Discovery of Thylacoleo carnifex:
Thylacoleo carnifex, which is commonly referred to as the "marsupial
lion", was a rather robustly built Pleistocene animal approximately the
size of a large leopard or medium-sized African lion. It had a broad
skull with a blunt rostrum and forward-facing binocular eyes. The
Thylacoleo is among its most peculiar features.
Its dental formula is expressed as I 3/1,
C 1/0, P 3/3,
M 1/2. This dentition is essentially
similar to that of the phalangerid marsupials, except that there is a reduction
in the size and number of molars. Thylacoleo's enormous caniniform
maxillary first incisors, semi-procumbent, laniariform mandibular first
incisors, and the gigantic upper and lower slicing third premolars (P 3/3)
are sure to attract the attention of even those who lack a specific interest
in mammalian dental anatomy.
life reconstruction of Thylacoleo carnifex.
Courtesy: Anne Musser.
The maxillary canine (C1) along with the
first two premolars (P1/1, P2/2)
are significantly reduced and generally considered to be functionless.
dentition is so unique that it has created a number of different views
on the phylogenetic position of the animal and generated great debates
regarding its feeding habits. Features of the skull, particularly
the dentition, were virtually the only evidence for early discussions of
as until quite recently, the postcranial skeleton was only known from a
few isolated limb bones which had been recovered in the proximity of Thylacoleo
To follow is a summary of the discovery and interpretation of the various
fossils which have been found of Thylacoleo carnifex. A functional
interpretation of the feeding habits and locomotion of Thylacoleo
will be presented based upon examination of the known, as well as some
First Discoveries and Descriptions:
plate from an 1838 work by T. L. Mitchell depicting some of Owen's drawings
of fossils from the Wellington Caves of New South Wales. Among them
are teeth which would later be classified as those of Thylacoleo.
The first evidence for the existence of
Thylacoleo came from material
collected in the early 1830s from the Wellington Valley region, New South
Wales, by Major (later Sir) Thomas Mitchell. Incisor and premolar
teeth, now known to be of Thylacoleo, were depicted in Mitchell's
1838 work "Three Expeditions into the Interior of Eastern Australia",
but were not detailed in the Zoological Appendix to volume 2 contributed
by Professor Richard Owen, the well known English palaeontologist.
Owen's opinion (1877, vol. 1: 107) was that the premolar, the "large,
two-fanged sectorial tooth", was so extraordinary in form that it was
quite impossible to make a determination of the animal's characters without
an examination of more substantial material.
Owen later obtained fragments of left and right maxillae, each including
P3 and M1,
and a section of a left dentary with P3 intact but
bearing only the roots of M1 and M2.
These specimens had been discovered in the bed of a tributary of the Condamine
River, Queensland, but no date of when they had been found was recorded.
Lydekker's 1887"Catalogue of the Fossil Mammalia in the British Museum
(Natural History)" lists M3653 and M3654, the right and left maxillary
fragments of Thylacoleo from Queensland, as having been figured
by Owen in 1887 and bestowed by him to the Museum.
Owen described the material from the Condamine River and commented on the
position of the "working surfaces" of both the maxillary and mandibular
sectorials in his summary of research on the fossil mammals of Australia
(1877). He made note of the vertical striae and concluded that these
teeth functioned as shearing blades used in the cutting of meat.
However, he could find no indication of how the animal could be reconciled
taxonomically among its marsupial or placental relatives.
Studies conducted by M. E. Finch (1982) of the specimens M3653 and M3654
have shown the presence of a well-defined ridge near the posterior end
of the wear facet of each maxillary and mandibular "carnassial" and a second,
more definite ridge at the interrootial level on the occlusal surface of
M3654. The latter ridge is not developed in other specimens available
for study and the former is usually only a low boundary between the wear
facets which result from contact of the lower carnassial and the adjacent
lower first molar. Owen made mention that the ridges were similar
a maxillary fragment
which retained the carnassial premolar and the single molar, which was
shown to be part of the fragmentary cranium. Owen concluded that
any valid interpretation of the similarities and functionality of this
amazing material could only be based upon detailed comparisons of Thylacoleo
with a variety of other mammals. Such examinations were not completed
until 1858, when Owen presented his research to the Royal Society.
