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Prehistoric Giant Kangaroo As Tall As an Adult Man Had a Powerful Bite

A researcher has revealed intriguing new details about a group of giant prehistoric kangaroos according to a study published in the open-access journal PLOS ONE.© N. Tamura Artistic reconstruction of the short-faced kangaroo, Simosthenurus occidentalis. According to the scientist, the skulls of these so-called “sthenurine” kangaroos were highly specialized, providing the animals with a powerful…

A researcher has revealed intriguing new details about a group of giant prehistoric kangaroos according to a study published in the open-access journal PLOS ONE.

a close up of a dinosaur: Artistic reconstruction of the short-faced kangaroo, Simosthenurus occidentalis.© N. Tamura
Artistic reconstruction of the short-faced kangaroo, Simosthenurus occidentalis.


According to the scientist, the skulls of these so-called “sthenurine” kangaroos were highly specialized, providing the animals with a powerful bite which enabled them to eat tough foods.

Unlike their modern counterparts, these kangaroos likely walked on two legs, much like humans, rather than hopping around to move. This animal family—sometimes referred to as “short-faced kangaroos”—had all gone extinct by the end of the Late Pleistocene Period (between around 126,000 and 5,000 years ago.)

“Sthenurine kangaroos are an entirely extinct group of robust marsupial herbivores that arose during the Miocene Epoch [around 23 to 5.3 million years ago] and diversified prolifically during the Ice Age of Australia,” author of the study D. Rex Mitchell, from the University of Arkansas, told Newsweek.

“Currently, there are 26 species across 6 genera [groups of species] known from across Australia, including the largest kangaroo to have ever existed, Procopton goliah,” he said. “In general, they would have appeared quite different to modern-day kangaroos, with more thick-set bodies, long, muscular arms with extended fingers, often only a single big toe on each foot, and box-shaped heads that were shaped more like a koala’s.”

Sthenurine kangaroos featured heavily-built skulls, short snouts and large jaws and teeth, which scientists had previously suggested was an indication that they ate tough foods such as mature leaves, stems and branches.

To determine if this was indeed the case, Mitchell tested the idea that the construction of the skulls of these kangaroos should be sturdy enough to deal with the powerful forces which would be generated by their bites.

To do this, Mitchell digitally recreated the skull of one sthenurine kangaroo species known as Simosthenurus occidentalis which roamed what is now Australia in the Late Pleistocene until going extinct around 42,000 years ago.

“A study I published back in January examined this species using shape analysis and biomechanical simulations,” Mitchell said. “The results showed that the skull of the extinct kangaroo was, out of a range of modern-day marsupial herbivores tested, shaped most similar to a koala.”

However, this kangaroo also differed from all species it was compared against in having a deeper skull, a very wide forehead, and enormous cheekbones. The latest study’s aim was to identify the significance of these reinforced, bony features of the skull and whether they permitted specialized feeding behaviors.

Simosthenurus occidentalis is a well-represented species of sthenurine, with remains found across much of the southern half of Australia. The species grew quite large, able to stand around as tall as an adult person and estimated to be around 118 kilograms [260 pounds]—around 30 kilograms heavier than the largest kangaroos of today. This makes it an interesting species to study, as a representative of Australia’s extinct megafauna,” he said.

Using the digital model, which was generated from CT scans of the skull of one S. occidentalis specimen, Mitchell simulated the animal’s bite and compared it to that of koalas.

“Simulations of biting at the molars and premolars were carried out to examine the distribution of forces across the skull,” he said. “Since the koala is the modern-day species with the most similar skull shape, the results were compared against models of a koala that underwent the same simulations.”

