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Fossil Ichthyosaur Blubber is proof that they were hot blooded

An approximately 180 million year old ichthyosaur fossil contains canned skin, with pigmentation and blubber. (Credit: Johan Lindgren) For the…

An approximately 180 million year old ichthyosaur fossil contains canned skin, with pigmentation and blubber. (Credit: Johan Lindgren)

For the first time, researchers have identified blubber and other soft tissue, preserved in an Early Jurassic ichthyosaur. The new interpretation of the 1

80 million-year-old fossil suggests that the extinct marine reptiles were hot blooded.

Ichthyosaurs swam the Mesozoic era and were about contemporary with dinosaurs. They are often compared with modern toothpicks, especially porpoises (although at least one ichthyosauric species achieved blue whale size). Many paleontologists have theorized that the animals, like the modern whales, were hot blooded, although evidence that supports the thought has been largely addictive.

Today, however, researchers describe the results of a new and more refined analysis of a sample of ichthyosaur species Stenopterygius, preserved with part of its skin, including pigmentation, blubber and possible liver tissue (and, bonus stomach content ).

The researchers used ultraviolet light, special x-rays and other techniques to determine the composition of the fossil. They identified residues of smooth skin that lack wave and resemble a porpoise. The upper and lower layers of the skin were preserved, together with an underlying layer of fat or blubber.

Identification of blubber, confirmed by further molecular analysis, provides the strongest evidence than ichthyosaurs were hot blooded. Blubber isolates, stores energy as fat and provides flowing power. Today, the only animals with the layer of protective fat are warm blooded amniots (mammals, reptiles and birds) who spend all or much of their lives in cold water (eg whales, seals, polar bears, leather turtles and penguins)

This is an example on convergence development when unrelated animals occupy similar ecological niches develops the same characteristics.

The preserved pigmentation on the skin suggests that Stenopterygius had countercurrent stomach, dark back), a common camouflage strategy for modern marine predators. In addition to the animal being harder to see, counter-scaling can help with thermoregulation.

The research is published today by Nature .

An illustration of ichthyosaur fossil preserved with stomach content (dotted contour), possible liver tissue (dotted contour) and skin and blubber (medium area). (Credit: Johan Lindgren)

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