Material Classified to Different Genera and Species:
To follow is an account of genera and species which have been described
at various times since Owen (1859), and more recently by Archer and Dawson
(1982), that have defined the position of some of these taxa.
Plectodon Krefft, 1870: A brief description was published by Krefft
(1870a) of material which included some badly damaged mandibular incisors
said to come from an animal "allied to Thylacoleo" which he named
No type specimen was named and no details regarding its locality of discovery
were mentioned. A specimen was sent to Owen but no species name was
ever recorded, despite the fact that Krefft made further references to
in later publications (1870b,
1882) and provided an illustration of the
Plectodon is considered by Archer and Dawson (1982)
as a junior synonym of Thylacoleo Gervais.
australis Krefft, 1870: Krefft found a large, hooded ungual phalanx
amongst some of the material collected from the Wellington Caves.
It rather resembled that of a South American ground sloth,
He assigned the specimen to the genus Mylodon? and made it the type
of Mylodon? australis. A short description was published (Krefft,
1870a), however, it was Owen (1871, 1877) who first illustrated the specimen
from a series of photographs of two variously shaped types of phalanges
which had been sent to him by Krefft. Owen produced figures of both
types of phalanges and, by excluding all other marsupials known to have
existed in the discovery locality at that time as being of the improper
size, he expressed that Thylacoleo must have been the possessor
of the curved ungual phalanges. He rejected the possibility that
had ever existed in Australia. Etheridge (1918) examined the confusing
situation which had developed out of Owen's referral of two distinct types
of phalanges to Thylacoleo and the listing by Lydekker (1887) of
a cast of a third form of phalanx as also being ascribed as that of a thylacoleonid.
Krefft's hooded, ungual bone was likely referable to Thylacoleo.
Of the two unhooded phalanges, the highly arched and compressed type was
morphologically most similar to that of the great flying phalanger while
the more elongate, less compressed claws were more like those of the koala.
In a study (1982), Archer and Dawson demonstrated that Thylacoleo carnifex
is a senior synonym of Mylodon australis.
Thylacoleo oweni McCoy, 1876: The innate difficulties in having to
base the taxonomy of fossil species upon a few incomplete specimens are
highlighted by the studies of McCoy (1876). In 1875, he had been
given a fragmentary skull and mandible collected by Adeney from the same
locality at Lake Colongulac as the specimens that had been sent to him
thirty years earlier. The skull appeared to be lacking part of Owen's
specimen and bore all precarnassial teeth in situ. McCoy made
a thorough comparison between the Victorian material (including the newly
obtained mandible) and that from darling Downs and the Wellington Caves
(Owen 1859, 1866, 1871) which led him to differentiate the New South Wales
Thylacoleo as a distinct species, T. oweni.
The basis provided by McCoy for the new species was as follows:
The longer convex margin of I3 was posteriorly
T. carnifex but oriented anteriorly in T. oweni.
Owen had based his description of T. carnifex, however, upon isolated
teeth and had obviously reversed I3.
The premaxillary-maxillary suture traversed the alveolus for the canine
tooth in T. carnifex but was said to meet the alveolus anterior
to that of the canine (i.e. the tooth initially classified as I3)
in Owen's 1871 account.
The dorsoventral depth of the mandibular ramus was measured anteriorly
to the carnassial and again posteriorly of M2.
The Victorian material showed the anterior distance to be greater while
the T. oweni mandibles were deeper at the posterior end.
The T. carnifex palate was narrower across the premaxillary area
and 6 mm greater in length anteroposteriorly that that seen in T. oweni.
and C1 were larger in the Victorian than
in the New South Wales specimens. Among these alleged differences,
the first two (a & b) have been demonstrated to be invalid by Owen
(1877) whist points c, d, & e would appear to be within the acceptable
variability range shown by T. carnifex.
Thylacoleo oweni is
regarded by Archer and Dawson (1982) as a junior synonym of
Thylacoleo robustus Krefft, 1872: The name of Thylacoleo robustus
was given by Krefft (1872a) to a right maxillary canine found at the Wellington
Caves. His only reason for assigning it to a distinct species was
because the homologous tooth of T. carnifex was said to be reasonably
smaller than that of the new species. T. robustus is now considered
a junior synonym of T. carnifex (Archer & Dawson, 1982).
australis Owen 1888: An array of fossil specimens from a newly found
cave in Wellington valley, New South Wales, gave Owen a skull lacking a
mandible, and that was smaller than his previous specimens of Thylacoleo.
