"At This Point, It looks Like They Just Dropped down Out of the Sky."

That is what a prominent palaeontologist once said about ichthyosaurs a few years back because their appearance in the fossil record gave little indication of where they had come from.  That has changed.  The Washington Post, in provocative fashion, has an article titled: Newly discovered fossil could prove a problem for creationists. Rachel Feltman writes

Researchers report that they've found the missing link between an ancient aquatic predator and its ancestors on land. Ichthyosaurs, the dolphin-like reptiles that lived in the sea during the time of the dinosaurs, evolved from terrestrial creatures that made their way back into the water over time.

But the fossil record for the lineage has been spotty, without a clear link between land-based reptiles and the aquatic ichthyosaurs scientists know came after. Now, researchers report in Nature that they've found that link — an amphibious ancestor of the swimming ichthyosaurs named  Cartorhynchus lenticarpus.

How is this a problem for creationists?

"Many creationists have tried to portray ichthyosaurs as being contrary to evolution," said lead author Ryosuke Motani, a professor of earth and planetary sciences at the University of California Davis. "We knew based on their bone structure that they were reptiles, and that their ancestors lived on land at some time, but they were fully adapted to life in the water. So creationists would say, well, they couldn't have evolved from those reptiles, because where's the link?"

Now the link has been found.

According to the researchers, this animal had larger bones and flippers, flexible wrists and a shorter snout, all which would have been a decided disadvantage in deep ocean water but are much more in keeping with the morphology of coastal animals. Of this transition, Feltman writes:

When other vertebrates have evolved from land to sea living, they've gone through stages where they're amphibious and heavy. Their thick bones probably allowed them to fight the power of strong coastal waves and stay grounded in shallow waters. Sure enough, this new fossil has much thicker bones than previously examined ichthyosaurs.

Another piece of the puzzle and one less argument for young-earth creationists to use.