Pterodactyls hung out with birds in prehistoric Japan

by **D.M** 25th May 2010, 2:23 pm

Pterodactyls hung out with birds in prehistoric
Japan

Washington, March 2 : Newly analyzed tracks in Japan show small
pterodactyls also roamed there and seemed to mingle with birds.

According to a report in Discovery News, the world's first pterosaur
tracks from Japan, documented in a new study, suggest these Dinosaur-Age
flying reptiles not only coexisted with birds, but that the two groups
also hung out together when they weren't soaring the Cretaceous skies.

A lone siltstone slab contains the fossilized footprints, made by
pterosaurs, birds and amphibians.

It provides a literal slice of what prehistoric life was like in Japan
around 127 million years ago.

"I think that a group of small pterosaurs was feeding together near a
pond or near a lake," lead author Yuong-Nam Lee told Discovery News,
adding "there are lots of feeding beak marks."

The scientists identified a total of 64 imprints made by five to six
individuals that "show a clear quadrupedal gait pattern" with feet
bearing curved "hook-like sharp" claws.

"The high density of the tracks suggest gregarious behavior, but the
random orientation of the trackways does not show that they were moving
in the same direction as a herd," Lee said.

He and his team instead think the pterosaurs and birds randomly gathered
to feed.

The eating marks consist of "small round depressions on the slab,"
possibly where the animals repeatedly pecked away for food.

Since the tracks don't match up with any other known pterosaur prints,
the researchers believe they were made by a new species, called
Pteraichnus nipponensis.

The only other evidence for pterosaurs in Japan is an incomplete spinal
column bone and a single print set, not yet fully documented, from
another location.

Nevertheless, this evidence and the siltstone slab prints suggest that
multiple tiny pterosaurs called Japan home from at least 113 to 127
million years ago.

Evidence for small pterosaurs at that time has also been found in Spain
and Korea.

Since the tracks are similar, yet appear to have been made by different
sized individuals, David Unwin, a senior researcher in paleobiology at
the University of Leicester, said that it is possible "that pterosaurs
of widely differing growth stages visited/walked around in the same
small area."

Unwin was also struck by the presence of the bird tracks.

He indicated that scientists have long puzzled over the relationship
between birds and pterosaurs, wondering if they enjoyed "a long peaceful
coexistence, or protracted competition."

The former now appears to be the case.