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PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 2795, pp. 1-1 8, figs. 1-7 October 9, 1984

On the Relationships of the Triassic-Liassic Redfieldiiform Fishes

BOBB SCHAEFFER'

ABSTRACT A survey of character distributions among the sumably independent reduction of the branchios- extinct lower actinopterygians has corroborated tegal series. the hypothesis that the freshwater, Triassic-Liassic The sister group of the redfieldiiforms among redfieldiiform fishes form a monophyletic group. the other extinct lower actinopterygians remains This proposal is based mainly on the pattern of unknown, but a survey ofthe dermal skull in these the dermal snout, loss of anterior nares, and pre- fishes has provided a hypothetical "sister" pattern.

INTRODUCTION Character analysis in the palaeonisciforms The primary purpose of the present paper and other extinct lower actinopterygian is to attempt a cladistic analysis ofone group groups has lagged well behind that for the ofextinct lower actinopterygians that has long extinct neopterygians. The reasons for this been regarded as a "natural" one, namely, include the absence of close living relatives, the Redfieldiiformes. They are Triassic and the apparent paucity of useful characters in early Jurassic freshwater fishes (fig. 1) whose taxa that are frequently represented by com- remains have been found in continental sed- pressed and inadequately preserved dermal iments in Australia, South Africa, Zambia, skeletons, the fragmentary fossil record, and Morocco, eastern and western United States, the not inconsiderable problems of morpho- and questionably in Madagascar. The design logical interpretation. More or less three di- of the redfieldiiform skeleton has suggested mensional specimens that can be prepared affinity with several other extinct lower ac- chemically or by air abrasion may yield a tinopterygian groups, but there has been no great deal of information, but they represent consensus about relationship. only a small fraction ofthe nearly 200 genera In regard to the living lower actinopteryg- in this paraphyletic assemblage. ians, Patterson (1982) has recently defined

I Curator Emeritus, Department of Vertebrate Paleontology, American Museum of Natural History.

