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.

20 ANTARCTIC JOURNAL Figure 1. Location map showing the trackway site (arrow) on the north side of Gordon Valley. Stippled areas are exposed rock or moraine.

The tracks occur on the top surface of the laminated unit. They depress the bedding plane by 0.1-0.5 centimeter. Three different types are recognized (figure 3): • Type 1: These are the most common. Individual prints are 1.5-2 centimeters long, hemi-ovoid to triangular in outline. The two long sides are unequal in length, with smooth sharp outlines. The short side is straight-crenulate, displaying 1-4 cusps depending on the depth. One print has a long tail, deepening toward the most acute apex of the print. This is probably the mark of a foot being scuffed through the mud. Prints are 4-8 centimeters apart, and alternate about an un- marked center line, defining a trackway 2-2.5 centimeters wide. The trackways are straight at the scale of the exposure, and the longest set of prints found imply a repeat of about 25 centimeters. • Type 2: Several examples of this type were found. Individual prints are depressed, with five toes. Toes all face within an arc of about 130° and are deeply divided. Individual prints are 3-4 centimeters long and appear to be paired 10-20 cen- timeters apart with toes on opposite feet pointing out and forward of an (unmarked) center line. • Type 3: This type is represented by a single print 7 centi- meters wide by 8 centimeters long. The print is poorly pre- served with at least three toes. These are less deeply divided Figure 2. Section through the Fremouw Formation at Gordon Valley than those of type 2, and appear to be broader and more showing the level of the trackway and of the main bone bed. The forward-facing. lowest 50 meters of unit A have been omitted for clarity. They are Tail marks are not associated with any of the types mentioned similar to the facies shown from 50-90 meters. (m denotes meter.) above, but smooth-edged, straight to gently curved indenta- tions, 0.3-0.5 centimeters wide and up to 10 centimeters long, are common. They tend to be in groups with a near-random bodied, and moving purposefully. The type 2 animal was orientation. larger, heavier, and/or slower-moving. The tracks were probably made in soft mud on the site of a Identification of the animals which made the trackway will ephemeral pool. Variability of individual prints within any one require careful matching with vertebrate remains from the Fre- type is a result of the depth of impression; this is a function of mouw Formation. This work is underway, but preliminary ex- the consistency of the mud, the weight of the animal and the amination suggests that the type 2 tracks may have been made length of time that it stood in that spot. It would appear that by the mammallike reptile Lystrosaurus. This could be impor- the animal that made the type 1 tracks was small, narrow- tant, as the bone bed at Gordon Valley is probably in or above

1991 REVIEW 21 the Cynognathus zone (Hammer et al. 1990). If the trackway did contain Lystrosaurus prints, the boundary between the Lystro- saurus and Cynognathus zones would lie in the 67-161-meter interval on the section. Continued work will assist the Triassic fossil zonation in the central Transantarctic Mountains. This research is supported by National Science Foundation grants DPP 89-17413 and DPP 88-17023, and by the British Ant- arctic Survey.

LAI : References \ A001A Barrett, P.J., and D.H. Elliot. 1973. Reconnaissance geologic map of the Buckley Island Quadrangle, Transantarctic Mountains, Antarctica (U.S.Geological Survey Map A-3). Washington, D.C.: U.S. Govern- ment Printing Office. Barrett, P.1 . , D. H. Elliot, and J. F. Lindsay. 1986. The Beacon Supergroup (Devonian-Triassic) and Ferrar Group (Jurassic) in the Beardmore Glacier area, Antarctica. In M.D. Turner and J.E Splettstoesser (Eds), Geology of the central Transantarctic Mountains. (Antarctic Research Se- ries, Vol. 36) Washington, D.C.: American Geophysical Union. Covacevich, V., and P.V. Rich. 1982. New bird ichnites from Fildes Peninsula, King George Island, West Antarctica. In C. Craddock (Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Collinson, J.D. 1986. Alluvial sediments. In H.G. Reading (Ed.), Sedi- mentari,, environments and facies (2nd ed.). Oxford: Blackwell Scientific Publications. Hammer, WR., J.W. Collinson, and W.J. Ryan. 1990. A new vertebrate fauna from Antarctica and its depositional setting. Antarctic science, : 2(2), 163-167 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. Hammer, WR., W.J. Ryan, J.W. Tamplin, and S.L. DeFauw. 1986. New vertebrates from the Fremouw Formation (Triassic), Beardmore Gla- • . cier region, Antarctica. Antarctic Journal of the U.S., 21(5), 24-26. I

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Figure 3. Photographs of the vertebrate tracks. Scales are in cen- timeters. A. Type 1 (arrows). B. Type 2. C. Type 3.

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