PROC. R. SOC. VICT. vol. 96, no. 4, 173-186, Decemb er 1984 NEW PLACODERM FISHES FROM THE EARLY DEVONIAN BUCHAN GROUP, EASTERN VICTORIA By J ohn A. L ong Department of G eology, Australian National Universi ty, P.O . Box 4, Canberra, A.C .T. 2601 A bstract : Three new placoderms are described from the McLarty Member of the Murrindal Limestone (Early Devonian, Buchan Group). M urrindalaspis wallacei gen. el sp. nov. is a palae- acanthaspidoid characterized by having a high m edia n dorsal crest and lacking a m edian ventral keel. M. bairdi sp. nov. differs from the type species in having a low median dorsal crest and a median ventral groove. Taem asosteus m aclarliensis sp. nov. differs from the type species T. novaustrocam bricus W hite in the shape of the posterior region of the nuchal plate, the presence of canals between the infranuch al pits and the posterior face o f the nuchal plate, th e shape of the paranuchal plate, and the developm en t of the apronic lam ina of the anterior lateral plate. The placoderm s, A renipiscis westoUi Young, Errolosleus cf. E. goodradigbeensis Young, W ijdeaspis warrooensis Young, are recorded from the Buchan Group indicati ng close sim ilarity to the ichthyofauna of the contem poraneous M urrumbidgee Group, New Sout h W ales. Few fossil fishes have been studied from the Early been described from the Murrumbidgee and Mulga Devonian Buchan Group. M cCoy (1876) described some Downs Groups in New South Wales and the Cravens placoderm plates from this region as Asterolepis ornata Peak Beds in Queensland, with numerous sites yielding var. australis, which Chapman (1916) queried when m icrovertebrate assemblages (Long 1982, 1983b, Turn er presenting a description of a placoderm skull from et at. 1981, Long & Turner 1984). Buchan. Chapman identified this specimen as a phly- Specimens are housed in the following institutions: ctaenioid, Phlyctaenaspis confertituberculatus, but Hills CPC, Commonwealth Palaeontological Collections, (1936b) assigned the skull to Coccosteus. Stensio (1945) Bureau of Mineral Resources, Canberra; MUGD, recognized differences between the parasphenoid of Geology Department, M elbourne University; and NMV, Coccosteus and the Buchan specimen and erected M useum of Victoria, M elbourne. Buchanosteus for the latter. Additional material of Buchanosteus has since been found from the M urrum­ SYSTEMATIC PALAEONTOLOGY bidgee G roup, New South W ales, making this genus on e Subclass P lacodermi M cCoy 1848 of the best known Early Devonian euarthrodires (W hite Superorder P etalichthyomorpha Miles & Young 1977 1952, W hite & Toombs 1972, Young 1979). The only Order P etalichthyida Jaekel 1911 other fish described from Buchan is a mandible of the dipnoan Dipnorhynchus sussmilchi (Hills 1936a, Thom ­ W iJdeaspis warrooensis Young 1978 son & Campbell 1971). This paper describes placoder m Fig. 4C ' fish material recovered from the Buchan Group durin g M aterial : A piece of trunk shield com prising the right Monash University third year geology field mapping spinal plate and a small sliver of the anterior lateral trips as well as some found by geology honours stud ents plate. NMVP159825, collected Dr. R . E. Fordyce, from both M elbourne and M onash Universities (Long February, 1981. 1983 b). O ccurrence : The uppermost division of the M cLarty The material was prepared using acetic acid with Member of the Murrindal Limestone, immediately dilute polyvinylbuterol to strengthen the exposed b one. northeast of Rocky Camp Quarry, north of Buchan. All specimens were found in the uppermost McLarty M ember or ihe lowermost Rocky Camp Member of the R emarks : The specimen is identified as belonging to M urrindal Limestone, with the richest concentration of Wijdeaspis because the spinal shows a relatively high vertebrates occurring near the contact of the M cLar ty num ber of ornam ental ridges (9-10) which are form ed of and Rocky Camp M embers on the eastern face of Rocky closely packed tubercles arranged in rows. On this basis Camp Hill (Fig. 1). In addition to the macrovertebr ate Young (1978, p. 112) distinguished Wijdeaspis spinal remains rich concentrations of microvertebrate foss ils plates from those of Lunaspis species. The Buchan were recovered from the residues during preparation , specimen is almost identical with that of Wijdeaspis and these have been forwarded to Dr. S. Turner warrooensis figured by Young (1978, figs 2E, 8B). (Queensland Museum) for detailed study. Amongst these are several types of acanthodian and elasm obr anch Order R henanida Broili 1930 scales similar to forms described from the M urrum­ Suborder P alaeacanthaspidoidei Miles & Young 1977 bidgee G roup by Giffin (1980). Recently a jaw of a new Family W eeja sper a spida e W hite 1978 ischnacanthid