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Home , Canadaspis, Emeraldella, Leanchoilia, Margaretia, Morania, Naraoia

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS

July 24, 1984 Paper 111

EXCEPTIONALLY PRESERVED NONTRILOBITE AND FROM THE MIDDLE OF '

D. E. G. BRIGGS and R. A. ROBISON

Department of Geology, Goldsmiths' College, University of London, Creek Road, London SE8 3BU, and Department of Geology, University of Kansas, Lawrence, Kansas 66045

Abstract—For the first time arthropods with preserved soft parts and appendages are recorded from Middle Cambrian strata in Utah. Occurrences of four nontrilobite taxa are described, including Branchiocaris pretiosa (Resser) and ? sp. from the , ? sp. from the Wheeler Formation, and ? hanceyi, n. sp., from the . A small specimen of the giant predator Anomalocaris nathorsti (Walcott) also is described from the Marjum Formation. These occurrences extend upward the observed stratigraphie ranges of Anomalocaris, Branchiocaris, and questionably Emeraldella and Sidneyia. Emeraldella, Leanchoilia, and Sidneyia hitherto have been recorded from only the Stephen Formation in British Columbia. Further evaluation indicates that Dicerocaris opisthoeces Robison and Rich- ards, 1981, is a junior synonym of Pseudoarctolepis sharpi Brooks and Caster, 1956.

DURING RECENT years, intensive collecting has 1983). Although providing little new morpho- produced rare but diverse, soft-bodied or scler- logic data, the Utah specimens are important otized Middle Cambrian from several because of new information they provide about localities in Utah. Most of the taxa are the same the geographic and stratigraphie distribution of as or similar to those previously described from a rarely preserved part of the Middle Cambrian the famous of the Stephen For- biota. They support the notions that the Bur- mation in British Columbia (e.g., Whittington, gess shale biota is unusual only in its preserva- 1980; Collins, Briggs, and Conway Morris, tion (Conway Morris and Whittington, 1979) and probably is representative of upper open-

I Manuscript received March 6, 1984. shelf Middle Cambrian environments of west-

2 The University of Kansas Paleontological Contributions—Paper 111

with preserved appendages and soft parts to be Wellsville Mountains reported from Utah. • Repositories. —Illustrated specimens are with collections of either the National Museum of Natural History (USNM) or the University of Salt Lake City OS Kansas Museum of Invertebrate (KUMIP). Acknowledgments. —Several of the specimens were collected by Lloyd, Metta, and Val Gunther. Other single specimens were collected by Robert Drachuk, Robert Fife, Jeff Hancey, • and Thomas T. Johnson. A preliminary draft of this paper was improved by helpful sug- gestions from Virginia Ashlock, Desmond Col- lins, Simon Conway Morris, M. N. Rees, A. J. UTAH Rowell, and H. B. Whittington. Illustrations were prepared by Roger B. Williams. Some of the Gunther's collecting expenses were sup- ported by National Science Foundation grant EAR-8201428 to Prof. J. Keith Rigby of Brig- km 100 ham Young University. D. E. G. Briggs' work was carried out while on sabbatical leave at the Field Museum of Natural History, Chicago, Visiting Scientist Fig. I. Areas in Utah (dots) where Middle Cambrian fossils under the auspices of the were collected. Program, with additional support from the Royal Society and Goldsmiths' College Re- search Fund. Some publication costs were sup- ern North America (Conway Morris and Robi- ported by NSF grant EAR-8024066 to R. A. son, 1982). The purpose of this paper is to Robison. We are grateful for all of this help. document new occurrences of Anomalocaris and four taxa of unmineralized arthropods from the GEOLOGIC SETTING House Range and Wellsville Mountains of Inferred temporal relationships of most Utah (Fig. 1). stratigraphic units cited in this paper are shown Few nontrilobite arthropods have previ- in Figure 2. Lithostratigraphic nomenclature ously been described from Cambrian strata of for the House Range conforms to usage by Utah. Most of these are valves of phyllocarids Hintze and Robison (1975). Lithostratigraphic or protocaridids from various Middle Cam- units in the Wellsville Mountains need further brian formations (Walcott, 1886; Brooks and study and possible revision of nomenclature. Caster, 1956; Briggs, 1976; Gtinther and Middle Cambrian lithofacies in western Gunther, 1981; Robison and Richards, 1981). North America indicate the presence of a broad A single specimen of the aglaspid Beckwithia typa continental shelf. Thick deposits of shallow- was described by Resser (1931). Single Molaria- water, platform sediment accumulated along and Mollisonia-like specimens from the Wheeler the inner shelf. Commonly, a carbonate shoal Formation and two merostomelike specimens complex along the seaward margin of the plat- from the Spence Shale were illustrated by form was flanked by a restricted inshore basin Gunther and Gunther (1981). Two specimens on one side and deeper open shelf on the other from the Wheeler Formation were described by side (Robison, 1976; Aitken, 1978). During Conway Morris and Robison (1982) as the much of the Middle Cambrian two almost medusoid cf. P. nathorsti; however, those mutually exclusive biotopes were separated by now are known to be the jaws of Anomalocaris probable salinity and temperature barriers over nathorsti (Whittington and Briggs, 1982, in the carbonate shoals. An inner restricted-shelf press). Specimens described here are the first biofacies generally is characterized by sparse,

Briggs & Robison—Cambrian Arthropods and Anomalocaris 3

CO ZONES FORMATIONS Lu cc - shelf House Wellsville LLI restricted - shelf open - shelf open w polymeroids polymeroids agnostoids Range Mountains

Lie commonly barren 0 rt3 Weeks cr) — upper ›, co a C3) — _ ...... (I) CL) Eldoradia -J al lower

Z Marjum Bloomington < Bolaspidella punctuosus ET co 2 commonly barren < Ptychagnostus U atavus Wheeler — — in Ptychagnostus gibbus o —o Ptychagnostus praecurrens Perono psis Glosso pleura bonnerensis Spence Albertella Plagiura

