Burial at sea can result in amazing preservation, including remains of the ichthyosaur, a marine reptile that swam the seas 180 million years ago. Fossil remains of ichthyosaurs have been found over the last hundred years that included outlines in the rock. Scientists didn't know whether the outlines surrounding the bones were remnants of the animal's original size, or were left by the microorganisms that consumed the carcass. What was between the outline and the bones? Did ichthyosaurs have a layer of blubber? Could there still be evidence of flesh or skin? Lund University paleontologist Johan Lindgren took an uncontaminated fossil and subjected it to a battery of modern chemical tests.
First, Lindgren's team analyzed the ichthyosaur's skin, which the fossil preserved in astounding detail. Researchers could make out the skin's individual layers and even the folds that formed as the animal decayed.
Strikingly, the researchers found traces of melanophores, specialized cells that contain the pigment melanin. While such a find dates back to the 1950s in ichthyosaurs, Lindgren's team took a decidedly 21st-century approach. Using high-powered spectroscopes and x-rays, researchers scanned the fossil for melanin and reconstructed the melanophores in 3-D. The team found that, like many marine animals today, the ichthyosaur's back was darker in color than its belly. This form of coloration, called countershading, would have helped the animal disguise itself in the water and regulate its body temperature.
Researchers also saw hints of blubber within the preserved skin. Chemical tests suggest that the layer isn't a modern contaminant or protein-based like the other skin layers. Instead, it's a yellowish, fatty band, approximately where dolphins and leatherback turtles have blubber today.
The scientists won't go as far as to say that the ichthyosaur was warm-blooded, but teh possibility is there, and their resemblance to modern dolphins and whales is intriguing. Read more on the latest research at National Geographic. -via Shaena Montanari