Agnostic Mom

This time it is the vital transition animal between land and sea. ID/Creationists love to talk about this “missing link” that biologists and palaeontologists have been confident about finding someday. Open a bottle of wine, because we have found Tiktaalik.

This according to New Scientist News about a team whose work has paid well:

After five years of digging on Ellesmere Island, in the far north of Nunavut, they hit pay dirt: a collection of several fish so beautifully preserved that their skeletons were still intact. As Shubin’s team studied the species they saw to their excitement that it was exactly the missing intermediate they were looking for. “We found something that really split the difference right down the middle,” says Daeschler.

Tiktaalik had a mobile neck and had lost the bony coverings of the gills that fish use to fan water to maximise their oxygen intake. These suggest that the fish may have been at least partly air-breathing, like modern tetrapods (Nature, vol 440, p 757 and p 764).

The transitional features are not just in the gills. They are also in the fins:

They found a wrist-like arrangement near the tip of the fin, so that the end could bend forward and provide vaguely foot-like support. “It could flex the elbow and extend the wrist so the tip of the fin could lie against the ground. It could do a push-up,” says Shubin. In other words, our ancestors’ limbs were probably co-opted to serve as support structures before they had evolved to look much like legs at all.

Here are a few other general descriptions of Tiktaalik from a different article:

1) 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.
2) “This is clearly an animal that is able to support itself on the ground,” probably both in very shallow water and for brief excursions on dry land. On land, it apparently moved like a seal, he said.
3) 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.
4) Yet, the creature’s jaws and snout were still very fishlike, showing that “evolution proceeds slowly; it proceeds in a mosaic pattern with some elements changing while others stay the same,” Daeschler said.