Fig. 2. Interred temporal relationships of some stratigraphic units in Utah (see Robison, 1976, I984a . The Burgess shale of the Stephen Formation in British Columbia contains a fauna representative or the Ptychagnostus praecurrem and upper 0;7/1w/thaw zones. Formation names not relevant to this paper are omitted. Dashed lines denote uncertain position of boundaries. Thicknesses of units are not shown to scale.

low-diversity, polymeroid . An outer verse open-shelf trilobite fauna containing Bath- open-shelf biofacies is characterized by com- yuriscus and Elrathina above a restricted-shelf mon, high-diversity, polymeroid and agnostoid fauna dominated by Glossopleura. These faunas trilobites. Fossils are usually most abundant have traditionally been assigned to different near the seaward margin of the carbonate plat- zones (e.g., Howell and others, 1944; Loch- form facies. man-Balk and Wilson, 1958). Nevertheless, In places during the early Middle Cam- total stratigraphie ranges of both brian, carbonate shoals were poorly developed and Elrathina have been observed to overlap and disjunct. This allowed the intermingling of completely the range of Glossopleura (Robison, faunas that more commonly were confined to 1976). In the Spence Shale of the Wellsville either restricted- or open-shelf environments. Mountains of Bathyuriscus, Elrathina, and An example of such intermingling is the fauna Glossopleura are associated in the same beds of the Spence Shale in the Wellsville Moun- (Campbell, 1974: fig. 4). These distribution tains. The Spence is characterized by abundant patterns are part of the basis for proposed fossils and high taxonomic diversity (e.g., Res- abandonment of Bathyuriscus-Elrathina as a zone ser, 1939; Campbell, 1974). It has yielded one name (Robison, 1976). The patterns also are of the fossils, Leanchoilia? hanceyi, n. sp., which important with regard to interpretations that is described here. have been made about the depositional setting A general marine transgression during the of the Burgess shale in British Columbia. Middle Cambrian widely superimposed a di- The Burgess shale has been determined to 4 The University of Kansas Paleontological Contributions—Paper 111

represent part of a sediment apron that accu- indicative of a low-energy, gently sloping ramp. mulated adjacent to a near-vertical submarine Coeval, intertidal, carbonate platform litho- escarpment (Fritz, 1971; McIlreath, 1975, facies are no more than a few kilometers away. 1977). Using the uppermost occurrences of Fossils here described from the Wheeler Forma- Glossopleura as a time surface, Fritz (1971:1161- tion are preserved in similar rocks; however, 1163, fig. 2) calculated that minimum water the platform margin was probably a few tens of depth at the front of the escarpment exceeded kilometers away and the water was probably 200 meters. Based on observed distribution deeper. Paleogeographic reconstruction (e.g., patterns of faunas containing Glossopleura and Bambach, Scotese, and Ziegler, 1980) indicates Bathyuriscus-Elrathina, we suggest that the a position in equatorial latitudes. boundary between these faunas may have Many Wheeler and Marjum beds are un- greater ecological than temporal significance fossiliferous. Others range from sparsely to and inferred water depths during Burgess shale abundantly fossiliferous. Rare bedding surfaces deposition may be exaggerated. are covered with well-preserved, articulated Of the fossils described here, most are from remains of arthropods, , , the Wheeler and Marjum formations of the and other , as well as shells House Range. These formations represent dep- and the thalli of various noncalcareous . osition in an open-shelf basin, mostly at depths Regularly aligned fossils on the bedding sur- below storm wave-base, but probably less than faces are indicative of current action at the time 200 meters. Major lithofacies changes in the of burial. The fossils and associated matrix Wheeler and Marjum formations of the House show many features of the "smoth- Range were described by Robison (1964b). ered-bottom assemblages" described by Brett Further study of the Marjum by Brady and (1983), which were interpreted as being buried Koepnick (1979) has documented a transition by episodic storm deposition on a gently sloping from shallow platform to deeper shelf-basin shelf. More aerobic conditions in the Wheeler lithofacies. Fossils here described from the and Marjum sediments probably account for Marjum are preserved in thin-bedded, hemi- the much less common preservation of soft- pelagic lime mudstone and interbedded shale bodied organisms than in the Burgess shale.

SYSTEMATIC DESCRIPTIONS

ANOMALOCARIS Whiteaves, 1892 the specimen near the point where it disappears ANOMALOCARIS NATHORSTI (Walcott), beneath the matrix is rough compared to that of 1911 the remainder, and the matrix does not flake off it readily. Therefore, it has not proved possible Figures 3, 4 to reveal the remainder of the by prepa- ration. Simonetta and Delle Cave (1983) described The trunk bears a series of paired lobes, some specimens as "unassignable to any known each overlapping that immediately in front of phylum," but did not identify or name them. it. The lobes are broad based and subtriangular Whittington and Briggs (in press) have given a in outline, and each tapers to a rounded distal full description and synonymy. extremity. Eight lobes are preserved on the left New material. —Posterior portion of a com- side, corresponding to lobes 4 to 11 on complete plete individual, USNM 374593, part and specimens from the Burgess shale (Whittington counterpart. and Briggs, in press). Lobes 5 to 8 preserve fine Description. —The specimen is compacted linear rays running roughly parallel to their dorsoventrally, in parallel aspect. The counter- axes. part comprises the posterior portion of the A wide dark feature runs along the axis of animal only; the anterior portion is concealed the trunk, tapering slightly posteriorly (outline beneath the matrix on the part. The surface of clearly evident on the part), which presumably

