A New Genus and Species of Amiidae (Holostei

Home , Amiidae, Caturus, Cleithrum

A New Genus and Species of Amiidae (Holostei; Osteichthyes) from the Late Cretaceous of North America, with Comments on the Phylogeny of the Amiidae Author(s): Laurie J. Bryant Source: Journal of Vertebrate Paleontology, Vol. 7, No. 4 (Jan. 22, 1988), pp. 349-361 Published by: Taylor & Francis, Ltd. on behalf of Society of Vertebrate Paleontology Stable URL: http://www.jstor.org/stable/4523160 Accessed: 10-11-2015 14:11 UTC

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This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions 129678, 2 tooth crowns from V80088. UCMP 129679, 2 North Dakota trunk vertebra from V8009 1. UCMP 129906, vertebra fragment; UCMP 129907, tooth crown, and UCMP Montana "1 8 129908, post-temporal fragment from V80092. UCMP tooth crown from V80119. UCMP .3 130288, 129680, 3 caudal vertebrae; UCMP 12968 1, fragments of oper- culum, post-temporals, ?parietal, other fragments of Wyoming South Dakota dermal bone, and fin rays; UCMP 130387, vertebra, 4. post-temporal, and other fragments from V81159. UCMP 129909, dermal bone fragment; and UCMP 129910, vertebra, from V81257. UCMP 129911, ver- Utah tebra, from V81258. UCMP 130088, tooth crown from UCMP 7 from V82013. Colorado V82210. 129682, tooth crowns UCMP 129683, anterior left maxilla, 2 trunk vertebrae 5. and 1 fragment, lepidotrichia and dermal bone fragments; UCMP 129912, dermal bone fragments; UCMP a6 129914, caudal vertebra; UCMP 129913, ?parietal fragment; UCMP 130089, maxillary fragment from V82060. UCMP from V83024. New Mexico 129915, vertebra, UCMP 129916, dermal bone fragments, from V83064. UCMP 129684, trunk vertebra fragment; UCMP 129917, tooth crown, from V83077. UCMP 129601, Texas nearly complete left cleithrum and infraorbital, fragments of ceratohyal, from V83100. UCMP 129602, trunk vertebra from V83104. UCMP 129877, caudal 800 km vertebra from V83130. UCMP 129918, trunk vertebra from V83198. UCMP 129685, trunk vertebra from V83254. UCMP 129686, trunk vertebra from V84002. UCMP 129687, caudal vertebra from V84003. UCMP 130388, caudal vertebra from V84016. UCMP 129692, FIGURE 1. Index map showingcollecting areas for Melvius left frontal, fragments of post-temporal, ?parietal, and thomasi. other skull bones, and trunk vertebra from V84050. UCMP 129876, trunk vertebrae, premaxilla, ?parietal, preopercular, other skull fragments, and lepidotrichia