Lystrosaurus Zone (Triassic) vertebrates from the ...
their relationship to the initial fragmentation of Gondwana. In M. Cresswell and P. Vella (Eds.), Gondwana V. Mensing, T.M., C. Faure, L.M. Jones, J.R. Bowman, and J . Hoefs. 1984. Petrogenesis of the Kirkpatrick Basalt, Solo Nunatak, North Victoria Land, Antarctica. Contributions to Mineralogy and Petrology,
87, 101-108. Morgan, V.I. 1982. Antarctic ice sheet surface oxygen isotope values. Journal of Glaciology, 28(99), 315-323. Schmierer, K., and R. Burmester. 1986. Paleomagnetic results from the Cambro-Ordovician Bowers Supergroup, Northern Victoria Land, Antarctica. In E. Stump (Ed.), Geological investigations in northern Victoria Land, (Vol. 46), Antarctic Research Series. Washington, D.C.:
American Geophysical Union.
Siders, M.A. 1983. Intraflow variability, chemical stratigraphy and petrogenesis of the Kirkpatrick Basalt from the Mesa Range area, North Victoria
Land, East Antarctica. (Unpublished master of science thesis, Ohio State University, Columbus, Ohio.) Siders, M.A., and D.H. Elliot. 1985. Major and trace element geochemistry of the Kirkpatrick Basalt, Mesa Range, Antarctica. Earth and Planetary Science Letters, 72, 54-64. Walker, G.P.L. 1972. Compound and simple lava flows and flood basalts. Bulletin Volcanologique, 35, 579-590. Wood, D.A., I.L. Gibson, and R.N. Thompson. 1976. Elemental mobility during zeolite facies metamorphism of the Tertiary basalts of eastern Iceland. Contributions to Mineralogy and Petrology, 55, 241254.
Lystrosaurus Zone (Triassic)
vertebrates from the Beardmore Glacier region, Antarctica WILLIAM R. HAMMER Department of Geology Augustana College Rock Island, Illinois 61201
In addition to the new Cynognathus Zone (Late Scythian) fossils reported from the Gordon Valley (Hammer et al. 1986; Hammer, Ryan, and DeFauw 1987; Hammer 1988 in press) an abundance of Lystrosaurus Zone (Early Scythian) material was collected in the Beardmore Glacier region during the 19851986 season. All of this material came from the lower member of the Fremouw Formation rather than the upper member which contains the younger Cynognathus Zone fossils. Bone was collected from the lower Fremouw at Willey Point, Lamping Peak, Coalsack Bluff, and Graphite Peak (for map see Hammer et al. 1986). Fossils were most abundant at Coalsack Bluff (figure 1) and Graphite Peak (figure 2), the other two sites yielded only four specimens of the nearly 300 that were collected during the season from this level. Three of these four were found in a small erosional remnant right at the cliff edge along the Beardmore Glacier at Willey Point, while a single specimen from Lamping Peak was found near the very top of the peak in a limited exposure; the extensive bedding planes lower in the section are Permian in age as evidenced by the occurrence of Glossopteris. For the most part, the lower Fremouw material is highly fragmentary. At four different places on Coalsack Bluff (figure 1), where vertebrates were first discovered in 1969 (Elliot et al. 1970), bone clasts were collected from poorly sorted channel conglomerates and sands. Although the largest pieces rarely exceed 5 or 6 centimeters in any dimension, many of these fragments are identifiable to genus. As might be expected, there are numerous cranial and limb fragments of Lystrosaurus. These include maxillary pieces, tusks, and numerous limb bones. In addition, there are small lizard-like jaws that probably per40
Figure 1. Fossiliferous exposures at Coalsack Bluff. Fossils occur in the light-colored, steeply dipping sediments.
