reconstruction of Thylacoleo carnifex (based upon a drawing by Peter
Schouten). Thylacoleo is thought to have been primarily an arboreal
(tree dwelling) animal which possessed a strong grip. Note the powerful
hand with robust digits. Another feature of the hand was the presence
of a large, hooded claw on the thumb which was apparently used as a weapon.
|| Few extinct
mammals have awakened as much curiosity and speculation as to their way
of life and their relationship to other forms as the remarkable Marsupial
Thylacoleo, described in 1859 by the distinguished British
palaeontologist Sir Richard Owen as 'the fellest and most destructive of
This explanation was
soon disputed in 1871 when Owen wrote in response:
'several eminent and experienced
investigators of Fossil Remains have endeavored to determine to which of
the groups specified the Thylacoleo was closely or immediately allied.
Some have been led to the belief of it having been a Kangaroo, some have
deemed it a Potoroo or Rat-Kangaroo, others would rank it with the arboreal
Phalangers or Koalas; but all concur in repudiating its carnivorous character....and
have sought with more or less ingenuity, to invalidate the conclusions
which I had been led to deduce from the parts of the fossilized remains....'
Hence, Owen began the defence of his theory; with the passing of 140 years
and more than 40 scientific papers, the general view of Thylacoleo
now agrees with Owen's original interpretation. To understand why
the argument ensued we must investigate the teeth of this amazing mammal.
The prominent front two teeth, the incisors, are characteristic of marsupials
of the order Diprotodonta, a group which includes the possums, koalas,
wombats and kangaroos. Most of these animals have an essentially
herbivorous diet. Thylacoleo's cheek-teeth are dominated by
enormous, blade-like third premolars, which work in a way similar to the
flesh shearing carnassial teeth of mammals of the placental order Carnivora.
The molar teeth are quite small and reduced to only one upper and two lowers
on each side. The canines are reduced to mere pegs, and apparently
serve little function. Owen (1871) asserted that in the living carnivores
the relative enlargement of the carnassial teeth was a good indicator of
the ferocity of the species. On that basis, Thylacoleo must
have been an animal of unprecedented ferocity! Moreover, the great
reduction in size of the canine teeth to mere stubs in Thylacoleo
was more than compensated for by the extreme enlargement of the first incisors,
which were 'adapted for piercing, holding and lacerating, like the canine
of a carnivore' (Owen 1871). Truly, as Broom (1898) noted, much of
the opposition to Owen's interpretation was based on the presumption that
'diprotodonts can't be carnivors', because all others were herbivorous.
This belief in turn had led to notions of more fancied diets such as ripe
fruit or eggs (Cope, 1882, 1884). However, Broom was not successful
in putting the matter to rest, as in 1929 Anderson drew attention to a
paper by Charles De Vis (1883) of the Queensland Museum which claimed that
was a marsupial 'hyena' rather than a 'lion'. Anderson pointed out
that hyenas crushed and ate bone and that such animals 'have broad strong
teeth with several cusps, and a well-developed cingulum (a low shelf around
the base of the tooth) on the molars and premolars, the purpose of which
is to protect the gums from injury by splinters of bone. The teeth
of Thylacoleo are not of this type; nor is a cingulum to be found
| After demonstrating
that Thylacoleo was not a 'hyena' Anderson proceeded to take an
illogical step; dismissing the carnivore theory completely he returned
to the presumption of a specialized plant-eater which fed on native curcubits
or cycad nuts, even though he was aware that 'there are difficulties in
accepting the view that Thylacoleo could obtain adequate food from
with the carnivore hypothesis arose from an examination of the large incisor
teeth set together at the front of the jaw, forming a structure similar
to the beak of a parrot (Gregory, 1951). In this position they may
have been capable of piercing and lacerating but 'a living animal caught
in such incisors could spin about as if on a pivot' (Gill, 1954a) and would
be 'particularly unsuitable for catching and holding anything alive and
struggling' (Marett Tims and Hopewell Smith, 1914).
skull of Thylacoleo. This one was recovered from a Pleistocene
cave deposit. Fossils such as this are quite fragile, and should
be treated with a protective sealant such as polyvinyl butyral to guard
them from the deteriorating effects of humidity and temperature extremes.
Note the large, projecting incisors in both the upper and lower jaw.
Over the passage of
time since Owen's description many skull and jaw fragments were discovered
in cave and swamp deposits throughout Australia, but it was not until 1956
that any firm image of what the animal's postcranial skeletal anatomy was
like became possible, when, during quarrying at Naracoorte in South Australia,
an associate skeleton was found. During the following five years
additional partial skeletons were unearthed in South Australian caves (Daily,
1960) and also in the sand dunes of Lake Menindee (Tedford, 1967).
In 1966, a discovery of immense significance was made at Moree in New South
Wales, where workers at a loam pit uncovered a nearly complete Thylacoleo
skeleton which was missing only its hind feet and the tip of the tail.
When the matrix was cleared away from the skeleton, it was found to contain
the fragmentary remains of a pouch young (Finch, 1971). In 1969 the
discovery of the fossil chamber in Victoria Cave, Naracoorte, lead to the
recovery of the remains of an additional 14 individuals, including well-preserved
and articulated fore and hind feet. (Wells, 1974; Wells and
Nichol, 1977). A clearer image of this unique marsupial is now forming.
Finch (1971) has portrayed Thylacoleo as 'an animal the size of
a leopard with comparatively long limbs for its size and a large, heavy
head supported on a thick muscular neck... The paws were strong, heavily
clawed, and probably used in striking prey and for tearing it'.
composite Thylacoleo skeleton (cast) assembled from bones found
in Victoria Fossil Cave, Naracoorte, South Australia.
and Nichol's (1977) study of the hands of Thylacoleo showed that
the thumb is robust, capable of moving quite independently of the other
digits and possesses a very formidable, hooded claw. The remaining
fingers are long and slender, bear small claws and only limited palmar
flexion. When standing, the weight of the animal would have been
borne by the ends of the toes in a similar way as that seen in cats.
In spite of this, Thylacoleo's hand would have had a powerful grip
through opposition of the thumb, not to the other digits as in primates,
but to a flattened bone (the pisiform) in the wrist.
The structure of the
hind foot implies that the weight of the animal was distributed along the
side of the foot (a plantigrade stance). Indeed, the hind foot is
very similar in design to that of the Brush-tailed possum, even to syndactyly
of digits II and III (i.e. the two toes are positioned very close to each
other, enclosed by a sheath of skin), evidence if its diprotodont ancestry.
Wells and Nichol (1977) were unable to note few significant anatomical
differences in the hands of terrestrial and arboreal carnivores, and proposed
that a hand well-adapted for climbing could be adapted equally well for
Apart from the data
now available regarding the skeleton of Thylacoleo, examinations
of recently found skulls and teeth have enabled further insights in feeding
habits, settling the old controversies that once raged about this marsupial.