FIG. 1. Restorations of three redfieldiiforms. A. Brookvalia. After Hutchinson, 1973 and AMNH 4706, 9254. Flank squamation omitted. B. Daedalichthys. After Brough, 1931 and BMNH 17532-3. C. Cyonichthys. From Schaeffer, 1967. 1 984 SCHAEFFER: REDFIELDIIFORM FISHES 3 two monophyletic groups, the Cladistia for fig. 54), and that the two groups arose from the polypteroids, and the Chondrostei for the a palaeonisciform complex including the acipenseroids and polyodontoids plus their Elonichthyidae, Acrolepidae, and the Rhad- fossil relatives. This restricted use ofthe term inichthyidae (ibid., p. 346). In recent pre- Chondrostei makes it still more imperative cladistic classifications ofthe extinct and liv- that the various taxa ofextinct lower actinop- ing actinopterygians (e.g., Andrews et al., terygians be restudied. The suspected pa- 1967; Romer, 1967) the Redfieldiiformes are raphyly ofnumerous fossil non-neopterygian listed as a suborder or order of the Chon- categories is emphasized by Patterson's (1982, drostei without comment on relationship. fig. 3B) decision to include the palaeonisci- Hutchinson's (1978) last paper on the red- form genus Pteronisculus in a trichotomy with fieldiiforms, which is mainly concerned with the Chondrostei and the Neopterygii on the the genus Helichthys, includes alternative basis of five shared characters. In addition, cladograms for the relationships ofthis genus Gardiner (in press) has concluded that the to the three redfieldiiform families that he Devonian palaeonisciform genera Mimia and defined in 1973 (the Brookvaliidae, Schizur- Moythomasia are successive sister taxa to the ichthyidae, and Redfieldiidae). Prior to his remaining actinopterygians. As such, they death in 1978, Peter Hutchinson and I had should provide us with information on the planned to write a joint paper on redfieldi- primitive state for the actinopterygian brain- iform affinities and interrelationships. case (Mimia is represented by abundant three- The present paper is dedicated to his mem- dimensional material), palate, dermal skull, ory. axial skeleton, fins, and squamation. This information, much of it recently acquired, is ABBREVIATIONS of importance in obviously considerable AMNH, The American Museum of Natural His- working out the patterns of character distri- tory bution within the palaeonisciforms and the BMNH, British Museum (Natural History) redfieldiiforms, and in relation to seeking a UTVPC, University of Texas Vertebrate Paleon- sister group for the latter. tology Collection Discussion of redfieldiiform relationships (see summary in Schaeffer, 1967, p. 329) ef- Anatomical abbreviations are included in the fectively began with Stensio's (1921) opinion legend for figure 4. that the catopterids (=redfieldiids) and the SYSTEMATIC RESUME colobodontids (=perleidids) should be grouped in the family Catopteridae, which, In order to facilitate later discussion, a di- he believed, is closely related to the palaeo- agnosis ofthe Redfieldiiformes is included in niscids. Lehman (1966) placed both fami- this section along with a list of genera ar- lies in the order Perleidiformes, which he ranged, as far as practicable, by character dis- considered to be one of numerous orders of tribution (fig. 6), relative age and source area. fossil, non-teleost actinopterygians (ibid., p. The vertical distribution of the Newark su- 71). Brough (1931, 1934) first considered the pergroup genera is summarized in Olsen, Catopteridae to be "closely related to, and McCune and Thomson (1982, fig. 7). derived from, the Palaeoniscidae," and, in DIAGNOSIS: Lower actinopterygians (non- 1936, to be derived from another palaeon- neopterygians) with a terminal or subtermi- isciform family, the Dicellopygidae. Schaef- nal gape, fusiform body outline and an equi- fer (1967, 1973) has favored derivation from lobate, hemiheterocercal tail. The braincase generalized palaeoniscids, while Lowney (Ms) is typically palaeonisciform with an open oti- has tentatively proposed a sister-group rela- co-occipital fissure and a nearly vertical hyo- tionship with the rhadinichthyid palaeonis- mandibular facet. The parasphenoid is short, ciforms. Hutchinson (1973, p. 345), suggest- with well-developed ascending processes. The ed that the redfieldiiforms and the vomerine area is covered by elongated paired perleidiforms had a common ancestor (ibid., tooth plates (in Ichnolepis). The endoptery- 4 AMERICAN MUSEUM NOVITATES NO. 2795 goids are relatively large and dentigerous. The 8. Molybdichthys Wade, 1935. Middle Triassic dermal snout is composed ofa median rostral (?Ladinian). Same locality as Schizurichthys. and postrostral, paired nasals and paired 9. Daedalichthys Brough, 1931. Lower Triassic "premaxillae" (=premaxillo-antorbitals of (Scythian). Same locality as Atopocephala. some authors). The single nostril is surround- 10. Cionichthys Schaeffer, 1967. Upper Triassic (Middle-Late Carnian) Chinle Group and ed by the nasal, adnasal and the enlarged Dockum Formation, western USA; Newark "premaxilla." The nasal is excluded from the Supergroup, eastern USA. orbit by the adnasal. The maxilla is fixed and 11. Redfieldius Hay, 1899. Lower Jurassic (Het- expanded posteriorly. The preopercular is tangian-Sinemurian), Newark Supergroup, angled; the subopercular is larger than, or eastern USA. about equal to, the size ofthe opercular. Both 12. Dictyopyge Lyell, 1847. Upper Triassic (Mid- a dermohyal and an antopercular are present dle Carnian), Newark Supergroup, eastern in the more generalized taxa. There is a sin- USA. gle, platelike branchiostegal (two in Daedal- 13. Mauritanichthys Martin, 1982. Upper Trias- sic, Argana Valley, Western Atlas, Morocco. ichthys) and a single median gular. The der- 14. Lasalichthys Schaeffer, 1967. Upper Triassic mopterotic is large and rectangular. The (?Carnian), Chinle Group and Dockum For- shoulder girdle includes a clavicle, postclei- mation, western USA. thrum, and a presupracleithrum (observed in 15. Synorichthys Schaeffer, 1967; Schaeffer and Helichthys). Fringing fulcra are probably Mangus, 1970. Upper Triassic (?Carnian), present on all fins. Basal fulcra border the Chinle Group and Dockum Formation, west- unpaired fins, including both lobes ofthe cau- ern USA; Newark Supergroup, eastern USA. dal. The rays of the remote, opposite dorsal Genera 1 through 5 were included by and anal fins are more numerous than the Hutchinson (1973) in his Brookvaliidae and basals. The scales are rhomboidal, with peg- 12, 14 and 15 in the Redfieldiidae. Schizur- and-socket articulation, and with dentine and ichthys was the only genus assigned to the ganoin layers. Family Schizurichthyidae. Hutchinson's (1973, 1978) division of the redfieldiiforms into the Brookvaliidae, Schi- CHARACTER ANALYSIS zurichthyidae and the Redfieldiidae left the The characters discussed below are ar- genus Helichthys (ibid., 1978) in an indeter- ranged as follows: neurocranium, snout, cir- minate status. The potential monophyly of cumorbital series, skull roof, cheek area, these families and the affinities of Helichthys opercular series, palate, mandible, paired and will be considered in the section on cladistic unpaired fins and squamation. analysis. NEUROCRANIUM: The only three-dimen- The redfieldiiform genera that I presently sional redfieldiiform neurocranium (UTVPC recognize are: 31089-44) comes from the Upper Triassic Dockum in Howard 1. Atopocephala Brough, 1934. Lower Triassic Group County, Texas. (Scythian), Lower Cynognathus Zone, Karroo On the basis of the incomplete skull roof, it Series, Orange Free State, South Africa. can be assigned either to Lasalichthys or Syn- 2. Schizurichthys Wade, 1935. Middle Triassic orichthys (Schaeffer, 1967, p. 315 and pl. 19). (?Ladinian), Hawkesbury Sandstone, New As noted in the diagnosis (above), the general South Wales, Australia. aspect of this braincase is palaeonisciform 3. Ischnolepis Haughton, 1934. Lower Triassic with an open otico-occipital fissure and a (Scythian), Madumabisa Shales, Zambia. nearly vertical hyomandibular facet. Al- 4. Brookvalia Wade, 1933. Middle Triassic though it is considerably weathered, com- (?Ladinian). Same locality as Schizurichthys. parison ofthe lateral surface with Patterson's 5. Phlyctaenichthys Wade, 1935. Middle Trias- (1975, 115) restoration ofan sic (?Ladinian). Same locality as Schizurich- fig. incomplete- thys. ly ossified Perleidus neurocranium indicates 6. Helichthys Broom, 1909. Lower Triassic that the Dockum specimen is composed of (Scythian). Same locality as Atopocephala. large opisthotic elements, somewhat smaller 7. Geitonichthys Wade, 1935. Middle Triassic prootic ones, as well as pterotic and sphenotic (?Ladinian). Same locality as Schizurichthys. ossifications. There is apparently a small in- 1984 SCHAEFFER: REDFIELDIIFORM FISHES 5 tercalar. The epioccipital-exoccipital-basioc- which has distinct toothed, anamestic pre- cipital complex is also similar to that of the maxillae and several sensory canal ossifica- immature Perleidus. As discussed by Schaef- tions that can be reasonably regarded as fer (1971) and Patterson (1975), these ossi- antorbital precursors (Pehrson, 1947). An fications form a pattern that was undoubtedly economical explanation for these observa- typical of the palaeonisciform and other ex- tions is that the pattern in the 24 mm Polyp- tinct lower actinopterygian neurocrania. It terus represents the primitive actinopterygi- also represents the basic pattern that, with an larval condition, whereas that in the modifications, gave rise to the neurocrania of mature Polypterus, and in the extinct, gen- the higher actinopterygians. eralized actinopterygians mentioned above, The parasphenoid is known in Redfieldius may be regarded as the primitive adult con- (Schaeffer and McDonald, 1978, fig. 3). It dition. A second, but less favored interpre- apparently ended at the ventral otic fissure, tation in view of the fossil evidence, is that and has narrow, well-developed ascending the condition in the larval Polypterus is the processes, as in the "more advanced" pa- primitive one. laeonisciforms (cf. Patterson, 1975, p. 533) With some reservation, Nielson (1942, pp. including Paramblypterus (Heyler, 1969, fig. 136 and 155) restored the snout of Ptero- 13). nisculus with separate premaxillae and canal- SNOUT: A review of the snout pattern in bearing antorbitals. According to Lowney generalized, extinct, lower actinopterygians (Ms), these elements are separate in the pa- by Gardiner (1963, and in press) and by Pat- laeonisciforms Canobius, Mesopoma, and terson (1975) has led them to conclude that Phanerosteon, as well as in the majority of this pattern consists of a single, median, ca- the palaeonisciforms from the Upper Mis- nal-bearing rostral bone situated between sissippian Bear Gulch Formation in Mon- paired nasals, and ofpaired dentigerous "pre- tana. There is also evidence for their sepa- maxillae" (premaxillo-antorbitals) that carry ration in the perleidiiforms (Stensio, 1921, the infraorbital canals. The "premaxillae" fig. 80; Lehman, 1952; Schaeffer, 1955; usually meet in the midline, but may be sep- Hutchinson, 1973a and 1973b). This is, of arated by the rostral, which is dentigerous course, the case in all neopterygians (Patter- when it enters the jaw margin. This snout son, 1975). Pending further investigation, it pattern (with or without the rostral in the jaw appears that the primitive larval condition margin) occurs in the Devonian genera Chei- was independently retained in the adult stage rolepis (Gardiner, in press), Mimia (Gardi- ofsome extinct lower actinopterygians ofun- ner, in press), Moythomasia (Jessen, 1968; known relationship, and also in the neopte- Gardiner, in press), a palaeoniscoid from the rygians. late Devonian ofAustralia (Long, 1983), var- The relationships of the prominent red- ious later palaeonisciforms, and in the adult fieldiiform "premaxilla" with its neighboring Polypterus. On the basis ofpresent evidence, bones, along with its distinctive shape, its the redfieldiiform snout differs from that of major contribution to the orbital border, and the primitive one only in having a horizon- the presence of a single naris on each side of tally subdivided rostral bone. The ventral, the snout represents a complex of synapo- canal-bearing element is here called the ros- morphies for the entire redfieldiiform group tral, and the more posterior, anamestic ele- (fig. 4B). To this list must be added the pres- ment is named the postrostral (fig. 4B). ence of separate median rostral and postros- Gardiner (1963, and in press) and Patter- tral elements. Although a complete separa- son (1975) have proposed that the "premax- tion between the canal-bearing and the illa" of the generalized actinopterygians was anamestic portions of the primitively single subdivided in more advanced forms into a rostral bone (Patterson, 1975, pp. 511-512) separate, dentigerous, anamestic premaxilla can be confirmed in most of the redfieldi- and an antorbital with its characteristic tri- iforms, the distribution of this condition radiate canal pattern. This is essentially the among other lower actinopterygians is less condition in the larval Polypterus (24 mm), certain. Lowney (Ms) found evidence for it in 6 AMERICAN MUSEUM NOVITATES NO. 2795

