Washington: A fossilised jaw discovered
from a hillside in Texas belongs to an ancient reptile or
pterosaur that flew over the region some 95 million years ago,
palaeontologists have claimed.
According to the scientists, the reptile called
Aetodactylus halli had a nine-foot wingspan and was soaring
over the sea in what is now North Texas when it fell into the
water and died.
Lance Hall, a member of the Dallas Paleontological
Society, had found the fossil embedded in soft, powdery shale
that had been exposed by excavation of a hillside next to a
highway in the Dallas-Fort Worth area in 2006.
"I was scanning the exposure and noticed what at first
I thought was a piece of oyster shell spanning across a small
erosion valley," Hall was quoted as saying by LiveScience.
"Only about an inch or two was exposed. I almost
passed it up thinking it was oyster, but 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."
Paleontologists later told Hall it was a pterosaur --
a group of flying reptiles commonly referred to as
pterodactyls -- and an important find.
Such "winged lizards", as their name suggests, are
thought to have dominated the skies from more than 200 million
years ago until the mass extinction event 65 million years ago
that wiped them out along with most dinosaurs and many other
plants and animals.
Aetodactylus halli is also one of the youngest members
of the pterosaur family Ornithocheiridae.
The mandible, which is about 15 inches long,
originally contained 54 slender, pointed teeth, but only two
remained in their sockets when discovered, according to
paleontologist Timothy S Myers of Southern Methodist
University (SMU) in Dallas, who identified and named the
animal.
From the way the teeth were spaced, the researchers
suspect the upper and lower teeth interlaced when the jaws
were closed. Just the fact that this pterosaur had teeth was
somewhat surprising as all North American pterosaurs were
toothless from that time period, except for Coloborhynchus.
When Aetodactylus halli was alive, much of Texas was
cloaked by the Western Interior Seaway the massive sea that
split North America from the Gulf of Mexico to the Arctic
Ocean. On shore, the terrain was flat and dotted with
flowering plants, according to paleobotanist Bonnie Jacobs,
associate professor of Earth Sciences at SMU.
"There were still conifers and ferns as well, but
mostly of the sort that had tiny needle leaves, like
junipers," Jacobs said. "Sycamores and their relatives would
have been among the flowering plants."
The team describes the flying reptile in the latest
issue of the Journal of Vertebrate Paleontology.
PTI
