Australia's Lost Giant
During the Pleistocene epoch, the forests of what is now Southwestern Australia contained a bizarre and giant mammal. Murrayglossus hacketti, also known as Hackett's giant echidna, was the largest monotreme (egg-laying mammal) ever to exist. It reached about one meter (3.3 feet) in length and weighed an estimated 30 kilograms (66 pounds), roughly the size of a modern sheep. This makes it significantly larger than its living relative, the short-beaked echidna, which weighs between 2 and 7 kilograms. Like modern echidnas, it would have been covered in spines for defense.
The animal belongs to an ancient line of mammals, the monotremes, which diverged from other mammals around 220 million years ago. This group, which today includes only the platypus and four species of echidna, retains primitive characteristics like laying eggs but also possesses mammal traits like producing milk and having fur. M. hacketti had proportionally longer and straighter legs than modern echidnas, which may have made it better suited for moving through the wooded environments of its time. Its diet likely consisted of invertebrates like worms and insect larvae, which it would have consumed with a long, sticky tongue. The genus name Zaglossus, to which it was formerly assigned, means "great tongue."
The Mammoth Cave Discovery
Our knowledge of this giant comes from just a few fossilized bones discovered in Mammoth Cave, Western Australia. The first bones were excavated around 1909 and later described in 1914 by paleontologist Ludwig Glauert. The finds were not a complete skeleton; they consisted mostly of vertebrae and leg bones, with no skull material ever found. The species name, hacketti, honors Sir John Winthrop Hackett, who sponsored the cave excavations.
The fossils were found among the remains of other extinct Australian megafauna, such as the giant kangaroo Sthenurus. Some of the M. hacketti bones show incisions and burn marks, suggesting that early humans hunted these giant echidnas. Aboriginal rock art found in Arnhem Land in the Northern Territory may even depict this or another species of long-beaked echidna. The species is thought to have gone extinct during the Late Pleistocene. While the hook notes a survival until 15,000 years ago, other estimates place its disappearance closer to 50,000 years ago, coinciding with the arrival of humans and the extinction of many other large Australian animals.