Comments on the fossil vertebrates from the Falla Formation Jurassic ...
Terrestrial geology and geophysics Comments on the fossil vertebrates from the Falla Formation Jurassic, Beardmore Glacier region, Antarctica WILLIAM R. HAMMER AND WILLIAM
J. HICKERSON
Augustana College Rock Island, Illinois 61201
The first fossil vertebrates from the Falla Formation of the central Transantarctic Mountains were collected during the 19901991 austral summer from Mt. Kirkpatrick in the Beardmore Glacier region (Hammer et al. 1991; Hammer 1992). Over 60 bones were recovered from one small exposure of tuffaceous siltstone near the top of the formation, and three isolated bones were found within 30 meters of the bone concentration at about the same stratigraphic level (Hammer et al. 1991). Although much of the material collected remains in the matrix, the preparation of the fossils is progressing, and at least four types of animals have been recognized in the fauna. Three of the four taxa are dinosaurs. Much of the skeleton (perhaps over 50 percent of a new, large, carnivorous theropod carnosaur) was recovered, and to date, most of the skull, pelvis, and a femur of this animal has been prepared. Its most unique feature is its large, furrowed crest that rises perpendicular to the long axis of the skull, just posterior to well-developed nasal ridges. The skull specimen, which is broken anteriorly, is approximately 55 centimeters in length; the actual skull length is probably 15 centimeters longer. The size and general features of the skull liken it to larger carnosaurs from other continents, such as the North American genus Allosaurus and the Chinese Yangchuanosaurus. However, the crest and postorbital construction of the skull indicate that the antarctic carnosaur represents a new genus. The pubis and ischium are similar to that of Piatnizkysaurus from southern Argentina which, geographically, is the closest carnosaur locality to the Antarctic. Unfortunately, Piatnizkysaurus is represented mainly by postcranial remains and limited information is available about its skull structure. At this point, few remains of the other animals have been identified, hence their affinities to the dinosaurs are less certain. A partially articulated pes including four large metatarsals appears to represent a sizable prosauropod or sauropod. The distal end of a large femur may also belong to the same animal. In addition, several small, serrated teeth of scavenging theropods were found in the matrix near the gnawed end of the carnosaur ischium. A single, small humerus that was one of the isolated bones found near the bone concentration belongs to a pterosaur. This
1992 REVIEW
humerus is hollow, has the very distinctive broad medial end that is characteristic of pterosaurs, and is larger than the humeri of forms such as Pterodactylus from the Jurassic Solenhofen Formation (Wellenhofer 1970). The nature of this fauna suggests that the upper portion of the Falla Formation is of Jurassic age. Similarly, advanced carnosaurs from other continents are Jurassic to early Cretaceous in age. Allosaurus and Yangchuanosaurus, for example, are late Jurassic (Molnar, Kurzanov, and Dong 1990; Zhiming 1983; Molnar, Flannery, and Rich 1985). Piatnizkysaurus, the only other wellknown carnosaur from a southern continent, is Middle Jurassic in age. Previously, the Dicroidium beds below the upper portion of the Falla Formation and the age of the overlying Kirkpatrick basalts place a Late Triassic to Middle Jurassic age constraint on this unit. Thus, the carnosaur indicates that the upper part of the Falla Formation is probably closer to the Middle Jurassic age of the basalts. The Mt. Kirkpatrick fossils represent the first Jurassic terrestrial vertebrate fauna known from the antarctic continent. The pterosaur and dinosaurs also represent the first members of the Order Pterosauria and the Order Saurischia from Antarctica. The previously reported Cretaceous dinosaurs from islands off the Antarctic Peninsula, a hypsilophodont and an ankylosaur, both belong to the dinosaurian Order Ornithischia (Hooker, Milner, and Sequeira 1991; Gasparini et al. 1987). This work was supported by National Science Foundation grants DPP 88-17023 and DPP 91-18620.
References deGasparini, Z., E. Olivero, R. Scasso, and C. Rinaldi. 1987. Unankylosaurio(Reptilia,Ornithischia)CampanianoenelcontinenteAntartico. Annals X Congress Brasil Paleontology, 131-41. Dong, Z. 1984. A new theropod dinosaur from the Middle Jurassic of Sichuan Basin. Vertebrata PalAsiatic, 22: 310-13. Hammer, W. R. 1992. Dinosaurs from the Falla Formation of Antarctica.
North-Central Section, Geological Society of America Abstracts Volume, University of Iowa, 1992:19. Hammer, W. R., W. J . Hickerson, S. Krippner, and J . Tamplin. 1991. Therapsids, temnospondyls and dinosaurs from the Fremouw and Falla Formations, Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 26(5): 19. Hooker, J . J. , A. C. Milner, and S. E. K. Sequeira. 1991. An ornithopod dinosaur from the Late Cretaceous of West Antarctica. Antarctic Science, 3(3): 331-32. Molnar, R. E., T. F. Flannery, and T. H. V. Rich. 1985. Aussie Allosaurus after all. Journal of Paleontology, 59(6): 1511-13. Molnar, R. E., S. M. Kurzanov, and Z. Dong. 1990. "Carnosauria." In D. B. Wieshampel, P. Dodson, and H. Osmoiska (Eds), Dinosauria. University of California Press, 169-210. Welinhoffer, P. 1970. Die Pterodactyloidea (Pterosauria) der OberjuraPlattenkalde Suddentschlands. Bayerische Akademie der Wissenschaften Abhandlungen, 141: 133.
