A 180-million-year-old fossil has allowed a group of scientists to rescue samples of skin, fat and even proteins (although this component generates debate). The level of conservation of these remains raises new challenges and debates among paleontologists.
A Jurassic whale
We are talking about a Stenopterygius fossil, a genus included in the famous order of Ichthyosaurs . These Lower and Middle Jurassic animals are extinct marine reptiles that look similar to today’s dolphins, although specialists detect features that bring them closer to modern toothed whales. A study published in 2018 in the journal “Nature” confirms this.
The most famous ichthyosaur fossils have been found in the Holzmaden shale quarries in Germany. In this area there was an ocean during the Jurassic that ended up becoming the tomb of many specimens of these marine reptiles. Many of the fossils from this paleontological site have preserved contours that mark the layout of the skin and even remains of the fins. It is a milestone that scientists can work on materials with so much information from an animal so far away from us in time. The key to this site that holds so many surprises for paleontologists lies in the low-oxygen sediments deposited on the seafloor of the ancient ocean . Ideal conditions to preserve fossilized remains.
A fossil with chemistry
Ever since paleontologist Mary Anning found the first complete ichthyosaur fossil in 1811, researchers have continued to increase our understanding of this group of animals. Several of the scientists who have had access to the best-preserved fossils have suspected that ichthyosaurs had whale-style blubber . Johan Lindgren, a paleontologist at Lund University, set out to check once and for all how certain we could be about these suspicions.
Together with his research team, he subjected various ichthyosaur fossils to as much chemical analysis as he could. Among the remains, there was a specimen that stood out for its extraordinary level of conservation:
“Our analyzes recovered still flexible remnants of the original scaleless skin, comprising morphologically distinct epidermal and dermal layers. These are supported by insulating fat that would have increased aerodynamics, buoyancy and homeothermy”.
Lindgren and his team were the first to find fossilized fat . In addition, the analyzes allowed to reconstruct the color of the skin of the ichthyosaurs. Like other marine animals, the back would be darker than the belly, which could have functions of camouflage and/or regulation of body temperature.
The protein controversy
In the published study it is stated that they have detected proteins from the ichthyosaur . They say that they were able to capture hemoglobin signals in the animal’s liver, and protein remains such as collagen and keratin. According to Benjamin Kear, a paleontologist at Uppsala University who was involved in the research:
“Not only can you analyze the structures and identify them at the cellular level, but there are remnants of the original protein. It’s the tip of the iceberg, it’s something worthy of Jurassic Park.”
If correct, they would have located one of the oldest biomolecules in the history of science. But some scientists have called for caution about these claims and criticize the method used to identify these molecules. According to opponents of the Lindgren-led team’s study, the way it has been worked tends to give false positives.
The doubts are logical and even necessary, since finding the proteins in a fossil of 180 million years would suppose a considerable revolution, since it would allow to know much more about the extinct species through chemical studies, instead of analysis, in general. , from only its fossilized bones.
References:
Greshko, M. 2018. This incredible Jurassic ichthyosaur fossil retains skin and fat. nationalgeographic.es.
Lindgren, J. et al. 2018. Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur. Nature 564, 359-365. DOI: 10.1038/s41586-018-0775-x.