lus. Dentary with 14 teeth; horizontal ramus wider from V84128. UCMP 129878, posterior trunk verte- than deep. Cleithrum lacking sculpture, forming a 90 bra, from V84130. UCMP 130147, vertebra and tooth degree angle between dorsal and ventral arms. Basioc- crown from V84171. UCMP 130289, anterior trunk cipital width more than twice its height. Differs from vertebra from V84182. UCMP 130144, 3 vertebrae, Enneles in having fused infraorbitals 4 and 5, and vertebra fragments and fin support; UCMP 130145, lacking the supramaxilla. Differs from all other amiids basioccipital and 3 vertebrae from V84225. UCMP except Pachyamia and Enneles in having carinate teeth 130146, 2 vertebrae, fin support, and skull fragment and alveoli with crenulated borders. from V84227. AMNH 6385, anterior trunk vertebra. Hypodigm -Hell Creek Formation, Montana; AMNH 11600, tooth crowns. AMNH 11604, oper- UCMP 129904, right frontal fragment from V70208. cular fragment. LACM 37887, 30783, 30412, 126131, UCMP 120226, tooth crowns from V73077. UCMP vertebrae. LACM 30412, right dentary, 5 vertebrae, 129673, trunk vertebra; UCMP 120323, tooth crowns tooth crowns, basicranium and angular fragments. from V73085. UCMP 123289, 150+ tooth crowns; LACM 37218, opercular fragment. UCMP 130386, dentary fragment from V73087. Bug Creek Anthills, Montana; UCMP 129671, trunk UCMP 123381, trunk vertebra from V73090. UCMP vertebra from V65127. 128813, tooth crown from V73103. UCMP 128852, Lance Formation, Wyoming; UCMP 72700, post- tooth crowns from V74116. UCMP 128894, tooth temporal from V5618. UCMP 54156 and 56277, trunk crown from V74117. UCMP 129677, 2 trunk verte- vertebrae; UCMP 72467, tooth crown from V5620. brae, 1 caudal vertebra; UCMP 129675, right maxilla UCMP 56276, vertebra fragment; UCMP 72470, ver- fragments; UCMP 129674, tooth crown and opercu- tebra fragment; UCMP 72688, tooth crowns from lum fragment; UCMP 129676, tooth crown, from V5711. UCMP 72647, vertebra from V5815. UCMP V76138. UCMP 129912, maxillary fragment and tooth 62936, vertebra from V5817. UCMP 72469, anterior crown from V76162. UCMP 130655, vertebra, from left maxilla fragment from V5921. UCMP 129951, V77121. UCMP 130287, tooth crowns from V77130. 129952, vertebrae from V84216. UW 14276, right UCMP 130286, tooth crown from V77119. UCMP maxilla; 14621, right maxilla fragment; 14619, left 129905, dermal bone fragments, from V78143. UCMP maxilla fragment; 14618, anterior right maxilla frag-

