Comments on the vertebrate fauna from the Fremouw Formation ...
fern possesses a mesarch, amphiphloic siphonostele embedded in a parenchymatous cortex. The pith is often scierified. In these stems there is relatively little support tissue. Only the vascular strand and thickened cells of the cortical or pith tissues function to reinforce the plant. An upright growth habit would be very unlikely for any of these ferns. The co-occurrence and similar growth habit of these three ferns is interesting and points to a similar habitat choice. The lack of large air spaces or lacunae in the cortex suggests these stems were not aquatic. The cycad Antarcticycas (which is associated with the ferns in the matrix) also appears to have a branching, probably subterranean stem like the extant cycad Zamia. Considering the need for water during the gametophyte generation of these ferns, the most likely habitats would have been in a forest understory, riparian, or a sheltered glen area.
This work was supported in part by National Science Foundation grants DPP 86-11884 and BSR 8440399.
References Barrett, P.J. 1969. Stratigraphy and petrology of the mainly fluviatile Permian and Triassic Beacon rocks, Beardmore Glacier area, Antarctica. (Ohio State University Institute for Polar Studies Report Number 34.) 1-32. Smoot, EL., T.N. Taylor, and T. Delevoryas. 1985. Structurally preserved fossil plants from Antarctica. I. Antarcticycas, gen. nov., a Triassic cycad stem from the Beardmore Glacier area. American Journal of Botany, 72, 1410-1423.
Comments on the vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Glacier region Antarctica WILLIAM R. HAMMER and WILLIAM J. RYAN
Department of Geology Augustana College Rock island, Illinois 61201 SIIERRI L. [)EFAuw
Departnu'n t of Biological Scu',iccs Wayne State University Detroit, Michigan 48202
As previously reported (Hammer et al. 1986), a diverse new fauna of reptiles and amphibians was recovered from the upper member of the Fremouw Formation in the deglaciated Gordon Valley (figure) during the 1985-1986 austral summer. Gordon Valley is located near Mount Falla in the Beardmore Glacier region of the Transantarctic Mountains. Specimens from this locality are under preparation and several new forms have now been identified. In addition, a paleoecological analysis of the lower Fremouw vertebrate community is in progress. All previous collections of fossil vertebrates from the lower Fremouw are considered biostratigraphically equivalent to the Lystrosaurus zone of South Africa (Hammer and Cosgriff 1981; Colbert 1982). It is apparent from its stratigraphic position that the fauna from the Gordon Valley locality is younger than that of the lower Fremouw. It also appears to share at least two genera with the Cynognathus zone of South Africa. Included in the collection from Gordon Valley is the right mandible of the cynodont reptile, Cynognathus, and what appears to be a partial maxilla of the large anomodont, Kannemeyeria. The Cynognathus zone, which occurs directly above the Lystrosaurus zone, has been renamed the Kannemeyeria assemblage zone by Keyser and 32
Upper Fremouw Formation vertebrate locality in the Gordon Valley. (Photo taken by W.R. Hammer.)
Smith (1978), since specimens of the herbivorous dicynodont Kannemeyeria are much more common than the carnivorous Cynognathus. The Gordon Valley assemblage represents the first non-Lystrosaurus zone terrestrial vertebrate fauna from the Transantarctic Mountains. At least two other synapsid reptiles occur, including a nearly complete maxilla of a large gomphodont cynodont. Three ternnospondyl amphibians represent new species and probably new genera. Included among the amphibian material is a wellpreserved mandible belonging to the family Benthosuchidae, a family previously unreported from the Antarctic and notably uncommon in Gondwana. Other amphibian taxa include a possible capitosaur and an extremely large temnospondyl of undetermined affinity. As the new material is prepared and described, specific comparisons with faunas of similar age from other Gondwana continents will be made. Since previous studies of antarctic vertebrates have established close faunal affinities between Antarctica, South Africa, and Australia, it will be of particular ANTARCTIC JOURNAL
interest to see if this new community maintains the strong correspondence evident for the lower Fremouw, or if Antarctica developed a unique fauna during the later portion of the Early Triassic. A paleoecological analysis of the lower Fremouw Formation is advancing concurrent with the description of this new fauna. Extensive collection of the lower Fremouw over four field seaSons has led to a data base that may allow us to determine preferred paleoenvironments for certain taxa. New specimens collected from the Coalsack Bluff and Graphite Peak localities during the 1985-1986 field season are under study, and a complete analysis of the collection made during the 1977- 1978 field season (Cosgriff et al. 1978) has recently been completed. This research is supported by National Science Foundation grants DPP 85-11334 and DPP 84-18354.
