansas Paleontological Contributions—Paper 109

Discussion. —L. laevigata is a widely dis- Occurrence. —L. laevigata has been described tributed species that has received much discus- from Sweden, Norway, Denmark, Germany (in sion (for references, see synonymy). Its origin glacial erratics), Soviet Union, China, Aus- and relationships to other species have been tralia, and the United States (Alaska). discussed by WestergArd (1946), Pokrovskaya Reports of L. laevigata from eastern Canada (1958), dpik (1961a), and Daily and Jago are open to question. Matthew (1896:233-235) (1975). described three varieties of Agnostus laevigatus Representatives of Lejopyge with moderate from eastern Newfoundland; however, all of proximal development of axial furrows on the Matthew's specimens were reassigned by cephalon and pygidium may possess spines of Hutchinson (1962:71-72, 85-86) to genera various length. Rare specimens may also pos- other than Lejopyge and I concur with that sess weak to moderately deep genal scrobicules. action. Poulsen and Anderson (1975:2075- Some authors have used these characters to 2076, pl. 2, figs. 1-9) assigned several poorly differentiate varieties or subspecies of L. preserved specimens from southeastern New- laevtgata (e.g., Linnarsson, 1869; WestergArd, foundland to L. laevigata. Those specimens ap- 1946; Daily and Jago, 1975). Others have pear to lack the characteristic short, distally assigned the spinose forms to a separate species, shallowing axial furrows on the cephalon and L. armata (e.g., Lermontova, 1940; dpik, pygidium. In my opinion, they do not belong to 1979). WestergArd (1946:88) justified the use of Lejopyge and may represent Grandagnostus. Mat- subspecies because of "considerable variabil- thew (1897:173, pl. 1, fig. 7) also reported an ity" with extreme forms being "connected by unnamed variety of A. laevigatus from New intermediate links." Although some collections Brunswick but his description and illustration contain associated nonspinose and spinose are inadequate for verification. Absence of L. forms, many collections from widespread lo- laevigata from later faunal lists for the same area calities and different lithologies contain speci- (e.g., Hayes and Howell, 1937) leaves uncer- mens that are uniformly either nonspinose or tain the presence of L. laevigata in New spinose. This rules out sexual dimorphism as a Brunswick. likely explanation for the presence or absence of L. laevigata here is documented for the first spines. The observed first appearance of spi- time from North Greenland and Nevada. nose forms is stratigraphically higher than that Many specimens are in GGU collections of nonspinose forms. Because of these distribu- 225535, 225543, 225552, 225561, and 225595 tion patterns, together with a lack of evidence from throughout most of Formation T2 of the for phenotypic control, I prefer to recognize Tavsens Iskappe Group in North Greenland. separate species, L. laevigata (nonspinose) and The specimens from Nevada are assigned to a L. armata (spinose). Spinose specimens that new geographic subspecies, L. laevigata rubyen- Westergard (e.g., 1946, pl. 13, fig. 25) assigned sis. to L. laevigata I reassign to L. armata. Biostratigraphically, L. laevigata has an ob- Specimens of Lejopyge with genal scrobicules served range through the zone bearing its are extremely rare. Westergard (1946) assigned name. two cephala with this character to L. laevigata rugifera. If present, scrobicules vary from weak LEJOPYGE LAEVIGATA RUBYENSIS, to moderately developed. Because of the rarity n. subsp. and variation of this character, together with its Figure 26 lack of uniform presence in any known popula- tion, I do not accord it taxonomic significance. Holotype.—Pygidium (Fig. 26,4), KUMIP Specimens of L. laevigata are rare to com- 204327. mon in six collections from North Greenland. Description. —L. laevigata having unusually Dorsal convexity of these specimens is relatively deep and wide axial furrows at sides of pygidial low; however, they are mostly preserved in anteroaxis. Border furrow widened in post- calcareous shale and original convexity was erolateral regions of pygidium. probably reduced by compaction of the enclos- Discussion. —Some specimens of Lejopyge in ing matrix. Nevada possess characteristic features of L. Robison—Cambrian Agnostida, Part I, Ptychagnostidae 45

laevigata except for slight differences in width accentuated during holaspid ontogeny. The rel- and depth of axial and border furrows on the ative influence of genetic and phenotypic fac- pygidium. These differences are progressively tors may never be determined. Because of

