New vertebrates from the Fremouw Formation (Triassic ...
New vertebrates from the Fremouw Formation (Triassic) Beardmore Glacier region, Antarctica W.R. HAMMER,
W.J. RYAN, and J.W. TAMPLIN
Department of Geology Augustana College Rock island, Illinois 61201 Si.
DEFAuw
Department of Biological Sciences Wayne State University Detroit, Michigan 48202
During the austral summer of 1985-1986, over 350 specimens of fossil vertebrates were recovered from sections in the Beardmore Glacier area of the Transantarctic Mountains. The field collecting team, which included all of the authors and, for
part of the season, Elizabeth Vrba of Yale University, thoroughly searched exposures of: (1) the Triassic Fremouw Formation (all localities except 11 listed in figures 1 and 2; (2) the Permian Buckley Formation (figure 1 localities 2 and 3; figure 2 localities 5, 9, 13, and 15) and; (3) the type section of the Falla Formation at Mount Falla (figure 2, locality 11). Although the Buckley and Falla Formations lacked bones, five of the Fremouw localities yielded well-preserved vertebrate material. Two of the fossil sites, Coalsack Bluff and Graphite Peak (figures 1 and 2), were previously known vertebrate localities from the 1969-1970 and 1970-1971 seasons when groups headed by E.H. Colbert (1969-1970) and James Kitching (1970-1971) collected in this area (Colbert 1970, 1971; Kitching et al. 1972). The other three, Willey Point, Lamping Peak, and Gordon Valley (figures 1 and 2), are new localities discovered 1985-1986. In past seasons, the lower 200 meters of the Fremouw Formation has been particularly productive of vertebrate material. Elliot, Collinson, and Powell's (1972) report on the stratigraphy of the tetrapod-bearing beds at Coalsack Bluff indicated fossil bones were recovered from the lower 90 meters of the section. Kitching et al. (1972) noted that all of the specimens collected
Figure 1. Map of portions of the Dufek and Shakleton Coasts, Central Transantarctic Mountains. Localities searched: 1, exposures along the Tillite Glacier; 2, Willey Point; 3, Graphite Peak; 4, exposures along the Koski Glacier. (Inset represents area covered by figure 2.)("km" denotes "kilometer.")
24
ANTARCTIC JOURNAL
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Figure 2. Map of the area near the Beardmore South Camp (represents an enlargement of inset from figure 1). Localities searched: 5, Mount Sirius; 6, unnamed ridge adjacent to Mount Sirius; 7, unnamed nunatak near Bauhs Nunatak; 8, unnamed ridges between Mount Sirius and Coalsack Bluff; 9, Coalsack Bluff; 10, Gordon Valley; 11, Mount Falla; 12, Fremouw Peak; 13, Lamping Peak; 14, exposures along the Wyckoff Glacier; 15, exposures along the Wahl Glacier. ("km" denotes "kilometer.")
