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Early and Middle Cambrian Trilobites from Antarctica Paleontological Investigations in the Ellsworth Mountains, West Antarctica

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Early and Middle Cambrian Trilobites from Antarctica Paleontological Investigations in the Ellsworth Mountains, West Antarctica again yielded no clear evidence of their nature. They Early and Middle Cambrian were then subjected to OX-DTA in a pure-oxygen atmosphere at a heating rate of 80°C./min in order Trilobites from Antarctica to emphasize DTA sensitivity and sample response ALLISON R. PALMER to oxygen combustion. Exotherm peaks for the 20-70 microgram samples resembled those of various coals State University of New York at Stony Brook and lay within the lignite-bituminous range-465°C. for the Wheeler Valley sample and 540°C. for the Eight trilobite faunules ranging in age from Early McKelvey Valley sample. On this basis, and on the to Late-Middle Cambrian have been recovered from basis of their physical properties and behavior toward fossiliferous boulders collected by J . M. Schopf in solvents, we concluded that the minute particles were 1966 from moraines on Mount Spann in the north- coal. Samples of this size are too small to be ranked eastern Argentina Range. One of the Late-Middle by the reflectance technique. Cambrian faunules and one additional Middle Cam- The particles were probably derived by wind ero- brian faunule were collected by D. L. Schmidt in sion acting against the cleat of the complex Mount 1964 and 1966 in place in the lowermost part of the Bastion measures at the head of Victoria Valley Nelson Limestone in the Neptune Range. A tenth (Gunn and Warren, 1962; Allen, 1962). In view of faunule, also of Middle Cambrian age, is represented the frequent occurrence of coal in the Antarctic, we in the Queen Maud Range by badly deformed and may expect to find low levels of mixed-rank coals in slightly metamorphosed trilobites collected by V. H. other dry-valley soils. Minshew in 1964. The faunules include a total of 28 The flotation-DTA micro-method should be ap- species representing 21 genera. plied to extraterrestrial returned samples as a means Almost all trilobites in these faunules are close of detecting any coalified fossil life present. Such relatives of Australian, Chinese, or Siberian forms. material would probably be missed by remote life- There are no significant relations between any of detection systems such as the Py-GC-MS experiment the faunules and the Cambrian trilobites of South suggested for the Mars lander (Simmonds et al., or North America. This observation creates prob- 1969; Horowitz et al., 1969). lems for an Early Paleozoic Gondwanaland because This paper presents the results of one phase of the contrasting antarctic and South American Cam- research carried out at the Jet Propulsion Laboratory, brian faunas would share a common coastline. More California Institute of Technology, under NASA con- work will be needed in South America and Antarc- tract No. NAS 7-100 and NSF contract No. CO- tica to explain this anomalous relationship. 585-000-00. Within Antarctica, the Cambrian data indicate that the Neptune and possibly also the Queen Maud Ranges were the last areas inundated by transgressing References Cambrian seas. Limestones in the Argentina Range at the Atlantic end of the Transantarctic Mountains Allen, A. D. 1962. Geological investigations in southern Vic- and the Shackleton Limestone at the Pacific end of toria Land, Antarctica. New Zealand Journal of Geology and Geophysics, 5: 278. the mountains are considerably older than the oldest Allison, L. E. 1960. Wet-combustion apparatus and pro- beds in the Neptune Range. cedure for organic and inorganic carbon in soil. Soil Sci- ence Society of America. Proceedings, 24: 36-40. Goin, L. J . and P. L. Kirk. 1947. Application of microchemi- cal techniques: Identity of soil samples. Journal of Crimi- nal Law and Criminology, 38 (3): 267-281. Grimshaw, R. W. and A. L. Roberts. 1957. Carbonaceous Paleontological Investigations in the materials. In The Differential Thermal Investigation of Clays, p. 404-417. Mineralogical Society of London. Ellsworth Mountains, West Antarctica Gunn, B. M. and Guyon Warren. 