FIG. 2. Restorations of redfieldiiform skulls and shoulder girdles in lateral aspect. A. Atopocephala. After Hutchinson, 1973 and BMNH P.16083. B. Schizurichthys. After Hutchinson, 1973 and BMNH P.15892. C. Ischnolepis. After Hutchinson, 1973 and BMNH P.27577 and 27578. D. Brookvalia. After Hutchinson, 1973 and AMNH 4705, 4706, 4707, 9254. E. Phlyctaenichthys. After Wade, 1935; Hutch- inson, 1973. F. Helichthys. After Hutchinson, 1978 and AMNH 8063, 11212, 11213. G. Geitonichthys. After Wade, 1935 and Hutchinson, 1973. H. Molybdichthys. After Wade, 1935; Hutchinson, 1973. I. Daedalichthys. After Brough, 1931; Hutchinson, 1973. J. Cionichthys. After Schaeffer, 1967. K. Red- fieldius. After Schaeffer, 1967; Schaeffer and McDonald, 1978. L. Dictyopyge. After Schaeffer and McDonald, 1978. M. Mauritanichthys. After Martin, 1982. N. Lasalichthys. After Schaeffer, 1967. 0. Synorichthys. After Schaeffer, 1967. For bone identifications see figure 4B.

several palaeonisciforms from the Bear Gulch absent in Schizurichthys, but the snout Formation. Stamberg (1978) has noted a sep- (BMNH P. 15891, USGD 305) is very poorly arate rostral and postrostral in some speci- preserved. What is known about the skull mens of the haplolepid palaeonisciform Py- suggests relationship with Ischnolepis and ritocephalus sculptus, but apparently not in other genera with an anteriorly elongated all individuals. Separation of the anamestic maxilla (figs. 2, 3). and canal-bearing parts ofthe rostral bone in In order to reduce confusion in snout der- various groups of extinct lower actinoptery- mal bone terminology, the term postrostral gians, however, only can be demonstrated in should be used only for the separate an- exceptionally well-preserved specimens. The amestic rostral element when it exists behind postrostral is reduced in Lasalichthys and ab- the rostral bone that carries the ethmoid ca- sent in Synorichthys. According to Hutch- nal. The canal-bearing rostral may be rela- inson (1973, p. 385) the postrostral is also tively small as in Polypterus and in most 1984 SCHAEFFER: REDFIELDIIFORM FISHES 7

