Paleobiology and Taphonomy of Exceptional Preserved Fossils from Jurassic Lacustrine Deposits, Beardmore Glacier Area and Southern Victoria Land, Antarctica

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a study of the paleobiology and taphonomy (postmortem history) of biotas from lacustrine interbeds within the Kirkpatrick Basalt of the Ferrar Group (Jurassic), Beardmore Glacier area and southern Victoria Land, Transantarctic Mountains, Antarctica. Sedimentary interbeds of the Kirkpatrick Basalt represent unusual deposits of exceptional preservation (or Konservat-Lagerstatten), characterized by the presence of a variety of non-biomineralizing (or so-called soft-bodied) organisms. Fieldwork in previous decades resulted in discovery of abundant remains of conchostracans (bivalved arthropods having non-mineralized exoskeletons) and fishes, less common remains of various arthropods such as insects, syncarids, and isopods, as well as plant fragments. The arthropod and fish fossils range in preservational quality from disarticulated pieces to articulated remains comparable to the finest known from the fossil record. Renewed collecting of the lacustrine deposits should yield additional exceptionally preserved fossils, possibly including additional taxa, and other data important for paleoecologic, taphonomic, and paleoenvironmental interpretation. Present indications are that the Kirkpatrick lake deposits offer important "windows" into the evolutionary history of high-latitude, freshwater ecosystems of the middle Mesozoic. Paleoecologic and taphonomic study of the Kirkpatrick lake deposits can be expected to provide additional clues to the general conditions under which exceptional preservation of non-mineralized skeletal parts, and perhaps soft parts, occurred in the geologic past. This is significant because nearly all of our current understanding of conditions surrounding exceptional preservation has been derived from studies of marine deposits, marginal-marine deposits, or freshwater deposits from low- to middle-paleolatitudes. Principal objectives of the research are: 1) to collect and systematically document the biota of the sedimentary interbeds of the Kirkpatrick Basalt sites in the Beardmore Glacier area and southern Victoria Land, Antarctica; 2) to document and interpret taphonomic information on the Kirkpatrick sites, including diagenetic alteration of fossils; 3) to describe and interpret trace fossils that are associated with the body fossils; and 4) to document and interpret the stratigraphic and sedimentologic context of exceptional preservation in the Kirkpatrick sites. Considerable importance attaches to the Jurassic sites in the Transantarctic Mountains area because few sites from aqueous ecosystems of high paleolatitude areas are known to contain non-biomineralized fossils. Completion of this study will result in a more complete understanding of the biota and paleoecology of high latitude lacustrine ecosystems of the middle Mesozoic. The Kirkpatrick sites will provide information useful for interpreting Jurassic biotas in a global context, as it will provide an improved basis for comparison with better-known, low- to middle-latitude deposits of exceptional preservation. Data from study of the Kirkpatrick deposits are expected to provide information concerning the fundamental question of why exceptional preservation of organisms has occurred in freshwater, high latitude settings.