5 6 8

9b 1 Ob

Fig. 26. Lejopyge lam:gain ruhyensis, n. subsp.; all from Lincoln Peak Formation of Nevada; 1-8 from locality R R78-35, one meter above base of upper shale member in Ruby Mountains; 9,10 from uppermost meter of middle limestone member in southern White Pine Range. /, Unexfoliated cephalon, KUMIP 204329, X 7. 2, Mostly exfoliated cephalon showing weak genal scrobicules on internal mold. KUMIP 204330, x 7. 3, Mostly exfoliated pygidium, KUMIP 204331, X' 7. 4, Unexfiiliated holotype pygidium, KUM IP 204332, X 7. 5, Partly exfoliated cephalon, KUM IP 204333, X 7. 6, Partly exfoliated, small holaspid cephalon, KUMIP 204334, x 10. 7, Small holaspid pygidium, KUM IP 204335, X 10. 8, MosilY exfoliated pygidium showing faint indication of tapered posteroaxis on internal mold, KUMIP 204336, X 7. 9,10, Cephalon and pygidium. KUMIP 204337 and 204338, both x8. 46 The University of Kansas Paleontological Contributions-Paper 109 morphologic gradation, particularly among Plychagnostus (Triplagnostus) lundgreni (Tullberg) early holaspides, I provisionally attribute these WESTERGÂRD, 1946, p. 75, pl. 10, figs. differences to geographic variation within L. 23-25; pl. 11, figs. 1, 2. laevigata. Ptychagnostus (Triplagnostus) lundgreni nanus Occurrence. -L. laevigata rubyensis is known (Griinwall) WESTERGARD, 1946, p. 75-76, from three localities in Nevada. More than 30 pl. 11, figs. 3-7. well-preserved specimens are in collections Ptychagnostus, species undetermined, KASETTI, RR78-27 and RR78-35 from 2 and 1 m, re- 1967, p. 29, pl. 10, figs. 27-31. spectively, above the base of the upper shale Leiopyge lundgreni (Tullberg) 61, 1x, 1979, p. 158. member of the Lincoln Peak Formation in the Leiopyge lundgreni nanus (Grônwall) OP1K, 1979, southern Ruby Mountains. Two poorly pre- p. 158. pygidia of Lejopyge, questionably belong- served Diagnosis. -Exoskeleton nonspinose and are in collection DKS76- ing to this subspecies, with little effacement of dorsal furrows. Axial above the base of the upper 124ee from 98 m length compared to exoskeletal length less than of the Lincoln Peak Formation in shale member in most ptychagnostid species. Cephalon mod- northern Schell Creek Range. About 50 the erately to highly convex, subcircular to suboval are in collection 795 from the upper specimens in outline. Cephalic axis broad at posterior, of the middle limestone member of the meter tapering to acute point at front; may have slight Lincoln Peak Formation in the southern White lateral constrictions at anterior ends of basal Range. If the two specimens from the Pine lobes and at F3. Anteroglabella low, generally Range represent the subspecies, it Schell Creek flush with or little elevated above genae. F3 range from the middle of the has an observed straight, narrow and well defined. Post- subzone the top of the upper subzone lower to eroglabella moderately elevated above genae, of the L. laevigata Zone. Otherwise, it is known Fl and F2 usually not developed. Preglabellar the middle of the lower subzone. from only median furrow narrow and commonly deeper L. gala rubyensis has been collected from laevi than axial furrow. Genae usually smooth, most seaward Lejopyge-bearing litho- only the rarely having weak to moderately deep scrob- in the Great Basin. Regional biofacies facies icules. Pygidium semicircular and usually of relationships suggest that L. calva was the domi- moderate convexity; F2 usually shallower than agnostoid species in some shallower open- nant Fl. Posteromedian structure on M2 varying shelf environments whereas coeval L. laevigata from weak node to small tubercle. Posteroaxis rubyensis was dominant over some of the deeper variable in width, slightly to moderately ogival, open shelf. tapering to rather sharp point at back; may have slight central depression. Postaxial me- LEJOPYGE LUNDGRENI (Tullberg) dian furrow generally shallow. Figures 27, 28 Discussion. -L. lundgreni, the ancestral spe- Agnostus lundgreni TULLBERG, 1880, p. 20-21, pl. cies of Lejopyge, is characterized by normal 1, fig. 8; GR6NWALL, 1902, p. 51, 197; ptychagnostid development of dorsal furrows, a STRAND, 1929, p. 345; COBBOLD and slightly shortened axis, simple basal lobes, usu- Pococx, 1934, p. 342, pl. 44, figs. 20, ?21. ally a weak posterior furrow (F2) on the Agnostus lundgreni var. nana GRONWALL, 1902, p. pygidial axis, and an absence of spines. The 51-52, pl. 1, fig. 2. species probably originated from a lineage con- Agnostus lundgreni nana (Grônwall) STRAND, taining Ptychagnostus intermedius. Comparative 1929, p. 345, pl. 1, figs. 5, 6. morphology indicates that the relatively short Agnostus atavus (Tullberg) STRAND, 1929, p. 344, axis, simple basal lobes, and absence of genal pl. 1, fig. 20. scrobicules in late holaspides of L. lundgreni Triplagnostus lundgreni (Tullberg) KOBAYASHI, (Fig. 27,7) may have been derived by 1939, p. 146; POULSEN, 1966, p. 121; Eco- paedomorphism from the early holaspid condi- ROVA, PEGEL, and TCHERNYSHEVA in Ego- tion in P. intermedius (compare Robison, 1982, rova and others, 1982, p. 65, pl. 54, fig. 16. pl. 3, fig. 7). Triplagnostus lundgreni nana (Grônwall) In L. lundgreni, as in many agnostoid spe- KOBAYASHI, 1939, p. 146. cies, average holaspid size in the Great Basin Robison—Cambrian Agnostida, Part I, Ptychagnostidae 47