References Colbert, E. H. 1982. Triassic vertebrates in the Transantarctic Mountains. In M. Turner and J. Splettstoesser (Eds.), Geology of the Central Transantarctic Mountains. Antarctic Research Series, 39(2), 11-35. Cosgriff, J.W., W.R. Hammer, J.M. Zawiskie, and N.R. Kemp. 1978. New Triassic vertebrates from the Fremouw Formation of the Queen Maud Mountains. Antarctic Journal of the U.S., 13(4), 23-24. Hammer, W. R., and j.W. Cosgriff. 1981. Myosaurus gracilis, an anomodont reptile from the Lower Triassic of Antarctica and South Africa. Journal of Paleontology, 55(2), 410-424. Hammer, W.R., W.J. Ryan, J.W. Tamplin, and S.L. DeFauw. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26. 86Keyser, A. W., and R.M.H. Smith. 1978. Vertebrate biozonation of the Beaufort Group with special reference to the western Karoo Basin. Annals of the Geological Survey (South Africa), 12, 1-36.
Multiple phases of early Paleozoic deformation in the central Transantarctic Mountains MARGARET
N. REES
Department of Geoscience University of Nevada Las Vegas, Nevada 89154 GARY H. GIRTY
Department of Geological Sciences San Diego State University San Diego, California 92192 SUSAN K. PANTTAJA
Department of Geoscience University of Nevada Las Vegas, Nevada 89154 PETER BRADDOCK
Queen Charlotte College Picton, New Zealand
New structural data from the lower Paleozoic Douglas Conglomerate in the northern Churchill Mountains (figure 1) indicate that the conglomerate was deformed at least three times before the deposition of the overlying Devonian beds of the Beacon Supergroup. Recognition of these post-Lower Cambrian and pre-Devonian events makes all existing tectonic models for the area too simplistic. Our geological investigation of the northern Churchill Moun tains revealed extensive outcrops of Douglas Conglomerate that were not observed or visited by previous field teams (Burgess and Lammerink 1979; Skinner 1964, 1965; Stump et al. 1979); consequently we produced a new geological map and propose new structural interpretations. In addition, south of the mapped area at location 14 (figure 2) trilobites were collected from the Shackleton Limestone and, at location 17, a previously unrecorded, 1000-meter-long exposure of pillow lava was examined and sampled. 1987 REVIEW
Figure 1. Location map showing position of area mapped within the central Transantarctic Mountains and the extent of the Churchill Mountains between the Byrd and Nimrod glaciers. ("MH" denotes Mount Hamilton, "CC" denotes "Crackling Cwm," and "MD" denotes Mount Dick.)
The field team (Rees, Girty, Panttaja, and Braddock) was put into the field by an LC-130 ski-equipped Hercules airplane on 24 November 1986 and picked up from the same location on 5 January 1987. The landing site was located on the Nicholson Peninsula (80°42'S 159°23'E). Overland travel by snowmobile to 33
This work was supported in part by National Science Foundation grants DPP 86-11884 and BSR 8440399.
References Barrett, P.J. 1969. Stratigraphy and petrology of the mainly fluviatile Permian and Triassic Beacon rocks, Beardmore Glacier area, Antarctica. (Ohio State University Institute for Polar Studies Report Number 34.) 1-32. Smoot, EL., T.N. Taylor, and T. Delevoryas. 1985. Structurally preserved fossil plants from Antarctica. I. Antarcticycas, gen. nov., a Triassic cycad stem from the Beardmore Glacier area. American Journal of Botany, 72, 1410-1423.
Comments on the vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Glacier region Antarctica WILLIAM R. HAMMER and WILLIAM J. RYAN
Department of Geology Augustana College Rock island, Illinois 61201 SIIERRI L. [)EFAuw
Departnu'n t of Biological Scu',iccs Wayne State University Detroit, Michigan 48202
As previously reported (Hammer et al. 1986), a diverse new fauna of reptiles and amphibians was recovered from the upper member of the Fremouw Formation in the deglaciated Gordon Valley (figure) during the 1985-1986 austral summer. Gordon Valley is located near Mount Falla in the Beardmore Glacier region of the Transantarctic Mountains. Specimens from this locality are under preparation and several new forms have now been identified. In addition, a paleoecological analysis of the lower Fremouw vertebrate community is in progress. All previous collections of fossil vertebrates from the lower Fremouw are considered biostratigraphically equivalent to the Lystrosaurus zone of South Africa (Hammer and Cosgriff 1981; Colbert 1982). It is apparent from its stratigraphic position that the fauna from the Gordon Valley locality is younger than that of the lower Fremouw. It also appears to share at least two genera with the Cynognathus zone of South Africa. Included in the collection from Gordon Valley is the right mandible of the cynodont reptile, Cynognathus, and what appears to be a partial maxilla of the large anomodont, Kannemeyeria. The Cynognathus zone, which occurs directly above the Lystrosaurus zone, has been renamed the Kannemeyeria assemblage zone by Keyser and 32
Upper Fremouw Formation vertebrate locality in the Gordon Valley. (Photo taken by W.R. Hammer.)