Briggs & Robison—Cambrian Arthropods and Anomalocaris 5 represents the gut. The counterpart preserves a absence of evidence for these, the specimen series of lateral extensions of this dark trace, cannot be positively identified. Rays on the corresponding roughly in position to the lateral lobes have been observed only in the better lobes and presumably segmentally arranged. known A. nathorsti, however, and the Utah These extensions, which have not been ob- specimen is therefore assigned to this species in served in specimens from the Burgess shale, the absence of evidence to the contrary. reach the base of the lobes, and the dark area Although isolated limbs of A. canadensis and appears to overrun the margin of the specimen A. nathorsti (appendage F of Briggs, 1979) are posteriorly. This posterior expansion may be well known from Lower and Middle Cambrian due to seepage of material from the alimentary localities in western North America (Briggs, system (compare dark stain in splendens, 1979; Briggs and Mount, 1982; Collins, Whittington, 1971; also other Burgess shale Briggs, and Conway Morris, 1983; Whit- animals). The gut appears to bifurcate at the tington and Briggs, in press), such limbs have anterior extremity of the preserved trace, but not been discovered in Utah. Conway Morris this is an effect of preservation. A series of large and Robison (1982), however, recorded the jaw irregular patches of a nodular mineral flanks of Anomalocaris (then interpreted as the medu- the gut trace; these patches also correspond in soid Peytoia) from the middle part of the position to the lateral lobes and presumably are Wheeler Formation (Ptychagnostus atavus Zone) segmentally arranged, although some coalesce. of the House Range. They also recorded a Similar patches are preserved in some speci- second possible medusoid from the Spence mens from the Burgess shale (Whittington and Shale of the Wellsville Mountains. The latter Briggs, in press). The trunk terminates in a specimen, which is under study together with short, narrow projection that is poorly pre- additional material of the same organism, is served. The nature of a short curved feature on neither a medusoid nor the jaw of Anomalocaris; the left side of this projection is unknown. its affinities are presently unknown. The length of the specimen from the ante- Occurrence and associated biota. —The new rior margin of lobe 4 to the posterior termina- specimen of A. nathorsti is preserved in moder- tion is 51 mm. This probably represents just ately hard, pale-yellowish-brown, platy part- under half the total length (see restoration, ing, laminated, calcareous clayshale. It was Whittington and Briggs, in press), indicating collected about 60 m above the base of the an individual just over 100 mm long. Marjum Formation (Fig. 2) in the central Discussion. —Although only a portion of the House Range (Fig. 1) by Thomas T. Johnson. specimen is preserved, the outline of lateral The locality (347 of R. A. Robison; 3 of Rigby, lobes, presence of lobe rays, and direction and 1983:243), informally called Gully, is in degree of overlap between lobes are sufficient to a dry stream gully about 4.7 km east-northeast identify the specimen as Anomalocaris nathorsti. of Marjum Pass in the NWViSEVISE 1/4 sec. 4 Recent work by Whittington and Briggs (1982, (unsurveyed), T. 18 S., R. 13 W. (Marjum in press) has shown that Anomalocaris is the Pass 71/2-minute quadrangle map, U. S. Geo- largest known Cambrian predator, reaching logical Survey, 1972). lengths of up to half a meter. The head bears a A diverse, well-preserved biota has been pair of raptorial appendages and a circular jaw collected from the Sponge Gully site. Associ- previously known in isolation and interpreted ated with A. nathorsti are sponges ( carteri, as the medusoid Pe_ytoia. Although the append- Choia utahensis, Diagonella hindei, Diagonella sp., ages are similar to those of arthropods (Briggs, Hamptonia bowerbanki, Leptomitus metta, Pro- 1979), the unique combination of characters tospongia? elongata, Testiispongia venula, Val- suggests that Anomalocaris represents a separate ospongia gigantis; see Rigby, 1983), trilobites phylum. There are two species, A. canadensis, of (Bolaspidella n. sp., H_ypagnostus parvifrons, Mo- which only one relatively complete specimen is docia typicalis, Modocia n. sp., compacta, known (in addition to isolated limbs), and A. Pseudoperonopsis? sp., Ptychagnostus occultatus, nathorsti, of which several specimens are known. Ptychagnostus punctuosus; see Robison, 1964a, The two species are distinguished by the nature 1984a,b), other arthropods (Branchiocaris pre- of the head appendages (Briggs, 1979; Whit- tiosa, guntheri; see Robison and Richards, tington and Briggs, 1982, in press). In the 1981; this paper), a priapulid ( prolifica),

6 The University of Kansas Paleontological Contributions—Paper 111

Fig. 3. Anomalocaris mahorsti (Walcott); posterior body, USNM 374593; from locality 347, Marjum Formation, House Range; I, counterpart; 2, part; both x I.

undetermined lingulide , trace fos- right valve in the hinge region. KUMIP sils ( sp.), and algae ( fragmenta; 204795 is preserved in parallel aspect, the two see Fig. 9,3). valves symmetrical about the hinge line (Figs. The specimen described here extends the 7,3, 9, 1 ). Only KUMIP 204796 preserves evi- observed stratigraphie range of A. nathorsti up- dence of the cephalic appendages and probably ward into the lower part of the Ptychagnostus the distal tips of the pair of 'principal' append- punctuosus Zone (Fig. 2). ages (Briggs, 1976: text-fig. 2), which project beyond the carapace. A large subcircular fea- BRANCHIOCARIS Briggs, 1976 ture in the exfoliated anteroventral part of the BRANCHIOCARIS PRETIOSA (Resser), left valve of KUMIP 204797 probably repre- 1929 sents the carapace adductor muscle or its scar. Paired dark linear traces running approxi- Figures 5-9 mately normal to the axis may correspond to Briggs (1976) has given a full description divisions of the anterior part of the trunk. They and synonymy. are also evident where some of the right valve New material. —Three specimens, KUMIP has been removed in the anterior part of the 204795-204797, each including part and coun- trunk of KUMIP 204796. They may coincide terpart, and each showing soft parts. Several with the 'proximal element' of the limbs ob- • carapaces, including KUMIP 204792-204794. served in specimens from the Burgess shale Description. —KUMIP 204796 and 204797 (Briggs, 1976:10). Similar dark traces are evi- are compacted in lateral aspect, affording right dent in KUMIP 204795. In the posterior part and left lateral views, respectively (Figs. 5,1,2; of the trunk of KUMIP 204796 and 204797 the 7 ,1,2). The compaction of KUMIP 204796 is intersomite boundaries are apparent. There are slightly oblique, revealing part of the folded at least 30 trunk divisions. Large flaplike ap- Briggs & Robison—Cambrian Arthropods and Anomalocaris 7