(Figs. 27 ,1 - 8; 28, 1 -4) is approximately half that ing Middle Cambrian time the Great Basin in northwestern Europe (Fig. 8,5). Paleomag- terrane was positioned near the equator netic and lithologic evidence indicates that dur- whereas the European terrane was in high

7a 8 7b 4c

Fig. 27. Lejopyge lunrigreni (Tullberg) from lower part of stratigraphic range in Nevada and Utah. 1, Cephalon, KUMIP 204295 from 804; 3 m below top of Geddes Limestone, Eureka mining district, Nevada; X 10. 2, Pygidium, KUMIP 204296 from 759; about 245 m above base of Marjum Formation, House Range, Utah; x 10. 3, Cephalon, KUNI1P 204297 from 106; near base of lower shale member, Secret Canyon Shale, Eureka mining district; X8. 4, Pygiditini, KUMIP 204298 from 398; about 140 m above base of Marjum Formation, House Range; x 8. 5, Cephalon, KUMIP 204299 from 759; x8. 6, Pygidium, KUMIP 204300 from 105; probably uppermost 3 m of Geddes Limestone, Eureka mining district; x8. 7, Complete dorsal exoskeleton, KUMIP 204301 from 113; talus, probably between 50-70 in above base of Marjurn Formation, House Range; x 10. 8, Early holasid exoskeleton KUMIP 204302 from 398; X 12. 48 The University of Kansas Paleontological Contributions—Paper 109

4c 5

Fig. 28. Lejopyge lundgreni (l'ullberg); 1-4, specimens from upper part of stratigraphie range in Nevada and Utah, all X 10; 5, specimens from Sweden, X5. 1, Cephalon, KUMIP 204303 from 816; about 20m above base of Weeks Limestone, House Range, Utah. 2, Cephalon, KUMIP 204304 from 154; top bed, member A, Emigrant Springs Limestone, southern Schell Creek Range, Nevada. 3,4, Cephalon and pygidium, KUMIP 204305 and 204306 from MNR81-187; about 285 m above base of Lincoln Peak Formation, Snake Range, Nevada. 5, Representative specimens on same piece of rock with pygidium illustrated by WestergArd (1946, pl. 10, fig. 25); cast, KUMIP 204307 from Vedjëon (boulder 6), ,Pmtland, Sweden (original in collections of Naturhistoriska Riksmuseet, Stockholm).

latitudes (Bambach and others, 1980). There- scrobicules, which are accentuated with in- fore, the geographic size difference in L. crease in cephalic size, tend to be better devel- lundgreni may be related to temperature; how- oped on specimens of L. lundgreni from Europe ever, such other factors as salinity and nutrients than on those from the Great Basin. Also, can not be ruled out. Some minor geographic during ontogeny, the posteroaxis of the variation in morphology probably relates to this pygidium shows significant allometric size in- difference in average size. For example, genal crease. As expected, larger holaspides of L. Robison—Cambrian Agnostida, Part I, Ptychagnostidae 49

