Paleontological Contributions
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THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS July 25, 1978 Paper 93 NEW GENERA OF ACROTRETIDS FROM THE CAMBRIAN OF AUSTRALIA AND THE UNITED STATES' A. J. ROWELL and R. A. HENDERSON University of Kansas, Lawrence, Kansas and James Cook University of North Queensland, Townsville, Queensland ABSTRACT Little is known about the paleobiogeography of Cambrian brachiopods. Cooperative studies have shown the presence of three new genera of inarticulate acrotretid brachiopods in Upper Cambrian rocks of both Australia and the United States, but none of their species are common to both regions. Ouadrisonia (type species O. minor), Dactylotreta their (type species D. redunca), and Anabolotreta (type species A. tegula) are erected and type species described from etched material. INTRODUCTION Contrary to popular belief, Cambrian brachio- two entirely different trophic groups. Some tri- pods are abundant, moderately diverse, and mor- lobites [nay have preyed upon, or inadvertently joint phologically variable. Typically, species of this consumed, young brachiopods, but their probably reflects environ- age are small forms, rarely exceeding 1.5 mm to presence in a rock more 2 mm in maximum dimension. Their abundance mental conditions appropriate to both rather than was not fully realized until Bell (1948) demon- some direct biological linkage between brachio- strated that the phosphatic-shelled forms could be pods and trilobites. been studying recovered from residues of limestones that had For the past few years, we have been digested in dilute organic acids. In many Cambrian brachiopods, particularly Upper Cam- his coworkers have been Middle and Upper Cambrian limestones deposited brian forms. Rowell and of the upper Dresbach- in open-shelf environments, brachiopods are the investigating brachiopods most numerous component of the fossil fauna. In ian and lower Franconian Pterocephaliid Biomere United States (Rowell terms of biomass, however, trilobites were prob- of the Great Basin of the ably dominant. It is unlikely that representatives & Brady, 1976). More recently, he has initiated of the underlying of these two phyla interacted to any significant a study of the inarticulates "Cedaria" zones of the lower extent. As far as is known, they belonged to "Crepicephalus" and Dresbachian of that region. Henderson has worked primarily on the inarticulate brachiopods Manuscript received July 15, 1977; revised manuscript received of the Mindyallan and Idamean stages of Queens- November 15, 1977. 2 The University of Kansas Paleontological Contributions—Paper 93 land, rocks that are of approximately the same with additional terms proposed by Krause and age as those investigated by Rowell (Opik, 1966; Rowell (1975). Henderson, 1976). Although some information is Repositories.—Material described here is held available on the stratigraphie distribution of by three institutions: James Cook University brachiopods from the Upper Cambrian of the (prefixed JCF), the Australian Bureau of Mineral North American craton (Palmer, 1954; Grant, Resources (prefixed CPC) and the Museum of 1965; Kurtz, 1971; Kurtz et al., 1975), little has Invertebrate Paleontology, University of Kansas been published on the distribution of the much (prefixed UKMIP). Localities are recorded only more diverse fauna of the miogeoclinal sequence in terms of reference numbers issued by the institu- in the Great Basin (Rowell & Brady, 1976). Es- tions to which the individual collections belong. sentially nothing is available in the literature on Full descriptions will be published elsewhere. the stratigraphie distribution of Australian Upper Acknowledgments.—We Cambrian brachiopods. Furthermore, although are indebted to our colleagues Drs. J. H. Shergold (Bureau of Mineral the paleobiogeography of Cambrian trilobites has Resources, Canberra), M. E. Taylor (United been a subject of concern for over eighty years, States Geological Survey), and A. R. almost nothing is known of the past distribution Palmer (State University of New York, Stony Brook) for of Cambrian brachiopods. Rowell and Krause the loan of material in their charge or (1973) noted that such genera as Linnarssonia collected by them. Henderson's investigations have and Acrothele were widespread in Middle Cam- been supported by the Australian Research brian rocks and seem to be cosmopolitan, but our Grants Commission. Rowell's studies of North American ignorance of the geographical distribution of most Cambrian brachiopods Cambrian brachiopods is virtually complete. have been supported by the National Science Foundation, Earth Sciences Because we both have systematic manuscripts Section grants GA-39692 and DES75-21499. The nearing completion, both lacked information on opportunity for Rowell to study Australian Cam- the degree of endemism of our faunas, and neither brian brachiopods