Wikipedia
Megalibgwilia is a genus of echidna known only from Australian fossils that incorporates the oldest known echidna species. It lived during the Pleistocene, becoming extinct about 50,000 years ago.
Megalibgwilia was first described from a broken left humerus by Richard Owen when he identified M. ramsayi in 1884. Complete skulls and postcranial fossils have since been described. A second species, M. robusta, was described in 1896 by Australian paleontologist William Sutherland Dun.
Although they are sometimes commonly referred to as giant echidnas, Megalibgwilia species are thought to have been similar in size to the contemporary western long-beaked echidna, but with slightly longer forearms. They were smaller than a large species known from fossils in Australia, Zaglossus hacketti. M. ramsayi fossils have been found in deposits across mainland Australia and on Tasmania. M. robusta has only been found in New South Wales. Megalibgwilia was probably an insect-eater, like the short-beaked echidna, rather than a worm-eater like members of Zaglossus.
M. robusta is the oldest known echidna and the only known Miocene species.