| Megalibgwilia Temporal range: | |
|---|---|
 | |
| M. owenii humerus | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Mammaliaformes |
| Class: | Mammalia |
| Order: | Monotremata |
| Family: | Tachyglossidae |
| Genus: | † Megalibgwilia Griffiths, Wells and Barrie, 1991 |
| Type species | |
| Echidna owenii Krefft, 1868 | |
| Species [1] [2] | |
Megalibgwilia is a genus of echidna known only from Australian fossils that incorporates the oldest-known echidna species. The genus ranged from the Pliocene until the late Pleistocene, becoming extinct about 50,000 years ago. [2] Megalibgwilia species were more widespread in warmer and moist climates. Their extinction can be attributed to increasing aridification in Southern Australia. [3]
Megalibgwilia was first described from a broken left humerus by Gerard Krefft in 1868 as "Echidna" owenii. [1] In the past, many researchers didn't recognize that "Echidna" ramsayi named by Richard Owen in 1884 represents a junior synonym, [4] though recent studies have reevaluated this. [2] Complete skulls and postcranial fossils have since been described. A second species, M. robusta, was described in 1895 by Australian paleontologist William Sutherland Dun. Megalibgwilia comes from Greek mégas (μέγᾰς) and Wemba Wemba libgwil (plus the Latin suffix -ia), meaning echidna. [5]
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. [6] They were smaller than a large species known from fossils in Australia, Murrayglossus . M. ramsayi fossils have been found in deposits across mainland Australia and on Tasmania. M. robusta has only been found in New South Wales. [6] Megalibgwilia was probably an insect-eater, like the short-beaked echidna, rather than a worm-eater like members of Zaglossus . [5]
M. robusta, once thought to be a species of Zaglossus , is the oldest-known echidna and the only known Pliocene species. [5] [2] It has been suggested that the supposed fossil platypus Ornithorhynchus maximus was based on a humerus of this species. [7] [8]
Stated from the brain and behaviour article, “the short-beaked echidna has become the most widespread and successful native mammal species on the Australian continent, whereas the long-beaked echidnas have become so restricted in distribution as to now be endangered”. [9]
