In a recent paper entitled "The predatory behaviour of the thylacine:
Tasmanian tiger or marsupial wolf?" published online in "Biology
Letters" (Figueirido and Janis 2012), comparison was made between the
elbow joint of the thylacine and those of dog-like and cat-like species.
The researchers state:
"An established morphological indicator of predatory behaviour can be found
in the elbow joint, specifically in the shape of the distal humerus.
Pursuit carnivores have a restricted range of motion at the elbow, while
less cursorial predators retain the ability to supinate the forearm, and
may use the forelimb to grapple with their prey".
The researchers used geometric morphometrics to explore the morphology
of the distal humerus of placental carnivores of known predatory behaviour.
A total of 103 humeri of adult individuals belonging to 32 species of mammals,
including eight thylacines, were used in the study. They found that
in the thylacine, the articular surface of the distal humerus was wider
and more rectangular in shape, and therefore more akin to that of feline
predators such as the tiger than that of the wolf or fox, whose articular
surface tended to be squarer.
of the shape of the distal humerus in the thylacine, tiger, wolf and fox.
Photos: Borja Figueirido (specimens from the American Museum of Natural
humerus of the thylacine.
Photo: ITSD 5th Revision
The Brown University press
"They (Figueirido and Janis) knew from previous research that the
elbow joint was a clue to predator habits, as it showed whether the animal
was built for flexibility and dexterity in handling prey or for chase and
speed in tracking down the next meal. Examining the bones, they found
that the thylacine's humerus, or upper arm bone, was oval and elongated
at the end closest to the elbow, implying that the animal's forearm bones,
the radius and ulna, were separate. That means the Tasmanian tiger
would have been able to rotate its arm so that the palm faced upwards,
like a cat. The distal humerus on dog-like animals, such as dingoes
and wolves, is 'more squared-up and shorter,' Janis said. This indicates
the radius and ulna were closer together in these species, reflecting that
these animals' hands are more fixed in the palm-down position. In
terms of hunting, the increased arm and hand movement would have given
the thylacine a greater capability of subduing its quarry after a surprise
attack. Since dingoes and other dog-like creatures have less latitude
in arm-hand movement, that helps explain why these animals hunt by pursuit
and in packs, rather than in an ambush setting, the researchers note".
left, the skeletal thylacine pes (foot), and at right, the manus (hand).
Photo: International Thylacine
Specimen Database 5th Revision 2013.
Figueirido and Janis conclude:
"We propose that the thylacine was more of an ambush predator than the
living Grey wolf, which is often considered as its ecological counterpart.
We provide quantitative support to the suspicions of earlier researchers
that the thylacine was not a pursuit predator, thus bringing into question
the degree of ecomorphological convergence between thylacines and wolves.
In fact, the predatory behaviour of the thylacine was probably closer to
that of ambushing felids than to that of large pursuit canids. Consequently,
at least in terms of the postcranial anatomy, the vernacular name of 'Tasmanian
tiger' may be more apt than that of 'marsupial wolf'".
No discussion on the post-cranial skeleton would be complete without brief
mention of the structure of the thylacine's manus or hand; the external
features of which are discussed in detail in the External
As can be seen from the image below of a thylacine feeding at the London
Zoo, the digits of the manus number 5, and are splayed. In a dog,
only 4 digits would be evident, and these would be rather tightly bound
together by webbing. The 5th digit in the dog is commonly referred
to as the "dew
claw"; it is vestigial, and unlike the thumb of the thylacine, does
not participate in weight-bearing.
from a motion
picture film of a thylacine feeding at the London Zoo.
the 5 digits of the hand or manus. Courtesy: Zoological Society of
- skeleton of manus. Photo: International Thylacine Specimen
Database 5th Revision 2013.