Early fish hit land to be better predators
James Randerson
19:00 28 July 04

Our distant fishy ancestors first hauled themselves on to land in order to
warm up in the Sun. So claims a team that says basking would have provided
an energy boost that made the fish more agile in the water, improving their
chances of snaring prey. It was also an evolutionary milestone that heralded
the rise of all land vertebrates, including us.

Numerous explanations have been put forward to explain why a group of
primitive fish decided to drag themselves out of the tropical Devonian
swamps on to dry land some 365 million years ago. Some say it allowed them
to escape predators or putrid, shrinking pools during drought, while others
have suggested it allowed them to scavenge stranded fish.

Now Robert Carroll at McGill University in Montreal, Canada, and his
colleagues suggest the transition was all about becoming a better predator
in water.

The team used fossil-record information about the bodies of early
tetrapods - the fish-like animals that crawled on to land - and the tropical
conditions at the time to work out how much solar energy they could have
absorbed. They predict a typical tetrapod could have warmed up to 35 °C in
two to three hours.

Read the Rest at New Scientist
http://www.newscientist.com/news/news.jsp?id=ns99996213

Posted by
Robert Karl Stonjek
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