Australia: The Land Where Time Began

A biography of the Australian continent 

Lower Cretaceous non-Marine Turtles

In the Lower Cretaceous of Australia non-marine turtles have been found to be reasonably common in a number of deposits such as the Wonthaggi Formation, Victoria, from the Aptian and a number of other sites of Albian age throughout eastern Australia. Indeterminate cryptodires have been recovered from these sites, a characteristic of which was retraction of the neck into the shell in a vertical fashion. Chelycarapookus arctuatus was the smallest known named species, about 200 mm long, from the Albian in the Merino Group strata near Casterton in western Victoria. It was described from an internal shell mould. Chelycarapookus, a primitive turtle with a rounded shell similar to that of the sinemydids, a group of Asian cryptodirans from the Cretaceous. The relationships of this species is uncertain because the only known specimen is too poorly preserved to allow a conclusive determination. 

In the Eumeralla Formation at Dinosaur Cove in Victoria a specimen of Otwayemys cunicularius from the lower Albian, a second cryptodiran, about 20 % larger than Chelycarapookus was found. It is known from the remains of several individuals, a shell, fragments of a skull and vertebrae. It has been suggested that Otwayemys may be related to the meiolaniids, very large turtles with horns and a tail club, that survived on the Australian mainland and surrounding islands until a few thousand years ago. In the Griman Creek Formation at Lightning Ridge what has been described as probably meiolaniid material from the lower-middle Albian has been found, indicating an animal that had a snout that was short and broad, claws that were hoof-like, and along the margins of the carapace were prominent triangular projections. It has been suggested that a very long evolutionary history, from the Cretaceous to the Holocene, would be implied if it is confirmed that Otwayemys and the specimens from Lightning Ridge are meiolaniid relatives, and on the Australian continent a radiation of primitive turtles during the Late Mesozoic that is unique.

Sources & Further reading

  1. Kear, B.P. & Hamilton-Bruce, R.J., 2011, Dinosaurs in Australia, Mesozoic life from the southern continent, CSIRO Publishing.
Author: M. H. Monroe
Email:  admin@austhrutime.com
Last updated  16/12/2011
 

 

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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading