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Therapsids, Temnospondyls, and Dinosaurs from the Fremouw and Union

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Therapsids, Temnospondyls, and Dinosaurs from the Fremouw and Union References vertebrate fauna from Antarctica and its depositional setting. Antarc- tic Science, 2(2), 163-167 Barrett, P.J., D. H. Elliot, and J.E Lindsay. 1986. The Beacon Supergroup Hammer, W.R., and J.W. Cosgriff. 1981. Myosaurus gracilus, an anom- (Devonian-Triassic) and Ferrar Group (Jurassic) in the Beardmore odont reptile from the Lower Triassic of Antarctica and South Amer- Glacier area, Antarctica. In M.D. Turner and J.F. Splettstoesser ica. Journal of Paleontology, 55(2), 410-424. (Eds.), Geology of the central Transantarctic Mountains. (Antarctic Re- Hammer, W.R., W.J. 1-lickerson, S. Krippner, and I. Tamplin. 1991. search Series, Vol. 36.) Washington, D.C.: American Geophysical Therapsids, temnospondyls, and dinosaurs from the Fremouw and Union. Falla formations, Beardmore Glacier region, Antarctica. Antarctic Jour- Colbert, E.H. 1982. Triassic vertebrates in the Transantarctic Moun- nal of the U.S., 26(5). tains. In M.D. Turner and J.F. Splettstoesser (Eds.), Geology of the Hammer, W.R., W.J. Ryan, and S.L. DeFauw. 1987 Comments on the central Transantarctic Mountains. (Antarctic Research Series, Vol. 36.) vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Washington, D.C.: American Geophysical Union. Glacier region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33. Collinson, J.W., and J.L. Isbell. 1986. Permian-Triassic sedimentology Hammer, WR., WI. Ryan, J.W. Tamplin, and S.L. DeFauw. 1986. New of the Beardmore Glacier region. Antarctic Journal of the U.S., 21(5), vertebrates from the Fremouw Formation (Triassic), Beardmore Gla- 29-30. cier region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26. Hammer, W.R. 1988. The Cynognathus zone (late Early Triassic) verte- Homer, T.C., and L.A. Krissek. 1991. Permian and Triassic paleosols brate fauna from Antarctica. Antarctic Journal of the U.S., 23(5), 10-11. from the Beardmore Glacier region, Antarctica. Antarctic Journal of the Hammer, W.R. 1989. Lystrosaurus Zone (Triassic) vertebrates from the U. S., 26(5). Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., Isbell, J.L., and D.I.M. Macdonald. 1991. Lithofacies analysis of the 24(5), 40-41. Triassic Fremouw Formation at the Gordon Valley vertebrate site, Hammer, W.R., J.W. Collinson, and W.J. Ryan. 1990. A new Triassic Antarctica. Antarctic Journal of the U.S., 26(5). Therapsids, temnospondyls, includes dinosaur material, represents only the third terrestrial vertebrate fauna known from the Transantarctic Mountains and and dinosaurs the antarctic mainland. from the Fremouw and Falla Because the upper Fremouw Formation vertebrates were formations, Beardmore Glacier found near the end of the 1985-1986 field season, a field party of six (including the four authors of this paper) returned to the region, Antarctica Gordon Valley during the 1990-1991 season to finish excavation of the remaining fossils and, in conjunction with a sedimento- logical team from Ohio State University, investigate the taphon- WILLIAM R. HAMMER, WILLIAM J. HICKERSON, omic and paleoecological setting of the upper Fremouw. During and STEPHEN KRIPPNER the first month of the 1990-1991 season over 100 specimens were collected from two sites in the Gordon Valley, the original Department of Geology locality excavated during the 1985-1986 season and a new one Augustana College about 8 kilometers away at the same stratigraphic level. Ta- Rock island, Illinois 61201 phonomic conditions have left these specimens largely scat- tered and fragmentary, however, excellent additional material JEFFREY TAMPLIN from taxa collected in 1985-1986 (see Hammer 1990) was re- covered. Fossils representing new taxa from these sites include cranial and postcranial material of smaller temnospondyls and Department of Zoology Louisiana State University therapsids, including at least one small dicynodont. Taphon- Baton Rouge, Louisiana 70803 omic data were taken at the localities and maps showing bone orientations on the bedding plane surfaces were made in the field. Since the first discovery of Triassic fossil tetrapods at Graph- The Falla Formation vertebrates were first discovered late in ite Peak in 1967 (Barrett, Baillie, and Colbert 1968), six expedi- December 1990, by a team of petrologists headed by David tions have searched for terrestrial vertebrate remains in the Elliot of Ohio State University and Richard Hanson of Texas Transantarctic Mountains (Hammer, Collinson, and Ryan 1990; Christian University. The fossils were mainly concentrated in Hammer, Ryan, and DeFauw 1987). Until the 1985-1986 season, one small area of siltstone exposure on Mount Kirkpatrick at only the lower Fremouw Formation of the Central Transantarc- about 4,500 meters above sea level. Of the over 50 bones col- tic Mountains near the Beardmore and Shackleton Glaciers had lected, only 3 were not from this single concentration. The yielded fossils of this type (Colbert 1982; Hammer and Cosgriff