lundgreni from Europe commonly have a wider plete specimens in collection 183 from an un- posteroaxis than do smaller ones from the Great named formation (possibly upper part of unit Basin. European specimens of L. lundgreni with B7 of Stewart and Palmer, 1967) in the Toiyabe a narrow posteroaxis have sometimes been Range. In Utah, numerous specimens are in assigned to the subspecies nanus (see syn- collections 113, 391, 397, 398, 737, 740, 759, onymy), but because of the observed gradation and 816 ranging from about 40 m above the in that character I find no justification for base of the Marjum Formation to about 20 in continued use of the subspecies name. above the base of the Weeks Limestone in die Pygidia of L. lundgreni illustrated by West- central House Range. ergArd (1946, pl. 10, figs. 24, 25; pl. 11, figs. 6, Biostratigraphically, L. lundgreni has an ob- 7) have a forty well-developed F2 on the axis; served range from near the base of the Ptychag- however, most other specimens in the same nostus punctuosus Zone to the middle of the lower collections have a weak F2 (e.g., Fig. 28,5). subzone of the L. laevigata Zone (Fig. 4). Most specimens from North America also have a weak pygidial F2. Therefore, this appears to LEJOPYGE RIGBYI, n. sp. be the more common condition throughout the Figure 29 species. A few specimens from the Taconic sequence Etymology. —The species name honors Prof. of eastern New York were assigned by Rasetti J. Keith Rigby of Brigham Young University (1967) to an undetermined species of Ptychag- for his many contributions to paleontology and nostus. Because all characters of those specimens geology. agree with the diagnosis above, they here are Holotype.—Nearly complete exoskeleton reassigned to L. lundgreni. (Fig. 29,4), KUMIP 204311. Yang (1978:23, 1)1. 2, figs. 1, 2) illustrated Description.—Lejopyge having pair of short agnostoids from China that were assigned to spines on posterolateral borders of cephalon, Tripla gnostus lundgreni (Tullberg). The cephalon one large median spine on posterior thoracic has elongate, divided basal lobes and does not segment, and one large median spine on represent L. lundgreni. The specimens resemble pygidial M2. Acrolobes lacking much efface- P. atavus; however, identification is uncertain. ment of dorsal furrows except pygidial F2. Occurrence.—L. lundgreni has previously been Axial length compared to exoskeletal length less reported from Sweden, Norway, Denmark, than in most ptychagnostid species. Pygidial F2 England, and the Soviet Union. Its occurrence usually effaced on dorsal surface, may be in New York has been documented by Rasetti weakly developed on internal mold. (1967, with nomenclatural emendation here). Discussion.—L. ri ghyi is characterized by its L. lundgreni here is reported for the first time spine morphology and its lack of much efface- from many localities in the Great Basin. In ment of dorsal furrows on the acrolobes. Large Nevada, more than 50 specimens are in collec- median spines on the posterior thoracic seg- tions 105, 106, and 804 from the upper 3 m of ment and the pygidial M2 are indicated by the Geddes Formation and the lower kw meters prominent broken stumps on all available speci- of the Secret Canyon Shale in the Eureka mens. A pair of smaller, delicate spines project mining district. Rare specimens are in the from the posterior cephalon, and are easily following collections: 154 from the top bed, broken. member A, Emigrant Springs Limestone, L. rigbyi differs from all species of Lejopyge by southern Schell Creek Range; 350 from the the presence of a median spine on the pygidial lower shale member, Lincoln Peak Formation, axis. Except for the presence of spines, it closely southern Ruby Mountains; and MNR81-I87 resembles L. lundgreni, its inferred ancestor. A from about 285 m above the base, Lincoln Peak minor difference between L. lundgreni and L. Formation, southern Snake Range. Probable rigbyi is the greater effacement of the pygidial representatives include two cephala in collec- F2 in L. rigbyi. tion 177 from 426 m above the base of the Occurrence. —About a dozen specimens of L. Secret Canyon Formation in the northern Egan rigbyi are in collection 398 from about 140 ni Range, and a few poorly preserved but com- above the base of the Marjuni Formation in the

50 The University of Kansas Paleontological Contributions—Paper 109

Fig. 29. Lejopyge rigbyi, n. sp.; all partly exfoliated and all from locality 398 in Marjum Formation, House Range, Utah. /, Cephalon retaining short posterolateral spine on right side, spine is broken off left side, KUMIP 204308, X 10. 2, Pygidium, showing broken base of median M2 spine, KUMIP 204309, X 10. 3, Nearly complete exoskeleton, KUMIP 204310, x 9. 4, Holotype, nearly complete exoskeleton. KUMIP 204311, x 8.

