Fossil Fish Sheds Light on Transition

An undated handout photograph released April 5, 2006 shows a model, by Tyler Keillor, of an ancient fish and its skeleton. Fossils of the 375-million-year-old species of ancient fish found north of the Arctic Circle fill an evolutionary gap in the transition between water and land animals, scientists said on Wednesday. Remains of the new species named Tiktaalik roseae were found encased in frozen rock. It has the fins and scales of a fish but its crocodile-like skull, neck and ribs resemble those of a land animal. REUTERS/Beth Rooney/Handout

It looks like we've found that missing link when that first fish crawled up onto land. From Yahoo News:

NEW YORK - Scientists have caught a fossil fish in the act of adapting toward a life on land, a discovery that sheds new light one of the greatest transformations in the history of animals.

Scientists have long known that fish evolved into the first creatures on land with four legs and backbones more than 365 million years ago, but they've had precious little fossil evidence to document how it happened.

The new find of several specimens looks more like a land-dweller than the few other fossil fish known from the transitional period, and researchers speculate that it may have taken brief excursions out of the water.

A chart depicts the possible evolution of Tiktaalik. Kalliopi Monoyios. From National Public Radio

"It sort of blurs the distinction between fish and land-living animals," said one of its discoverers, paleontologist Neil Shubin of the University of Chicago.

Experts said the discovery, with its unusually well-preserved and complete skeletons, reveals significant new information about how the water-to-land evolution took place.

The new find includes specimens, 4 to 9 feet long, found on Ellesmere Island, which lies north of the Arctic Circle in Canada. It is reported in Thursday's issue of the journal Nature by Shubin, Ted Daeschler of the Academy of Natural Sciences in Philadelphia and Farish A. Jenkins Jr. of Harvard.

Graphic shows site new fish fossil was found on Ellesmere Island, Canada. (AP Graphic)


Some 375 million years ago, the creature looked like a cross between a fish and a crocodile. It swam in shallow, gently meandering streams in what was then a subtropical climate, researchers say. A meat-eater, it lived mostly in water.

Yet, its front fins had bones that correspond to a shoulder, upper arm, elbow, forearm and a primitive version of a wrist, Shubin said. From the shoulder to the wrist area, "it basically looks like a scale-covered arm," he said.

It might have pulled itself onto stream banks, perhaps moving from one wet area to another, and even crawled across logs in swamps, said Daeschler.

The researchers have not yet dug up any remains from the hind end of the creature's body, so they don't know exactly what the hind fins and tail might have looked like.

The creature was dubbed Tiktaalik (pronounced "tic-TAH-lick") roseae, and also had the crocodile-shaped head of early amphibians, with eyes on the top rather than the side. Unlike other fish, it could move its head independently of its shoulders like a land animal. The back of its head also had features like those of land-dwellers. It probably had lungs as well as gills, and it had overlapping ribs that could be used to support the body against gravity, Shubin said.

You know, when stories like these come out, I have to wonder what would have happened if evolution had taken a different turn:

Copyright (C) 1998 by Thaves. From www.thecomics.com.