tain to the Eosuchia. Labyrinthodonts are also represented, including several extremely small mandibles that could belong to a new lydekkerinid. At Graphite Peak, where the first vertebrate specimen from the Transantarctic Mountains was discovered during the austral summer of 1967-1968 (Barrett, Baillie, and Colbert 1968), the bones occur in a green-gray silt-mudstone (figure 2). Since this is an overbank deposit, the specimens are often larger and less fragmentary than the Coalsack fossils; however, the material is also less abundant. Partial to nearly complete skulls and postcranial skeletons of Lystrosaurus were collected. These specimens occur in extremely well-cemented silicate sediments and complete removal of the fossils from the matrix is a difficult, time-consuming task. Fortunately, some of them are well enough exposed on the surface that this type of preparation has not been necessary. A maxilla and partial mandible of what appears to be Thrinaxodon or another similar cynodont represents the only therapsid carnivore reported from Graphite Peak. Preparation of all of the vertebrate material collected during the 1985-1986 season should be largely completed by the end of 1989. Research on both the Lystrosaurus and Cynognathus Zone faunas will continue beyond that date. A large enough database now exists for the lower Fremouw material to allow AN FARCliC JOURNAL
some paleoecological analysis. Since less than 2 weeks of excavation was accomplished after the discovery of the fauna from the upper Fremouw at Gordon Valley, additional field work will be necessary to explain fully the unusual animals and taphonomy of this unit (Hammer in press). This work was supported by National Science Foundation grants DPP 86-11334, DPP 86-14140, and DPP 84-18354.
References -
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Figure 2. Fossiliferous exposures at Graphite Peak. Fossils occur in the slightly darker colored sediments at the base of the sandstone cliff.
1989 REVIEW
Barrett, P.J., R.J. Baillie, and E.H. Colbert. 1968. Triassic amphibian from Antarctica. Science, 161, 460-462. Elliot, D.H., E.H. Colbert, W.J. Breed, J.A. Jensen, and J.S. Powell. 1970. Triassic tetrapods from Antarctica: Evidence for continental drift. Science, 169, 1,197-1,210. Hammer, W.R. 1988. The C vnognathus Zone (late Early Triassic) vertebrate fauna from Antarctica. Antarctic Journal of the U.S., 23(5), 10. Hammer, W.R. In press. Triassic terrestrial vertebrate faunas of Antarctica. In T.N. Taylor and E. Taylor (Eds.), Antarctic paleobiology: Its role in the reconstruction of Gondwana. New York: Springer-Verlag. Hammer, W.R., S.L. DeFauw, W.J. Ryan, and J.W. Tamplin. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26. Hammer, W.R., W.J. Ryan, and S.L. DeFauw. 1987. Comments on the vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33.
41
87, 101-108. Morgan, V.I. 1982. Antarctic ice sheet surface oxygen isotope values. Journal of Glaciology, 28(99), 315-323. Schmierer, K., and R. Burmester. 1986. Paleomagnetic results from the Cambro-Ordovician Bowers Supergroup, Northern Victoria Land, Antarctica. In E. Stump (Ed.), Geological investigations in northern Victoria Land, (Vol. 46), Antarctic Research Series. Washington, D.C.:
American Geophysical Union.
Siders, M.A. 1983. Intraflow variability, chemical stratigraphy and petrogenesis of the Kirkpatrick Basalt from the Mesa Range area, North Victoria
Land, East Antarctica. (Unpublished master of science thesis, Ohio State University, Columbus, Ohio.) Siders, M.A., and D.H. Elliot. 1985. Major and trace element geochemistry of the Kirkpatrick Basalt, Mesa Range, Antarctica. Earth and Planetary Science Letters, 72, 54-64. Walker, G.P.L. 1972. Compound and simple lava flows and flood basalts. Bulletin Volcanologique, 35, 579-590. Wood, D.A., I.L. Gibson, and R.N. Thompson. 1976. Elemental mobility during zeolite facies metamorphism of the Tertiary basalts of eastern Iceland. Contributions to Mineralogy and Petrology, 55, 241254.