central House Range, Utah. The single locality Diagnosis. —Exoskeleton of moderate to is within the Ptychagnostus punctuosus Zone (Fig. large size, in some species length probably 4). exceeds 20 mm. Cephalic axis long, broadly rounded to obtusely pointed at front. Post- Genus ONYMAGNOSTUS Opik eroglabella commonly having convex lateral sides and broadly rounded rear. Basal lobes Onymagnostus 6PIR, 1979, p. 107-108. simple to slightly elongate. Pygidial axis long, Type species. —6pik (1979:107) designated M2 hexagonal with large median tubercle Onymagnostus angulatus as the type species of deeply embaying F2. Postaxial median furrow Onymagnostus. As revised herein, I consider O. present during meraspid period, usually be- angulatus to be a subjective junior synonym of coming effaced during early to middle holaspid O. hybridas (Brogger). Therefore, the valid period. Furrows on cephalic and pygidial acro- name of the type species of Onymagnostus be- lobes secondarily effaced in some species. comes O. hybridas. Discussion. —Onymagnostus is a ptychagnostid

Robison-Cambrian Agnostida, Part I, Ptychagnostidae 51

genus generally having smooth genae, short hybridus are geographically widespread and basal lobes, and a long pygidial axis with a common. O. semiermis is known from only a few large median tubercle that deeply embays the localities in Australia. O. ciceroides and O. grandis posterior (F2) transverse furrow. During on- are variably effaced forms known with certainty togeny, the postaxial median furrow usually from only eastern Newfoundland and north- became effaced prior to the late holaspid pe- western Europe. A single cephalon, possibly riod. Spines are lacking except for O. semiermis representing O. grandis, has been described Ôpik, which has a pair of short spines on the from Australia (Opik, 1979:113, pl. 53, fig. 6). pygidial border. As in other ptychagnostid gen- Onymagnostus has an observed stratigraphic era, some species of Onymagnostus show evolu- range from near the base of the P. gibbus Zone tionary effacement of dorsal furrows on the to the upper part of the P. punctuosus Zone. acrolobes. This effacement was accompanied by secondary reduction in size of the median tu- bercle on the pygidial M2. ONYMAGNOSTUS HYBRIDUS (Brogger) The oldest known species of Onymagnostus is Figures 30, 31 O. seminula (Whitehouse), which first appears Agnostus gibbus var. hybrida BROGGER, 1878, p. near the base of the P. gibbus Zone in western 62, pl. 5, figs. 4a, b; GR6NWALL, 1902, p. North America. Comparative morphology in- 49, 197. dicates that O. seminula was probably derived Agnostus stenorrhachis GR6NWALL, 1902, p. 76-77, from Ptychagnostus praecurrens (compare Figs. 19 pl. 1, fig. 16; COBBOLD and POCOCK, 1934, and 32). Both species have smooth genae, p. 342-343, pl. 44, fig. 22. slightly elongated basal lobes that are anteriorly Agnostus cf. intermedius Tullberg ILLitsto, 1916, p. ill-defined, and an absence of spines. In O. 408, pl. 28, figs. 11, 12. seminula the acrolobes are more convex, the axis Agnostus pulchellus ILLING, 1916, p. 410-41 1 , pl. is slightly longer and wider, the median node on 30, figs. 1, 2. the posteroglabella is slightly more anterior, the Agnostus triangulatus ILLING, 1916, p. 412, pl. 30. median tubercle on the pygidial M2 is en- figs. 7, 8. larged, and the postaxial median furrow is Agnostus gibbus hybridus Brogger STRAND (in commonly effaced in late holaspides. Basal part), 1929, p. 343. lobes are reduced to a simple condition in some Agnostus cf. gibbus hybridus Bregger THORSLUND later species of Onymagnostus. in Asklund and Thorslund, 1935, p. 106, Opik (1979:107) assigned eight previously fig. I. described species to Onymagnostus. Additionally, Agnostus sp. THORSLUND in Asklund and Thors- he described seven new species groups from lund, 1935, p. 108, pl. 1, fig. 8. Australia, three of which were left in open Triplagnostus stenorrhachis (Griinwall) KoBA- nomenclature. Based on variation observed in YASHI, 1939, p. 146; EGOROVA, PEGEL, and numerous collections of Onymagnostus from TCHERNYSHEVA in Egorova and others, North America, Greenland, Europe, and Aus- 1982, p. 65, pl. 11, figs. 9, 10; pl. 12, figs. tralia, as well as in illustrated material from the 7-9; pl. 13, figs. 4, 5, 7; pl. 14, figs. 1-3; pl. Siberian platform (Egorova and others, 1982), 15, figs. 2,3; pl. 18, figs. 2,3; pl. 19, fig. 1; I conclude that several synonyms are repre- pl. 21, fig. 4, pl. 22, figs. 8,9; pl. 61, figs. 1, sented. Herein, I recognize only five species of 2. Onymagnostus; these being O. hybridus (Brogger, TrtPlagnostus triangulatus (Illing) KOBAYASHI, 1878), 0. ciceroides (Matthew, 1896), 0. seminula 1939, p. 146. (Whitehouse, 1939), 0.. grandis (Hutchinson, Ptychagnostus (Triplagnostus) hybridus (Brogger) 1962), and O. semiermis Opik (1979). Synonyms WESTERGARD, 1946, p. 71-72, pl. 9, figs. 25, of O. hybridus are listed below. Synonyms of O. 26; pl. 10, figs. 1, 2; HUTCHINSON, 1962, p. ciceroides are A. laevigatus terranovicus Matthew 82, pl. 8, figs. 12-15. (part, 1896), A. I. mammilla Matthew (1896), A. Ptychagnostus (Triplagnostus) stenorrhachis (Gr6n- altus Gr6nwall (1902), and Ptychagnostus convexus wall) WESTERGARD, 1946, p. 72, pl. 10, figs. Westergard (1946). 3, 4; HUTCHINSON, 1962, p. 80-81, pl. 8, Occurrence. -Of the five presently recognized figs. 1-5. species of Onymagnostus, O. seminula and O. Ptychagnostus (Triplagnostus) vinicensis SNAJDR (in

