Oldest Crustacean Found

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

Not entirely dino related but...

(has a small picture too)

http://news.bbc.co.uk/hi/english/sci/tech/newsid_1441000/1441879.stm

This tiny half-billion-year-old fossil throws up some tricky questions
about how and when life evolved on Earth.

It is a crustacean - a relative of modern day lobsters and shrimps - and
it is less than half a millimetre long.

"It is the oldest complete crustacean ever found. We found it in rocks in
Shropshire which are 511 million years old," co-finder Mark Williams, of
the British Geological Survey, told BBC News Online.
...

Looking back at the fossil record, a large range of species begins to
appear at the beginning of the Cambrian Period, 545 million years ago.

Older fossils tend to be of very small organisms like bacteria. There are
two main theories which try to explain this.

One says that there was a "Cambrian Explosion": a period of rapid
evolution during which a huge number of species developed.

The other says that evolution proceeded at a much slower pace but that few
of the creatures that were around before the Cambrian were not preserved.

They may have been soft-bodied, which would make fossilisation very rare,
or the geological conditions may simply not have been right to preserve
anything.

Because this crustacean is so old, yet so advanced, it lends weight to the
second theory.
...

"It is a really wonderful fossil. Most fossils only have their skeletons
preserved, but this one is virtually mummified, with legs and soft parts
preserved.

"Because the soft tissues are so soft, there must have been a very special
kind of preservation. It was probably fossilised immediately after death,"
he said.

The unusually complete fossil bears all the distinguishing feeding
appendages of a crustacean, including an extra antenna and a jaw.