Related Slideshow – Species that have gone extinct in our lifetime (Provided by Photo Services)

  • Slide 1 of 24: CAPTION: Golden Toad on a leaf, Costa Rica

  • Slide 2 of 24: CAPTION: SANTA CRUZ, GALAPAGOS ISLANDS, ECUADOR - FEB 28: Lonesome George, a Pinta giant tortoise, and the last of his kind on February 28, 2009 at the Charles Darwin Research Station in Santa Cruz, Galapagos. He is probably from 60 to 90 years old and was found on Pinta in 1971. Before then, scientists thought the Pinta species was extinct. Two females of slightly different species live in his enclosure. The hope is that he will successfully breed with them - but so far, the eggs have not been fertile. (Photo by Melanie Stetson Freeman/The Christian Science Monitor via Getty Images)

  • Slide 3 of 24: CAPTION: A female Western Black Rhino and her calf graze on bushes in South East Zimbabwe.

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  • Slide 10 of 24: UNSPECIFIED - OCTOBER 08: Birds: Prince Ruspoli's Turaco, (Cuculiformes: Tauraco ruspolii), Dalmatian Pelican (Pelecaniformes: Pelecanus crispus), Aldabra Brush Warbler (Nesillas aldabrana), Seychelles Black Paradise Flycatcher (Terpsiphone corvina) - critically endangered (Photo by De Agostini Picture Library/De Agostini/Getty Images)

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  • Slide 17 of 24: State of Queensland [CC BY 3.0 au (http://creativecommons.org/licenses/by/3.0/au/deed.en)], via Wikimedia Commons Bramble cay melomys Melomys rubicola. In 2016 declared extinct on Bramble cay, where it had been endemic, and likely also globally extinct, with habitat loss due to climate change being the root cause.

  • Slide 18 of 24

  • Slide 19 of 24: Dusky seaside sparrow

  • Slide 20 of 24: Tecopa-pupfish

  • Slide 21 of 24: CAPTION: Digital illustration of the extinct North American passenger pigeon

  • Slide 22 of 24: CAPTION: 19th century illustration of a thylacine, also known as Tasmanian tiger, or Tasmanian wolf, native to continental Australia, Tasmania and New Guinea - extinct species, who was the largest known carnivorous marsupial of modern times.. Published in Systematischer Bilder-Atlas zum Conversations-Lexikon, Ikonographische Encyklopaedie der Wissenschaften und Kuenste (Brockhaus, Leipzig, 1875)

  • Slide 23 of 24: CAPTION: Digital illustration of the extinct Great auk

  • Slide 24 of 24: Digital illustration of the extinct Steller's sea cow

Golden toad

Cause: Restricted range, global warming, chytridiomycosis (an infectious disease) and airborne pollution

The species has not been recorded since 1989.

Pinta Giant Tortoise

Cause: Over-exploitation by whalers and other mariners in the 19th century and deforestation of land habitat by goats

The last-known Pinta Tortoise, Lonesome George (pictured), died on June 24, 2012. 

Western black rhinoceros

Cause: Widespread wildlife poaching

There have been no reports of any sightings since 2006. 

Southern Gastric brooding frog

Cause: Habitat loss and degradation, pollution and possible infectious disease

It has not been recorded in the wild since 1981.

Caribbean monk seal

Cause: Hunting

The seal has not been sighted since 1952 despite extensive search. 

Mariana mallard

Cause: Hunting and habitat loss

The bird was declared extinct after the last bird died in captivity in 1981. 

Caspian tiger

Cause: Habitat loss and hunting of both tigers and their prey

The last record of the tiger in the wild date to early 1970s.

Javan tiger

Cause: Hunting, loss of forest habitat and prey base

It is believed that the Javan tiger became extinct in the mid-1970s. 

Arabian ostrich

Cause: Poaching

The last recorded sighting of the ostrich was in Jordan in 1966. 

Aldabra brush warbler

Cause: Possible habitat degradation by tortoises, goats and invasive species such as rats and cats

It was last recorded in 1983 and searches conducted in 1986 confirmed its extinction. 

Japanese sea lion

Cause: Hunting for skin, whiskers, internal organs and oil

There have been no documented reports of the species since the late 1950s. 

Guam flycatcher

Cause: Predation by the brown tree snake, which were introduced to the island of Guam

The species became extinct in 1983. 

