Prehistoric Fossil Sheds Light on Parenting in Reptiles

A newly discovered prehistoric fossil found in China is shedding light on parenting in reptiles from the Middle Jurassic, a new study says.

Modern adult reptiles are known for taking care of their offspring well beyond birth - for example, crocodilians protect their young from potential predators while birds not only provide protection but food as well. Even though this type of post-prenatal care seems to have evolved numerous times in vertebrates, evidence of such behavior is few and far between in the fossil record. It was only previously reported for two types of dinosaurs and varanopid 'pelycosaurs' - a reptile which resembled a monitor lizard.

Now, a new study published in the Geosciences Journal describes the oldest record of parental care dating back to the Middle Jurassic period in a group of reptiles - Philydrosauras, a choristodere from the Yixian Formation of western Liaoning Province in China.

Choristoderes are a group of relatively small aquatic and semi-aquatic diapsid reptiles that emerged in the Middle Jurassic Period more than 160 million years ago. Diapsids are a group of amniotes that developed holes in each side of the skull about 300 million years ago, and from which all lizards, snakes and birds alive today are descended.

Found by a farmer in China, the well-preserved specimens seem to make up a family aquatic choristoderan Philydrosauras, with an adult surrounded by six smaller juveniles of the same species.

"That Philydrosauras shows parental care of the young after hatching suggests protection by the adult, presumably against predators. 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," researcher Dr. Charles Deeming from the UK's University of Lincoln said in a statement.

But whether post-natal parental care is an ancestral behavior, passed down over the course of evolution in amniotes, remains to be seen.

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