Tuesday, May 11, 2010

Giant flying dinosaur fossil found

Evidence of flying dinosaurs with a 9ft wingspan and more than 100 razor-sharp teeth that dominated the skies 95 million years ago has been discovered on a building site.

A 14 inch long lower jaw belonging to one of the reptiles was found by an amateur fossil hunter.

Two of its teeth were still present and experts were able to analyse it and produce an artists impression of what the beast looked like.

Paleontologists are now hailing the discovery as 'remarkable'.

They have named it Aetodactylus halli after it was uncovered by amateur fossil collector Lance Hall on a construction site near Dallas, Texas.

The long, narrow bone was embedded in a powdery shale but had been exposed by the excavation of a hillside next to a road.

Mr Hall said: "I was scanning the exposure and noticed what at first I thought was a piece of oyster shell spanning across a small erosion valley.

"Only about an inch or two was exposed and I almost passed it up thinking it was oyster, but then I realised it was more tan-coloured like bone.

"I started uncovering it and realised it was the jaw to something but I had no idea what.

"It was upside down and when I turned over the snout portion it was nothing but a long row of teeth sockets, which was very exciting."

Mr Hall donated the fossil to the Shuler Museum of Palaeontology at southern Methodist University, in Dallas, where it was examined by experts.

Paleontologist Dr Timothy Myers, from the university, said the animal would have had a wingspan of around 9ft.

He said: "The roughly 14 inch long lower jaw is nearly complete and would have held 54 sharp, pointed teeth.

"Almost all the teeth fell out shortly after the animal died, leaving only a single, broken tooth base and the tip of a small replacement tooth visible in the sockets.

"The jaw itself is very thin and delicate and widens slightly near the tip to accommodate the slightly larger first four tooth pairs.

"This find is remarkable because of its excellent three-dimensional preservation.

"Pterosaur bones were exceedingly delicate, so these animals are relatively poorly represented in the fossil record.

"When they are preserved, their bones are often flattened and distorted by compaction."

Dr Myers said the creature's lower teeth were evenly spaced and extended far back along the jaw, covering nearly three quarters of its length.

The upper and lower teeth interlaced when the jaws were closed.

He said the thinness of the jaws, the upward angle of the back half of the mandible and the lack of a pronounced expansion of the jaw tips indicate Aetodactylus is a new genus and species

Aetodactylus halli is a type of pterosaur, a group of flying reptiles commonly referred to as pterodactyls.

Pterosaurs ruled the skies from the late Triassic period, more than 200 million years ago, to the end of the Cretaceous period, about 65 million years ago, when they went extinct.

They represent the earliest vertebrates capable of flying.

Dr Myers said the Aetodactylus halli is one of the youngest examples of the pterosaur family, which are known as Ornithocheiridae, worldwide.

He added: "Aetodactylus represents one of the final occurrences of ornithocheirids prior to the transition to toothless species."

Aetodactylus halli would have soared above the Dallas-Fort Worth area during the Cretaceous Period when much of the state was under water.

Professor Louis Jacobs, from SMU's Huffington Department of Earth Sciences, said the conditions found in the area have proved perfect for preserving fossils.

He said: "The ancient sea that covered Dallas provided the right conditions to preserve marine reptiles and other denizens of the deep, as well as the delicate bones of flying reptiles that fell from their flight to the water below.

"The rocks and fossils here record a time not well represented elsewhere."

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