Scientists have identified an extraordinary specimen of fossilized fat from a "fish lizard" experienced 180 million years ago, according to a new report published in the journal Nature.
Fat, a layer of fat beneath the skin of modern marine mammals that helps conserve heat, indicates that the ancient "sea monster" was warm-blooded, an unusual quality in a reptile, according to the authors of the report.
The sea creature of the Jurassic era, called ichthyosaur, seems to have both a mammal and a reptile's shared qualities, according to Johan Lindgren, a lecturer at the University of Lund in Sweden.
"They looked similar to dolphins, but the caudal fin was vertical rather than horizontal," Lindgren told ABC News. "They were reptiles," he said, while "the dolphins are mammals like you and me But the ichthyosaurs were reptiles."
The ichthyosaurs did not look like dolphins, Lindgren explained.
"In many ways, I would say they lived like dolphins," he said. "They were really dark … almost blackish."
"I imagine a kind of dorsal skin, and some forms were deep divers who could venture up to several hundred meters and then go back up". Several hundred meters are more than 1000 feet.
We can not possibly predict the future of our planet without understanding the past. This is where all data resides. Understanding how animals have worked in their past environments sheds light on how they could adapt to our changing planet.
Lindgren said that until today, researchers have not been able to identify their exact age or gender.
Lindgren said the researchers found concentrated pigment cells on the dorsal side of the creature's body.
"So this animal was originally flared, which means it had a dark upper surface and a light belly."
This natural "camouflage" is common to modern animal groups, both terrestrial and marine.
In many respects, I would say that they lived like dolphins.
"It's a form of camouflage that is used when you need to hide in plain sight," Lindgren said.
Marine minerals seem to have helped to preserve and fossilize the creature's fat.
"If you remove the minerals, the original soft tissues are still there," Lindgren said. "They were extremely quickly buried in the minerals, so it must have happened, you know, during the decay of the animal." They were buried in calcium phosphate and that burial apparently preserved the tissues. "
The fossil dates back to the Jurassic era, said another co-author Mary Schweitzer, a professor of life sciences at North Carolina State University.
Schweitzer said that studying this fossil could help explain "biological diversity" and "what makes animals thrive".
"We can not predict the future of our planet without understanding the past," said Schweitzer. "This is where all the data resides."
"Understanding how animals have worked in their past environments sheds light on how they could adapt to our changing planet."