Possible evidence about the great Permian extinction.
Below article from AAP NEWSWIRE reprinted for fair use purposes only -- copyright acknowledged.
This Megalania page has been visited times since April 20, 1998.
Copyright 1998 AAP Information Services Pty. Ltd.
April 19, 1998, Sunday
SECTION: Nationwide General News; Overseas News
ANCIENT BONES MAY SHED LIGHT ON BIG EXTINCTION
By David Morgan
PHILADELPHIA, April 18 Reuters - Ancient reptile remains discovered in eastern Pennsylvania may hold clues to the mysterious disappearance of more than half the earth's land animals 200 million years ago, a scientist said today.
Three skulls belonging to animals of the genus Hypsognathus present paleontologists with a rare addition to the scarce fossil record of the late Triassic and early Jurassic periods, when dinosaurs first began to dominate the planet.
Paul Olsen, a Columbia University paleontologist who made the discovery with the help of two amateurs from Reading, Pennsylvania, described the hypsognathus reptiles as 30cm-long, horned herbivores that resembled the modern-day groundhog in stature.
They were among the crawling reptiles and salamander-like amphibians that prevailed in the animal kingdom just before the age of dinosaurs at the dawn of the Mesozoic Era 248 million years ago.
Two of the white, partly preserved skulls showed up in a purplish mudstone deposit at a construction site in Exeter Township, Pennsylvania. The third was discovered in the town of Pennsburg. Both sites lie within 50km of Philadelphia, between Allentown and Pottstown.
A fourth skull, found among 150 ancient bones unearthed in Exeter, has yet to be identified.
"We were looking at rocks at a construction site and there was so much new clean rock exposed after a rain, I thought there might be a lot more bones there than we had originally thought," Olsen said. "And lo and behold, once I really paid attention, there were."
Olsen was scheduled to present his findings today at a dinosaur symposium sponsored by Philadelphia's Academy of Natural Sciences.
The area where the hypsognathus skulls were discovered is part of the Newark rift basin, a geological formation created 190 million to 230 million years ago as North America pulled away from the ancient supercontinent known to scientists as Pangea.
At about the same time, near the end of the Triassic Period and the beginning of the Jurassic Period, a mass extinction occurred among the older, established lines of animals, scientists like Olsen believe.
The course of evolution changed as a result, and dinosaurs were able to develop into giants such as the tyrannosaurus and brachiosaurus. Before the mass extinction, the biggest dinosaur had been no heavier than a cow.
The cause of the extinction remains a mystery to science, largely because skeletal remains from the period have been very rare. The Exeter fossils have been dated to just 500,000 years before the extinction, which Olsen puts at about 202 million years ago.
"The greatest thing about this find is that it is in well-dated rock near the Triassic-Jurassic boundary," observed Hans-Dieter Sues, curator of vertebrate paleontology at the Royal Ontario Museum in Toronto, where the Exeter skulls were being prepared.
"Now we have evidence that these animals lived right up to the boundary, which supports our ideas about a large-scale extinction there," he said.
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