Umoonasaurus, crested plesiosaur from Australia

[Tim Williams <twilliams_alpha@hotmail.com>]

Apparently plesiosaurs could be crested too..

Benjamin P. Kear, Natalie I. Schroeder, and Michael S.Y. Lee.  An archaic 
crested plesiosaur in opal from the Lower Cretaceous high-latitude deposits 
of Australia.  Proceedings of the Royal Society B:  Biology Letters.  
FirstCite Early Online Publishing.

Abstract: "_Umoonasaurus demoscyllus_ gen. et sp. nov. is a new small-bodied 
(approx. 2.5m) pliosauroid plesiosaur from the Lower Cretaceous 
(Aptian-Albian) of southern Australia. It is represented by several partial 
skeletons (one with a near complete skull is the most complete opalized 
vertebrate fossil yet known), and is unique in having large crests on the 
skull midline and above the orbits. _Umoonasaurus_ is surprisingly archaic 
despite its relatively late age (approx. 115Myr ago) - being simultaneously 
the most basal (primitive) and last surviving rhomaleosaurid. Notably, it 
lacks the ?pliosauromorph? features (large head, short neck, gigantism) 
typically characterizing many more derived Jurassic rhomaleosaurids; thus, 
reinforcing the suspected convergent evolution of the ?pliosauromorph? 
hypercarnivore body plan. _Umoonasaurus_ inhabited an Early Cretaceous 
high-latitude (approx. 70°S) inland seaway subject to seasonally 
near-freezing climatic conditions. This extreme environment supported a 
diverse range of plesiosaur taxa, suggesting that these marine reptiles 
might have possessed adaptations (e.g. heightened metabolic levels) to cope 
with cold-water temperatures. Indeed, survival of ancient endemic lineages 
such as _Umoonasaurus_ is a common phenomenon in Australian Cretaceous 
vertebrate assemblages and might have been facilitated by isolation in 
low-temperature high-latitude regions."