Palaeotrionyx, like its modern relatives, had no scutes on its carapace, which probably had leathery, pliable skin at the sides. Despite living several million years ago, Palaeotrionyx would have looked very similar to its modern relatives, with a long neck, a sharp beak, and three toes on each foot. It grew to around 45 centimetres (18 in) in length, somewhat smaller than many modern day species. Based on the diet of modern softshell turtles, it was an omnivore, eating water plants, invertebrates, and perhaps small fish.