acanthodian was found in residues fro m D ia g nosis : Palaeacanthaspidoids having a well the Rocky Camp Member (under current study by the developed median dorsal crest on the median dorsal author). Lower Devonian macrovertebrates have also plate, which has a posterior face with a smooth med ial 173 174 JOHN A. LONG BUCHAN D ia g nosis : A weejasperaspid of m oderate size having a median dorsal plate with a sm ooth ventral surface w hich may have a median ventral groove developed; dermal ornam entation of short ridges, approxim ately one-th ird as long as broad, on the dorsal surfaces with pointed stellate tubercles densely concentrated near the an terior and posterior margins; median dorsal crest develope d; a short dorsal transverse sensory line canal situated at the anterior base of the median dorsal crest; the poste rior face of the median dorsal crest with a smooth media n prominence throughout. T y pe S pec ies : Murrindalaspis wallacei sp. nov. R emarks : This palaeacanthaspid is similar to Wee­ jasperaspis gavini W hite (1978) but differs in the absence of the median ventral keel on the median dorsal pla te. Palaeacanthaspis Stensio 1944 also possesses a median dorsal crest but differs from both Murrindalaspis and Weejasperaspis in possessing a large nutritive foramen for the crest on the ventral surface of the median dorsal plate, and by its simple tubercular ornam entation. Of the remaining described palaeacanthaspids none has a well developed median crest; where the median dorsa l plate is unknown (Brindabellaspis Y oung 1980, Romun- dina Orvig 1975, Kimaspis Mark-Kurik 1973a, Kolymaspis in Denison 1978) Murrindalaspis is dis­ tinguished by the characteristic dermal ornam entati on. M urrindalaspis wallacei sp. nov. Figs 2A, D, E, G, 3, 8C, D E tymology : After Mr. M. Wallace, Dept. Geology, University of Tasmania, who discovered several fish es from the Buchan area in 1982, including the type specimen of Murrindalaspis gen. nov., and kindly allowed me to study the material. D ia g nosis : A member of Murrindalaspis with a median dorsal plate having a high median dorsal crest whic h is strongly curved posteriorly and tapers narrowly at its apex. Ventral surface of median dorsal plate smooth , Fig. 1 —Locality map of placoderm fossils collected in the and there are paired prominences developed at the Buchan region. G eology from Teichert & Talent (1958 ). posterior end of the ventral surface near the base of the crest. Ratio of median dorsal crest height/plate le ngth prominence. M edian dorsal plate with a B /L index ap­ approxim ately 64. proximately 80. Coarse ornamentation consisting of H olotype : M UGD6066 (Figs 2A, D, E , G, 3), an almost short ridges and pointed tubercles each with well d efined complete median dorsal plate from the top of the grooves. M cLarty Member of the M urrindal Limestone from the R emarks : W hite’s diagnosis (1978) has been m odified to vicinity of Rocky Camp Quarry, north of Buchan incorporate features of the new genus from Buchan. (Fig. 1). Weejasperaspis White 1978 and Murrindalaspis gen. D escr ipt ion : The holotype is almost complete, missing nov. are similar in the proportions of the m edian d orsal only the top of the crest and a small part of the left plate, in their median dorsal crests and in the mor ­ anterolateral corner. It bears a high, slender median phology of the derm al ornam entation; they differ ch iefly dorsal crest (cr.d) which starts approximately 28% of in the well-developed median ventral ridge on Wee­ the plate length from the anterior margin, and exte nds jasperaspis only, and in the size of tubercles of the backwards beyond the level of the posterior margin (Fig. external ornam ent. 3). In profile the crest is strongly curved, being propor­ tionately much narrower than the broad crest of Wee­ M urrindalaspis gen. nov. jasperaspis (Fig. 8). The anterior m argin of the plate has E tymology : A fter the settlement of M urrindal, north of a short median convexity and lateral to this region the Buchan. anterior margin extends forward at an angle of abou t NEW PLACODERM FISHES Fig. 2 —M urrindalaspis gen. nov., Emsian, Buchan. A , D, E, G, M . wallacei sp. nov., M UGD6066. H olotype m edian dorsal plate in A , ventral, D , post erior, E, right lateral and G, dorsal views, x l. B, C, F, H . M . bairdi sp. nov., NM VP59892. H olotype median dorsal plate in B, posterior, C, ventral, and F, right lateral views. H , detail of derm al ornam entat ion. B, x2; C, F, x l; H, x4. All specimens whitened with am m onium chloride. 176 JOHN A. LONG 40° to the lateral margin of the plate. There is a narrow D ia g nosis : A Murrindalaspis having a median dorsal overlap platform (ant.oa) along the extent of the plate which bears a low median dorsal crest.