during the 1970-1971 season were found within the first 200meter interval. With the exception of the fragmentary postcranial remains of a small reptile 239 meters above the formational base (Cosgriff 1978), the 1977-1978 collection also derives from the lower 200 meters. The composite fauna represented by the three previous collections is large and varied (Colbert 1982; Hammer and Cosgriff 1981), and establishes close correlation between the lower Fremouw Formation of Antarctica and the Lystrosaurus zone of South Africa (Colbert 1972, 1982; Kitching et al. 1972; Hammer and Cosgriff 1981). Four of the five localities (all except Gordon Valley) quarried during the 1985-1986 season yielded a wide variety of specimens from similar Lystrosaurus zone equivalents in the lower 200 meters of the Fremouw Formation. Individual specimens from the lower portion of the formation range from skulls and disarticulated postcranial elements to partial skeletons. Included in this collection are fossils representing many of the previously reported Fremouw taxa (Colbert 1982) plus several species new to the Antarctic. Excellent specimens of Lystrosaurus were found, including a relatively large partial skeleton with a skull. Thrinaxodon is represented by jaws and a 1986 REVIEW
partial skull. Other material recovered pertains to a new theriodont and a larger reptile, perhaps a thecodont similar to that reported by Cosgriff (1983). Smaller reptiles in the assemblage probably include procolophonids and eosuchians. The lower Fremouw localities also produced an abundance of labyrinthodont material, including fragments of brachyopid, lydekkerinid, capitosaurid(?), and rhytidosteid dermal elements. Some of this material may be assignable to taxa already described from the Antarctic (Colbert and Cosgriff 1974; Cosgriff and Hammer 1983, 1984), however, at least one or two forms new to the continent are included in this assemblage. Because these lower Fremouw fossils occur in a variety of depositional environments this collection has excellent potential for taphonomic and paleoecological analysis. The fifth vertebrate locality, in the Gordon Valley (figure 2), is of particular importance because stratigraphically it is considerably higher in the section than the other vertebrate sites (Collinson and Isbell, Antarctic Journal, this issue); hence it represents the first major occurrence of vertebrates in the upper member of the Fremouw Formation. Labyrinthodonts, including at least one very large form (estimated skull length 0.75 meter), are well 25
preserved and abundant here. Jaws and partial skulls of synapsids also occur, including a fairly large theriodont. Little of the material was well exposed in the field so more specific taxonomic determinations are difficult to make at this time, however, the size and general nature of these animals indicate that, in many cases, they do not appear to represent forms typical of the Lystrosaurus zone. They occur considerably higher in the section, hence, it is not unlikely that they are somewhat younger in age than the fossils of the lower Fremouw. Whatever their age, these animals represent species new to the fauna of the Fremouw Formation. We wish to thank members of the support crew and other science projects at the Beardmore South camp for their help in the field. A particular thanks goes to Elizabeth Vrba, for her contributions to our field party. This project was supported by National Science Foundation grants DPP 85-11334 and DPP 84-18354. References
Colbert, E.H. 1970. The fossil tetrapods of Coalsack Bluff. Antarctic Journal of the U.S., 5(3), 57-61.
Colbert, E. H. 1971. Triassic tetrapods from McGregor Glacier. Antarctic
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). Washington, D.C.: American Geophysical Union. Colbert, E.H., and J.W. Cosgriff. 1974. Labyrinthodont amphibians from Antarctica. American Museum Novitiates, 2552, 1-30. Collinson, J.W., and J . Isbell. 1986. Permian-Triassic sedimentology of the Beardmore Glacier region. Antarctic Journal of the U.S., 21(5). Cosgriff, J.W. 1983. Large thecodont reptiles from the Fremouw Formation. Antarctic Journal of the U.S., 18(5), 52-55.
Cosgriff, J.W., and W.R. Hammer. 1983. The labyrinthodont amphibians of the earliest Triassic from Antarctica, Tasmania and South Africa. In R.L. Oliver, P.R. James, and J.B. Jago, (Eds.) Antarctic Earth science. Canberra: Australian Academy of Science. Cosgriff, J.W., and W.R. Hammer. 1984. New material of labyrinthodont amphibians from the Lower Triassic Fremouw Formation of Antarctica. Journal of Vertebrate Paleontology, 4(1), 47-56.
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. Elliot, D.H., J.W. Collinson, and J.S. Powell. 1972. Stratigraphy of Triassic tetra pod-bearing beds of Antarctica. In R.J. Adie (Ed.), Antarctic geology and geophysics. Oslo: U niversitetsforlaget. Hammer, W.R., and J.W. Cosgriff. 1981. Myosaurus gracilis, an anomod()nt reptile from the Lower Triassic of Antarctica and South Africa. Journal of Paleontology, 55(2),410-424.
Journal of the U.S., 6(5), 188-189. Colbert, E. H. 1972. Antarctic Gondwana tetrapods. In Second Gondwana Symposium, South Africa, 1970.
