Ancient Fossil Reveals Jurassic Reptiles Cared for Their Young

Reptiles may be cold blooded, but they're not cold hearted. Scientists have discovered preserved fossils that reveal that reptiles in the Middle Jurassic took care of their young after they were born.

The new fossil is a specimen that was discovered by a farmer in China. It's of an apparent family group with an adult, surrounded by six juveniles of the same species. Because the smaller individuals are similar in size, scientists believe that the fossil represents a parent with its offspring from the same clutch.

The tendency for adults to care for their offspring beyond birth is a key feature of the reproductive biology of living birds and crocodilians. In fact, it seems as if this behavior evolved numerous times in vertebrates; there's even evidence of a long evolutionary history in diapsids, a group of amniotes which developed holes in each side of the skull about 300 million years ago and from which all existing lizards, snakes and birds are descended.

Yet evidence of post-natal care is extremely rare in the fossil record. In this latest study, the scientists found that Philydrosauras apparently took care of its young. This relatively small aquatic and semi-aquatic diapsid reptile is part of a group that emerged in the Middle Jurassic Period more than 160 million years ago.

"That Philydrosauras shows parental care of the young after hatching suggests protection by the adult, presumably against predators," said Charles Deeming, one of the researchers, in a news release. "Their relatively small size would have meant that choristoderes were probably exposed to high predation pressure and strategies, such as live birth, and post-natal parental care may have improved survival of the offspring. This specimen represents the oldest record of a post-natal parental care in diapsides to our knowledge and is the latest in an increasingly detailed collection of choristoderes exhibiting different levels of reproduction and parental care."

The findings are published in Geosciences Journal.

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