FIG. 3. Restorations of redfieldiiform skulls in dorsal aspect. Identifications and sources as in figure 2. For A through E and G through I, the dorsal views have been drafted by projection from the lateral aspect and are therefore partly diagrammatic. For bone identifications see figure 4B. neopterygians which still retain it, but it may ticularly evident in some specimens of also be large and extend posteriorly between Brookvalia (e.g., AMNH 4705). However, re- the nasals to the frontals as in the teleost cent examination of specimens in the British Elops (Nybelin, 1967) and in Polypterus. Museum previously studied by Hutchinson The presence of separate, anamestic pre- has not confirmed the presence of separate maxillae in the Scythian-Ladinian redfieldi- anamestic premaxillae in any of the South iforms was proposed by Hutchinson (1973), African or Australian taxa, and there is no who showed (correctly) that the upper mar- evidence of these elements in the American ginal dentition extends forward below the genera (Schaeffer, 1967). The maxillae in the rostral and nearly to the midline. This is par- more generalized forms are attenuated an- 8 AMERICAN MUSEUM NOVITATES NO. 2795 teriorly and to some extent must underlie the suggested that it represents an anterior frag- rostral. I have found no indication that the ment of the dermosphenotic (fig. 5C). How- rostral is dentigerous or that it enters into the ever, the adnasal is barely in contact with the functional jaw margin. In most or all the red- falcate dermosphenotic in the more gener- fieldiiform genera there is evidence that the alized redfieldiiforms. It does, however, rostral bone is covered with strong, bluntly eliminate the nasal from the rim ofthe orbit, pointed tubercles or denticles that resemble a condition that has been regarded as a red- those on the "premaxilla." These tubercles fieldiiform synapomorphy. Poor preserva- are usually larger than the marginal teeth of tion has made it difficult to confirm the the maxilla and the dentary, and there is no presence of the adnasal in Ischnolepis, Ato- reason to believe that the ventral ones func- pocephala, and Phyctaenichthys, but the oc- tioned as teeth. currence of this bone in Brookvalia and in Except for Lasalichthys (fig. 3N), possibly the more advanced genera make this prob- Mauritanichthys (fig. 3M), and Synorichthys able (fig. 2). (fig. 30), the nasals are slim bones situated There are three other possibilities regard- between the adnasals and the postrostral. In ing the identity of the adnasal. It might rep- the first two genera, the nasals meet in front resent a neomorph, which seems unlikely. It of the reduced postrostral; I have found no could represent a "fragment" of the dorsal, indication in Lasalichthys that the nasals ac- postnarial part of the enlarged "premaxilla," tually covered the postrostral posteriorly. Ac- or it might be a relic supraorbital (fig. 5D). cording to Hutchinson (1973) the nasals also The last interpretation is suggested by the meet in Manlietta, which is presently regard- position of an anterior supraorbital in the ed as a perleidid. palaeonisciforms Cheirolepis (Pearson and CIRCUMORBITAL BONES: The ventral rim of Westoll, 1979; BMNH P.60533) and Par- the redfieldiiform orbit is framed in part by amblypterus (fig. 4A, 5B; Blot, 1966; Heyler, the enlarged "premaxilla" and by one or two 1969; and BMNH P.607), which is in contact narrow infraorbitals. There is usually a single with the anterior border of the dermosphen- bar-like postorbital; according to Hutchinson otic and is situated lateral to the nasal bone.2 (1973), Daedalichthys has two (fig. 21). The The diagrams in figure 5 illustrate the pro- upper border of the orbit is formed by the gressive enlargement ofthe "premaxilla," plus so-called adnasal and the dermosphenotic, the hypothesis that the redfieldiiform adnasal which is more or less sickle-shaped. The is derived from the dermosphenotic (C) or dermosphenotic, which is situated in front of from the dorsal part of the "premaxilla" (E). the spiracle, contains the bend in the infraor- The sequence B-D-F begins with a form such bital sensory canal as it follows around the as Paramblypterus (B), and shows a progres- ventral border of the orbit. In palaeonisci- sive reduction of the anterior supraorbital forms that have numerous separate supraor- along with enlargement of the "premaxilla." bital bones such as Elonichthys serratus A few other palaeonisciforms (e.g., Palaeo- (Moy-Thomas and Dyne, 1938), Perleidus niscus and Oxygnathus) have a series ofsmall (Lehman, 1952), and various groups of ex- anamestic supraorbitals in series with the tinct neopterygians, the dermosphenotic is dermosphenotic. It may be assumed that in typically reduced in size and resembles the some taxa, such as Paramblypterus, the su- anamestic supraorbitals. In some ofthe Lad- praorbital ossifications extended anteroven- inian, and all the late Triassic-Liassic red- trally behind the nasal until they reached the fieldiiforms (fig. 2F-O), the dermosphenotic "premaxilla." In this regard, it should be not- is widened and has a broader contact with ed that the Paramblypterus supraorbital is in both the adnasal and the dermopterotic. It is contact posteriorly with the subdivided also subequal in size with the dermopterotic. dermosphenotic. The homology of the redfieldiiform ad- As noted by Patterson (1982, p. 250), the nasal bone remains somewhat in doubt. It was called the prefrontal by Brough (1931) 2 Lawnia (Wilson, 1953) and Coccocephalichthys and, for topographic reasons, the adnasal by (Cocconiscus; see Poplin, 1974) may have the same basic Schaeffer (1967). Hutchinson (1973, p. 345) pattern but the evidence is still equivocal. 1984 SCHAEFFER: REDFIELDIIFORM FISHES 9

FIG. 4. Skull restorations in lateral aspect. A. Paramblypterus. (Modified after Blot, 1966, Heyler, 1969 and BMNH P.607. B. Helichthys. After Hutchinson, 1978 and AMNH 8063, 11212, 11213. Abbreviations: ana, anterior naris; ang, angular; br, branchiostegal; cl, cleithrum; den, dentary; dhy, dermohyal; dpt, dermopterotic; dsph, dermosphenotic; ex, extrascapular; fr, frontal; gu, gular; inf, infraorbital; mx, maxilla; na, nasal; op, opercular; pa, parietal; pcl, presupracleithrum; "pmx," premaxillo- antorbital; pna, posterior naris; po, postorbital; pocl, postcleithrum; pro, postrostral; ro, rostral; scl, suprascapular; so, supraorbital; sop, subopercular. nasal bone in generalized actinopterygians is In the redfieldiiforms there is no evidence of notched for the anterior and posterior nares. an anterior narial notch. The single, large nar- 10 AMERICAN MUSEUM NOVITATES NO. 2795