350 JVP 7(4), December 1987

This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions fragment is indistinguishable from LACM 30412 except for its larger size. I estimate from the proportions of LACM 30412 that UCMP 131681, if complete, would be at least 270 mm long. Angular--The left angular of the type specimen /' (UCMP 129600) is convex laterally and thickened on A '"B the dorsal and ventral margins. It is externally somewhat rugose but not sculptured. The antero-ventral border is thick and tapers to a blunt point. The dorsal border has a wide longitudinal groove. The area of overlap with the dentary is indicated by an anteriorly convex ridge on the lateral surface (Fig. 11B). Pores on the postero-dorsal and postero-ventral edges indi- cate the course of the preopercular-mandibular canal. Teeth-Two lanceolate tooth crowns are associated FIGURE 7. Melviusthomasi, n. gen., n. sp. A, preopercular with the UCMP 129600. Their oval fragment,UCMP 129876; B, basioccipitalfragment, UCMP type specimen, 130145, ventral view. Scale bar = 1 cm. bases suggest association with the coronoids or one of the palatal elements rather than the maxilla or dentary. They are enamelled, sharply pointed, and translucent. A strong carina extends from tip to base along each degrees. The postero-ventral border curves gently down side of the crown. and forward. There is only a faint trace of sculpture A number of other tooth crowns from the Hell Creek along the ventral margin. The antero-ventral limb is Formation closely resemble those of the type specimen. thick and lies nearly in the vertical plane. It is perfo- Most are from localities where other elements of Mel- rated by a large foramen and crossed on its medial vius have been found. With them are a number of larger surface by a prominent ridge that descends from near tooth crowns (Fig. 12) that are blunter and have round the dorsal border posteriorly toward the ventral bor- or oval bases. A few, including some from the Lance der. The dorsal tip is sharply grooved and tapers to a Formation, have remains of hollow dentine shafts that blunt point. probably were longer than the enamelled crowns. Dentary-The holotype specimen (UCMP 129600) Fin Supports -A number of fragmentary lepido- includes the anterior left dentary (Fig. 9) and fragments trichia, epurals, and hypurals are associated with spec- of the right dentary. LACM 30412 includes a nearly imens of Melvius in the UCMP collections. None is complete right dentary (Fig. 10). The toothed portion articulated with vertebrae or limb girdles, so it is im- is shallow and broad, and smoothly convex laterally. possible to determine their position or total number. There are 14 alveoli of subequal size, although the most Vertebrae--All the vertebrae are completely ossi- posterior is somewhat smaller than the others. The fied; the notochordal pit is occupied by bone that forms alveoli have crenulated margins, some with thin-walled a plug or spike. The anterior trunk vertebrae are as tooth root fragments in place. A shelf medial to the described and figured by Estes (1964) and Boreske tooth row exceeds the tooth row in width. The most (1974), being short antero-posteriorly and with broadly medial one-third of this shelf is roughened, probably oval articular surfaces. Central trunk vertebrae (Fig. for the articulation of coronoids and the prearticular. 13) have deeply excavated ventro-lateral surfaces be- The medial surface of the dentary lies in the vertical tween the basapophyses and aortal facets. The most plane and has a prominent Meckelian groove that ex- posterior trunk vertebrae are nearly circular in outline tends forward to the symphysis. A large foramen within where the basapophyses are most steeply inclined and the groove lies at the level of the ninth alveolus. Pos- may be twice the length of anterior vertebrae. terior to the tenth alveolus the medial surface is open Caudal vertebrae decrease in width toward the tail in a large Meckelian fossa, the ventral margin of which until they are almost perfectly rectangular in cross sec- is broken away. tion and a little higher than wide. At least some caudals On the lateral surface the dentary is marked by nu- are longer antero-posteriorly than some anterior trunk merous foramina. Posterior to the last alveolus the vertebrae. The two known urals are virtually square. dorsal border turns sharply up into a coronoid process. Each has a small, rounded spur of bone on the postero- At the base of the coronoid process is a prominent scar dorsal surface, but no other evidence of a fused neural on the lateral surface, presumably for the insertion of arch. part of M. adductor mandibulae (terminology of Allis, 1897). Specimens Tentatively Referred to Melvius A fragment of a particularly large dentary (UCMP A number of specimens that may be referable to 131681, Fig. 11A) was collected in 1986 from the Hell Melvius thomasi or perhaps a related species come Creek Formation in southwestern North Dakota (see from older sediments or areas far removed from east- Fig. 1). Although the Hell Creek Formation there may ern Montana. Their identification should be possible be slightly younger than in northeastern Montana, this when articulated material becomes available.

