96. Cambrian Faunas in South Australia with a Brief Note on the History of the Nullagine Basin*

96. Cambrian Faunas in South Australia with a Brief Note on the History of the Nullagine Basin*

484 [Vol. 18, 96. Cambrian Faunas in South Australia with a Brief Note on the History of the Nullagine Basin*. By Teiichi KoBAYA8rn**. (Comm.by T. KATo,M.Y.A., Oct. 12, 1942.) Parara limestone of the Yorke's Peninsula :-In South Australia the Cambrian strata are exposed as patches aligned in submeridional parallels. In the Yorke's peninsula a formation composed of archaeo- cyathid limestone above and dolomitic limestone below overlies the Pre-Cambrian basement with a thin sandstone bed at its base, while in many other places it is underlain by a thick purple slate series con- formably and this in turn by the Proterozoic Adelaide series with the Brighton limestone at the top, disconformably. The slate series measures 1500 to 10000 feet in thickness and contains thin beds of' oolitic )ime- stane, arenaceous limestone and reddish quartzite, which are occasionally cross-bedded and ripple-marked. It is certainly interesting that this slate which was .deposited after the Sturian glaciation is, according to David (1932), loessic. Since Woodward described two trilobites from the Parara limestone of the peninsula in 1884, its fauna has been amplified by Etheridge (1889), Tate (1892), and Chapman (1918), yet its age has been thought various- ly to be Lower Silurian of Murchison by Tate (1882) and Woodward, Lower Cambrian by Tate (1892) and Upper Cambrian by Etheridge (1890). Later in 1898, the last author suggested roughly Cambrian for ith age, while the Upper Cambrian age was re-affirmed by Howchin (1907) and Chapman (1918). Basedow (1909), Chapman (1914), David (1982), Whitehouse (1936) and several others however considered it to be Lower Cambrian, following Tate's later opinion, while in 1935 I suggested that the two trilobites from the Yorke's peninsula are related to Middle Cambrian members. A glance at the fossil list inserted here will show that Ordovician and Cambrian members are mingled in the fauna in, question and this co-mingling is the reason why such adverse opinions have been expressed. It has since been found, however, that most of the original generic references were incorrect. Neither Orthisina comptanor Orthis? peculiaris is properlyplaced in the genus. HenceWalcott (1912) has alreadysuggested Nissusia for the former and Kutorgina for the latter, the two generaranging fromLower to MiddleCambrian. Tate'sStenotheca rugosa is most probablya Helcionellaand Resser(1938) is correct in calling it by a new name,H, tc~ttei.Incidentally more speciesof Helcionellaare known in Lower Cambrianthan in MiddleCambrian. Ophileta subangulatawhich has a spiral keel alongthe middleof its apicalside of whorl is by no meansan Ophileta. It appears to me to be mostclosely allied to MiddleCambrian Pelagiella chronus walcott with whichI. (1939)established Proeccyliopteris. Platyceras etheridgei having a triangular ' Papers to which reference was madee are cited in the second paper (No. 67) of this Journal. *'* I wish to express my thanks to Prof . T. Kato for giving me encouragement and for reading these companion papers at the academy. No. 8.] Cambrian Faunas in South Australia with a Brief Note. 485 false area is not a gastropod. Walcott considered it as a Middle Cambrian atremate brachiopod closely allied to Micromitra (Paterina) superba, but as noted by him, the ventral valve is extraordinarily high. Furthermore, because it appears to have a foramen at, the apex, I think it is more probably an Acrotreta. This genus, though it occurs througbi Cambrian and to some extent also in Ordovician, flourished most in Middle Cambrian. Hyolithid like H, conularioides and H. communis are also common- ly met with in the Middle Cambrian faunas, although a deep longitudinal groove provided with a sharp ridge on each side in the former species is unusual. The oc- currence of Salterella is of course confined to the Lower Cambrian Strata (Kobayashi, 1937), but .S. planoconvexa does not belong to the genus because it has no.central tube and its conical tabulae are fused. On these accounts it agrees with Biconulites which was founded on Middle Cambrian B. grabaui from Shansi (Teilhard, 1931). Later Salterella hardemanni Foord,1890, from the Lower Cambrian of Kimberly was referred to the genus (Spath,1936). It should be noted here that these two species of Biconulites have no longitudinal groove as in planoconvexa. Incidentally, this was found in the lowest fossil horizon jn the Cambrian of South Australia which is located 500 feet below the archaeocyatliid limestone. Older Palaeozoic Fossils from the Yorke's Peninsula. Original reference Revised reference Girvanella sp. Hyalostella sp. Protopharetra (?) scoularis Etheridge Protopharetra or Metaldetes Ethmophyllum hindei Etheridge