J. HICKERSON
Augustana College Rock Island, Illinois 61201
The first fossil vertebrates from the Falla Formation of the central Transantarctic Mountains were collected during the 19901991 austral summer from Mt. Kirkpatrick in the Beardmore Glacier region (Hammer et al. 1991; Hammer 1992). Over 60 bones were recovered from one small exposure of tuffaceous siltstone near the top of the formation, and three isolated bones were found within 30 meters of the bone concentration at about the same stratigraphic level (Hammer et al. 1991). Although much of the material collected remains in the matrix, the preparation of the fossils is progressing, and at least four types of animals have been recognized in the fauna. Three of the four taxa are dinosaurs. Much of the skeleton (perhaps over 50 percent of a new, large, carnivorous theropod carnosaur) was recovered, and to date, most of the skull, pelvis, and a femur of this animal has been prepared. Its most unique feature is its large, furrowed crest that rises perpendicular to the long axis of the skull, just posterior to well-developed nasal ridges. The skull specimen, which is broken anteriorly, is approximately 55 centimeters in length; the actual skull length is probably 15 centimeters longer. The size and general features of the skull liken it to larger carnosaurs from other continents, such as the North American genus Allosaurus and the Chinese Yangchuanosaurus. However, the crest and postorbital construction of the skull indicate that the antarctic carnosaur represents a new genus. The pubis and ischium are similar to that of Piatnizkysaurus from southern Argentina which, geographically, is the closest carnosaur locality to the Antarctic. Unfortunately, Piatnizkysaurus is represented mainly by postcranial remains and limited information is available about its skull structure. At this point, few remains of the other animals have been identified, hence their affinities to the dinosaurs are less certain. A partially articulated pes including four large metatarsals appears to represent a sizable prosauropod or sauropod. The distal end of a large femur may also belong to the same animal. In addition, several small, serrated teeth of scavenging theropods were found in the matrix near the gnawed end of the carnosaur ischium. A single, small humerus that was one of the isolated bones found near the bone concentration belongs to a pterosaur. This
1992 REVIEW
humerus is hollow, has the very distinctive broad medial end that is characteristic of pterosaurs, and is larger than the humeri of forms such as Pterodactylus from the Jurassic Solenhofen Formation (Wellenhofer 1970). The nature of this fauna suggests that the upper portion of the Falla Formation is of Jurassic age. Similarly, advanced carnosaurs from other continents are Jurassic to early Cretaceous in age. Allosaurus and Yangchuanosaurus, for example, are late Jurassic (Molnar, Kurzanov, and Dong 1990; Zhiming 1983; Molnar, Flannery, and Rich 1985). Piatnizkysaurus, the only other wellknown carnosaur from a southern continent, is Middle Jurassic in age. Previously, the Dicroidium beds below the upper portion of the Falla Formation and the age of the overlying Kirkpatrick basalts place a Late Triassic to Middle Jurassic age constraint on this unit. Thus, the carnosaur indicates that the upper part of the Falla Formation is probably closer to the Middle Jurassic age of the basalts. The Mt. Kirkpatrick fossils represent the first Jurassic terrestrial vertebrate fauna known from the antarctic continent. The pterosaur and dinosaurs also represent the first members of the Order Pterosauria and the Order Saurischia from Antarctica. The previously reported Cretaceous dinosaurs from islands off the Antarctic Peninsula, a hypsilophodont and an ankylosaur, both belong to the dinosaurian Order Ornithischia (Hooker, Milner, and Sequeira 1991; Gasparini et al. 1987). This work was supported by National Science Foundation grants DPP 88-17023 and DPP 91-18620.
References deGasparini, Z., E. Olivero, R. Scasso, and C. Rinaldi. 1987. Unankylosaurio(Reptilia,Ornithischia)CampanianoenelcontinenteAntartico. Annals X Congress Brasil Paleontology, 131-41. Dong, Z. 1984. A new theropod dinosaur from the Middle Jurassic of Sichuan Basin. Vertebrata PalAsiatic, 22: 310-13. Hammer, W. R. 1992. Dinosaurs from the Falla Formation of Antarctica.
North-Central Section, Geological Society of America Abstracts Volume, University of Iowa, 1992:19. Hammer, W. R., W. J . Hickerson, S. Krippner, and J . Tamplin. 1991. Therapsids, temnospondyls and dinosaurs from the Fremouw and Falla Formations, Beardmore Glacier region, Antarctica. Antarctic Journal of the U.S., 26(5): 19. Hooker, J . J. , A. C. Milner, and S. E. K. Sequeira. 1991. An ornithopod dinosaur from the Late Cretaceous of West Antarctica. Antarctic Science, 3(3): 331-32. Molnar, R. E., T. F. Flannery, and T. H. V. Rich. 1985. Aussie Allosaurus after all. Journal of Paleontology, 59(6): 1511-13. Molnar, R. E., S. M. Kurzanov, and Z. Dong. 1990. "Carnosauria." In D. B. Wieshampel, P. Dodson, and H. Osmoiska (Eds), Dinosauria. University of California Press, 169-210. Welinhoffer, P. 1970. Die Pterodactyloidea (Pterosauria) der OberjuraPlattenkalde Suddentschlands. Bayerische Akademie der Wissenschaften Abhandlungen, 141: 133.
