Ichthyosaurus Communis is one of the first-known species of ichthyosaur to exist on Earth, and some U.K.-based paleontologists recently happened upon quite the fascinating fossil of one.
Image Credit: Julian Kiely
Although many fossils are incomplete upon discovery, it just so happens that this very well-preserved specimen was hiding in the back of the Lapworth Museum of Geology at the University of Birmingham.
Image Credit: Dean Lomax
The researchers found much more than they expected to, and rock samples from the specimen date back to 199-196 million years ago – the Jurassic period. The findings are published in the journal Historical Biology.
Not only was this the smallest-known ichthyosaur fossil on record at just 70cm (2.3 feet) long, but traces of its last meal still reside inside of its fossilized stomach. As it would seem, this fossil was of a newborn – the first ever discovered.
A closer look at the remains by way of micro-CT scanning and 3D-modeling revealed that the infant ichthyosaur just finished eating a prehistoric squid, but the reptile must’ve died shortly after its snack because it wasn’t fully digested.
“It is amazing to think we know what a creature that is nearly 200 million years old ate for its last meal,” said University of Manchester paleontologist Dean Lomax. “We found many tiny hook-like structures preserved between the ribs. These are from the arms of prehistoric squid. So, we know this animal's last meal before it died was squid.”
Amazing indeed, but this entrée of oddity comes with a side of unusual. Ichthyosaurs aren’t known for eating squid, so the researchers were stumped as to why the sudden change in diet.
"This is interesting because a study by other researchers on a different type of ichthyosaur, called Stenopterygius, which is from a geologically younger age, found that the small - and therefore young - examples of that species fed exclusively on fish. This shows a difference in prey-preference in newborn ichthyosaurs."
These findings highlight just how much there is to learn about life on early Earth and how important fossil evidence is for helping us understand it. Perhaps future studies involving ichthyosaur fossils will help us learn more about their diets back in the day.
Source: University of Manchester