E F

C D

A B FIG. 5. Snout pattern diagrams arranged to illustrate the origin ofthe adnasal bone from the anterior part of the dermosphenotic, as in hypothetical stage C, or from a supraorbital, as in hypothetical stage D. Diagram A is essentially the snout pattern of Mimia (after Gardiner, 1963). B represents Param- blypterus. After Blot, 1966 and Heyler, 1969. E. Brookvalia. After Hutchinson, 1973 and AMNH 4706. F. Cionichthys. After Schaeffer, 1967. Bone identifications as in figure 4.

ial opening is framed in part by the posterior snout (slightly indented) and by the rostral. border of the nasal bone on each side of the It is also behind the supraorbital sensory ca- 1 984 SCHAEFFER: REDFIELDIIFORM FISHES I1I nal. It follows, therefore, that the narial open- der of the opercular. Although this distinc- ing in these fishes is the posterior naris of tion may seem superficial, it, at least, does other lower actinopterygians. not falsify the hypothesis that the antoper- SKULL ROOF: As discussed by Hutchinson culars of Pteronisculus and the more gener- (1978, p. 889), three genera assigned by him alized redfieldiiforms are non-homologous. to the family Brookvaliidae (Ischnolepis, This presumed parallelism is also corrobo- Brookvalia and Phlyctaenichthys) have two rated by other character distributions. pairs of rectangular parietals (figs. 3C-E). Most redfieldiiforms have a single subor- Atopocephala (fig. 3A) and Schizurichthys (fig. bital bone that is more or less separated from 3B), both of which are incompletely known, the dermohyal by the preopercular (fig. 2, fig. have been restored with one pair of parietals 4B). Phlyctaenichthys is distinctive in having (the primitive actinopterygian number). Hel- this element subdivided into six small bones ichthys (fig. 3F) has two pairs ofparietals, but and Redfieldius into two. Dictyopyge, on the otherwise this genus shows no particular re- other hand, has no suborbitals. It is evident semblance to Hutchinson's brookvaliids. that the number, shape, and arrangement of A broad abutment between the dermo- these elements varies considerably among the sphenotic and the dermopterotic is charac- extinct lower actinopterygians. Suborbitals teristic of most generalized actinopterygians. are absent in representatives ofthe stem-group A falcate dermosphenotic is known outside actinopterygians, and the origin ofthese bones of the Redfieldiiformes in Pteronisculus is obscure (see Gardiner, 1967, p. 199). (Nielson, 1942) and in some other palaeo- OPERCULAR SERIES: The single, platelike nisciform genera whose relationships are branchiostegal (two in Daedalichthys) has long presently unknown (Schaeffer, 1973). The been regarded as a unique redfieldiiform wider, nearly rectangular dermosphenotic, character (Brough, 1934, p. 563). As in the which approaches the size of the dermopter- case of the antopercular, the distribution of otic, is peculiar to Helichthys, Daedalichthys, other characters favors independent reduc- Geitonichthys, Molybdichthys, Mauritani- tion ofthe branchiostegal series, even though chthys and the North American taxa (fig. 3). it is also reduced to one or two elements in All the redfieldiiforms seem to have the usual the distinctive haplolepids and in the ae- single pair ofextrascapulars except for Cion- duellids (Westoll, 1944; Heyler, 1969). The ichthys and Redfieldius, which have these ele- opercular bone is smaller than, or about equal ments doubled on each side of the midline. in size to, the subopercular in the redfieldi- CHEEK AREA: The cheek pattern resembles iforms-as in various other lower actinop- that of a palaeonisciform with a nearly ver- terygians. Sakamenichthys (Lehman et al., tical suspensorium. There is, however, an ex- 1959) from the Lower Triassic ofMadagascar tra bone, the antopercular, between the has a small opercular and a single platelike dermohyal and the opercular in those red- branchiostegal. It may be a redfieldiiform, fieldiiforms with a relatively narrow, falcate but unfortunately the snout area remains un- dermosphenotic (figs. 2A-E) and in Heli- known and, as noted, the opercular-bran- chthys (fig. 2F), which has a widened dermo- chiostegal pattern in the redfieldiiforms has sphenotic. Otherwise an antopercular has by itself a limited value in cladistic analysis. been noted only in Pteronisculus (Nielson, PALATE: The dermal bones of the redfield- 1942, figs. 27 and 30). In the redfieldiiforms, iiform palate are fairly well displayed in a the antopercular, in its shape and position, specimen of Brookvalia gracilis (BMNH resembles an ossification that has separated P. 15813; figured somewhat diagrammatical- from the anterodorsal part of the opercular ly by Hutchinson 1973, fig. 10). Although the bone rather than a wedge-shaped element that dermometapterygoid is partly covered by the appears to be quite distinct from the oper- right opercular and the sutures are nearly cular as in Pteronisculus. In the latter, the obliterated, it is evident that the generalized antopercular (which is sometimes doubled in actinopterygian pattern is present, as recently P. magna; Nielson, 1942, p. 181, fig. 30) is discussed by Rosen et al. (1981) and Patter- situated in front of the straight anterior bor- son (1982). The bone fragment labeled by 12 AMERICAN MUSEUM NOVITATES NO. 2795

FIG. 6. Proposed cladogram of the hypothetical taxon discussed in text plus the 15 genera of redfieldiiforms. Numbers refer to characters in the lists on pages 14 and 15.