354 JVP 7(4), December 1987

Pachyamia, known from a single specimen in the 14 15 16-17 Cenomanian of is similar to in a num- Israel, Melvius 11-13 /18-20 ber of characters (see Character analysis and Fig. 17), and also in the presence of an elongate frontal (length more than three times width). There are insufficient data to determine whether this character is derived. 9-10 The morphology of the cleithrum and angular are 5-8 known to differ in Pachyamia and Melvius. The cleithrum in Pachyamia has a very narrow antero-ventral limb; that of Melvius was apparently broad, but in both 1-4 genera the two limbs of the cleithrum lie in the same plane. The angular in Pachyamia rises to a blunt point FIGURE 17. Derived characterstates in Melvius,Enneles, at the postero-dorsal tip; that of Melvius apparently and Pachyamia. 1, vomer differentiated.2, maxilla with in- lacked this extension. ternally-directedarticulatory head. 3, supramaxillapresent. Enneles, like Pachyamia, shares several characters 4, interopercularpresent. 5, amiid scales. 6, 1:1 hypural:fin with Melvius (see Character analysis and Fig. 17). ray ratio. 7, 1:1 hypural:ural centrum ratio. 8, trunk ver- However, it lacks the elongate frontal, and has multiple tebrae shorter than high. 9, carinate teeth with enamelled supraorbitals and a supramaxilla. crowns and crenulatedalveoli. 10, posteriorlynotched max- Until of other amiid illa. 11, loss of supramaxilla.12, fusion of infraorbital4 and comparable specimens genera 5. frontal width ratio are it seems inadvisable to 13, length: 3:1. 14, dermosphenotic available, attempt fitting excluded from orbit. central trunk vertebrae ventrolat- into a such as that of Schultze and 15, Melvius phylogeny erally concave. 16, infraorbital5 much reduced. 17, super- numerary supraorbitals. 18, loss of supraorbitals. 19, long dorsal fin. 20, long nasal process on premaxilla. TABLE 1. Measurements(in mm) of MNA P1.1809, Mel- vius thomasi, n. gen., n. sp. Vertebrae 1-17 are articulated; 14-15 fused. Vertebrae 18-23 follow an unknown number Wiley (1984, fig. 1). However, even with the present of missing vertebrae. Vertebra24 is an isolated caudal. Ab- it is still to some breviations: at dorsal limitations, possible develop hy- a-p = antero-posteriordiameter mid- about the of within the ami- w = h = at midline aortal potheses position Melvius line; greatest width; height (between idae and neural facets); * = possible error due to breakage or (Fig. 17). crushing. Polarity--Schultze and Wiley (1984) cited several characters in support of considering the Parasemio- Vertebra# a-p w 1 notidae the sister-group of amiids + Caturus, and Amia as the most derived amiid. I have these 1 accepted po- 12.0 40.9 29.9 decisions. Olsen 2 13.4 40.6 30.0 larity (pers. comm.) thinks that the 3 13.4 39.9 30.3 parasemionotid Watsonulus in particular is an appro- 4 13.75 40.4 30.2 priate sister-group to the Amiidae + Caturus. Wat- 5 14.7 42.0 31.6 sonulus is the most primitive neopterygian (amiids, 6 14.8 42.45 31.2 gars, teleosts, and their most recent common ancestor, 7 15.5 43.9* 30.85* sensu Patterson, 1973), having unreduced clavicles and 8 15.7 43.2 30.0 a broad dorsal limb on the preoperculum (Olsen, 1984: 9 15.75 42.8 30.7 493). Amia may be considered the most derived amiid 10 15.75 43.9 30.4 in having a very long dorsal fin (Schultze and Wiley, 11 16.25* 45.15* 30.35 and a with much nasal 12 16.5 43.5 29.7 1984:153), premaxilla elongated 13 16.65 43.9 29.9 processes (Olsen, 1984, fig. 19). Watsonulus, Caturus, 14 -15.7 42.0 - and Amia share a uniquely derived jaw joint in which 15 -15.5 42.8 29.8 the symplectic takes part. Characters derived within 16 17.7 44.1 29.6 the amiidae include the uniquely ossified vertebrae, 17 16.8* 43.6 30.4 fusion of the hypurals and neural centra, and a 1:1 hypural: fin ray ratio. For details on halecomorph and 18 20.3 37.35 - 19 19.65 36.4 30.45 neopterygian relationships, see Olsen (1984:493). 20 19.8 34.8 29.8 Character Analysis - if Watsonulus is the sister group 21 19.4 33.1 29.4 of amiids + Caturus, and Amia is the most derived 22 18.2 33.4 29.8 amiid, then it is possible to recognize some characters 23 20.15 32.3 29.8 shared by Melvius, Enneles and Pachyamia (Fig. 17) 24 8.15 17.0 20.0 that appear to be derived. All three genera share the posteriorly notched maxilla, crenulated alveoli, and

JVP 7(4), December 1987 359

This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions but it is also possible that they tolerated saline water, pt - and that living in fresh water may be the derived con- ,pa dition for amiids.

