Are you my mummy? Earliest post-natal care from the reptile fossil record
Researchers from the University of Lincoln have announced the discovery of the oldest known post-natal care in the reptile fossil record. The specimen shows what appears to be a family group of Philydrosauras, strongly suggesting that adults were involved in caring for their young. This amazing find, dated to the Middle Jurassic, comes from Liaoning Province, north east China and was first discovered by a local farmer.
Philydrosauras belongs to a group called the Choristoderes, semi-aquatic reptiles which lived alongside the dinosaurs but are not closely related to them. Sometimes informally referred to as the ‘champsosaurs’. the question of exactly when this group first evolved or how they are related to other reptiles is still a matter of some controversy. The best known species resemble modern-day gharials and probably lived a similar lifestyle, mainly eating fish, but they are a varied group and some may even have been terrestrial insectivores. This latest specimen was almost certainly aquatic.
The fossil remains show a large Philydrosauras, which appears to be an adult, surrounded by six smaller but similar animals interpreted as juveniles. Since they closely resemble the adult and are all roughly the same size, the smaller animals appear to be offspring, probably all from the same clutch and therefore represent a family group. This close association of adults and young is suggestive as it is rarely seen in animals which don’t actively care for their offspring. Today, parental care is widespread throughout the animal kingdom, particularly the mammals and birds but crocodiles also protect their young. There is some evidence that dinosaurs may also have displayed this behaviour, perhaps most famously Maiasaura who’s name means ‘caring mother lizard’. More recently Oviraptor was redeemed from its reputation as an egg thief when it was discovered that the eggs it was associated with were actually its own, and many specimens had in fact died incubating their eggs.
The question however remains as to whether parental care is an ancient characteristic that was shared by all these groups or whether it simply evolved several times. More finds of this kind could help to shed some light on this enduring mystery as well as giving us a deeper insight into the behaviour of these ancient creatures.
Junchang Lü, Yoshitsugu Kobayashi, D. Charles Deeming, Yongqing Liu. 2014. Post-natal parental care in a Cretaceous diapsid from northeastern China. Geosciences Journal. Access at: Springer Online
Featured Image: Reconstruction of a related species, Champsosaurus. Wikimedia Commons