Hutchinson (1973, fig. 10) "?pmx" is prob- fins in all genera have both basal and fringing ably part of the attenuated anterior portion fulcra. Patterson (1982, p. 247) notes that of the maxilla, as the associated teeth seem basal fulcra occur on the dorsal margin ofthe too large for the dermopalatine. tail in the most generalized actinopterygians, MANDIBLE: In agreement with their many whereas the presence of fringing fulcra is a other generalized aspects, the redfieldiiforms more advanced condition. The hemihetero- lack a coronoid process on the mandible. The cercal tail is a common advanced lower ac- angular, which is small and confined to the tinopterygian character, also without useful- posterior part of the mandible, is rarely ev- ness in this connotation. There are differences, ident in the American forms because of the however, in the relative length of the caudal prominent ornamentation. The supra-angu- axis in some redfieldiiform genera (fig. 1A- lar may be absent, or it may be very small C). Also Schizurichthys has a distinctive and obscure as in Mimia (see Patterson, 1982, "epaxial lobe" (Hutchinson, 1973, fig. 28; p. 248). The pores ofthe mandibular sensory Patterson, personal commun.) which is bor- canal are usually obvious in spite of the or- dered dorsally and ventrally by fringing ful- namentation. cra. Actually this lobe represents a modifi- PAIRED AND UNPAIRED FINS: Most of the cation in the first six upper principal rays. girdle and fin characters are generalized ac- The most unusual aspect is the presence of tinopterygian ones such as the retention of fringing fulcra partway along the lower bor- the clavicle, the presupracleithrum (positive- der of the sixth ray. Although Hutchinson ly identified in Helichthys, fig. 2F, but it must (1973, pp. 323-324) assigned Schizurichthys be more generally distributed), and the ex- to a separate family, mainly on the basis of cessive number offin rays over basals. There this specialization in the caudal fin, I regard may be an increase in ray segmentation and it as an autopomorphy for this genus, which subdivision between the Scythian and the late is otherwise a generalized redfieldiiform (fig. Triassic-early Jurassic genera, but this is 2B and fig. 3B). equivocal. It is probable that most or all the SCALES: Redfieldiiform scales have been 1984 SCHAEFFER: REDFIELDIIFORM FISHES 13

FIG. 7. Redfieldiiform localities related to a reconstruction of Triassic Pangea (Based on Dietz and Holden, 1970)

