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NEW MIDDLE AND UPPER JURASSIC BELEMNITE ASSEMBLAGES FROM WEST ANTARCTICA (LATADY GROUP, ELLSWORTH LAND): TAXONOMY AND PALEOBIOGEOGRAPHY
ABSTRACTSix belemnite genera and up to 24 species (some informal) represented mainly by moulds are recorded from the Middle and Late Jurassic Latady Group, Ellsworth Land, West Antarctica. Belemnopsis and Hibolithes are moderately abundant, Dicoelites, Duvalia, Produvalia, Pachyduvalia, and Rhopaloteuthis are rare. The assemblages are best described as: a sparse aff. Brevibelus-Hibolithes fauna (Bajocian); a Belemnopsis fauna with rare Hibolithes, Duvaliidae and Dicoelitidae (late Bathonian-Oxfordian); and a more abundant fauna of Belemnopsis and Hibolithes, with less common Duvaliidae (Kimmeridgian-Tithonian). The Duvaliidae and short grooved Hibolithes likely migrated from Madagascar to Ellsworth Land via a trans-Gondwana seaway. Most Hibolithes are endemic to the region; they resemble and may be in part conspecific with the New Zealand Hibolithes arkelli-H. marwicki group (middle Tithonian). They appeared first in Ellsworth Land and migrated to New Zealand. The Belemnopsis are also endemic. One group resembles the New Zealand Belemnopsis annae-B. stevensi-B. keari group of the New Zealand Heterian Stage (Callovian to Kimmeridgian) and may have appeared first in Ellsworth Land. A second group of small robust Belemnopsis resembles broadly similar forms from the early Callovian and Kimmeridgian of New Zealand. The belemnite occurrences and time distributions suggest that faunal links between West Antarctica and New Zealand, and South America, West Antarctica and Madagascar, existed during the Middle and Late Jurassic.
KEY WORDS: Middle and Upper Jurassic; new belemnite assemblages; West Antarctica; taxonomy; paleobiogeography
Copyright: Paleontological Society April 2007 |
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