fr CONCLUSIONS op po The large North American Late Cretaceous amiid formerly referred to Protamia or Amia cf. A. uintaensis is here referred to a new genus and species, Melvius thomasi the of known amiids clc (Fig. 18). Among largest (standard length estimated to be at least 160 cm), Mel- ma is most related to Cre- anp vius closely Pachyamia (Late pm taceous of Israel) and Enneles (Early Cretaceous of de Brazil). The parasemionotid Watsonulus is the sister- group of Amiidae + Caturus, and Amia is the most gu derived amiid. Loss of the supramaxilla, presence of teeth with enamelled, carinate crowns and crenulated FIGURE 18. Reconstruction of the skull of Melvius tho- alveoli, a posteriorly notched maxilla, and fusion of masi, n. gen., n. sp. Based on holotype UCMP 129600 and infraorbitals 4 and 5 to be characters derived = appear isolated elements from other specimens illustrated.an an- within the Amiidae. These characters define a clade cl = de = fr = = gular; cleithrum; dentary; frontal; gu gular; and Enneles. Melvius io = infraorbital ma = maxilla; op = opercular; pa = including Melvius, Pachyamia, 4-5; other Mesozoic were not restrict- parietal; pm = premaxilla; po = post-orbital; pt = post-tem- and amiids probably poral. ed to fresh water. Melvius apparently became extinct by the end of the Cretaceous. Acknowledgments--This work was funded in part by carinate teeth with enamelled crowns on long, hollow National Science Foundation Grant BSR 81-19217, shafts. Pachyamia and Melvius also have in common under the direction of W. A. Clemens, who encouraged a fused infraorbital 4-5, and loss of the supramaxilla. me to study the lower vertebrates of the Hell Creek Although Melvius and Enneles share a wide medial and Tullock formations. I am grateful to the Regents shelf on the dentary, this part of the skull is unknown of the University of California for awarding me a Re- in Pachyamia and the character cannot be used to gents Fellowship during 1984-1985. establish relationships. Because none of these char- I very much appreciate the assistance of D. Baird, acters is present in Amia, these genera cannot be in- Princeton University, and J. Maisey, of the American cluded in its ancestry and must form another clade Museum, who made comparative material available. within the Amiidae. P. Olsen, while a Miller Post-Doctoral Fellow in the In the most parsimonious hypothesis, Melvius and Department of Paleontology, University of California, Pachyamia are more closely related to each other than Berkeley, generously shared his insights on fish rela- to any other genus, and Enneles is most closely related tionships. C. Patterson offered many helpful sugges- to Melvius and Pachyamia. The posteriorly notched tions, which I have tried to incorporate. Reviewers M. maxilla, shared by Melvius, Pachyamia, Enneles, and V. H. Wilson and R. Estes made many helpful com- Urocles and Amiopsis, may define a larger clade. ments that improved this paper greatly. Y. Chalifa and Distribution - Remains of Melvius in the Hell Creek E. Tchernov, Hebrew University of Jerusalem, gen- Formation almost always occur in large-scale channel erously provided photographs and other data on fills, often with other large fish such as gars. Melvius Pachyamia. Figures 2-13 and 16 were drawn by J. P. may occur as far south as the Big Bend region of Texas, Lufkin, with photographic assistance from H. Schorn. distributed along the western margin of the Western Kyoko Kishi drew Figure 14. Harley Garbani found Interior Seaway. Such a distribution implies that the and collected the type specimen. I am particularly in- fish entered marine waters at least occasionally, al- debted to J. H. Hutchison, University of California though its preferred habitat may have been the major Museum of Paleontology, who willingly participated drainages flowing eastward across the broad coastal in endless discussions of taxonomy, cladistics, and plain. morphology of fish, all with apparent interest. There is considerable evidence that other Mesozoic amiids were marine. Enneles occurs in rocks contain- REFERENCES and ing echinoids, aspidorhynchids, ostracods, along E. P. 1897. The cranial muscles and cranialand first with and Allis, turtles, crocodiles, plants (Santos, 1960). spinalnerves in Amia calva.Journal of Morphology12(3): Pachyamia is associated with ammonites, echinoids, 487-814. and elasmobranchs, as well as remains of Podocnemis Archibald, J. D. 1982. A study of Mammalia and geology and terrestrial plants (Chalifa and Tchernov, 1982). across the Cretaceous-Tertiaryboundary in Garfield Urocles is common in the Solnhofen Plattenkalk. These County, Montana. University of CaliforniaPublications may be freshwater fish washed into marine deposits, in Geological Sciences 122:1-286.

