History Files

Please help the History Files

Contributed: 175

Target: 400

Totals slider

The History Files still needs your help. As a non-profit site, it is only able to support such a vast and ever-growing collection of information with your help, and this year your help is needed more than ever. Please make a donation so that we can continue to provide highly detailed historical research on a fully secure site. Your help really is appreciated.



Mesozoic World

Australia's 'Nessie'

Edited from BBC News, 27 July 2006

Recently-examined fossil evidence in 2006 suggested that Australia was once home to ancient reptiles which swam in huge icy lakes.

The large, carnivorous reptiles lived 115 million years ago, in the very middle of the long period of dominance of the planet by dinosaurs, when much of the continent was covered in water. Fossils of two then-new species of plesiosaur were discovered near Coober Pedy in South Australia.

These specimens were described in editions of the journals, Biology Letters and Palaeontology. One is known as Umoonasaurus demoscyllus, and this was about 2.4m long with crests on its head. It may have used these for display or mating purposes, a common-enough behaviour.

The lead author of the two papers, Dr Benjamin Kear of the University of Adelaide, suggested imagining a compact body with four flippers, a reasonably long neck, small head, and short tail, much like a reptilian seal.

The other species, Opallionectes andamookaensis, grew to about 5m in length and had small needle-like teeth.

Treasure trove

Something like thirty fossils were discovered at an opal mine near the outback mining town of Coober Pedy. They were made up of the mineral opal, which filled the spaces left by bones when the original fossil-bearing rock was dissolved away by acidic groundwater.

The fossils included several skeletons and a complete skull of Umoonasaurus, plus a partial skeleton of Opallionectes.

They were thought to be examples of juvenile animals, suggesting that the lake was a breeding and nursery ground.

The researchers behind the project stated in their report that they believed the sea-dwelling adults returned to the shallow inland waters to breed and raise their young (much as many aquatic mammalian species do today). They were carnivorous, feeding on fish and squid.

At the time, Australia was much colder, still connected as it was to Antarctica as part of the fracturing super-continent of Gondwana and being located closer to the South Pole. The inland ocean would have frozen over in places during the winter. However, the creatures may have evolved mechanisms to cope with the harsh climate, such as a faster metabolic rate.

  • A genus of extinct marine reptiles, having a long neck, a small head, a short tail, and four large paddling limbs
  • First appeared at the start of the Jurassic, and thrived until 65 million years ago
  • Lake or sea monster sightings are occasionally explained as plesiosaurs but scientific evidence points to them being extinct


Some images and original text copyright © BBC or affiliates. Reproduction is made on a 'fair dealing' basis for the purpose of disseminating relevant information to a specific audience. No breach of copyright is intended or inferred.