Bugs The First Land Creatures? 460 MYA Tracks...

[Richard W Travsky <rtravsky@uwyo.edu>]

with picture

http://dsc.discovery.com/news/briefs/20020422/landwalk.html

April 26 Jumbo bug-like creatures may have been the first animals to
venture onto land, some 40 million years earlier than previously believed.

That's the story being told by tracks left in 460- to 500-million-year-old
sandstone found in a quarry near the town of Kingston in Ontario, Canada.
The tracks were made on what appear to have once been seaside sand dunes.

"It's far older than anything we've previously seen on land,"  said Simon
Braddy, a paleontologist at the University of Bristol and an expert on
reconstructing how ancient animals moved. He is one of the authors of a
paper describing the discovery in the May issue of the journal Geology.

Braddy said the best bet is that the land-roving track-makers were members
of a poorly understood group called euthycarcinoids. Euthycarcinoids
resembled pumped up versions of today's pill bugs or wood louses, only
with a more triangular rear and a tail spine dragging behind.

"We're reasonably confident that it's a euthycarcinoid," said Braddy.
"There's no other arthropod with the right number of legs and a tail
spine."

Braddy made that determination by plugging body characteristics into a
computer model he has developed that mimics the tracks left by long-lost
animals.

The model also confirmed that the first land explorers animals were
probably slow and cumbersome and still moved their legs like swimmers
"rowing" opposing legs in synch rather than walking them alternately like
later land animals.

"It's probably an amphibious animal," said Braddy.