Sea worm fossil gives clues to 'common ancestor'

Fossils of a sea worm that lived on the ocean floor about 500 million years ago are giving new insights into how early creatures evolved.

Tube-like structures once thought to be a type of seaweed were made by a worm that lived a solitary life on the sea bed, say scientists.

Prof Simon Conway Morris, from St John's College, University of Cambridge and a co-researcher on the study, said: "Now we know that they were primitive hemichordates - perhaps the most primitive of all."

"Through them, we can get clues about the anatomy and lifestyle of the last common ancestor that we all share, and this adds further evidence to the hypothesis that the ancestor was a filter-feeder like Oesia."

The specimens, found near Marble Canyon in the Canadian Rockies, are exceptionally well preserved, giving details of the animal's internal anatomy. They rival or are even better than the nearby Burgess Shale.

Evolution 'favours bigger sea creatures'

The animals in the ocean have been getting bigger, on average, since the Cambrian period - and not by chance.

That is the finding of a huge new survey of marine life past and present, published in the journal Science.

It describes a pattern of increasing body size that cannot be explained by random "drift", but suggests bigger animals generally fare better at sea.

In the past 542 million years, the average size of a marine animal has gone up by a factor of 150.

It appears that the explosion of different life forms near the start of that time window eventually skewed decisively towards bulkier animals.

Measured by volume, today's tiniest sea critter is less than 10 times smaller than its Cambrian counterpart; both are minuscule, sub-millimetre crustaceans. But at the other end of the scale, the mighty blue whale is more than 100,000 times the size of the largest animal the Cambrian could offer: a trilobite less than half a metre long.

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Ichthyosaurs

A fossil stored in a Doncaster museum for 30 years and thought to be a plaster copy has turned out to be a new species of ancient reptile.

A young palaeontologist working with the University of Manchester found the fossil in 2008, in the collections of Doncaster Museum and Art Gallery.

He realised it was the 189-million-year-old remains of an ichthyosaur - further study confirmed it to be a previously unknown species.

It was so well preserved he could determine the contents of its stomach, which were actually the hooks from the tentacles of squid.

It is not uncommon to find ichthyosaur fossils in England. The sharp-toothed marine reptiles swam in large numbers in the seas around Britain when the dinosaurs roamed.

Ichthyosaurs

• Often misidentified as "swimming dinosaurs", they first appeared in the early Triassic period (251 million to 199 million years ago)
• The name means fish-lizard, although the creature has been classified as a reptile since the mid-19th Century
• Its length ranged from 1m to 14m - although the average length was 2m to 3m (the Doncaster fossil is 1.5m)
• The creature was noted for its sharp, robust teeth.
• Ichthyosaurs became extinct before the dinosaurs, dying out in the early part of the late Cretaceous period (145.5 million to 65.5 million years ago)

This new species has now been named Ichthyosaurus anningae - in honour of Mary Anning, the British fossil-hunter who discovered the first ichthyosaur on the Dorset coast in about 1811.

Thanks to Tom Penhall for sending a link

THE FIRST DINOSAUR?

http://www.dailymail.co.uk/sciencetech/article-2242981/Scientists-dinosaur--say-similar-size-golden-retriever-5-foot-tail.html
Thanks George for the link. This is our first post from the Daily Mail website!