carapaces from the same locality (Fig. 9,2-4) range in length from 36 to 65 mm. All display a small angular projection of the hinge line both anteriorly and posteriorly, and are almost sym- metrical about the midline, expanding slightly anteroventrally. Discussion. —Five known specimens of Pro- tocaris pretiosa (Resser, 1929) from the Middle Cambrian Burgess shale of British Columbia formed the basis for a redescription by Briggs (1976) who assigned the to a new , Branchiocaris. A large number of smaller specimens, apparently juveniles of the same species (Briggs, in preparation), have since been discovered on Mount Stephen at a new locality (9 of Collins, Briggs, and Conway Morris, 1983) in a geologic setting similar to the Burgess shale quarries. This locality yields also Glossopleura (D. H. Collins, personal com- munication, 1983). The specimens described here are the first of Branchiocaris with soft parts discovered outside British Columbia. The features preserved are sufficient to Fig. 4. Anomalocaris nathorsti (Walcott), USNM 374593, identify the specimens beyond reasonable doubt explanatory drawing if part (compare Fig. 3,2); stipple as conspecific with the material from British denotes nodular mineralized patches. Columbia. The exact number of trunk somites is not known. Although more than 30, there pendages of the left side of KUMIP 204797 are appear to be significantly fewer than the 46 apparent, overlapping posteriorly. The outline recorded in the two most completely preserved of the more anterior of these flaps is fairly clear: Burgess shale specimens (Briggs, 1976:8-9). gently convex anteriorly, and curving to run Length of the 30 somites immediately anterior approximately parallel to the valve margin. of the telson in KUMIP 204797 is also greater Only the telson extends beyond the posterior relative to that of the carapace than in the three margin of the valves (but is not evident in Burgess shale specimens in which this param- KUMIP 204795); KUMIP 204796 shows both eter can be measured. The sample is small, telson spines or processes. A dark trace in the however, and some variability is to be expected axial region of both KUMIP 204795 and in a multisegmented arthropod (as in recent 204796 may represent the gut. KUMIP 204795 branchiopod and myriapods, for shows lateral extensions of this trace in the example). In the absence of more distinct mor- anterior part of the trunk, which may represent phological differences, the specimens from digestive glands. A dark area lying dorsal of the Utah are assigned to the same species as speci- process projecting from the ventral margin of mens from British Columbia. the telson in KUMIP 204797 may indicate the Briggs (1976) redescribed the holotype of position of the anus. Dioxycaris argenta Walcott from the Ophir Shale The greatest length of the valves parallel to (lower Middle Cambrian, Glossopleura Zone) of the hinge line is 58 mm (KUMIP 204795), 63 the Wasatch Range, Utah, and pointed out the mm (204797), and 64 mm (204796). The total similarity in valve outline between it and sagittal length (from the anterior of the hinge Branchiocaris. He retained the latter as a sepa- line to the distal extremity of the hinge pro- rate genus, however, as Dioxycaris is based on a cesses) is about 68 mm in KUMIP 204797 and single poorly preserved valve lacking any trace 67 mm in KUMIP 204796. The length of the of soft parts, and bivalved arthropods with 30 somites anterior of the telson in KUMIP different soft-part morphologies may have very 204797 is about 43 mm. Laterally compacted similar carapaces (for example, Perspicaris recon- 1

Fig. 5. Brachiocaris pretzosa (Resser); KUMIP 204797 from locality 347, Marjum Formation, House Range; /, counterpart; 2, part; both X 2. Briggs & Robison—Cambrian Arthropods and Anomalocaris 9

intersomite boundaries

Fig. 6. Branchiocaris preliosa (Resser), KUMIP 204797, explanatory drawing of counterpart; t-14 denotes 14th somite anterior of the telson, other such numbers denote other somites (compare Fig. 5, 1 ).

dila and perfecta; Briggs, 1977, 1978). having larger terminal hinge processes, particu- On the basis of carapace outline, Robison larly at the posterior end." This is difficult to and Richards (1981:6) referred two specimens demonstrate on the basis of the holotype alone, from the upper Wheeler Formation (Ptychag- however, as "the posterior end of the hinge or nostus atavus Zone) of the Drum Mountains, fold is poorly preserved and partly destroyed as Utah, to Branchiocaris? sp. The discovery of new a result of some earlier worker's misguided specimens of B. pretiosa with soft parts now preparation" (Briggs, 1976:14). allows the range of the genus and species to be The type locality of D. argenta is probably extended with confidence to Utah. It also paved over by a highway (Briggs, 1976), and prompts a reconsideration of the possibility that therefore a more complete description based on B. pretiosa may be a synonym of Dioxycaris new topotype specimens is not likely. To avoid argenta. potential confusion between Dioxycaris and Briggs (1976) confined Dioxycaris argenta to Branchiocaris, which are now both known from the holotype, but noted that a number of the Middle Cambrian of Utah, we restrict the additional valves from other localities in the name D. argenta to the poorly preserved holo- Middle Cambrian of Utah and British Colum- type (USNM 15401), which is indeterminate bia may also belong to the genus. Robison and by present taxonomic standards. Briggs (1977: Richards (1981:7, 8) also tentatively assigned 613) took a similar action in dealing with the additional specimens to D. argenta from the poorly preserved lectotype of Canadas-pis ovalis Spence and Ute formations of the Wellsville from the Burgess shale. This action has the Mountains, Utah. They pointed out the simi- additional merit of focusing attention on the larity in outline between D. argenta and Pseudo- much more completely known arthropods from arctolepis sharpi Brooks and Caster, 1956, apart the Burgess shale and Marjum Formation. We from the apparent lack of prominent lateral assign isolated valves from the locality yielding spines in the former. They considered (1981:7) the soft - bodied Utah specimens to Branchiocaris that Dioxycaris differs from Branchiocaris "by pretiosa, and similar isolated valves from else- 1

3

Fig. 7. (Explanation on facing page.) Briggs & Robison—Cambrian Arthropods and Anomalocaris 11

