Western Australian Cretaceous pliosaurid 
275 
dinosaurs (e.g., Kukuru kujani Long 1993) together 
with fossilised wood. Thus the noted occurrence of 
a theropod dinosaur hone found near WAM 
986.8.1 along with the high abundance of fossilised 
wood from the Birdrong Sandstone strongly 
suggests that this unit would be a potentially good 
target to direct future exploration for dinosaurs. 
SUMMARY AND CONCLUSIONS 
Two partial skeletons from the Early Cretaceous 
Birdrong Sandstone of Western Australia are 
ascribed to the pliosauroid genus Leptockidus as L. 
clemai sp.nov. Leptockidus is a small-sized genus 
(under 4 m), known from the Early Cretaceous of 
England, South Africa and Australia. It seems to 
have occupied a close inshore or shallow marine 
habitat, as opposed to the more typical open 
marine habitat of the larger forms such as 
Kronosaurus. Leptockidus is close to, but smaller 
than, the Early Jurassic genus Rhomaleosaurus. It 
may be ancestral to the later Cretaceous forms 
known as the Polycotylidae. It is noted that the 
large pliosaurids died out by the Turonian and 
were replaced by the mosasaurs, leaving the 
polycotylids as the last remaining pliosaurs. An 
anomaly is that the plesiosauroid plesiosaurs 
continued very successfully as predators on small 
and soft-bodied marine animals until the end of 
the Mesozoic. 
ACKNOWLEDGEMENTS 
We thank the generous sponsorship of Mr John 
Clema, of Forrestfield, and Forrestania Gold Pty 
Ltd, for grants fully supporting field exploration of 
the Birdrong Sandstone over three field seasons 
(1992-1994), and partial funding of preparation of 
specimens. Many helpers assisted in the field 
excavations or offered helpful discussion of the age 
of the sites, so we extend our sincere thanks to 
Greg Milnar, Ian Copp and Glynn Ellis, Kristine 
Brimmell, David Haig, Alex Ritchie, Mikael 
Siverson, Alex Baynes and John Clema. We thank 
Kristine Brimmell for the photography of the 
specimens, Jenny Bevan for preparation of 
specimens, and Danielle Hendricks for drafting 
assistance. ARIC is indebted to the Royal Society of 
London for travel support, and to the three women 
in his life for encouragement and help in 
undertaking a long research visit to the antipodes 
in early 1996. 
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