successfully sectioned in Redfieldius and Dic- forms than "some or any other lower acti- tyopge (Schaeffer and McDonald, 1978). True nopterygians." On the basis of the previous ganoin and dentine layers are present, and discussion, however, a possible candidate both presumably exist in the scales of the might be expected to have at least one su- other genera. No specialized scale characters praorbital that excludes the nasal bone and have been detected aside from ornamenta- the posterior naris from the orbital rim. The tion that may be meaningful at the generic or suspensorium should be around 40 degrees, specific level. The prismatic structure of the with a fairly sharp angle between the hori- ganoin (Orvig, 1967), which is characteristic zontal and vertical -arms of the preopercular. of many late Paleozoic and Mesozoic lower The cheek should include one or more sub- actinopterygians, can be observed with po- orbitals and a dermohyal. As discussed above, larized light in thin sections ofboth Redfield- the antopercular was probably independently ius and Dictyopyge. acquired by the redfieldiiforms. This description ofa hypothetical redfieldiiform sister taxon is based on a current re- CLADISTIC ANALYSIS view of the dermal bone skull pattern in all It is not surprising in view of our insuffi- extinct lower actinopterygians in which this cient knowledge of the extinct lower acti- pattern is adequately known. Although ex- nopterygians, that it is difficult to designate clusion of the nasal bone and the posterior a more specific sister group for the redfieldii- naris from the orbital rim by an anamestic 14 AMERICAN MUSEUM NOVITATES NO. 2795 supraorbital occurs in Cheirolepis (Pearson fin (also on ventral margin in Daedal- and Westoll, 1979), Paramblypterus (Blot, ichthys) 1966; Heyler, 1969; BMNH P.607) and the Fringing fulcra redfieldiiforms, there is no evidence that these D. Characters present in redfieldiiforms and taxa are closely related. Cheirolepis is a most various other lower actinopterygians that generalized actinopterygian (Gardiner, in belong to unrecognized groups at some press), and its "anterior suborbital" may have undetermined hierarchical level: a sarcopterygian homologue. Paramblypterus Cheek pattern reflecting a more vertical is a derived palaeonisciform-level genus with suspensorium than in stem-group acti- several specializations, such as the relatively nopterygians large anterior supraorbital and marginal teeth Separate postorbital, presumably derived implanted in deep sockets. It is not closely from large "jugal" in stem-group acti- related to the redfieldiiforms, but it does pro- nopterygians vide clues about the origin of the redfieldi- Suborbitals, which are absent in the stem- iform snout pattern. group actinopterygians On the basis of the preceding section, it is E. Redfieldiiforms plus hypothetical sister possible to recognize (as might be expected) group (numbered characters refer to the characters in the redfieldiiforms that are syn- cladogram, fig. 6). apomorphic for the Osteichthyes, the Acti- 1. Nasal bone more or less excluded nopterygii, the Actinopteri, the Redfieldi- from orbit by an anterior supraor- iformes plus their hypothetical sister group, bital proposed as homologue of the and finally the Redfieldiiformes alone. An ad- redfieldiiform adnasal ditional list has been added before the final F. Redfieldiiforms: redfieldiiform one for characters ofuncertain 2. Distinctive shape and size of "pre- position that are more advanced than those maxillae" which may be in contact of stem-group actinopterygians. with rostral 3. Separate rostral and postrostral bones 4. Adnasal (?supraorbital) between A. Osteichthyan: "premaxilla" and demosphenotic Maxilla fixed to cheek and expanded pos- 5. Single external naris surrounded by teriorly "premaxilla," rostral, nasal and ad- Mandible without coronoid process nasal bones Clavicle present 6. Orbit bordered anteriorly by adnasal B. Actinopterygian: and "premaxilla" Generalized, fused braincase with single, 7. Antopercular present, possibly rep- vertical hyomandibular facet resenting subdivision of opercular Parasphenoid with ascending process, but 8. Branchiostegals reduced to one or two elongated as in more advanced lower ac- platelike bones, probably indepen- tinopterygians dently of other extinct lower acti- Nasal bones separated by rostral nopterygian groups that show the "Premaxilla" (premaxilla-antorbital) same condition Boomerang-shaped preopercular Mandibular sensory canal The characters listed under D also empha- Dermohyal size some of the character distribution prob- Presupracleithrum (presumably present lems that clearly involve the redfieldiiforms in at least more generalized redfieldi- and other extinct lower actinopterygian iforms) groups but cannot be presently resolved. Rays ofmedian fins more numerous than There is, nevertheless, sufficient information basals about various characters among the extinct Scales with ganoin and dentine layers lower actinopterygians to propose that the Scales with peg-and-socket articulations Redfieldiiformes represent a monophyletic C. Actinopteran: group. Although the Redfieldiiformes are still Basal fulcra on dorsal margin of caudal incertae sedis among the extinct lower acti- 1 984 SCHAEFFER: REDFIELDIIFORM FISHES 15 nopterygians, it is now possible to provide a In addition to two pairs of parietals, Hel- reasonable description of the hypothetical ichthys has antoperculars, shortened maxillae sister group. The fact that this group has not that do not extend forward under the "pre- been recognized supports the conclusion that maxillae," and widened dermosphenotics that it is unknown. meet the dermopterotics in a nearly trans- The proposed cladogram for the redfield- verse suture. The most economical hypoth- iiforms (fig. 6) is based on the above delib- esis is to regard the extra pair of parietals in erations plus the character states listed below this genus as an independent acquisition. In- that are unique to particular genera or groups terpreted in this way, Helichthys fits neatly of genera. between Hutchinson's "brookvaliids" and "redfieldiids." The pattern of the skull roof 9. Two pairs of parietals is clearly of the "redfieldiid" type (fig. 3). 10. Supraorbital canal reaching the der- Geitonichthys and Molybdichthys, along with mopterotic the succeeding taxa, have no antoperculars. 11. Jaws and tooth rows shortened, max- Their maxillae are about the same length as illa not extended below "premaxilla" in Helichthys, and the "premaxillae" are dis- 12. Dermosphenotic broadened, rect- tinctively broad and stocky. Daedalichthys angular, suture with dermopterotic and the remaining genera have relatively nar- broad and transverse row "premaxillae" that are recurved ven- 13. Antopercular absent trally. The two branchiostegals and a nearly 14. "Premaxillae" broadened and rela- heterocercal tail are distinctive features (fig. tively shorter 1 C) of Daedalichthys. 15. "Premaxillae" relatively narrow and Although the dermal skull pattern of Dae- recurved ventrally dalichthys closely resembles that of the 16. Maxilla further shortened and snout American taxa, the ventral arm of the "pre- profile lowered maxilla" is longer and more vertical, and the 18. Postrostral reduced, nasals meeting snout profile is correspondingly higher than anteriorly in the American redfieldiiforms. I have not 19. Supra and infraorbital canals with been able to resolve a trichotomy consisting double row of pores of Cionichthys, Redfieldius, and Dictyopyge. 