It’s usually rather difficult to speak of the behavior of organisms based solely on the fossil record. However, sometimes we are lucky enough to have material that tells us more than we would normally expect.
Sandra C. Jasinoski and Fernando Abdala from the University of the Witwatersrand studied the fossil remains belonging to the early cynodont species Galesaurus planiceps and Thrinaxodon liorhinus. Cynodontia is a large that includes mammals and their close relatives. The first cynodonts appeared during the Permian, more than 260 million years ago. Galeasaurus and Thrinaxodon lived during the Early Triassic, approximately 250 million years ago, in what is now the Karoo Basin, South Africa.
Previous studies showed evidence that the two cynodonts were spending at least a part of their time living within burrows. In some cases, the cynodonts were found in association with other organisms. A 2006 study described an aggregation of fossils belonging to Galesaurus, two procolophonids and a millipede, and interpreted it as a case of shelter-sharing between different species. Thrinaxodon, on the other hand, was discovered in an association with an injured temnospondyl.
The new study by Jasinoski and Abdala presents a detailed analysis of the intraspecific aggregations of the cynodonts – the accumulations of individuals belonging to the same species. The researchers analyzed 35 specimens belonging to Galesaurus planiceps and 104 specimens of Thrinaxodon liorhinus. In both species, the authors were able to notice aggregations of same-age as well as mixed-age individuals.
Interestingly, in some cases, adults were found in close association with small babies, leading the researchers to interpret them as parental care aggregations. The authors noted that these babies were similar in size which suggests that they were part of the same clutch.
Why was it beneficial for early cynodonts to care about their babies? As the authors say, except for the obvious reasons, such as protection and food supply, the presence of an adult individual might have helped the babies to keep a more stable body temperature in times of extreme temperature changes.
Featured image by Smokeybjb. CC BY-SA 3.0.