Kitching, J.W., J.W. Collinson, D.H. Elliot, and E.H. Colbert. 1972. Lystrosaurus zone (Triassic) fauna from Antarctica. Science, 175(4021),
Paleoenvironment of Lower Triassic plants from the Fremouw Formation
trunk (1.0 meter diameter, 13.5 meters long) occurred within a few meters and at the same stratigraphic level as the isolated blocks. The blocks represent large chunks of heterogeneous peat that were rafted and eventually buried in the stream. The directions of trough axes in the sandstone appear to have been deflected around the blocks during deposition, suggesting that the blocks were grounded in shallow water. The abundance of silicified plant material at this horizon and the lack of any preserved
T.N. TAYLOR, E.L. TAYLOR,* and J.W. COLLINSON Institute of Polar Studies Ohio State University Columbus, Ohio 43210
During the 1985-1986 field season, collections of silicified plant remains were made from a site located in a col north of Fremouw Peak, Queen Alexandra Range, central Transantarctic Mountains (84°16'S 164°21'E) Buckley Island Quadrangle (Barrett and Elliot 1973). The fossil plant locality occurs in the upper Fremouw Formation, a braided stream deposit of early-to-middle Triassic age. The fossils occur within several allochthonous clasts that are at approximately the same stratigraphic level within a trough-crossbedded, medium-grained, greenish-gray volcaniclastic sandstone. The clasts are block shaped; the largest was 1.0 meter thick and 2.5 x 2.5 meters in width (figure 1). The lower 0.4 meter consisted of light gray mudstone that graded upward into a silicified, dark gray, carbonaceous mudstone with abundant plant remains. Another block (0.5 meter thick, 1.5 x 2.0 meters wide) and a large silicified tree
* Dr. E.L. Taylor was formerly E.L. Smoot. 26
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Figure 1. Section through clast showing heterogeneous silicified plant material on top, with dark gray mudstone immediately below (arrow), and lighter mudstone at base (x 4). ANTARCTIC JOURNAL
W.J. RYAN, and J.W. TAMPLIN
Department of Geology Augustana College Rock island, Illinois 61201 Si.
DEFAuw
Department of Biological Sciences Wayne State University Detroit, Michigan 48202
During the austral summer of 1985-1986, over 350 specimens of fossil vertebrates were recovered from sections in the Beardmore Glacier area of the Transantarctic Mountains. The field collecting team, which included all of the authors and, for
part of the season, Elizabeth Vrba of Yale University, thoroughly searched exposures of: (1) the Triassic Fremouw Formation (all localities except 11 listed in figures 1 and 2; (2) the Permian Buckley Formation (figure 1 localities 2 and 3; figure 2 localities 5, 9, 13, and 15) and; (3) the type section of the Falla Formation at Mount Falla (figure 2, locality 11). Although the Buckley and Falla Formations lacked bones, five of the Fremouw localities yielded well-preserved vertebrate material. Two of the fossil sites, Coalsack Bluff and Graphite Peak (figures 1 and 2), were previously known vertebrate localities from the 1969-1970 and 1970-1971 seasons when groups headed by E.H. Colbert (1969-1970) and James Kitching (1970-1971) collected in this area (Colbert 1970, 1971; Kitching et al. 1972). The other three, Willey Point, Lamping Peak, and Gordon Valley (figures 1 and 2), are new localities discovered 1985-1986. In past seasons, the lower 200 meters of the Fremouw Formation has been particularly productive of vertebrate material. Elliot, Collinson, and Powell's (1972) report on the stratigraphy of the tetrapod-bearing beds at Coalsack Bluff indicated fossil bones were recovered from the lower 90 meters of the section. Kitching et al. (1972) noted that all of the specimens collected
Figure 1. Map of portions of the Dufek and Shakleton Coasts, Central Transantarctic Mountains. Localities searched: 1, exposures along the Tillite Glacier; 2, Willey Point; 3, Graphite Peak; 4, exposures along the Koski Glacier. (Inset represents area covered by figure 2.)("km" denotes "kilometer.")
