Scientists have unearthed an incredibly well-preserved fossil of an ancient "sea monster" called ichthyosaur, believed to have existed 180 million years ago.

In a paper, the scientists revealed that the fossil still has skin and blubber, a layer of fat that help preserve heat and possibly, a liver tissue.

"You can clearly see both the body outline and remains of internal organs," said Johan Lindgren, a co-author of the paper. "We can even distinguish the different cellular layers within the skin."

Their findings were published in the journal Nature.

Jurassic Sea Monster

The ichthyosaurs were creatures that existed during the Jurassic Period. The reptiles looked like modern-day dolphins and swam in a vast ocean that covered most of present-day Europe.

However, the unearthed fossil have provided new details about the creatures. The researchers used ultraviolet light, X-ray imaging, and other techniques to identify the composition of the fossil. They found smooth skin without scales and an underlying layer of blubber.

The presence of blubber under the creature's skin is proof that it is warm-blooded, a quality typically found in marine mammals but considered unusual in reptiles. Blubber is also linked to higher metabolism and body temperature, allowing it to swim in cold waters. It also supports the theory that ichthyosaurs were deep divers.

The analysis also found pigment-carrying cells called chromatophores, revealing that the creature had darker shading in the upper half of its body and lighter shading below. The researchers explained that the coloration acted as either camouflage or UV protection. Its darker color also probably helped in keeping the creature warm despite its cold environment.

Lindgren, in an interview with ABC News, compared the appearance of the ichthyosaurs to dolphins, but with a tail fin that was vertical rather than horizontal.

Relevance Of The Study

The researchers added that the discovery of the fossil provides additional insights not just on the biology, physiology, and ecology of now-extinct ichthyosaurs, but also changes what is already known about fossilization.

Minerals helped preserve and fossilize the creature's remains, including its tissues. Once the researchers removed the mineral phase, the original soft tissues of the creature were still intact.

Moreover, the researchers said that the new findings can offer valuable additions to convergent evolution. They added that the ichthyosaurs had an interesting mix of qualities that can also be found in toothed whales and leatherback sea turtles.

"Understanding how animals functioned in their past environments sheds light on how they might adapt to our own changing planet," added Mary Schweitzer, co-author of the study.