was made possible by a grant had access to the stratigraphie distribution of the from the National Science Foundation Inter- taxa recognized by the other, it seemed advanta- national Program (INT76-11757) as a part of the geous that we cooperate. Our immediate ob- "United States–Australian Cooperative Science jectives were to avoid problems of synonymy and Program" administered by to gain some insight into the geographic distribu- the National Science Foundation and the tion of taxa. This contribution bears on the first Australian Department of of these two objectives, making available names Science. Partial support for this visit was gener- for three genera that are common to the Cambrian ously provided by the Wallace E. Pratt Fund of of both continents. the Paleontological Institute, University of Kansas, In the subsequent taxonomic descriptions and underwritten by the Exxon U.S.A. Foundation. discussions, we have employed the morphological We share jointly and equally in the authorship terminology used in the Treatise on Invertebrate of this contribution: the sequence of our names Paleontology (Williams & Rowell, 1965) together was decided by the toss of a coin. STRATIGRAPHIC DISTRIBUTION The stratigraphie distribution of species of the bachian Aphelaspis Zone to basal Franconian three new acrotretid genera Ouadrisonia, Dacty- Elvinia Zone). Although we are fairly confident lotreta, and Anabolotreta are shown in Figure 1. of the stratigraphie distribution of the Pteroce- To avoid the creation of nomina nuda, only the phialiid Biomere brachiopods, the same claim can- type species of each genus is named, the remaining not now be made for lower Dresbachian or higher species being left in open nomenclature. These Franconian and Trempealeauan forms. Lower presently undescribed species from Australia are being monographed by Henderson; Rowell and Upper and upper Upper Cambrian brachiopods McBride are describing the North American taxa of North America are still inadequately known, from the Pterocephaliid Biomere (middle Dres- and recent studies of them have largely been Rowell & Henderson—New Genera of Acrotretids 3 confined to low-diversity cratonic sites (e.g., Pal- to occur in both Australia and the United States. mer, 1954; Bell & Ellinwood, 1962; Grant, 1965; The closest phenetic similarity is between the late Lochman & Hu, 1960). It is certainly possible that pre-Payntonian Dactylotreta sp. 4 and the basal additional work will increase the stratigraphie Franconian Dactylotreta sp. 6. Even these two range of all three of the new genera in North taxa may be readily distinguished; and if the sug- America. Although all three genera are present gested chronocorrelation is accurate (Fig. I), then in both continents, none of the species are known they are of slightly different ages. z c'''''' cLcrw' 4z—z z 0 m z 1— o o .1 z s-) I a. u.i » Z I lc .1 •— I cc Toenicephotus 1 _ mi u_ E/r/nia 11: 11 I rropico ill z S °di/orna < ! 1ii w Dander bergio 1 1 E sen/urn Prehous/o 1 M a I 1 I 1 P crypt/cc a _ DIconthopyge _o m I i G re/oil/ala 0 Apnetospis 1 .. a 1 • 'Ti , 1 1 1 1 0 Crep/cepholus ' l 1 i 1 F G stohdotus . z I II I >- w 1111 II 1 1 , C. quostvespo o 4 cr. , z -1 o Cedor/a ' 1111 I 1 1 E eretes i Zi 1111 1 1 1 i I I I IiII I z 1 1 1 1 1 I z 5 1 I 1 L. toevtgata a_ rr I i I I I i I 1 I cr co I 1 1 1 I m 1 1 1 1 o m o M 1III 1 i I...1 < I 1 i 1 I 1 ILI < (...) (....) i I I I 1 I II < I i I I < Z I I 1 1 1 I Z Z lal I III 1 I Z Lu 0 ..J 1 1 1 1 1 D _I 0 'iii 11 1 1 1 0 I 0 II I I 1 1 1 I 1 1 0 -2- I I I I 1 1 1 I 1 1 i o -- N n o,.- -- N to o v- ,,) - -- o_ o. o. o. o o, t, t; ...,o.. ,..,o, ,,,a c- ,.., ,,, ,.,„ , ,,-, ,.., ., :.....:. ,.,„ .t. ‘, o o ... o .-Z.%, .....-- Ô .... ô ,.., :62. Z.: c, 1:, ..t• 4:. 0 ,.., 0 0 C . C.) C21 C.). 6 6 6 6 ci cc ci ‘z .4 FIG. I. Strafgraphic ranges of known species of Quadrisonia, Dadylotreta, and Anabolotreta. Approxii late correlation of North American stages and zones (on the left) with those of Australia (on the right) based on Henderson (1976). Australian species ranges in solid black, North American species in heavy broken line. SYSTEMATICS AND MORPHOLOGY Order ACROTRETIDA Kuhn, 1949 Type species.—Dactylotreta red ttnnt RowELL Superfamily ACROTRETACEA Schuchert, 1893 AND HENDERSON, fl. Sp. Family ACROTRETIDAE Schuchert, 1893 Diagnosis. — Acutely conical Acrotretinae, ven- Subfamily ACROTRETINAE Schuchert, 1893 tral valve catacline to slightly procline; unusually large apical process completely occluding apex of Genus DACTYLOTRETA valve, flat or slightly ridged medianly, perforated Rowell and Henderson, new posteriorly by internal pedicle opening. Dorsal 4 The University of Kansas Paleontological Contributions—Paper 93 pseudointerarea long, relatively large; median DACTYLOTRETA REDUNCA plate conspicuous, concave, separating anacline- Rowell and Henderson, new species orthocline propareas, supported by median but- tress.