A constant creationist claim is that there are no transitional fossils. And yet as palaentologists will tell you the fossil record is full of transitional forms-indeed as Larry Martin at the University of Kansas puts it "My drawers are crawling with transitional forms". Now the creationists do have a technical point-namely one cannot PROVE that a certain fossil that appears to be transitional really is the direct ansestor of another species.
But the more one looks, the more transitions one sees, to the point where the creationist'c claim strains comon sense. The latest transitional form (Tiktaalik roseae) reported in Nature (http://www.nature.com/nature/journal/v440/n7085/edsumm/e060406-01.html)
fills in a critical gap between fish and land vertebrates.
As Dr. Michael J. Novacek from the American Museum of Natural History noted:
"We've got Archaeopteryx, an early whale that lived on land and now this animal showing the transition from fish to tetrapod. What more do we need from the fossil record to show that the creationists are flatly wrong?"
How many more indeed.
Other Links and additional comments:
Scientists Call Fish Fossil the 'Missing Link'
Graphic from The Times: http://www.timesonline.co.uk/article/0,,11069-2120609,00.html
Was Darwin Wrong? http://magma.nationalgeographic.com/ngm/0411/feature1/fulltext.html
Transitional Fossils. http://www.origins.tv/darwin/transitionals.htm
List if Transitional Fossils.http://www.answers.com/topic/list-of-transitional-fossils
Transitional Forms: http://www.indiana.edu/~oso/evolution/teaching/te2a.htm
Also see this page (http://www.indiana.edu/~oso/evolution/transitions/t3k.html#1) from the Indiana site that shows two alternative predictions as to what transitional forms should be like. First is the popular conception that all traits change in parallel and a model of transitional form evolution based on modern genetics. This model predicts that different traits will change at different times so that transitional forms should be a mosaic of ancestral and derived characteristics. The new transitional form is the sort of mosaic as predicted by modern theory:
"Like its immediate ancestors, Tiktaalik is scaly and displays gill and fin features that indicate it lived mostly in the water. But it lost its gill cover and its snout grew, suggesting that changes were under way in the creature's breathing mechanism and in its food sources. It boasts a heftier rib cage than its ancestors, presumably to support it when it leaves the water. It's skull has lost related bones associated with fish but missing in tetrapods. Another gill feature, a tiny slit that became part of the ear in tetrapods, has grown wider. And the bones in the fins along its sides point to proto-limbs with enough strength and flexibility at the shoulder, elbow, and wrist to allow Tiktaalik to lift itself off the bottom and perhaps temporarily move about on land."