24
ANTARCTIC JOURNAL
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Figure 2. Map of the area near the Beardmore South Camp (represents an enlargement of inset from figure 1). Localities searched: 5, Mount Sirius; 6, unnamed ridge adjacent to Mount Sirius; 7, unnamed nunatak near Bauhs Nunatak; 8, unnamed ridges between Mount Sirius and Coalsack Bluff; 9, Coalsack Bluff; 10, Gordon Valley; 11, Mount Falla; 12, Fremouw Peak; 13, Lamping Peak; 14, exposures along the Wyckoff Glacier; 15, exposures along the Wahl Glacier. ("km" denotes "kilometer.")
during the 1970-1971 season were found within the first 200meter interval. With the exception of the fragmentary postcranial remains of a small reptile 239 meters above the formational base (Cosgriff 1978), the 1977-1978 collection also derives from the lower 200 meters. The composite fauna represented by the three previous collections is large and varied (Colbert 1982; Hammer and Cosgriff 1981), and establishes close correlation between the lower Fremouw Formation of Antarctica and the Lystrosaurus zone of South Africa (Colbert 1972, 1982; Kitching et al. 1972; Hammer and Cosgriff 1981). Four of the five localities (all except Gordon Valley) quarried during the 1985-1986 season yielded a wide variety of specimens from similar Lystrosaurus zone equivalents in the lower 200 meters of the Fremouw Formation. Individual specimens from the lower portion of the formation range from skulls and disarticulated postcranial elements to partial skeletons. Included in this collection are fossils representing many of the previously reported Fremouw taxa (Colbert 1982) plus several species new to the Antarctic. Excellent specimens of Lystrosaurus were found, including a relatively large partial skeleton with a skull. Thrinaxodon is represented by jaws and a 1986 REVIEW
partial skull. Other material recovered pertains to a new theriodont and a larger reptile, perhaps a thecodont similar to that reported by Cosgriff (1983). Smaller reptiles in the assemblage probably include procolophonids and eosuchians. The lower Fremouw localities also produced an abundance of labyrinthodont material, including fragments of brachyopid, lydekkerinid, capitosaurid(?), and rhytidosteid dermal elements. Some of this material may be assignable to taxa already described from the Antarctic (Colbert and Cosgriff 1974; Cosgriff and Hammer 1983, 1984), however, at least one or two forms new to the continent are included in this assemblage. Because these lower Fremouw fossils occur in a variety of depositional environments this collection has excellent potential for taphonomic and paleoecological analysis. The fifth vertebrate locality, in the Gordon Valley (figure 2), is of particular importance because stratigraphically it is considerably higher in the section than the other vertebrate sites (Collinson and Isbell, Antarctic Journal, this issue); hence it represents the first major occurrence of vertebrates in the upper member of the Fremouw Formation. Labyrinthodonts, including at least one very large form (estimated skull length 0.75 meter), are well 25
preserved and abundant here. Jaws and partial skulls of synapsids also occur, including a fairly large theriodont. Little of the material was well exposed in the field so more specific taxonomic determinations are difficult to make at this time, however, the size and general nature of these animals indicate that, in many cases, they do not appear to represent forms typical of the Lystrosaurus zone. They occur considerably higher in the section, hence, it is not unlikely that they are somewhat younger in age than the fossils of the lower Fremouw. Whatever their age, these animals represent species new to the fauna of the Fremouw Formation. We wish to thank members of the support crew and other science projects at the Beardmore South camp for their help in the field. A particular thanks goes to Elizabeth Vrba, for her contributions to our field party. This project was supported by National Science Foundation grants DPP 85-11334 and DPP 84-18354. References
Colbert, E.H. 1970. The fossil tetrapods of Coalsack Bluff. Antarctic Journal of the U.S., 5(3), 57-61.
