fossils

Komodo dragon's extinct cousin from Athens

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Pete
Buchholz

Senior Writer
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Lucas
Lima

Staff Artist
Two small bone fragments found in Athens represent the last known monitor lizard in Europe. This small lizard lived at the onset of the last Ice Age in the last warm refuge in Europe.

Fossils of the last known European monitor lizard have been discovered near Athens. The fossils are dated to the Middle Pleistocene, approximately 750,000 years ago. They were found in a fissure fill deposit only a few kilometers from the Acropolis and are made up of fragmentary bones from the upper and lower jaws. The discovery was announced in May of 2017 by paleontologists Georgios Georgalis, Andrea Villa, and Massimo Delfino.


Monitor lizards, technically known as varanids, are almost all medium to large predators. The most famous member, the Komodo dragon, is the largest living lizards. Living monitors are known from warm areas of Africa, Asia, and Australia, but are also known from fossils throughout Europe. These Greek fossils can be assigned to the living genus Varanus, but don't represent any living species. They seem to be least like varanids from Africa, and probably represent an Asian origin.


Over the last few million years, the Earth's climate has gotten colder, culminating in the Pleistocene with a series of ice ages. At their greatest extent, massive continental glaciers covered much of northern Europe. The glaciers did not get as far as south as Greece, but the local climate was substantially cooler than today.


As glaciers advanced and global climate cooled, the home ranges of plants and animals moved toward the equator. The paper's lead author Georgios Georgalis said, “The Pleistocene is generally considered a cool epoch, with colder temperatures in comparison with its preceding Pliocene epoch, that have driven several animal clades (lineages) that once roamed Europe, either to extinction or to a significant geographic constriction of their range.”


This appears to be the case with European monitors lizards as living monitors are limited to warm regions of the world. The reduction of their range to the south through the Balkan Peninsula before disappearing from Europe forever was probably the result of changing climate as the glaciers advanced to the south.


Comparisons to other recent European monitor lizards show that there was a reduction in size over time, with the Athens specimen representing an especially small individual. This may have been an evolutionary response to the reduced range at the far southern end of the Balkan Peninsula.


The monitor lizard fossils were collected in the 1980s when the site was originally explored by paleontologists looking for mammals. Said Georgalis, “The Varanus remains, along with other reptile fossils, had remained unnoticed until our study.” Additional discoveries of this monitor lizard from the locality or others in Greece can help clear up its affinities and teach us more about the last European monitor.


“I am currently unaware if there is any excavation planning for this site again, but I really hope that more material from the last monitor lizard of Europe will be eventually found there,” Said Georgalis, “We are currently describing more fossil reptiles from several different localities from Greece, spanning from the early Miocene until the late Pleistocene.”


Read the original research in the Journal of Vertebrate Paleontology.

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Pete
Buchholz

Senior Writer


http://sulc.us/x3fwn
http://www.eartharchives.org/articles/komodo-dragon-s-extinct-cousin-from-athens/