A carnivorous rat-kangaroo with fangs—15 million years ago; kangaroos were not peaceful herbivores.
SeismicShrimp, CC BY 4.0, via Wikimedia Commons
A different kind of kangaroo
In the lush rainforests that covered Queensland during the Miocene Epoch, between 25 and 11 million years ago, a strange marsupial stalked the forest floor. This was Ekaltadeta, a member of an extinct family of rat-kangaroos known as Propleopinae. Unlike its modern, plant-eating relatives, Ekaltadeta had a taste for meat. Fossils of this creature, primarily skulls and jaws found at the Riversleigh World Heritage Area, show a formidable set of teeth designed for a carnivorous or at least highly omnivorous diet.
The main feature is its third premolar, a large, buzz-saw-shaped tooth adapted for shearing and slicing. This specialized cheek-tooth, along with elongated lower incisors that may have been used for stabbing, points to a predatory lifestyle. Juvenile Ekaltadeta had a serrated second premolar that functioned as a blade for slicing flesh. Analysis of its powerful jaws suggests it could generate high-amplitude vertical shearing forces, capable of crunching through bone. Roughly the size of a small dog, Ekaltadeta ima likely used its powerful forelimbs to grasp prey.
An ancient, wetter world
The world Ekaltadeta inhabited was vastly different from modern Queensland. During the early to middle Miocene, the area was a cool, wet, lowland rainforest, similar to modern Borneo or the Amazon. The fossil record at Riversleigh shows a diverse ecosystem. Ekaltadeta shared its environment with a variety of other strange creatures, including giant flightless birds, tree-climbing crocodiles, marsupial lions, and other kangaroo relatives like the small, herbivorous "fangaroo," which may have been its prey.
Ekaltadeta belongs to the family Hypsiprymnodontidae, making its closest living relative the musky rat-kangaroo (Hypsiprymnodon moschatus), a small omnivore that still lives in the rainforests of northern Queensland. This family represents an early branch in the evolution of kangaroos and their relatives. The existence of carnivorous forms like Ekaltadeta shows that early macropodiforms occupied a variety of ecological niches before the familiar grazing kangaroos came to dominate the continent as it grew drier. The shift from a wet, forested continent to a drier, more open landscape beginning around 15 million years ago likely contributed to the extinction of these "killer kangaroos" and many other rainforest specialists.
💡Fun Facts
The name *Ekaltadeta* comes from an Indigenous language of the McDonnell Ranges, combining words for "powerful" (*ekalta*) and "tooth" (*eta*).
This creature is part of an extinct subfamily sometimes called "killer kangaroos," which were some of Australia's dominant predators during the Miocene.
Unlike modern kangaroos that hop, some evidence suggests *Ekaltadeta* may have galloped on four feet.
Its closest living relative, the musky rat-kangaroo, is considered a living fossil and still eats insects and fungi in addition to fruit.
The best place to see *Ekaltadeta* fossils is the Riversleigh Fossil Discovery Centre in Mount Isa, open daily from 9:00 AM to 4:30 PM. The Queensland Museum in Brisbane also holds significant fossil collections.
Admission
Entry fees apply for the Riversleigh Fossil Discovery Centre. Admission to the Queensland Museum is generally free, with charges for special exhibitions.
Accessibility
The Discovery Centre and Queensland Museum are wheelchair accessible. The actual fossil fields at Riversleigh are remote and involve rugged terrain.