Kama’o

Cause: Mosquito-borne disease, predation and degradation of habitat

The last definite record of the species dates to 1985. 

Kaua’i ‘O’o

Cause: Habitat destruction, mosquito-borne diseases and invasive species like black rats and pigs.

Known from the Hawaiian island of Kaua’i, U.S., the species was last recorded in 1987. 

Alaotra grebe

Cause: Loss of natural habitat, poaching, predation and introduction of exotic plants and fish that depleted the food supply

The last confirmed sighting of the species was in 1982. 

Japanese river otter

Cause: Poaching for pelt, pollution and habitat loss

The species was last spotted by the locals in 1979 and the Japanese government officially declared it extinct in 2012. 

Bramble Cay melomys

Cause: Probably due to storm surges across the island and episodic reduction in vegetation. 

The last individual was spotted in 2009. 

Eastern cougar

Cause: Habitat loss and poaching of their prey.

The species was last officially recorded in the late 1930s. However, it was officially declared extinct in the U.S. on Jan. 22, 2018. 

Dusky seaside sparrow

Cause: Habitat loss by drainage and construction activities and possible toxic effects of sprayed insecticides

The bird became extinct when the last-known bird died in 1987. 

Tecopa pupfish

Cause: Habitat destruction.

The fish was declared extinct by the Interior Department’s Fish and Wildlife Service in 1981. 

Passenger Pigeon

Cause: Widespread clearance of their natural habitat, excessive shooting and Newcastle disease

The last reliable wild record of the pigeon dates to 1900. 

Tasmanian tiger

Cause: Hunting, extreme weather and drought

The last known Thylacine died in 1936 in Hobart Zoo. 

Great Auk

Cause: Hunting for feathers, meat, fat and oil

The last bird was spotted in 1852. 

Steller’s Sea Cow

Cause: Slaughtered for its meat and leather, human predation.

It is believed that the species became extinct around 1768. 

24/24 SLIDES

These simulations indicated that the cheekbones of S. occidentalis supported large muscles that prevented dislocation of the jaw when the animal used its powerful bite.

“Interestingly, the short-faced kangaroo models were found to have a much higher risk of injury than the koala models during biting at the back teeth,” Mitchell said. “This is because its teeth were much larger and extended farther back towards the jaw joints. This greatly increased how hard the animal could bite, but also increased the risk of jaw dislocation when biting.”

“However, I found that an enlargement of a muscle located on the inner surface of its immense cheekbones would help to reduce this risk,” he said. This muscle is also enlarged in the giant panda, another similarly sized animal that feeds on thick, resistant vegetation such as bamboo.

Furthermore, the scientist found that the bones of the front and roof of the skull provided sufficient structural support to resist the twisting forces that would have been generated during these bites.

“This study revealed that the short-faced kangaroo model could withstand torsion much more effectively than the koala during such bites,” Mitchell said. “Its deep skull and broad forehead could spread stress more evenly, preventing excessive twisting and protecting it from damage.”

This finding supports previous suggestions about short-faced kangaroos that the toughest, thickest vegetation that it could have eaten, such as the woody twigs and branches of trees and shrubs, may have been fed directly to its premolars and molars to be crushed or otherwise broken apart. Such actions would appear similar to how giant pandas crush bamboo,” he said.

Taken together, these results led Mitchell to the conclusion that kangaroos in the sthenurine group were able to produce powerful bites due to these adaptations, enabling them to eat tough foods that other species were not able to consume.

“The research provides support for the hypothesis that at least some short-faced kangaroos could persist on thick and woody, poor-quality vegetation at times of low productivity, such as during droughts, and prolonged glacial periods and associated continental drying,” he said. “The ability to consume parts of plants that other herbivores of the time could not would have offered them a competitive edge when times were tough.”

In this sense, S. occidentalis is similar to modern animals such as the giant panda, which also eats tough food in the form of bamboo.

“The similarities between the skulls of this kangaroo and the giant panda offer a good example of convergent evolution, whereby similar features of the skull have independently evolved to serve potentially similar functions,” Mitchell said.

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