20. Postrostral absent and nasals meet- All three have four extrascapulars in a trans- ing throughout their length verse row. Redfieldius alone has three pari- I have not found it possible to resolve sev- etals in a transverse row. Dictyopyge (Schaef- eral polychotomies in this cladogram. The fer and McDonald, 1978) has the entire front number of parietals in Atopocephala and ofthe skull covered with tubercles, unusually Schizurichthys is uncertain (the former is de- broad frontals, and no dermohyal. scribed by Hutchinson (1973, p. 249) with The Moroccan genus Mauritanichthys some reservation as having one pair. Ischno- (Martin, 1982), appears to have a reduced lepis, Brookvalia, and Phlyctaenichthys have postrostral, which suggests that the nasals two pairs. The last two genera are unique in meet in front of this bone as in Lasalichthys having the supraorbital canals extending into (fig. 3M). Few specimens have been found, the dermopterotics. Phlyctaenichthys alone however, and further confirmation is desir- has four or five suborbitals. Together these able. Lasalichthys and Synorichthys are clear- genera are the most plesiomorphic ofthe red- ly related in having double rows of sensory fieldiiform taxa in terms of conserving rela- canal pores that cross triangular parietals to tively long jaws and a wide gape. One pair of meet the extrascapular commissure (fig. 3N parietals is obviously the primitive actinop- and 0). Synorichthys is the only redfieldi- terygian as well as the primitive osteichthyan iform known to lack a postrostral. Its possible number. Although the parietal number in absence in Schizurichthys (Hutchinson, 1973, Atopocephala and Schizurichthys remains to p. 385) cannot be confirmed because the snout be confirmed, the presence of two pairs in area of BMNH P.15891 is too poorly pre- certain other redfieldiiforms including Hel- served. ichthys is surely a derived condition. In general, the hypotheses of relationship 16 AMERICAN MUSEUM NOVITATES NO. 2795 proposed in this character analysis corrobo- knowledge of the extinct lower actinopteryg- rate the cladogram proposed by Hutchinson ians. The selection of the palaeonisciforms (1978, fig. 4a) in which he assumes that Hel- Paramblypterus (Blot, 1966; Heyler, 1959), ichthys is more closely related to redfieldiids which was my original decision, has proved than to the brookvaliids. Also, by implica- to be difficult to substantiate, and its desig- tion, he relates Schizurichthys to the brook- nation as such might be misleading. Never- valiids. theless, the redfieldiiform outgroup must have shared, probably in more generalized form, CONCLUSIONS some or most ofthe redfieldiiform snout syn- apomorphies. Ifthis were not the case, it ob- 1. The Triassic-Early Jurassic redfieldi- viously could not be recognized. As Par- iform fishes are part ofa large complex (near- amblypterus does not fill the sister-group role, ly 200 genera) of extinct lower actinopteryg- we may conclude that the latter remains un- ians (non-neopterygians) that includes the known. palaeonisciforms and an array of more ad- 6. In order to test the hypothesis of red- vanced groups whose relationships are essen- fieldiiform monophyly, it will be necessary tially unresolved. to provide a more detailed and objective 2. The evidence in favor of redfieldiiform analysis of character distributions in the ac- monophyly is based on a survey and an eco- tinopterygians. The recognition ofstem-group nomical interpretation of certain character actinopterygians by Patterson (1982) and distributions among the more adequately Gardiner (in press), plus the redefinition of known extinct lower actinopterygians. As the Chondrostei by Patterson (1982), are sig- noted earlier, the generally useful characters nificant steps in this direction. In regard to are limited to those in the dermal skeleton the relationships ofthe redfieldiiforms to oth- (skull, fins, squamation). er extinct lower actinopterygians, most ofthe 3. The uniqueness of these fishes is dem- characters in Patterson's recent cladogram onstrated by a complex of characters mostly (1982, fig. 3B) have not been observed in the in the snout-postorbital region of the skull. redfieldiiforms. However, the robust ascend- These include "subdivision" of the medial ing processes on the parasphenoid and the rostral bone, exclusion ofthe nasal bone from presence of both basal and fringing fulcra the orbit by the enlarged "premaxilla," loss places the redfieldiiforms above the gener- of the anterior naris, exclusion of the poste- alized stem-group level, but certainly not rior naris from the orbit by the adnasal (?su- within the neopterygians. Furthermore, red- praorbital) and the "premaxilla," and reduc- fieldiiform scales, as noted above, have pris- tion ofthe branchiostegal series to one or two matic ganoin. platelike elements. 7. Attempts to deal with the historical bio- 4. Subdivision ofthe Redfieldiiformes into geography of the redfieldiiforms have been the Brookvaliidae and Redfieldiidae (Hutch- thwarted by the absence of cladistic data for inson, 1973, 1978) is more or less supported other groups of aquatic and terrestrial organ- by this cladistic analysis. The problematical isms that occupied some part of Pangea dur- Helichthys is regarded as the sister taxon of ing the Triassic Period. This additional evi- the more derived taxa as arranged in figure dence is required to corroborate a particular 6. At this stage of analysis, however, I can distributional pattern in terms of separating find no useful purpose in recognizing Hutch- random from non-random (vicariant) distri- inson's families except in a vernacular sense. bution. The fact that the earliest and most Although the relationships of the genera generalized redfieldiiforms have been found within the Redfieldiiformes are based mostly in Australia and South Africa and the most on single characters, no contradictions have specialized in North America and Morocco been found that might alter the configuration (fig. 7) tells us little about a possible distri- of the cladogram. butional pattern. Redfieldiiforms are still un- 5. The problem of discerning the sister known, but not necessarily absent, from the group of the Redfieldiiformes is obviously continental Lower Triassic rocks of North impeded by our insufficient and imprecise America (e.g., the Moenkopi Formation). It 1984 SCHAEFFER: REDFIELDIIFORM FISHES 17 should also be noted that we are concerned Hay, 0. P. here with distribution on a single, great land 1899. On some changes in the names, generic mass-Pangea. Assuming that the redfieldi- and specific, of certain fossil fishes. iforms were primary freshwater fishes, the Amer. Nat., vol. 33, pp. 783-792. Heyler, D. distributional barriers would be within the 1969. Vertebres de l'Autunien. Cahiers de Pa- boundaries ofthis mass and unrelated to later leont. C.N.R.S., Paris, 259 pp. continental movements. Hutchinson, P. 1973a. A revision ofthe redfieldiiform and perleidiform fishes from the Triassic of LITERATURE CITED Bekker's Kraal (South Africa) and Brookvale (New South Wales). Bull. Brit. Andrews, S. M., B. G. Gardiner, R. S. Miles, and Mus. (Nat. Hist.), Geol., vol. 22, pp. C. Patterson 233-354. 1967. Pisces. In W. B. Harland et al. (eds.), 1973b. Pseudobeaconia, a perleidiform fish The fossil record. London, Geol. Soc., from the Triassic Santa Clara Forma- pp. 637-683. tion, Argentina. Breviora, no. 398, pp. Blot, J. 1-24. 1966. Etude des Palaeonisciformes du Bassin 1978. The anatomy and phylogenetic position de Commentry. Cahiers de Paleont. ofHelichthys, a redfieldiiform fish from C.N.R.S., Paris, 99 pp. the Triassic of South Africa. Paleontol- Broom, R. ogy, vol. 21, pp. 88 1-891. 1909. The fossil fishes of the Upper Karroo Jessen, H. beds of South Africa. Ann. S. African 1968. Moythomasia nitida Gross und M. cf. Mus. vol. 7, pp. 251-269. striata Gross, Devonische Palaeonisci- Brough, J. den aus dem oberen Plattenkalk der 1931. On fossil fishes from the Karoo System, Bergisch-Gladbach-Paffrather Mulde and some general considerations on the (Rheinisches Schiefergebirge). Palae- bony fishes ofthe Triassic Period. Proc. ontographica, vol. 128, pp. 87-1 14. Zool. Soc. London, pt. 1, pp. 235-296. Lehman, J.-P. 1934. On the structure of certain catopterid 1952. Etude complementaire des Poissons de fishes. Proc. Zool. Soc. London, pt. 3, l'Eotrias de Madagascar. K. Svenska pp.559-571. Vetenskapsakad. Handl., ser. 4, vol. 2, 1936. On the evolution of bony fishes during 201 pp. the Triassic Period. Biol. Rev., Cam- 1966. Actinopterygii. In Piveteau, J. (ed.), bridge vol. 11, pp. 385-405. Traite de Paleontologie. Tome 4, vol. 3, Forey, P., and B. G. Gardiner Paris, Masson et Cie, 242 pp. 1973. A new dictyopygid from the Cave Sand- Lehman, J.-P., C. Chateau, M. Laurain, and M. stone of Lesotho, Southern Africa. Pa- Nauche laeont. Afr., vol. 15, pp. 29-31. 1959. Paleontologie de Madagascar xxviii. Les Gardiner, B. G. poissons de la Sakamena Moyenne. Ann. 1963. Certain palaeoniscoid fishes and the Paleont., vol. 45, pp. 1-45. evolution of the snout in actinopteryg- Long, J. A. ians. Bull. Brit. Mus. Nat. Hist. (Geol.), 1983. The structure and relationships ofa new vol. 8, pp. 257-325. palaeoniscoid fish from the Late De- 1967. 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