A study analyzing the skull biomechanics of the species Desert rat-kangaroos finds that it ate a softer diet than previously believed, offering new insights into potential habitat.
Desert rat-kangaroos (Caloprymnus campestris) were officially declared extinct by the IUCN in 1994. These small marsupials, relatives of living bettongs and potoroos, were native to areas of the Sturt Stony Desert in northeast South Australia and southwest Queensland.
Originally documented in 1843, desert rat-kangaroos were thought to be extinct by the end of the 19th century. However, additional specimens were discovered in 1905, 1931 and 1935. The elusive nocturnal species is thought to have perished due to predation by invasive species such as cats (Felis domesticus) and red foxes (Vulpes vulpes) and destruction of its habitat by livestock grazing.
Sporadic sightings have since emerged, most recently in 2013, but none have been verified. Now, a study in the Journal of Experimental Biology published February 25, 2025 offers new insights into the species’ probable diet—and has spurred hope that it may be rediscovered.
Due to the shape of its skull, it had previously been assumed that the species ate tough foods.
“The species had a very stocky head, with a short and deep face,” explained lead author Rex Mitchell, a zoologist at Flinders University. “These features are more common in animals that need harder bites. In most cases, an ability to bite hard is associated with accessing harder or tougher foods.”
However, computer analysis of how the interaction between the skull shapes and muscle force of five other related marsupial species impact their diets found that the rat-kangaroo probably preferred softer foods than previously assumed. While some similar studies have removed size differences in comparing bite force, the new study retains size as a variable.
“When we retain size differences between species, and test the ability to bite with the same exact bite force, the smaller-sized desert rat-kangaroo performs quite poorly,” Mitchell claimed. “It only performed about as well as the long-nosed potoroo—an animal with a softer diet focused on soft, underground truffles.”
These insights may narrow down areas where potential remnant populations of desert rat-kangaroos have persisted.
“The Sturt Stony Desert is quite an inhospitable place, but if there are patches of low-level, softer, higher quality vegetation, it would make sense to focus any searches towards these areas,” said Mitchell.