Included in his account was information about a cast of a mandibular section
which he had received from Samuel Stutchbury, Geological Surveyor of New
South Wales. This cast consisted of much of the ramus and included
the carnassial premolar (P3), M1,
and the alveolus of M2, and it easily indicated the
nature of the characters of the symphysis. This initial account of
was based upon fossil material from two widely separated locales, the skull
from Victoria and the mandible from King Creek, Darling Downs, Queensland.
The definitive description of the species was not published until 1859,
as only an abstract and an article "Odontology" appeared in the
1858 edition of the Encyclopaedia Britannica.
seen in the sectorial teeth of Felis spelaea and Hyena spelaea,
however, on present evidence is can be considered quite probable that the
Condamine animal had been afflicted with a deformity of, or damage to,
its mandibular dentition during life, leading to a peculiar wear pattern
on the maxillary premolar.
Fragmentary skull material of Thylacoleo was collected by W. Adeney
in 1845 from his property at Lake Colongulac, some eighty miles southwest
of Melbourne, Victoria, and was forwarded a year later by Dr. H. Hobson
of Melbourne to Owen at the British Museum. Included was a cranium
with an incomplete posterolateral surface and missing its zygomatic arches.
Also in this series was
of the right side of a Thylacoleo mandible. Source: Owen (1887).
view of a Thylacoleo cranium. Source: Owen (1866).
An even earlier reference to Thylacoleo is to be found in Gervais'
et Paleontologie Francaises" published in sections between the years
of 1848 and 1852, but no dates are stated for the individual sections.
Apparently, when Gervais visited Owen in London in 1848, he was shown the
lake Colungulac fossils during a discussion on the affinities of Hyaenodon,
a placental creodont which at the time was thought by many authorities
to be a marsupial. Gervais states in his book that Owen had named
the Australian material
Thylacoleo but provided no description of
it. This reference to Thylacoleo was apparently unknown to
Stutchbury who, in a technical report (1853) to the Colonial Secretary,
had given the name Schizodon
to the original specimen of the mandibular
cast which he had provided to Owen after making a comparison of the carnassial
with that figured by Mitchell (1838). Owen (1859) makes note that
even if Schizodon Stutchbury had priority over Thylacoleo,
it was a homonym of Schizodon Agassiz and
names which had been assigned to a fish in 1829 and to a mammal in 1842,
In his paper of 1859, Owen gave a condensed yet comprehensive description
of the Lake Colongulac and Darling Downs material. However, he stated
Hodgson's Creek rather than King Creek as the source of the mandible.
In the paper, he used the species name carnifex but did not specify
a holotype which has led Mahoney and Ride (1975) to record as syntypes
both the cranium and the mandible upon which Owen's description is based.
Based upon extensive comparisons between Thylacoleo and and the
Dasyurus (Sarcophilus) ursinus
(harrisii) and Thylacinus harrisii (cynocephalus),
and also with Felis spelaea, the placental cave lion, Owen had no
doubt that Thylacoleo was a marsupial. He pointed
out its large posterior palatal vacuities, the position of the basicranial
foramina, the participation (though a small one) of the alisphenoid in
the auditory bulla whilst the tympanic process was essentially free, the
extension of the lachrymal bone on to the face, the extraorbital position
of the lachrymal foramen and the rather small size of the brain in relation
to skull size. He proposed that Thylacoleo was most closely
related to the dasyurids and to Dasyurus ursinus in particular "although
the interval be still very great between them" (Owen, 1859: p. 321).
famous British vertebrate palaeontologist Sir Richard Owen, circa 1846,
with the leg bones of an extinct New Zealand Moa.