52 The University of Kansas Paleontological Contributions-Paper 109

part), 1958, p., 71-72, pl. 4, figs. 19, 20, 23, formation as well as personal review of many 24 (not figs. 21, 22). collections from North America, Greenland, Ptychagnostus hybridus (Brogger) ROBISON, 1964, and Europe, I consider several described spe- p. 523, pl. 79, figs. 10, 11, 13, 14; PALMER cies to be synonyms of O. hybridus (Bregger). and others, 1984, fig. 2F. These include Agnostus stenorrhachis Griinwall, A. Ptychagnostus punctuosus (Angelin) POULSEN (in pulchellus Illing, A. triangulatus Illing, Triplag- part), 1969, p. 4-5, Fig. 4B (not 4A). nostus formosus Pokrovskaya and Khairullina, T

Triplagnostus . formosus POKROVSKAYA and urbanus Pokrovskaya and Khairullina, Ony- KHAIRULLINA in Repina, Petrunina, and magnostus angulatus Opik, O. durusacnitens bpik, Khairullina, 1975, p. 108, pl. 9, fig. 9. O. mundus bpik, O. seminula of bpik (not Triplagnostu.s urbanus POKROVSKAYA and Whitehouse), and O. prokopi Fatka, Kordule, KHAIRULLINA in Repina, Petrunina, and and Snajdr. Most original descriptions of these Khairullina, 1975, p. 106, pl. 9, fig. 6. species were based on few specimens. Among Ptychagnostus (Ptychagnostus) stenorrhachis (Gr6n- the diagnostic differences cited are a rounded wall) jAco, 1977, p. 45-46, pl. 1, figs. 7-12. versus obtusely pointed anterior glabella, Onymagnostus hybridus (Brogger) dPix, 1979, p. straight versus convex sides on the poster- 107. oglabella, smooth versus slightly scrobiculate Onymagnostus angulatus 6PIK, 1979, p. 108-110, genae, differences in width of the posteroaxis on pl. 50, figs. 1-8; pl. 51, figs. 1-3. the pygidium, slight variation in depth of fur- Onymagnostus sp. nov. all. angulatus CIPIK, 1979, rows on the acrolobes, and minor variation in p. 110, pl. 51, figs. 4, 5. width of the posterolateral border of the Onymagnostus durusacnitens bPix, 1979, p. 110- pygidium. Although in some collections one or 111, pl. 53, figs. 2 4 . more of these characters may be fairly constant, Onymagnostus mundus ()Pm, 1979, p. 111-112, in some large collections (e.g., 765), gradations pl. 51, fig. 6; pl. 52, figs. 1, 2. in each of the cited characters can be observed. Onymagnostus seminula (Whitehouse) bPix, WestergArd (1946:72) mentioned unfigured 1979, p. 112-113, pl. 52, figs. 3-5; pl. 53, Swedish specimens that are gradational be- fig. 1. tween hybridus and stenorrhachis. Under the name Onymagnostus cf. stenorrhachis (Griinwall) bP1K, Triplagnostus stenorrhachis, Egorova, Pegel, and 1979, p. 113-114, pl. 53, fig. 5. Tchernysheva (in Egorova and others, 1982) Ptychagnostus triangulatus (hung) RUSHTON, 1979, have illustrated many specimens from the Sibe- p. 53-54, fig. 5E-G. rian platform that show variation in some of the Onymagnostus prokopi FATKA, KORDULE, and characters mentioned above. Width of the axis gNAJDR, 1981, p. 368, pl. 1, figs. 2-9. may also be secondarily decreased by collapse of the exoskeleton along the axial furrow during Diagnosis. -Exoskeleton moderately large compaction in argillaceous matrix. with well-developed dorsal furrows. Cephalon moderately convex, dorsal outline subcircular. As revised here, O. hybridus is characterized Axis generally having irregular taper, sides by simple basal lobes, mostly smooth genae, a rarely subparallel. Anteroglabella broadly prominent median tubercle that deeply embays rounded to obtusely pointed at front. Post- the pygidial F2, and an absence of spines. A eroglabella commonly having convex lateral postaxial median furrow is present during early sides and broadly rounded rear, Fi unde- ontogeny but usually becomes effaced during veloped and F2 weak; median node anterior the early or middle holaspid period. from midpoint. Basal lobes simple. Genae nor- Many late holaspides of O. hybridus from mally smooth, rarely having very weak scrob- western North America and North Greenland icules. Late holaspides may have tiny median possess an unusual, tiny, median opening or pit opening or pit on back slope of glabella, above and a short sagittal ridge on the posterior slope short sagittal ridge. Pygidium moderately to of the cephalon (Figs. 30,5,8,10 and 31). Simi- highly convex. Posteroaxis elongate, variable in lar indentations can also be seen on some width, weakly ogival to lanceolate. Border lack- specimens illustrated from eastern Newfound- ing spines, posterolateral swellings rare. land (Hutchinson, 1962, pl. 8, fig. 13a), Swe- Discussion. -Based on much published in- den (Westergird, 1946, pl. 9, fig. 25), the Robison—Cambrian Agnostida, Part I, Ptychagnostidae 53

