Giant short-faced kangaroos had a flat face and forward-pointing eyes. On each foot they had a single large toe somewhat similar in appearance like a horse's hoof. On these unusual feet they moved quickly through the open forests and plains, where they sought grass and leaves to eat. Their front paws were equally strange: each front paw had two extra-long fingers with large claws. It is possible that they were used to grab branches, bringing leaves within eating distance. Their robust skull architecture and shortened face has been thought to be related to increased masseter muscles used to chew foods. Dental microwear of P. goliah supports a browse diet; however, stable isotopic data suggested its diet consisted of plants utilising a C4 photosynthetic pathway, typically associated with grasses. In this case, however, chenopod saltbushes found throughout semi-arid Australia were considered a more likely source of the C4 signature.
The genus was present until at least about 50,000 years ago before going extinct, although there is some evidence they may have survived to as recently as 18,000 years ago. Its extinction may have been due to climate shifts during the Pleistocene, or to human hunting.
Fossils of giant short-faced kangaroos have been found at the Naracoorte World Heritage fossil deposits in South Australia, Lake Menindee in New South Wales, Darling Downs in Queensland, and at many other sites. A full-size, lifelike replica is on permanent display with other ancient native Australian animals at the Australian Museum.
The genus is paraphyletic, derived from Simosthenurus.