Fig. 8. Branchiocaris pretiosa (Resser), KUMIP 204796, explanatory drawing of part; dashed lines denote details added from counterpart (compare Fig. 7,1). where to ?Branchiocaris pretiosa. present at the Mount Stephen locality. In Utah, From further evaluation of the three speci- B. pretiosa is present in the Marjum Formation mens originally assigned to Dicerocaris opisthoeces (Ptychagnostus punctuosu.s Zone) of the House Robison and Richards, 1981, we conclude that Range. Isolated valves of ?B. pretiosa are known they represent juveniles of Pseudoarctolepis sharpi. from British Columbia in the Eldon Formation Apparent differences between specimens, par- of Mount Bosworth (upper Oryctocephalus, = ticularly in the position and orientation of Bathyuriscus-Elrathina, Zone; Briggs, 1976). In lateral spines, have actually resulted from dif- Utah isolated valves are known from the ferent orientations of carapaces to bedding and Spence Shale (Glossopleura Zone; Robison and compaction in shale of the Wheeler Formation. Richards, 1981) and Bloomington Formation Therefore, D. opisthoeces is a junior synonym of (lower? Bolaspidella Zone; Briggs, 1976) of the P. sharpi. Wellsville Mountains, the Ute Formation (Glos- Occurrence and associated biota. —The new sopleura Zone; Robison and Richards, 1981) of specimens of Branchiocaris pretiosa are all pre- the Bear River Range, and the Wheeler For- served in pale-yellowish-brown to medium- mation (Ptychagnostus atavus Zone; Robison and gray, platy parting, laminated, calcareous clay- Richards, 1981) of the Drum Mountains. shale. All were collected from the lower Mar- jum Formation in the House Range by Lloyd EMERALDELLA Walcott, 1912 and Metta Gunther. The locality, stratigraphic EMERALDELLA? sp. occurrence, and associated biota are the same Figure 10 as described herein for Anomalocaris nathorsti. Specimens of B. pretiosa showing soft parts Material. —KUMIP 204791, part and coun- are known from British Columbia in the Bur- terpart. gess shale of the Stephen Formation on Description. —The specimen comprises a part Ridge (Ptychagnostus praecurrens Zone; Briggs, and incomplete counterpart compacted dorso- 1976); specimens of Branchiocaris from the Ste- ventrally in parallel-oblique aspect. The cuticle phen Formation of Mount Stephen (locality 9 is moderate-reddish-brown, presumably due to of Collins, Briggs, and Conway Morris, 1983) oxidized iron, and has exfoliated in places from may be conspecific. D. H. Collins (personal the underlying matrix, which is a pale-reddish- communication) reports that Glossopleura also is brown clayshale. The exoskeleton consists of a

Fig. 7. Branchiocaris pretiosa (Resser) from locality 347, Marjum Formation, House Range. 1,2, KUM I P 204796, part (after preparation) and counterpart, both X 1.7. 3, KUMIP 204795, part (after preparation; compare Fig. 9, /), x 2.0.

1 2 The University of Kansas Paleontological Contributions—Paper 111

Fig. 9. Branchiocaris pretiosa (Resser) from locality 347, Marjum Formation, House Range. 1, KUMIP 204795, part (before preparation; compare Fig. 7,3), x 1.2. 2, KUMIP 204792, counterpart of laterally compacted carapace, x 1.1. 3, KUMIP 204793, counterpart of laterally compacted carapace associated with Morania fragmenta Walcott (dark spots) and possible coprolites (dark curved strands), X 1.1. 4, KUMIP 204794, counterpart of laterally compacted carapace, X 1.1. cephalic shield and 11 trunk tergites. Internal part; they terminate in a straight lateral margin structures are indicated by color variations, and subparallel to the axis of the trunk. Although there is evidence of poorly preserved limbs. the outline of the more posterior pleurae is The cephalic shield is semicircular in out- obscured, the tergites appear to increase in line. An axial structure, delimited by darker width to about the fourth, the trunk then red color, bifurcates anteriorly into two ante- tapering gradually to about the seventh and rolaterally directed spurs. To the left of the axis more rapidly in the posterior somites. The are two subcircular gaps in the cuticle, the telson is not clearly preserved. nature of which is unknown. Faint traces of The darker red axial structure in the ceph- four appendages extend beyond the margin of alic shield continues posteriorly through the the cephalic shield on the right side, at least the trunk as a linear feature flanked by circular to posterior two being long and slender. ovoid structures in at least the first six trunk Lateral margins of trunk tergites are not somites. These may represent the gut trace and clear because most are either exfoliated or laterally extending digestive glands (compare compacted against the limbs beneath. The out- Naraoia; Whittington, 1977; Robison, 1984b). line of pleural regions on the left side of the two Abaxial of the gut trace are paired nodular anteriormost tergites is evident on the counter- features that apparently coincide with inter-

Briggs & Robison—Cambrian Arthropods and Anomalocaris 13

2

Fig. 10. Emeraldella? sp.; KUMIP 204791 from locality 716, Marjuni Formation, House Range; /, part, x 1.5; 2, explanatory drawing.

somite boundaries from the posterior margin of Whittington, 1979), Alalcomenaeus (Whitting- the cephalic shield to the posterior margin of ton, 1981), Emeraldella and Leanchoilia (Bruton the ninth tergite. These nodular features may and Whittington, 1983) of known Cambrian represent sites of muscle attachment. Linear arthropods. The aglaspidids have a phosphatic features outlined in darker red, particularly on cuticle that is characteristically tuberculate, and the left side of the trunk, extend laterally from the head shield is wider than succeeding trunk the axis and then curve posterolaterally, almost tergites. New material of Alalcomenaems- from the reaching the margin of the tergites. They do Stephen Formation of British Columbia (lo- not appear to represent intersomite boundaries, cality 9 of Collins, Briggs, and Conway Morris, which were presumably oriented more normal 1983) shows that it has 11 and not 12 trunk to the axis, and may represent a segmented somites, but the cephalic shield is more rec- inner branch of the trunk appendages. Indis- tangular in outline than in the Utah specimen, tinct outlines evident below the exfoliated cuti- and bears eyes, and the trunk tapers rather than cle on the anterior and posterior right of the expanding posteriorly. Emeraldella and Lean- trunk may represent outer rami of the append- choilia are superficially similar in dorsal view ages. (disregarding the head appendages and telson). Discussion. —Lack of evidence for the nature The head shield of Leanchoilia, however, is of appendages and telson of this arthropod larger and tapers forward; that of Emeraldella is makes the determination of its affinities dif- short, semicircular, and similar to the Utah ficult. The cephalic shield, 11 trunk tergites, specimen. In addition, Emeraldella has long and biratnous appendages eliminate all but the segmented cephalic limbs projecting beyond the aglaspidids (Raasch, 1939; Briggs, Bruton, and margins of the exoskeleton in a fashion similar