Siberian platform (Egorova, Pegel, and Tcher- 51, fig. 6). Function of the opening is unknown, nysheva in Egorova and others, 1982, pl. 18, but it probably was glandular. fig. 3), and possibly Australia (Opik, 1979, pl. O. hybridus closely resembles O. seminula;

1 3

8a 9a 8b 9b

look. 8C 9c Pn1 Oc 17111c

1 Oa 1 1 a 10b 11b

Fig. 30. Onymagnostus hybridus (Brogger); 1,2,10,11, from Formation Ti, Tavsens Iskappe Group, North Greenland; 3-9, from Marjum Formation, House Range, Utah; all preserved in lime mudstone. /, Early holaspid exoskeleton with wide postaxial median furrow, MGUH 16.283 from GGU 218644, x 10. 2, Early holaspid pygidium with narrow postaxial median furrow, MGUH 16.284 from GGU 218644, x 10. 3,4, Middle holaspid cephalon and pygidium, latter with effaced postaxial median furrow; KUMIP 204284 and 204285 from 765, both x8. 5, Rare late holaspid cephalon with weak genal scrobicules; KUMIP 204286 from 765, x 6. 6,7,9, Late holaspid pygidia, KUMIP 204287-204289 from 765, all X 6. 8, Late holaspid cephalon with typically smooth genae, KUMIP 204290 from 765, x 6. 10,11, Cephalon and pygidium with solution-pitted surfaces; MGUH 16.285 and 16.286 from GGU 218647 and 218644, respectively; both x6. 54 The University of Kansas Paleontological Contributions—Paper 109

