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WINDSOR STAR (Ontario) 22 November 10 Canadian find may rewrite evolution of Komodo lizard (Randy Boswell)
A Canadian-led team of researchers that discovered the 33-million-year-old fossilized remains of a large lizard in an
Egyptian desert is rewriting the evolutionary history of the iconic Komodo dragon and its closest carnivorous cousins.
The African find is being described as the oldest known specimen of the Varanus reptile group, which includes Indonesia's giant Komodo -- at three metres and 75 kilograms, the world's largest lizard -- and all other species of monitor lizards inhabiting ranges in Africa, Asia and Australia.
The discovery, led by University of Alberta biologists Robert Holmes and Alison Murray, challenges the prevailing theory that monitor lizards originated in Asia about 20 million years ago before spreading to Africa and Australia.
Instead, the researchers contend, the much older varanid lizard bones found at the well-known Fayum fossil bed south of Cairo indicates that these predatory lizards -- perhaps 1.5 metres in length at the time -- probably evolved first in that region before making their way out of Africa.
That finding has potentially major implications in several fields, because geologists and paleontologists are still trying to understand the configuration of land masses and water routes in prehistoric Africa -- then completely surrounded by ocean -- that would have allowed animal migration to other continents.
"It has generally been assumed that the genus Varanus originated in Asia, and then dispersed westward into Europe and then eventually into Africa, as well as eastward into the Indonesian archipelago and into Australia," Holmes told Postmedia News.
"The discovery of 33-million-year-old Varanus in Africa turns this hypothesis on its head, since it is by far the oldest record of the genus in the fossil record."
The fossilized lizard vertebrae were found in a desert in northern Egypt that was once the bottom of a river or small lake, said Murray, who has been studying ancient fish remains from the region since 2001. The bones were unearthed by study co-authors Yousry Attia -- an Egyptian geologist who is now deceased -- and Duke University scientists Elwyn Simons and Prithijit Chatrath. But it took until 2008, when Holmes first saw the vertebrae, that their significance in reconstructing the evolution of monitor lizards was first realized.
The specimen's apparent ability to swim is seen as a clue to the long-standing lizard migration mystery. "Whether the animals lived in the water or surrounding land, we don't know, but we do know that some modern-day species of Varanus are comfortable swimming in fresh water," Holmes stated in a summary of the study, published in the journal Paleontology.
Canadian find may rewrite evolution of Komodo lizard

Must read "at three metres and 175 kilograms" not 75kg