Largest egg-laying mammal ever

The largest egg-laying mammal (monotreme) of all time was the Hackett's giant echidna (Murrayglossus hacketti), known from fossil remains in Western Australia. Weighing up to 30 kg (66 lb) and up to 1 m (3 ft 3 in) long, this giant relative of today's spiny anteaters was about the same size as a wombat, and lived during the Pleistocene Epoch (2.6 million years to 11,700 years ago).

First discovered in 1909, this species was originally considered part of the long-beaked echidna (Zaglossus) group, but the new genus of Murrayglossus was designated in 2022. It is named after Dr Peter Murray, an Australian palaeontologist who specialized in the fossils of echidnas.