Smith (1978), since specimens of the herbivorous dicynodont Kannemeyeria are much more common than the carnivorous Cynognathus. The Gordon Valley assemblage represents the first non-Lystrosaurus zone terrestrial vertebrate fauna from the Transantarctic Mountains. At least two other synapsid reptiles occur, including a nearly complete maxilla of a large gomphodont cynodont. Three ternnospondyl amphibians represent new species and probably new genera. Included among the amphibian material is a wellpreserved mandible belonging to the family Benthosuchidae, a family previously unreported from the Antarctic and notably uncommon in Gondwana. Other amphibian taxa include a possible capitosaur and an extremely large temnospondyl of undetermined affinity. As the new material is prepared and described, specific comparisons with faunas of similar age from other Gondwana continents will be made. Since previous studies of antarctic vertebrates have established close faunal affinities between Antarctica, South Africa, and Australia, it will be of particular ANTARCTIC JOURNAL
interest to see if this new community maintains the strong correspondence evident for the lower Fremouw, or if Antarctica developed a unique fauna during the later portion of the Early Triassic. A paleoecological analysis of the lower Fremouw Formation is advancing concurrent with the description of this new fauna. Extensive collection of the lower Fremouw over four field seaSons has led to a data base that may allow us to determine preferred paleoenvironments for certain taxa. New specimens collected from the Coalsack Bluff and Graphite Peak localities during the 1985-1986 field season are under study, and a complete analysis of the collection made during the 1977- 1978 field season (Cosgriff et al. 1978) has recently been completed. This research is supported by National Science Foundation grants DPP 85-11334 and DPP 84-18354.
References Colbert, E. H. 1982. Triassic vertebrates in the Transantarctic Mountains. In M. Turner and J. Splettstoesser (Eds.), Geology of the Central Transantarctic Mountains. Antarctic Research Series, 39(2), 11-35. Cosgriff, J.W., W.R. Hammer, J.M. Zawiskie, and N.R. Kemp. 1978. New Triassic vertebrates from the Fremouw Formation of the Queen Maud Mountains. Antarctic Journal of the U.S., 13(4), 23-24. Hammer, W. R., and j.W. Cosgriff. 1981. Myosaurus gracilis, an anomodont reptile from the Lower Triassic of Antarctica and South Africa. Journal of Paleontology, 55(2), 410-424. Hammer, W.R., W.J. Ryan, J.W. Tamplin, and S.L. DeFauw. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26. 86Keyser, A. W., and R.M.H. Smith. 1978. Vertebrate biozonation of the Beaufort Group with special reference to the western Karoo Basin. Annals of the Geological Survey (South Africa), 12, 1-36.
Multiple phases of early Paleozoic deformation in the central Transantarctic Mountains MARGARET
N. REES
Department of Geoscience University of Nevada Las Vegas, Nevada 89154 GARY H. GIRTY
Department of Geological Sciences San Diego State University San Diego, California 92192 SUSAN K. PANTTAJA
Department of Geoscience University of Nevada Las Vegas, Nevada 89154 PETER BRADDOCK
Queen Charlotte College Picton, New Zealand
New structural data from the lower Paleozoic Douglas Conglomerate in the northern Churchill Mountains (figure 1) indicate that the conglomerate was deformed at least three times before the deposition of the overlying Devonian beds of the Beacon Supergroup. Recognition of these post-Lower Cambrian and pre-Devonian events makes all existing tectonic models for the area too simplistic. Our geological investigation of the northern Churchill Moun tains revealed extensive outcrops of Douglas Conglomerate that were not observed or visited by previous field teams (Burgess and Lammerink 1979; Skinner 1964, 1965; Stump et al. 1979); consequently we produced a new geological map and propose new structural interpretations. In addition, south of the mapped area at location 14 (figure 2) trilobites were collected from the Shackleton Limestone and, at location 17, a previously unrecorded, 1000-meter-long exposure of pillow lava was examined and sampled. 1987 REVIEW
Figure 1. Location map showing position of area mapped within the central Transantarctic Mountains and the extent of the Churchill Mountains between the Byrd and Nimrod glaciers. ("MH" denotes Mount Hamilton, "CC" denotes "Crackling Cwm," and "MD" denotes Mount Dick.)
The field team (Rees, Girty, Panttaja, and Braddock) was put into the field by an LC-130 ski-equipped Hercules airplane on 24 November 1986 and picked up from the same location on 5 January 1987. The landing site was located on the Nicholson Peninsula (80°42'S 159°23'E). Overland travel by snowmobile to 33
