Varanopid from the Carboniferous of Nova Scotia reveals evidence of parental care in amniotes.

Here we report on a fossil synapsid, Dendromaia unamakiensis gen. et sp. nov., from the Carboniferous period of Nova Scotia that displays evidence of parental care-approximately 40 million years earlier than the previous earliest record based on a varanopid from the Guadalupian (middle Permian) period of South Africa. The specimen, consisting of an adult and associated conspecific juvenile, is also identified as a varanopid suggesting parental care is more deeply rooted within this clade and evolved very close to the origin of Synapsida and Amniota in general. This specimen adds to growing evidence that parental care was more widespread among Palaeozoic synapsids than previously thought and further provides data permitting the identification of potential ontogeny-dependent traits within varanopids, the implications of which impact recent competing hypotheses of the phylogenetic affinities of the group.