basin of west Texas, a single early holaspid cephalon of O. hybridas is associated with other agnostoids in a Cambrian boulder from a con- glomeratic unit of the Haymond Formation of Pennsylvanian age (Palmer and others, 1984). In North Greenland, O. hybridus is common in collections (GGU 218626, 218644, 218647) from 75 to 85 m above the base of Formation Ti of the Tavsens Iskappe Group of Peary Land. A single pygidium from Nyeboe Land, Fig. 31. Posterior cephalon of Onymagnostus hybridus (Brog- which Poulsen (1969) assigned to Ptychagnostus ger); KUMIP 204286 from 765 (same specimen as Fig. 30,5), X 15. Note the small median opening on the back punctuosus, is here reassigned to O. hybridus (see slope of the glabella. Extending downward from the open- P. punctuosus, Occurrence). ing is a short sagittal ridge that crosses the edge of the O. hybridus has a reported range from the glabella and a narrow occipital band, connecting to the upper P. atavus Zone to the upper P. punctuosus crest of the cephalic recess. A raised, narrow rim on the Zone. Generally, it is most common in the P. cephalic recess bounded the dorsal half of a cephalothoracic aperture on the enrolled exoskeleton before disarticulation punctuosus Zone. (for definitions of some terms, see Robison, 1964:515). ONYMAGNOSTUS SEMINULA however, O. hybridus can be differentiated by its (Whitehouse) simple rather than slightly elongate basal lobes, Figure 32 slightly shorter axis on both cephalon and Agnostus seminula WHITEHOUSE, 1939, p. 254, pl. pygidium, and usual lack of posterolateral 25, fig. 24; HILL, PLAYFORD, and WOODS, swellings on the pygidial border. 1971, pl. 13, fig. 1. Occurrence. —O. hybridus is a widespread ag- not Onymagnostus seminula (Whitehouse) ()Pm, nostoid. Specimens here assigned to the species 1979, p. 112, pl. 52, figs. 3 - 5; pl. 53, fig. I. have been previously described (see synonymy) Ptychagnostus seminula (Whitehouse) ROBISON, from Sweden, Norway, Denmark, England, 1982, p. 148-150, pl. 4, figs. 1-6. Czechoslovakia, Canada (eastern Newfound- land), United States (Texas, Utah), Australia, Diagnosis.—Exoskeleton moderately large and the Soviet Union (Siberian platform, Tur- with well-developed dorsal furrows. Cephalon kestan). moderately to highly convex. Axis long, aver- Hayes and Howell (1937:88) reported Tri- aging about 0.8 cephalic length in mature plagnostus cf. gibbus hybrida from the Porter Road holaspides. Anteroglabella rounded to obtusely Formation, along Porter Road, New Bruns- pointed at front. Posteroglabella having sub- wick, Canada; however, specimens were not parallel to slightly convex lateral sides, broadly described or illustrated. From the same forma- rounded rear; Fl undeveloped and F2 weak; tion and locality, I have collected (783) a few median node anterior from midpoint. Basal agnostoids that may represent O. hybridus, but lobes entire and slightly elongate, anterior ends poor preservation precludes confident identi- poorly defined. Genae smooth. Pygidium fication. highly convex; posterior part of acrolobe rising The first report of O. hybridus in the United steeply from border furrow in large holaspides. States (Robison, 1964) was based on a few Axis long, almost reaching posterior border specimens (collection 3309-CO) from a lime- furrow in largest holaspides. Posteroaxis stone bed 134m above the base of the Marjum weakly ogival. Border commonly with post- Formation, House Range, Utah. Additional erolateral swellings but lacking spines. collecting (765) has yielded more than 100 well- Discussion. —O. seminula has recently been preserved specimens from the same bed. A more fully diagnosed and discussed (Robison, single pygidium in collection 176 from 398 ni 1982:148-150). Additional representative speci- above the base of the Secret Canyon Forma- mens here are illustrated from Utah and North tion, northern Egan Range, Nevada, also prob- Greenland. ably represents this species. In the Marathon Occurrence. —O. seminula is known from Aus- Robison—Cambrian Agnostida, Part I, Ptychagnostidae 55

a

Fig. 32. Onymagnostus seminula (Whitehouse). Specimens preserved in limestone. 1,2, Cephalon and pygidium, MGUH 16.287 and 16.288 from GGU 271492; Formation 2, Bronlund Fjord Group, North Greenland; x5 and 5.5. 3,4, Cephalon and pygidium, KUMIP 204291 and 204292 from 305; Wheeler Formation, Wasatch Mountains, Utah; X5.5 and 6..5,6, Cephalon and pygidium, MGUH 16.289 and 16.290 from 271492, both X5. 7,8, Middle holaspid cephalon and pygidium, latter with weak postaxial median furrow; KUMIP 204293 and 204294 from 305; both X6.

tralia, the United States (Nevada, Utah), Can- 420 from boulders of the Cow Head Conglom- ada (western Newfoundland), Greenland, and erate. In North Greenland the species is rare to probably Sweden and Norway. Many collec- common in GGU collections 218614, 271411, tions with O. seminula were recently listed from 271428, 271488, 271489, and 271492 from the Nevada and Utah (Robison, 1982). From west- upper half of Formation 2 of the Bronlund ern Newfoundland, many specimens are in C. Fjord Group. O. seminula has an observed range H. Kindle collections 362, 378, 380, 409, and through most of the Ptychagnostus gibbus Zone.

56 The University of Kansas Paleontological Contributions-Paper 109

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