14 The University of Kansas Paleontological Contributions—Paper 111

Fig. II. Leanchoilia? hanceyi, n. sp.; holotype, USNM 374592; Spence Shale, Wellsville Mountains; X 2.2. /, Part photographed under alcohol. 2, Part lightly coated with magnesium oxide and photographed in low-oblique light. to those preserved in the Utah specimen (com- Occurrence and associated biota. —The specimen pare Bruton and Whittington, 1983: pl. 5, fig. of Emeraldella? is preserved in hard, pale-red- 23), and unlike the head appendages of Lean- dish-brown, platy parting, laminated, calcare- choilia. Although the Utah specimen cannot be ous clayshale. It was collected about 300 m identified with confidence, it shows a greater above the base of the Marjum Formation (Fig. similarity to Emeraldella brocki than to any other 2) in the House Range (Fig. 1) by Val Gunther. known Cambrian arthropod. The locality (716 of R. A. Robison; 1 of Rigby, Briggs & Robison—Cambrian Arthropods and Anomalocaris 15

position is about 240 m higher in the Marjum Formation. Associated with Emeraldella? sp. at the Red Wash locality are sponges (Choia hindei, Diagonella cyathiformis, Hampton la bowerbanki, Leptomitus metta; see Rigby, 1983), trilobites (Bolaspidella n. sp., H_ypagnostus parrafrons, Mo- docia typicalis, Pseudoperonopsis? sp., Ptychagnostus germanus, Schmalenseeia sp., Utaspis marjumensis; see Robison, 1964a, 1984a), other arthropods (Perspicaris? ellipsopelta, Tuzoia guntheri; see Robison and Richards, 1981), undetermined lingulide brachiopods, trace fossils (Planolites sp.), and algae (Moran la fragmenta). If this tentative identification could be con- firmed, it would represent the first record of Emeraldella outside the Walcott quarry (Bruton and Whittington, 1983:559) in British Colum- bia. Also, it would extend the observed bio- stratigraphic range of Emeraldella from the Ply- chagnostus praecurrens Zone to the upper Ptychag- nostus punctuosus Zone (Fig. 2).

LEANCHOILIA Walcott, 1912

LEANCHOILIA? HANCEYI, n. sp. Figures ii, 1 2 Etymology. —The species is named for Jeff Hancey of Farmington, Utah, who collected the holotype. Holotype. —Part and incomplete counter- part, USNM 374592, the only known speci- men. Description. —The specimen is compacted in parallel aspect (dorsoventrally). The exoskel- eton is elongate and divided into a cephalic shield, a trunk of 11 tergites, and a telson. Attitude of the longitudinal axis of the specimen to the bedding (i.e., tilt to the horizontal) is not Fig. 12. Leanchoilia? hanceyi, n. sp., USNM 374592, explan- known and in the absence of additional speci- atory drawing of part (compare Fig. 11). mens the effect of this orientation on the pre- served configuration cannot be assessed. 1983:243), informally called Red Wash, is The cephalic shield is subrectangular in about 4 km due south of Wheeler Amphitheater outline, the width slightly expanding anteriorly. in lower ledges along the south side of a large The anterior margin is gently convex, the wash in the SWIANW 1 /4 sec. 24 (unsurveyed), posterior more strongly so. The central part of T. 17 S., R. 13 W. (Marjum Pass 7'/2-minute the cephalic shield (about 60 percent of the quadrangle map, U. S. Geological Survey, width) is exfoliated and may be part of a more 1972). convex axis that extends the length of the trunk. The lithology and biota at the Red Wash A pair of small semicircular features projecting locality arc similar to those at Sponge Gully, beyond the anterior margin of the cephalic about 6.5 km south; however, the stratigraphic shield may represent eyes. 1 6 The University of Kansas Paleontological Contributions—Paper 111

Trunk tergites expand slightly in both width onymous with Actaeus armatus, which is based on and length as far as the fourth or fifth, these a single imperfectly preserved specimen. A dimensions decreasing gradually beyond that large collection of A. cambricus from the Middle point. The posterior margin of the tergites is Cambrian Stephen Formation of Mount Ste- gently concave anteriorly at the front of the phen (locality 9 of Collins, Briggs, and Conway trunk, becoming gradually straight at about the Morris, 1983) is presently under study (Briggs, sixth tergite, and then convex anteriorly in in preparation) and shows that this arthropod tergites immediately in front of the telson. had 11 tergites. A. cambricus is much narrower Folding of the compacted cuticle parallel to the than Leanchoilia, and therefore similar to the lateral margin of the trunk indicates a wide specimen described here, and has a more rec- axial region that becomes relatively narrower tangular cephalic shield. It also possesses eyes. posteriorly (Fig. 11,2). An even greater concen- The telson, however, is paddle shaped, expand- tration of folding adjacent to the trunk margin ing to a straight posterior margin fringed with suggests that the pleural regions may even fold spines. Leanchoilia superlata has a telson essen- underneath in the anterior tergites at least; tially identical to that in the Utah specimen, but sharp angular terminations are evident in its head shield is pointed anteriorly, and ex- tergites 10 and 11. tends into a dorsally curved 'snout.' The ante- The outline of the telson is partially ob- rior margin of the cephalic shield in L. superlata scured by a dark stain (Fig. 11, 1 ), which would appear less pointed in specimens pre- probably represents organic material exuded served tilted posteriorly to the bedding, and from the anus (compare Marrella splendens,. such tilting would also increase the anterior Whittington, 1971). The telson is triangular in concavity of the posterior margin of the ter- shape, tapering to a point, and bearing at least gites. However, the shield of L. superlata would four pairs of lateral spines, graded in length. not become as blunt anteriorly as in the Utah Additional spines may have been removed at a specimen. The ratio of maximum width (at the break in slope along the anterolateral margins 4th or 5th tergite) to length (from the anterior of the telson. margin of the cephalic shield to the distal tip of A dark linear stain, which is clearly evident the telson) is much greater in L. superlata than in when the specimen is immersed in alcohol (Fig. the Utah specimen. The ratio in specimens of 11, 1 ), may represent a gut trace. This, together L. superlata preserved in parallel or parallel- with the stain around the telson, suggests that oblique aspect figured by Bruton and Whit- the specimen represents a carcass rather than tington (1983: pl. 13, fig. 79, 81), together with an exuvia, and that although appendages are additional material in Walcott's collection, not evident, they may be preserved beneath the ranges from 37 to 53 percent. That in the Utah exoskeleton. specimen is 29 percent. If the possibility of The specimen is 59.5 mm in length from the lateral expansion during compaction is dis- anterior margin of the cephalic shield to the tip counted (Walton, 1936; Briggs and Williams, of the telson. Maximum width is 17.5 mm at 1981), this difference must be a function of the the fourth trunk tergite. original width and convexity of the arthropod. Discussion. —In the absence of additional Bruton and Whittington (1983:578) dis- specimens (to allow three-dimensional restora- cussed additional species of Leanchoilia and con- tion) and information about appendages, the cluded that none appears valid. One of these, affinities of this arthropod remain equivocal. A L. persephone Simonetta, 1970, is characterized head shield, 11 trunk tergites, and a short spiny by a much narrower trunk than L. superlata and telson are also present in Alalcomenaeus cambricus therefore merits comparison with the present (Whittington, 1981; Briggs, in preparation) specimen. Of the six specimens assigned to L. and Leanchoilia superlata (Bruton and Whit- persephone by Simonetta (1970:38), Bruton and tington, 1983). Both of these arthropods have a Whittington (1983:578) considered four pair of large branched head appendages, which (USNM 155635, 155646, 155652, 155653) to although not evident, may have been present in be unidentifiable. We concur with this assess- the specimen described here. ment, although USNM 155653 shows a poorly Alalcomenaeus cambricus is poorly known preserved elongate telson with spines and a (Whittington, 1981) and may prove to be syn- rounded anterior margin to the cephalic shield.