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This content downloaded from 128.184.220.23 on Tue, 10 Nov 2015 14:11:38 UTC All use subject to JSTOR Terms and Conditions Boreske, J. 1974. A review of the North American fossil Jain, S. L. 1985. Variability of dermal bones and other amiid fishes. Museum of Comparative Zoology, Har- parameters in the skull of Amia calva. Zoological Jour- vard University, Bulletin 146(1):1-87. nal, Linnean Society, London 84:385-395. Breithaupt, B. 1982. Paleontology and paleoecology of the Janot, C. 1967. A propos des amiides actuel et fossiles. Lance Formation (Maastrichtian), east flank of Rock Colloques Internationaux du Centre National de la Re- Springs Uplift, Sweetwater County, Wyoming. Contri- cherche Scientifique 163:139-153. butions to Geology, University of Wyoming 21(2): 123- Olsen, P. E. 1984. The skull and pectoral girdle of the 151. parasemionotid fish Watsonulus eugnathoides from the Brown, B. 1907. The Hell Creek beds of the Upper Cre- Early Triassic Sakamena Group of Madagascar, with taceous of Montana. American Museum of Natural His- comments on the relationships of the holostean fishes. tory, Bulletin 23:823-845. Journal of Vertebrate Paleontology 4(3):481-499. Bryant, L. J., Hutchison, J. H., Clemens, W. A. and Archi- Patterson, C. 1973. Interrelationships of holosteans; pp. bald, J. D. 1986. Diversity changes in lower verte- 203-335 in Greenwood, P. H. et al. (eds.), Interrela- brates (non-dinosaurian) across the Cretaceous/Tertiary tionships of fishes. Zoological Journal, Linnean Society boundary in N.E. Montana. Geological Society ofAmer- of London, vol. 53, Supplement 1. ica Abstracts with Programs 18(6):552. Santos, R. da Silva. 1960. A posiCiaosistematica de Enneles Chalifa, Y. and Tchernov, E. 1982. Pachyamia latimax- audax Jordan e Branner da chapada do Araripe, Brasil. illaris, a new genus and species (Actinopterygii: Ami- Brazil, Divisio de Geologia e Mineralogia, Monografia idae) from the Cenomanian of Jerusalem. Journal of XVII, 25 pp. Vertebrate Paleontology 2(3):269-285. Schultze, H.-P. and Wiley, E. 0. 1984. The neopterygian Estes, R. 1964. Fossil vertebrates from the late Cretaceous Amia as a living fossil; pp. 153-159 in Eldredge, N. and Lance Formation, eastern Wyoming. University of Cali- Stanley, S. (eds.), Living fossils. Springer Verlag, New fornia Publications in Geological Sciences 49:1-187. York. Fastovsky, D. E. and Dott, R. H. 1986. Sedimentology, Sternberg, C. M. 1924. Notes on the Lance Formation of stratigraphy, and extinctions during the Cretaceous-Pa- southern Saskatchewan. Canadian Field-Naturalist 33: leogene transition at Bug Creek, Montana. Geology 14: 66-70. 279-282. Thurmond, J. T. 1974. Lower vertebrate faunas of the Gilmore, C. W. 1924. Report on a collection of vertebrates Trinity Division in north-central Texas. Geoscience and from Wood Mountain, southern Saskatchewan. Cana- Man 8:103-129. dian Geological Survey Department of Mines, Bulletin Wilson, M. H. V. 1982. A new species of the fish Amia 38:13-26. from the Middle Eocene of British Columbia. Palaeon- Greenwald, M. 1971. The lower vertebrates of the Hell tology 25(2):413-424. Creek Formation (upper Cretaceous), Harding County, South Dakota. Master's thesis, South Dakota School of Mines and Technology, Rapid City, South Dakota, 76 pp. Received 11 May 1985; accepted 28 September 1986.

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