Lystrosaurus Zone (Triassic)
vertebrates from the Beardmore Glacier region, Antarctica WILLIAM R. HAMMER Department of Geology Augustana College Rock Island, Illinois 61201
In addition to the new Cynognathus Zone (Late Scythian) fossils reported from the Gordon Valley (Hammer et al. 1986; Hammer, Ryan, and DeFauw 1987; Hammer 1988 in press) an abundance of Lystrosaurus Zone (Early Scythian) material was collected in the Beardmore Glacier region during the 19851986 season. All of this material came from the lower member of the Fremouw Formation rather than the upper member which contains the younger Cynognathus Zone fossils. Bone was collected from the lower Fremouw at Willey Point, Lamping Peak, Coalsack Bluff, and Graphite Peak (for map see Hammer et al. 1986). Fossils were most abundant at Coalsack Bluff (figure 1) and Graphite Peak (figure 2), the other two sites yielded only four specimens of the nearly 300 that were collected during the season from this level. Three of these four were found in a small erosional remnant right at the cliff edge along the Beardmore Glacier at Willey Point, while a single specimen from Lamping Peak was found near the very top of the peak in a limited exposure; the extensive bedding planes lower in the section are Permian in age as evidenced by the occurrence of Glossopteris. For the most part, the lower Fremouw material is highly fragmentary. At four different places on Coalsack Bluff (figure 1), where vertebrates were first discovered in 1969 (Elliot et al. 1970), bone clasts were collected from poorly sorted channel conglomerates and sands. Although the largest pieces rarely exceed 5 or 6 centimeters in any dimension, many of these fragments are identifiable to genus. As might be expected, there are numerous cranial and limb fragments of Lystrosaurus. These include maxillary pieces, tusks, and numerous limb bones. In addition, there are small lizard-like jaws that probably per40
Figure 1. Fossiliferous exposures at Coalsack Bluff. Fossils occur in the light-colored, steeply dipping sediments.
tain to the Eosuchia. Labyrinthodonts are also represented, including several extremely small mandibles that could belong to a new lydekkerinid. At Graphite Peak, where the first vertebrate specimen from the Transantarctic Mountains was discovered during the austral summer of 1967-1968 (Barrett, Baillie, and Colbert 1968), the bones occur in a green-gray silt-mudstone (figure 2). Since this is an overbank deposit, the specimens are often larger and less fragmentary than the Coalsack fossils; however, the material is also less abundant. Partial to nearly complete skulls and postcranial skeletons of Lystrosaurus were collected. These specimens occur in extremely well-cemented silicate sediments and complete removal of the fossils from the matrix is a difficult, time-consuming task. Fortunately, some of them are well enough exposed on the surface that this type of preparation has not been necessary. A maxilla and partial mandible of what appears to be Thrinaxodon or another similar cynodont represents the only therapsid carnivore reported from Graphite Peak. Preparation of all of the vertebrate material collected during the 1985-1986 season should be largely completed by the end of 1989. Research on both the Lystrosaurus and Cynognathus Zone faunas will continue beyond that date. A large enough database now exists for the lower Fremouw material to allow AN FARCliC JOURNAL
some paleoecological analysis. Since less than 2 weeks of excavation was accomplished after the discovery of the fauna from the upper Fremouw at Gordon Valley, additional field work will be necessary to explain fully the unusual animals and taphonomy of this unit (Hammer in press). This work was supported by National Science Foundation grants DPP 86-11334, DPP 86-14140, and DPP 84-18354.
References -
t. 4 i-'.
&
: .
)
Figure 2. Fossiliferous exposures at Graphite Peak. Fossils occur in the slightly darker colored sediments at the base of the sandstone cliff.
1989 REVIEW
Barrett, P.J., R.J. Baillie, and E.H. Colbert. 1968. Triassic amphibian from Antarctica. Science, 161, 460-462. Elliot, D.H., E.H. Colbert, W.J. Breed, J.A. Jensen, and J.S. Powell. 1970. Triassic tetrapods from Antarctica: Evidence for continental drift. Science, 169, 1,197-1,210. Hammer, W.R. 1988. The C vnognathus Zone (late Early Triassic) vertebrate fauna from Antarctica. Antarctic Journal of the U.S., 23(5), 10. Hammer, W.R. In press. Triassic terrestrial vertebrate faunas of Antarctica. In T.N. Taylor and E. Taylor (Eds.), Antarctic paleobiology: Its role in the reconstruction of Gondwana. New York: Springer-Verlag. Hammer, W.R., S.L. DeFauw, W.J. Ryan, and J.W. Tamplin. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26. Hammer, W.R., W.J. Ryan, and S.L. DeFauw. 1987. Comments on the vertebrate fauna from the Fremouw Formation (Triassic), Beardmore Glacier Region, Antarctica. Antarctic Journal of the U.S., 22(5), 32-33.
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