Download Full Article 960.5KB .Pdf File
Total Page:16
File Type:pdf, Size:1020Kb
. https://doi.org/10.24199/j.mmv.1977.38.03 4 April 1977 GASTROPODS FROM SOME EARLY DEVONIAN LIMESTONES OF THE WALHALLA SYNCLINORIUM, CENTRAL VICTORIA By C. B. Tassell Albany Residency Museum, Port Road, Albany, W.A. Abstract Seventeen gastropods from Devonian limestones at Marble Creek (also known as Toon- gabbie), Deep Creek and Loyola within the Walhalla synclinorium are described. These include four new forms: Platyceras (Platyceras) mansfieldense and P. (Praenatica) sp. A. from Loyola, and P. {Platyceras) sp. A. and P. (Orthonychia) sp. A. from Marble Creek. The other described forms are all platyceratids except Tremanotus cyclocostatus and Michelia sp. from Marble Creek, Oriostoma sp. n., and an indeterminate turbiniform gastropod from Deep Creek and Scalaetrochus lindstromi from Loyola. Tropidodiscus centrifugalis and ITemnodiscus pharetroides from the mudstones at Loyola are also redescribed. The gastropod faunas of the limestones are dominated by coprophagic platyceratid gastropods and constitute further examples of this widely known crinoid-gastropod association. Introduction Gastropods from the Toongabbie Limestone, The limestone deposits along the eastern Marble Creek, were first noted by McCoy who limb of the Walhalla synclinorium each consist observed 'some traces of Gasteropoda, appar- of a number of small lenses of limestone. The ently of the genus Acroculia, too imperfect to determination possible, and a fragment deposits extend about 120 km from Loyola in render of Chap- the north, about 130 km north-east of Mel- Bellerophort Murray (1878, p. 49). Nisa (Veto- bourne, to Marble Creek in the south, about man (1907) noted the presence of brazieri Etheridge and Trochus (Scalae- 140 km east of Melbourne. The limestone at tuba) trochus) sp. In 1916 he noted Tremanotus Loyola was the first to be noted in print. Selwyn pritchardi Cresswell and Coelocaulus brazieri and Ulrich (1867, p. 35) provided a chemical (Etheridge) described Diaphorostoma analysis of a 'white limestone from near Mans- and incisitm. field'. The first note of fossils appears to be that of McCoy, who considered the limestone Talent and Philip (1956), when describing to be Palaeozoic and was quoted to this effect the gastropod fauna from Marble Creek, by Couchman (1877, p. 19). Chapman (1914) erected two new genera, Ostlerina and Cow- mentioned an unidentified form of gastropod warrella. They also described eight new species and in 1916 he described two gastropods from and mentioned three poorly known forms. the Loyola Limestone, Platyceras cornutum These two new genera were subsequently Hisinger and Orthonychia brevis Chapman. synonymized by Knight et ah ( 1960) However, the latter is one of the nautiloids The lack of work both locally and inter- which are quite common at Loyola. He also nationally on Middle Palaeozoic gastropod described two species of gastropods from the faunas makes comparison with assemblages of associated mudstones, Temnodiscus phare- similar age difficult, and has also resulted in a troides and Euomphalus centrifugalis. Since number of genera being used in a very wide then no further work on the gastropod fauna sense. As a result of the lack of definition of has been undertaken. generic limits, the species described here are The limestone deposit with the least known compared with the type species as well as other south-eastern Australia. fauna is that at Deep Creek, about 6 km east species from following abbreviations of Walhalla. Together with the limestone at In this study the Marble Creek (also known as Toongabbie), have been used: National of Victoria Palaeonto- it appears to have been first noted by Murray P, Museum Collection; (1878, p. 48). The only mention of a gastro- logical , Melbourne University Geology pod from this locality is by Chapman (1916) M.U.G.D. who described Platyceras minutum. Department; 231 232 C. B. TASSELL G.S.V., Geological Survey of Victoria Collec- by Philip (1974). He discussed the current tion, now housed in the National Museum uncertainty in correlations between the dif- of Victoria. ferent facies of the Lower Devonian stages in All measurements are in millimetres and the Europe. Because of this present uncertainty, following symbols relating to the measurements their application in Australia should not be have been used: dogmatic. The gastropod Hap, height of aperture; Ht, total height of evidence for age determin- ations at Loyola is shell; L, length measured at the selenizone in minimal. Scalaetrochus lindstromi the bellerophontids; Lap, length of aperture; occurs at both Lilydale and Loyola. It is generally Wap, width of aperture; Wh, total number of considered that the Lilydale Limestone whorls in shell; Wit, width at last