Twenty-five years ago, Jurassic Park captured our imagination of what we could unlock by studying tiny insects trapped in amber. But reality has surpassed the fantasy. Paleontologists have already discovered a huge array of creatures trapped in fossilized resin, the latest of which are two Cretaceous snakes. One of them is the oldest fossilized baby snake ever discovered.

As reported in Science Advances, the two specimens come from the Late Cretaceous, both dating roughly to 99 million years ago. Both species are the first snakes dwelling in forest environments from the Mesozoic era, the 186-million-year-long period when dinosaurs roamed the Earth. The baby belongs to Xiaophis myanmarensi. The second specimen, called DIP-V-15104, is a skin fragment but doesn't have enough to allow for a certain classification.

"There are two important scientific consequences of this new fossil," corresponding author Professor Michael Caldwell from the University of Alberta told IFLScience. "Because it is a baby and because uCT and Synchrotron technologies can let us look at and inside of tiny things, we can both image this baby snake's anatomy and also look inside of its bones and compare it to the bones of potentially closely related living snakes."

"[Secondly] because the amber resin is produced by a tree and contains plants and insects, along with the baby snake and the skin, we know these snakes were living in a forest of some kind – this is a first, that when coupled with the unique plate tectonic history, links Xiaophis to other ancient snakes from Gondwanan continents (South America, Africa, Madagascar, India, and Australia)," Professor Caldwell added.

The discovery of such a juvenile creature in excellent preservation conditions also tells us about the evolution of snakes over the last 100 million years and the changes in their development, what scientists call ontogeny (how an animal goes from embryo to adulthood). The Xiaophis myanmarensi has in its neonate state 97 vertebrae, including ribs. The anatomy of this prehistoric reptile is quite similar to many living baby snakes, which suggests that the ontogeny of snakes have changed very little over the last several eras.

The team suggests that these snakes might have a wide distribution across the supercontinents of the Cretaceous. Modern-day Myanmar, where the specimens were found, would have been part of Laurasia. One of the hypotheses they put forward would have the Xiaophis go from Austral-Gondwana all the way to Laurasia by island hopping. To do so, these snakes would have found ecological niches and remained roughly unchanged for tens of millions of years. Although this is an intriguing idea, the team admits that there are many possibilities and that more work is needed. 

"My research on fossil snakes has proven that a bit of knowledge (what to look for and where to look), and then a great deal of luck in the form of discovering new specimens, means you cannot quite predict what you will learn from any one discovery," said Professor Caldwell. "You never know when the next new discovery will turn up, but I am confident that someone already has found the front half of Xiaophis and I really want to see that skull! I only hope it is a baby as well."

The dating of these specimens was possible thanks to tiny zircons trapped in the amber. By studying the amount of lead in these minerals compared to Uranium, researchers can establish when they formed.