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The remains of the fossil snake Sanajeh (left) associated with sauropod eggs (upper right) and a partial baby sauropod skeleton (lower right). From the PLoS Biology paper.

When discussing dinosaurs, the topic of what they ate often comes up, but what about the creatures that ate them? Obviously some dinosaurs ate other dinosaurs, but the famous prehistoric archosaurs were not immune to predation from other kinds of hunters, especially when the archosaurs were babies. In 2005, for example, paleontologists described a specimen of the 130-million-year-old mammal Repenomanus giganticus with the remains of baby dinosaurs preserved inside it, and now a new study in the journal PLoS Biology adds a prehistoric snake to the list of dinosaur predators.

About 67.5 million years ago, in what is now western India, sauropod dinosaurs laid nests of up to 12 eggs. Unlike their parents, the developing and newborn sauropods were not large enough to defend themselves from most predators, and so it is not surprising that the bones of the newly-described snake Sanajeh indicus seem to be common among the preserved dinosaur nests. At an estimated 3.5 meters long, this boa-like snake would certainly have been large enough to eat baby dinosaurs for breakfast, and one peculiar specimen suggests that it did so.

Even though there are many associations between sauropod nests and snake bones, one particular fossil appears to show a Sanajeh caught in the act of nest robbing. The remains of the snake are coiled around a crushed sauropod egg, with an additional two eggs and the partial skeleton of a baby sauropod found right next to it. By all appearances this snake died in a sauropod nest when a storm caused a mudslide, burying predator and prey together.

Interestingly, though, it appears that the snake did not simply swallow the eggs. According to the authors of the new study, Sanajeh had a relatively limited gape, so instead they propose that the snake crushed dinosaur eggs with its body and then ate the contents of the eggs. Baby sauropod dinosaurs probably outgrew the threat of predation from these snakes by time they were about one year old, the authors estimate, but in the egg and as newborns they were very vulnerable.

Jeffrey A. Wilson, Dhananjay M. Mohabey, Shanan E. Peters, Jason J. Head (2010). Predation upon Hatchling Dinosaurs by a New Snake
from the Late Cretaceous of India PLoS Biology, 8 (3) : 10.1371/journal.pbio.1000322