Briggs & Robison—Cambrian Arthropods and Anomalocaris 17

Fig. 13. Leanchoilia superlata Walcott; USNM 155651 from Walcott quarry (35k) (holotype of Leanchoilia persephone Simonetta, 1970), Burgess shale, Stephen Formation, British Columbia; I, counterpart in oblique light, x 2.5; 2, explanatory drawing.

It is probably an obliquely compacted L. super- counterparts are known (the specimens have lata. Both of the other two specimens, USNM split along the dorsal surface of the exoskeleton) 155649 and the holotype 155651, show the and the outlines are not well defined. The better characteristic telson, and part of a great ap- preserved of the two (Fig. 13, USNM 155651) pendage is evident on the former. The trunk in illustrates the nature of the preservation. The both appears relatively narrow, but only the cephalic shield is rounded anteriorly, there are

18 The University of Kansas Paleontological Contributions—Paper 111

4

Fig. 14. Sidneyia? sp. from locality 114, Wheeler Formation, House Range. I, KUMIP 204799, X 2.3. 2, Explanatory drawing of KUMIP 204799. 3, Explanatory drawing of KUMIP 204798. 4, KUMIP 204798, X 1.3.

11 tergites, and the telson is clearly that of the anterior cephalic snout characteristic of Leanchoilia. The gut trace (dark nodular masses, Leanchoilia but it may also be preserved in the presumably apatite) and telson, however, are matrix of the part, due to the oblique compac- significantly displaced to the left (right in coun- tion. We agree with Bruton and Whittington terpart) indicating a pronounced obliquity of that L. persephone should be synonymized with compaction, and the outline of the right margin L. superlata. The Utah specimen, however, of the trunk is indistinct suggesting that it is shows no evidence of oblique compaction and partly obscured in the matrix of the unknown we therefore designate it a new species, and part. Thus, the narrowness of the trunk is an tentatively assign it to Leanchoilia. effect of preservation. There is no evidence of Occurrence and associated biota. —The single Briggs & Robison—Cambrian Arthropods and Anomalocaris 19

?endite spines

Fig. 15. Sidneyia? sp.; reconstructed limb based on KUMIP 204798 and 204799.

specimen of L.? hanceyi is preserved in hard, L.? hanceyi. Rigby (1980) described the sponge medium-dark-gray, flaggy parting, noncalcar- magna and an undescribed specimen eous mudshale. It was collected near the middle resembling Vauxia gracilenta has been subse- of the Spence Shale (Fig. 2) in Cataract Canyon quently collected (KUMIP 113279). Robison on the west side of the Wellsville Mountains and Richards (1981) described representatives (Fig. 1). The locality is in the NEVINE1/4 sec. of the larger bivalve arthropods Canadaspis and 23, T. 10 N., R. 2 W. (Brigham City 7'/.i- Tuzoia. Conway Morris and Robison (1982) minute quadrangle map, U. S. Geological Sur- described a specimen superficially resembling vey, 1955), about 4 km north of Brigham City, the jaw of Anomalocaris nathorsti. Also, many Box Elder County, Utah. representatives of the Spence biota from the The Spence Shale of the Wellsville Moun- Wellsville Mountains have been illustrated by tains contains a diverse biota representing the Gunther and Gunther (1981). agnostoid bonnerensis Zone and inter- mingled taxa of the polymeroid Glossopleura and SIDNEYIA Walcott, 1911 Spence Oryclocephalus zones. Descriptions of the SIDNEYIA? sp. biota from Cataract Canyon and nearby lo- Figures 14, 15 calities are recorded in several publications. Resser (1939) described several species of tri- Material. —Two incomplete specimens of ap- lobites as well as a few species of brachiopods, pendages, KUMIP 204798 and 204799, each hyolithes, priapulids, and echinoderms. Robi- including part and counterpart. son (1965), Robison and Sprinkle (1969), and Description of KUMIP 204798. —This speci- Sprinkle (1973) described additional echino- men (Fig. 14,3,4) preserves a pair of segmented derms. Robison (1969) described two different appendages in lateral aspect. The designation together with some associated trace left and right is based on the assumption that fossils. Campbell (1974) documented 54 species the gnathobasic spines (see below) are situated of trilobites and 3 species of echinoderms from nearer to the anterior than to the posterior face the Spence Shale in Antimony Canyon, which of the limb (compare Bruton, 1981, fig. 106a); is about 2 km south of Cataract Canyon. the part then affords a view of the anterior face Sattert Ilwait (1976) described representatives of of the appendages. Most of the left appendage, the algae and Marpolia. Many speci- apart from the distal and proximal extremities, mens of the alga Morania fragmenta are on pieces is preserved. Partial preparation of the part has of mudshale with the part and counterpart of revealed some gnathobasic spines and part of 20 The University of Kansas Paleontological Contributions—Paper 111