Colbert, E. H. 1971. Triassic tetrapods from McGregor Glacier. Antarctic
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). Washington, D.C.: American Geophysical Union. Colbert, E.H., and J.W. Cosgriff. 1974. Labyrinthodont amphibians from Antarctica. American Museum Novitiates, 2552, 1-30. Collinson, J.W., and J . Isbell. 1986. Permian-Triassic sedimentology of the Beardmore Glacier region. Antarctic Journal of the U.S., 21(5). Cosgriff, J.W. 1983. Large thecodont reptiles from the Fremouw Formation. Antarctic Journal of the U.S., 18(5), 52-55.
Cosgriff, J.W., and W.R. Hammer. 1983. The labyrinthodont amphibians of the earliest Triassic from Antarctica, Tasmania and South Africa. In R.L. Oliver, P.R. James, and J.B. Jago, (Eds.) Antarctic Earth science. Canberra: Australian Academy of Science. Cosgriff, J.W., and W.R. Hammer. 1984. New material of labyrinthodont amphibians from the Lower Triassic Fremouw Formation of Antarctica. Journal of Vertebrate Paleontology, 4(1), 47-56.
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. Elliot, D.H., J.W. Collinson, and J.S. Powell. 1972. Stratigraphy of Triassic tetra pod-bearing beds of Antarctica. In R.J. Adie (Ed.), Antarctic geology and geophysics. Oslo: U niversitetsforlaget. Hammer, W.R., and J.W. Cosgriff. 1981. Myosaurus gracilis, an anomod()nt reptile from the Lower Triassic of Antarctica and South Africa. Journal of Paleontology, 55(2),410-424.
Journal of the U.S., 6(5), 188-189. Colbert, E. H. 1972. Antarctic Gondwana tetrapods. In Second Gondwana Symposium, South Africa, 1970.
Kitching, J.W., J.W. Collinson, D.H. Elliot, and E.H. Colbert. 1972. Lystrosaurus zone (Triassic) fauna from Antarctica. Science, 175(4021),
Paleoenvironment of Lower Triassic plants from the Fremouw Formation
trunk (1.0 meter diameter, 13.5 meters long) occurred within a few meters and at the same stratigraphic level as the isolated blocks. The blocks represent large chunks of heterogeneous peat that were rafted and eventually buried in the stream. The directions of trough axes in the sandstone appear to have been deflected around the blocks during deposition, suggesting that the blocks were grounded in shallow water. The abundance of silicified plant material at this horizon and the lack of any preserved
T.N. TAYLOR, E.L. TAYLOR,* and J.W. COLLINSON Institute of Polar Studies Ohio State University Columbus, Ohio 43210
During the 1985-1986 field season, collections of silicified plant remains were made from a site located in a col north of Fremouw Peak, Queen Alexandra Range, central Transantarctic Mountains (84°16'S 164°21'E) Buckley Island Quadrangle (Barrett and Elliot 1973). The fossil plant locality occurs in the upper Fremouw Formation, a braided stream deposit of early-to-middle Triassic age. The fossils occur within several allochthonous clasts that are at approximately the same stratigraphic level within a trough-crossbedded, medium-grained, greenish-gray volcaniclastic sandstone. The clasts are block shaped; the largest was 1.0 meter thick and 2.5 x 2.5 meters in width (figure 1). The lower 0.4 meter consisted of light gray mudstone that graded upward into a silicified, dark gray, carbonaceous mudstone with abundant plant remains. Another block (0.5 meter thick, 1.5 x 2.0 meters wide) and a large silicified tree
* Dr. E.L. Taylor was formerly E.L. Smoot. 26
524-526.
-!
* '
-4r
I I , . '.
Figure 1. Section through clast showing heterogeneous silicified plant material on top, with dark gray mudstone immediately below (arrow), and lighter mudstone at base (x 4). ANTARCTIC JOURNAL