1962. Geology of Victoria Land between the Mawson and Mulock Glaciers, Antarc- GERALD F. WEBERS tica. New Zealand Geological Survey. Bulletin, 71: 109. Horowitz, N. I-I., A. J . Bauman, R. E. Cameron, P. J . Geiger, Department of Geology J. S. Hubbard, G. P. Shulman, P. G. Simmonds, and Macalester College K. Westberg. 1969. Sterile soil from Antarctica: Organic analysis. Science, 164: 1054-1056. Reconnaissance geologic mapping of the Ellsworth Simmonds, P. G., G. P. Shulman, and C. H. Stembridge. Mountains (centered at 79°S. 85°W.) by three 1969. Organic analysis by pyrolysis, gas chromatography and mass spectrometry, a candidate experiment for the expeditions of the University of Minnesota has re- biological exploration of Mars. Journal of Chromato- sulted in the discovery of 11 fossiliferous localities graphic Science, 7: 36-41. (Table 1). The fauna and flora range in age from 162 ANTARCTIC JOURNAL COLUMNAR SECTION ELLSWORTH MOUNTAINS ANTARCTICA Australian-Asiatic affinity and include at least a dozen species referable to Pseudagnostus, Homag- nostus, Eugonocare?, Aphelaspis?, and to new genera. -111E0.1 CON-MERATE The trilobite fauna is dominated by forms very close to those described by Ivshin (1956) from the Upper SITE Cambrian of Kazakstan, U.S.S.R., and referred to QUARTZITE 30.000 Aphelaspis. However, Ivshins use of Aphelaspis is a broad interpretation of the genus, and the assignment u. of Heritage forms to Aphelaspis? indicates a close relationship to Asiatic rather than North American trilobite faunas. Monoplacophorans are abundant and are repre- sented by six species referable to Hypseloconus, Pro plina, Ozarkoconus and to new genera. Two of the monoplacophorans are septate and one has as many as four septa. This latter form is a high-coned, multiseptate, non-siphuncular hypseloconid which is representative of the ancestral group from which the cephalopods evolved. Gastropods are common and include four species Figure 1: from Boucot, Doumani, and Webers, Macluritella, Scaevogyra, and to new 1967. Proceedings of the International Sympo- referable to sium on the Devonian System, v. 1, p. 642. genera. Brachiopods are represented by Billingsella, acrotretids, and an unidentified linguloid. Pelmato- zoans are represented by scattered columnals. Archa- Cambrian to Permian (Fig. 1). All invertebrate eocyathids survived in Antarctica until at least late faunas are presently under study and several are Cambrian and are represented by a single species nearing completion. Among the latter is an unusual close to Archaeocyathus. Upper Cambrian fauna from the north central Heri- tage Range (Table 1, Locality #3). Reference This well-preserved fauna is unusual in its diversity Ivshin, N. K. 1956. Upper Cambrian Trilobites of Kazak- of trilobites and unique in its abundance of primitive stan, Pt. 1. Akademiia Nauk Kazakhstan S.S.S.R. (Alma mollusks and archaeocyathids. Trilobites show an Ata). 221 p. Table 1. Presently known fossil localities in the Ellsworth Mountains Locality Location Age Fauna or flora and formation 1 Northern Sentinel Permian Glossopteris and Gangamopteris flora: Polarstar Formation Mountains 2 Southern Sentinel Paleozoic ? Possible straight-shelled cephalopod: Crashsite Quartzite Mountains 3 Webers Peaks Area, Upper Well preserved fauna of trilobites, primitive mollusks, archaeocyathids, Heritage Range Cambrian articulate and inarticulate brachiopods, pelmatozoan echinoderms: Upper Heritage Group 4. North-central Lower Inarticulate brachiopods and a single specimen of articulate brachiopod: Heritage Range Devonian Crashsite Quartzite 5 Pipe Peak, Cambrian ? Inarticulate brachiopods: Crashsite Quartzite Heritage Range 6 Windy Peak, Cambrian ? Inarticulate brachiopods: Crashsite Quartzite Heritage Range 7 Springer Peak, Cambrian ? Inarticulate brachiopods: Crashsite Quartzite Heritage Range 8 Soholt Peaks, Middle Trilobites: Upper Heritage Group Heritage Range Cambrian ? 9 Inferno Ridge, Middle Trilobites: Upper Heritage Group Heritage Range Cambrian ? 10 Meyer Hills, (Reworked) Fossiliferous carbonate boulders: Whiteout Conglomerate Heritage Range 11 Anderson Massif, Cambrian (?) Highly deformed articulate brachiopods: Upper Heritage Group Heritage Range September—October 1970 163.
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