the questionable fourth podomere of a second number of podomeres than similar muscles in appendage, which appears to be preserved fac- living arthropods, but there is no obvious alter- ing the more complete one. The symmetrical native interpretation for the structure. arrangement of the two limbs about a midline Description of KUMIP 204799. —This speci- suggests that they may represent both members men (Fig. 14,/, 2) preserves the distal portion of of an opposing pair. The rest of the arthropod is a slightly larger appendage apparently similar not preserved. The cuticle ranges in color from to that described above. The limb curves ven- dark brown to dusky yellow. trally and the ventral side is armed with elon- Near the proximal end of each appendage gate spines of varying width. Articulations the ventral margin bears a row of short spines between podomeres are not clear except for one that face ventrolaterally toward the opposing separating the two distalmost spines from the limb. These probably functioned in capturing rest of the fragment. By analogy with Sidneyia and processing food and may therefore be (Bruton, 1981), however, this specimen may termed gnathobasic. The cuticle connecting the represent podomeres 5, 6, and 7 and the distal row of spines to the limb is incompletely pre- claw. Figure 15 is a composite reconstruction served. Preparation of the area dorsal and based on this assumption, using both speci- proximal of these spines has failed to reveal mens. more spines, such as might have been borne by Discussion. —As Briggs (1979:657) has a coxa (Bruton, 1981: figs. 46-48); however, pointed out, individual limbs of arthropods preservation is poor and they may have been may provide little evidence of affinity. Of destroyed. A dorsal extension of the proximal known Cambrian arthropods, however, the part of the right limb (Fig. 14,4) may represent specimens illustrated here show a striking simi- a coxal bar. A number of lines are preserved larity to the limbs of Sidneyia inexpectans. The traversing the cuticle in this proximal area in only other Cambrian arthropod with a similar the left limb (Fig. 14,3) and it is difficult to limb is Emeraldella brockt (Bruton and Whit- determine which represent articulations. The tington, 1983: fig. 65), but the distal podomere boundary between podomeres is assumed, how- in that arthropod is elongate and terminates in ever, to coincide with a pronounced angle, a 'foot' of four short spines. The preserved concave dorsally, in the dorsal margin of the basal spines in KUMIP 204798 (Fig. 14,3,4) limb. By analogy with Sidneyia (Bruton, 1981), may represent either the endite or ventral part this articulation is considered to represent that of the gnathobasic lobe. The dorsal flexure between podomere 1 (attached to the coxa) and between podomeres 1 and 2, the configuration the remainder of the limb. of podomeres, and the presence of ventral The distal margins of podomeres 2, 3, and 4 spines and a terminal 'claw' are all features of are clearly evident (Fig. 14,4). Double struc- Sidneyia (Bruton, 1981:637, figs. 46-48). The tures are presumably the result of overlap reconstructed limb (Fig. 15) shows more and between podomeres. The dorsal margin is longer ventral spines than does any limb stepped at the articulations and this may indi- figured by Bruton, although there is some cate the former position of spines. Podomeres variability in Sidneyia appendages from the Bur- taper distally as the limb narrows, and increase gess shale (compare Bruton, 1981: figs. 46-48). slightly in length in podomeres 2 to 5. Pod- The size of both Utah specimens indicates a omeres 3 to 5 bear ventral spines that appear to larger individual than those from the Burgess increase in length toward the distal end of the shale. Approximate scaling based on Bruton's limb, but their terminations are not evident. (1981) reconstruction, assuming body length is The articulation between podomeres 5 and 6 is about 3.8 times limb length, suggests a body not clear. more than 27 cm long. This is some three times A dark linear trace running from the proxi- larger than the upper end of the size range mal part of the ventral margin of podomere 2, observed in the Burgess shale (Bruton, 1981: through 3 and 4 to the mid-dorsal margin of 625). podomere 5 (Fig. 14,4) may represent a mus- The most complete of the Sidneyia-like ap- cle. It is not clear why a single muscle should be pendages (KUMIP 204798) was collected by preserved nor why it extends through a greater Robert Drachuk. A less complete specimen

Briggs & Robison-Cambrian Arthropods and Anomalocari 21

(KUMIP 204799) was collected by Robert Fife. that is supplied by water piped from Swasey Both specimens subsequently came into the Spring. possession of Lloyd Gunther, who contributed The locality has yielded abundant fossils of them to the University of Kansas Museum of the Ptychagnostus atavus Zone. Associated taxa Invertebrate Paleontology. have been listed by Robison (in press) and Occurrence and associated biota. -Both of the include 13 species of trilobites, one other ar- Sidneyia-like appendages are preserved in light- thropod (Pseudoarctolepis sharpi), jaws of Anoma- gray, platy parting, laminated, calcareous clay- locaris nathorsti, and a new species of the ony- shale. They were collected about 100 m below chophoran , an undetermined species of the top of the Wheeler Formation (Fig. 2) on inarticulate brachiopod, a new species of the the east side of the House Range (Fig. 1). The sponge Choia, and 2 species of noncalcareous locality is on the crest of a low, north-trending algae. Several of the invertebrate species have ridge in section 24 (unsurveyed), T. 16 S., R. been described by Robison (1971, 1982), Robi- 13 W. (Swasey Peak Th-minute quadrangle son and Richards (1981), and Conway Morris map, U. S. Geological Survey, 1972), and and Robison (1982). The paleoecology has about 700 m south of a stock-watering trough been discussed by Robison (in press).

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