trema; Wt, is Late Siegenian (Strusz, 1972). total width of shell; *, specimen incomplete. However, the only other known occurrence of this genus is Scalaetrochus fragosus from the Acknowledgements Middle Devonian Anderdon Limestone, On- tario, Canada (Linsley, 1968). I wish to thank Mr T. A. Darragh, of the Within the mudstone surrounding the lime- National Museum of Victoria, Melbourne, for stone lenses at Loyola, Straparollus his discussion and criticism of this work; Dr O. (Strapa- rollus) serpenteus Talent and P. Singleton and Dr P. J. Coleman for their Loxonema sp. nov. of Talent occur. helpful comments, criticisms and discussions; (1963) These gastropods were originally Mr M. Cooper, of the University of Melbourne, described from the Kilgower Member, Tabberabbera Geology Department, for the loan of type by Talent (1963). This unit was considered specimens; Margaret Tassell for the photo- by Strusz (1972) to be Late Siegenian-Emsian in graphs and discussion throughout this study. age. Palaeoecology Age of the faunas The limestone at Marble Creek is composed As knowledge of Middle Palaeozoic gastro- largely of crinoidal fragments together with a pods is limited, they do not contribute signifi- few corals and stromatoporoids. In comparison cantly towards age determinations of the with the crinoids and coelenterates the other limestones. In this instance the situation is faunal elements comprise only a small per- further aggravated by the domination of centage of the fauna. These minor elements Platyceratids in each of the gastropod faunas. include gastropods, bivalves, nautiloids, rostro- Most discussions about the age of the lime- conchians (notably Conocardium), brachiopods stones at Marble Creek and Deep Creek have and trilobites. This faunal abundance and usually considered them to be of the same age. diversity is in complete contrast to that of the This is supported by the presence of the dis- surrounding mudstones which are virtually tinctive Platyceras (Visitator) cylindricum at unfossiliferous (Talent, 1956). both localities. Strusz (1972) assessed the The commensal relationship between the available information from both these localities coprophagic gastropods of the family Platy- and considered them to be Late Siegenian. ceratidae and crinoids has been known for a The age of the Loyola Limestone has been long time. Lane (1973) described in detail argued for some time. Most recently Cooper such a relationship from the Carboniferous of (1973) noted the presence of a polygnathan Indiana. At Marble Creek the disarticulated conodont element in the fauna and considered nature of the crinoid crowns implies some post- the limestone to be Early Emsian. This age mortem transport. Although the gastropod determination has been accepted by other fauna at Marble Creek is dominated by mem- workers (Strusz, 1972; Vandenberg et a/., bers of the Platyceratidae, none have been 1976). found in situ on a crinoid crown. Discussion of the ages of these limestones Apart from the dominant platyceratids, the must be placed in the perspective of comments gastropod fauna from Marble Creek is limited. GASTROPODS FROM WALHALLA SYNCLINORIUM 233 Tremanotus cyclocostatus is considerably tinct bodies of limestone interbedded with the smaller than T. pritchardi from the Lilydale surrounding highly fossiliferous mudstones Limestone of comparable age. Also present (Cooper, 1973). This limestone exhibits a are poorly preserved specimens of Michelia sp. great deal more variation in composition than Again considerably larger forms are known the limestones from Deep Creek and Marble from both the Lilydale Limestone and the Creek. In part it is composed largely of slightly younger limestone at Taemas, N.S.W. crinoidal material only slightly disarticulated. Chapman (1907) noted the presence at Marble Coelenterates dominate the limestone in other Creek of Scalaetrochus sp. but this specimen areas. has not been relocated. The total fauna of the limestones is diverse The gastropod fauna of the Toongabbie but the gastropod component is quite limited Limestone is markedly different from the only being represented by only a few species. How- other adequately known Lower Devonian ever, there is no tendency at Loyola towards gastropod fauna from Victoria, that of the reduction in size; rather the platyceratids from Lilydale Limestone. This latter fauna from a this limestone are comparable in size to, or protected shallow marine environment is larger than, those from Marble Creek. dominated by large gastropods, both high- The low gastropod diversity of the lime- spired and planispiral (Tassell, 1976). Signi- stones is in marked contrast to the gastropod ficantly, no coprophagic gastropods are known fauna of the associated mudstones. Chapman from this limestone. Also this limestone is not (1916)