A NEW SPECIES OF PLIOSAURID REPTILE FROM THE EARLY CRETACEOUS BIRDRONG SANSTONE OF WESTERN AUSTRALIA

WA Museum Records and Supplements | Updated 1 decade ago

Abstract - Of three partial skeletons of small pliosauroid plesiosaurs from near Kalbarri in the Carnarvon Basin, Western Australia, two are described as Leptocleidus clemai sp. nov. The third is indeterminate. These constitute the first associated partial skeletons of Mesozoic reptiles recovered from Western Australia, and the first named species of fossil reptile from the State (excluding footprint inchnotaxa). They came from the (upper) glauconitic facies of the Birdrong Sandstone, a late Hauterivian-Barremian (Early Cretaceous) transgressive unit representing a nearshore shallow-marine episode of deposition. Fossil wood associated with the pliosaurs contains fossil pholadid bivalve borings and hyphae of saprophytic fungi. Leptocleidus is a small-sized (ca 3 m) genus of pliosauroid plesiosaur which is known from 'Wealden' deposits in England, South Africa and Australia. It retains many characters seen in Rhomaleosaurus, a pliosauroid of the English Lias (Hettangian -Toarcian; Early ]urassic). The new species Leptocleidus clemai sp. nov. is characterised by being the largest of the known species. Characters of the genus Leptocleidus are discussed. A brief review of the distribution of pliosauroids in time shows that the large, open-water, sarcophagous forms appear to have died out at the end of the Turonian and are replaced by the mosasaurs which first appear in the Cenomanian. Leptocleidus-like forms seem to have been restricted to inshore habitats.

Author(s) CRUIKSHANK, ARTHUR R.I. AND LONG, JOHN A. : Part 3
Page Number
263