The fossils of a Pelycosaurier family show that there were about 260 million years ago brood care. Picture: Jennifer Botha-Brink
Read aloud Already 260 million years ago, lizard-like terrestrial vertebrates intensively looked after their offspring. Scientists were able to demonstrate this with the help of a fossilization of five South Africa pelycosaurs, which consists of one larger and four smaller, equally sized animals. Pelycosaurs are counted among the reptiles and today resembled living lizards such as iguanas or monitor lizards. Researchers Jennifer Botha-Brink of the National Museum in South Africa and Sean Modesto of Cape Breton University in Sydney conclude from various fossil features that the five Pelycosaurs were traveling as a family group. The researchers assigned the animals to the group of Varanopseidae, which in turn are counted among the pelycosaurs. In the fossil, the individual skeletons are all oriented in the same direction and have a back-up posture. The largest specimen has typical features of an adult animal such as complete ossification of the skeleton, while the four smaller animals have characteristic features of the juvenile stage such as incomplete ossification. Since these smaller four pelycosaurs are all the same size, the scientists suspect that they are siblings.

The main task of the parents was probably to protect the progeny from predators, much as it does to living reptiles today. Due to the size of the juveniles, which is about two-thirds that of the adult animal, the researchers assume an intensive and long-lasting brood care. With an age of 260 million years, the new fossil is by far the earliest indication of such a pronounced sense of family and surpasses the oldest reference so far, dated to an age of 120 million years, by 140 million years.

Jennifer Botha-Brink (National Museum in South Africa) and Sean Modesto (Cape Breton University in Sydney): Proceedings of the Royal Society B, online pre-release, DOI: 10.1098 / rspb.2007.0803 ddp / science.de? Tobias Becker

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