Coprolite with exposed bone fragment

The fossilized poo of a prehistoric wild dog includes a fragment of grey bone (lower right) from an unidentified animal. Credit: X. Wang et al./eLife

Palaeontology

Ancient poo reveals extinct dogs crunched big bones

Faecal remains suggest small but mighty canids hunted in packs.

Fossil poo shows that dogs with a ferocious bite roamed North America 5 million years ago, crushing the skeletons of their prey in massive, muscular jaws.

Scientists have long suspected from its anatomy that the ancient dog known as Borophagus parvus dined on bones. This theory has been confirmed by Xiaoming Wang at the Natural History Museum of Los Angeles County in California and his colleagues, who analysed 14 coprolites — fossilized faeces — from a Californian site that also included B. parvus fossils.

In the coprolites, the researchers identified chunks of bone from deer-like mammals that may have weighed as much as 100 kilograms. The team estimates that the dogs weighed roughly 25 kilograms, the same as a small Dalmatian.

The contrast between the dogs’ size and that of their prey suggests that the hounds hunted in cooperative packs.