Ethmophyllum Coscinocyathus tatei Etheridge Coscinocyathus ? Orthis ? peculiaris Tate Kutorgina Orthisina compta Tate Nissusia Ambonychia (?) macroptera Tate 1 opteridae or Machaeridia Ophileta subangulata Tate Proeccyliopteris Plat'ceras eheridge Tate Aerotreta or Micrarnitra $tenotheca rugosa Hall by Tate HelcioneUQ tatei Resser Hyolithes communis B}llings by Tate Hyolithes conulariotid es Tate Dolichometopus tatei Woodward Microdiscus subsagittatus Tate Pararaia tatei~(Woodward) Olenellus ? pritchardi Tate Conocephalites australis Woodward Xorkella anstralis (Woodward) Ptychoparia howchini. Etheridge Leperiditia eapsella Chapman Univalved Conchostracan Leperiditia tatei Chapman Univalved Conchostraean Isochilina sweeti Chapman Univalved Conchostracan So revised, the Ordovician aspect first seen in the list becomes obscured and the Lower and Middle Cambrian appearance emerges un- mistakably. But more important for age-determination are the trilobites on which I carried out a study with the plaster-casts of the type specimens. As a result of this study it was determined that Dolicho- rnetopus tatei, Microdiscus subsagittatus and Olenellus pritehardi belong to one species and Conocephalites australis and Ptychoparia howchini to another, but that they do not belong to any of the formerly suggested genera. The former species is called here Pararaia tatei and the latter Yorkella australis. Pararaia and Yorkella are, as will be discussed in the next paper, intimate relatives respectively of Lorenzella and Solenopleura s. str. both of which are typical members of the Middle Cambrian faunas. It must be noted here in passing that 486 T. KOBAYASHI. [Vol. 18, a species of protolenid was contained among the plaster-casts at hand . An enigma in the Parara fauna is Ambonychia (?) macroptera which is a small fragmentary shell less than a quarter of an inch in length. If it is really a pelecypodits proper position may be found somewhere in the Aviculidaeor the Conocardiidae,instead of Ambonychiafrom which it is quite distinct. Whatever the genus of Pelecypodait belongsto, it is known at present that undoubted members of Pelecvpodaappear first in Ordovician. It appears to me, however, to be more probably a new univalvel Conchostracanor a new Machaeridian,because its resemblance to Technophorusand Pseudotechwphorus (Kobayashi, 1933) as well as isolated plates of Turrilepis can hardly be overlooked. As noted elsewhere(Kobayashi , h1936B), the occurrence of the Eopteridae to which the former two genera belong is, owever, restricted to the Ordovician except Upper Cambrian Wanwania cambrica. The Machaeridiaon the other hand occur in the strata from Ordovician to Devonian, b ut probably not in Cambrian (Withers, 1926). Which one of these suggestions is correct, must remainnunknown until the specimenis re-studied, but at any rate it is recognized that thEeenigmatic macroptera is allied to Upper Cambrian and later organisms. As regards Chapman'sthree species of ostracod Ulrich and Bassler (1931) suggested their being Cambrian univalved Conchostracans; Etheridge's archaeocyathids were revised by Talyer (1910); Girvanella and Hyalostella are not important for age- determihation because they are wide ranged. Cambrian in the Flinders Range and outer Places in South Aqu tralia In connection with the upper limit of the Eo-Palaeozoic formation in South Australia one must bear in mind that Walcott (1908) denominated Etheridge's Orthis (or Orthisina) sp. 1905, from Wirrialpa in the Flinders Range as Hitenella etheridgei because Huenella is known to have lived. from Upper Cambrian to Lower Ordovician . Further- more he placed Orthis (?) tatei Etheridge,1905, in the Eoorthis remnicha group. These together with a dubious Ambonychia suggest that the top of the limestone formation in question is possibly younger than Middle Cambrian. David (1932) and Whitehouse (1936), however, re- grded it as early Middle and Lower Cambrian, the former author classifying it into four stages. The highest containing Obolella wirrial- pensis Etheridge, 1905, was considered as early Middle Cambrian, not- withstanding the fact that other species of Obolella are all Lower Cambrian. The next is called the Redlichia stage and the third, the Protolenws stage. I cannot understand, however, how. the superposition of the secondabove the third stage was determined, because so far as I am aware, an undescribed protolenid is known only from the Yorke's peninsulawhile Redlichia is distributed from the Flinders to the northern territpries as far as the KimberIey district. The arehaeocyathidlime- stone is placed at the lowest of the four stages. Although it may be proper to con- sider the archaeocyathid limestone of the continent to be mostly.Lower Cambrian (Davjd, 1927),we must wait for future research to tell us whether the archaeocyathid limestones

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