bones are very well preserved, large, and include much of the 1981). During the 1985-1986 austral summer, a new, younger skeleton of one dinosaur and, perhaps, portions of a second. fauna of vertebrates was found in the upper Fremouw Forma- At least one of the three isolated postcranial bones is from yet tion of the Gordon Valley (Beardmore Glacier region). A third another smaller animal. A "Megalosaurus" type theropod assemblage of even younger terrestrial animals was recently tooth was found among the initial bones removed. Since most discovered in the Falla Formation on Mount Kirkpatrick near of the fossils are still largely encased in rock, the number and the Beardmore Glacier in 1990-1991. This new collection, which type of animals represented is not entirely certain at this point. 1991 REVIEW 19 From what can be seen, however, it is apparent that the collec- This research is supported by National Science Foundation tion contains at least the top portion of a skull, over 20 verte- grant DPP 88-17023 and the Augustana Research Foundation. brae, numerous ribs, portions of at least eight limb bones in- Special thanks go to our colleagues David Elliot (Ohio State cluding a humerus and part of a femur, one side of a shoulder University) and Richard Hansen (Texas Christian University) girdle, part of a pelvis and a number of pes elements. Excava- for their discovery of the dinosaur site, and Larry Krissek (Ohio tion of the large fossils was accomplished with the aid of a State) and Tim Homer (Ohio State University) for their sedi- gasoline-powered impact hammer/drill (see figure). In total, mentological work. We would also like to acknowledge the ex- over 1,800 kilograms of fossil-bearing rock was removed from cellent logistical support given by the Beardmore South Camp the site. staff and Helicopters New Zealand. References Barrett, P.J., R.J. Baillie, and E.H. Colbert. 1968. Triassic amphibian from Antarctica. Science, 161(3840), 460-462. Colbert, E.H. 1982. Triassic vertebrates in the Transantarctic Moun- tains. In M.D. Turner and J.F Splettstoesser (Eds.), Geology of the central Transantarctic Mountains. (Antarctic Research Series, Vol. 36.) Washington, D.C.: American Geophysical Union. Hammer, W.R. 1990. Triassic terrestrial vertebrate faunas of Antarctica. In TN. and E.L. Taylor (Eds.), Antarctic paleobiology: Its role in the reconstruction of Gondwanaland. New York: Springer-Verlag. Hammer, W.R., J.W. Collinson, and W.J. Ryan. 1990. A new Triassic vertebrate fauna from Antarctica and its depositional setting. Antarc- tic Science, 2(2), 163-169. Hammer, W.R., W.J. Ryan, and S.L. Defauw. 1987 Comments on the vertebrate fauna from the Fremouw Formation, Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33. Hammer, W.R., and J.W. Cosgriff. 1981. Myosaurus gracilis, an anom- Researchers use a gasoline-powered impact drill/hammer to ex- odont reptile from the Lower Triassic of Antarctica and South Africa. cavate dinosaur fossils at the Mount Kirkpatrick site. Journal of Paleontology, 55(2), 410-424. Vertebrate trackways During the 1990-1991 field season, a party of geologists from the British Antarctic Survey, Ohio State University, and Augus- from the Triassic tana College, discovered a Triassic vertebrate trackway in the Fremouw Formation, Gordon Valley area of the Queen Alexandra Range (figure 1). Queen Alexandra Range, This is the first Mesozoic vertebrate trackway to be found in Antarctica Antarctica. The only other known vertebrate trace fossils are Oligocene-Miocene bird tracks, reported from the South Shet- land Islands (Covacevich and Rich 1982). DAVID I.M. MACDONALD The trackway horizon occurs in a 167-meter-thick section of the middle and upper (basal part) members of the Fremouw British Antarctic Survey Formation exposed along the north side of Gordon Valley (fig- Natural Environment Research Council ure 2; cf. Barrett and Elliot 1973; Barrett, Elliot, and Lindsay Cambridge CB3 0ET UK 1986). A vertebrate bone bed was found near the top of this section in the 1985-1986 season (Hammer et al. 1986; Hammer, Ryan, and DeFauw 1987; Hammer, Collinson, and Ryan 1990). JOHN L. ISBELL The trackways are at a stratigraphic height of 67 meters, in the middle Fremouw member. They occur on the top surface Byrd Polar Research Center of a 65-centimeter-thick composite bed, which appears to be a and silicified paleosol. The upper part of the bed comprises a 10- Department of Geological Sciences centimeter massive layer with rootlets, overlain by a rubbly, Ohio State University nodular unit, which is in turn overlain by 2 centimeters of Columbus, Ohio 43210 stylolitized chert, 5 centimeters of structureless siliceous mud- stone, and 1 centimeter of laminated siliceous mudstone. These WILLIAM R. HAMMER sedimentary rocks resemble a soil profile, which could either be a silicified calcrete (see examples in Collinson 1986) or an Department of Geology unusual style of silcrete. The structureless and laminated units Augustana College at the top of the profile were probably deposited in an ephem- Rock Island, Illinois 61201 eral lake.
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