He called it Thylacopardus australis, the name first being published
in Nature (1888). Owen presented his complete description
of the specimen to the Royal Society of London in 1888, however, the paper
itself was only published by title (1889 or 1888). Two characteristics
were used to make a distinction between this new genus and Thylacoleo,
its small size and its possession of a small molar or "molariform prominence"
on the posterior margin of the palate behind M1.
Owen wrote in his yet to be published manuscript (quoted by C. Anderson
in 1929) that
"the dentinal structure" of the molariform prominence
has been shown, thus exhibiting the existence of a second maxillary molar.
The manuscript and type specimen (which was then in the collection of the
Geological and Mining Museum, Sydney) was examined by Anderson and he came
to the determination (1929) that the "M2"
was merely the broken edge of the post-palatine bar and showed no evidence
of dentine material. He held that the animal was in fact Thylacoleo
carnifex, but could only have been a young individual on account of
its small size and the fact that it had unworn teeth. Anderson pointed
out that even though Owen's measurements of the skull bones of Thylacopardus
and Thylacoleo displayed a reasonable degree of difference in size,
the lengths of the maxillary carnassials were virtually the same.
Therefore, it is unlikely that Thylacopardus represents a valid
genus and species. It is considered as a junior synonym of T.
carnifex by Archer and Dawson (1982).
localities around Australia where thylacoleonid fossils have been found.
Archer, Clayton and Hand 1984; Vertebrate Zoogeography and Evolution
Press, Carlisle, Aust.)
crassidentatus Bartholomai, 1962: Included in the material from
the Darling Downs area kept at the Queensland Museum in Brisbane is a collection
which comes from Chinchilla, northwestern Darling Downs. These specimens
were thought by Woods (1956) to be significantly different enough to warrant
continuing study, and proposed that they were of Pliocene age. All
known Thylacoleo carnifex material is considered to be of Pleistocene
age. Acquiring a partial right mandibular ramus from Chinchilla gave
Bartholomai (1962) the necessary material for the classification of a new
species, T. crassidentatus. Bartholomai lists the basic distinguishing
characteristics of this species as compared to T. carnifex as:
P3 is broader posteriorly and more convex buccally
than is that of T. carnifex.
M1 is wider over the anterior and posterior roots
than as seen in T. carnifex. The posterior section of the
crown possesses a wide median ridged area and a shallow posterolabial fossette.
M2 is also more robust in form and one specimen gives
an indication of an alveolus for M3.
crassidentatus' mandibular ramus is broader and not as concave medially.
I1 is more recumbent, with the angle between the tooth
and the base of the mandible being smaller. The maxillary material
was fragmented, and did not display and notable distinctions from
carnifex although one specimen may have had an M2.
Further material which can be referred to T. crassidentatus has
been described from the Allingham Formation (Lower Pliocene) of Northern
Queensland (Archer & Wade, 1976) and at Bow in New South Wales (Archer
& Dawson 1982).
Balladonia specimens: Glauert (1912) and Merrilees (1968) both refer
to Thylacoleo material from caves near Balladonia, Western Australia.
Merrilees makes note that Glauert failed to differentiate between the various
caves around Balladonia but Merillees himself mentions Wonberna Cave as
being the source of Thylacoleo "probably not carnifex".
This animal was significantly smaller than T. carnifex and may be
a distinct species (Finch & Freedman, 1982). The age of the deposit
from which the material came is not known.
hilli Pledge, 1977: An isolated left P3
of Thylacoleo found in 1956 in a cave at Curramulka, South Australia
has been described by Pledge (1977). The fossil is of unknown age,
but is thought to be Late Miocene or Early Pliocene. It is quite
peculiar due to its small size (Finch & Freedman, 1982), being roughly
half the length of the P3 of T. carnifex.
Because of this, it has been designated a new species, Thylacoleo hilli.
A discovery of new material referable to this species at Bow, New South
Wales, has been reported by Archer and Dawson (1982).
From the Miocene deposits of South Australia and the Northern Territory
have come thylacoleonids which are considered by Clemens and Plane (1974)
to be a genus which bears notable dissimilarities from Thylacoleo.
These animals had a different dentition, as they had retained three mandibular
molars, had a comparatively shorter carnassial tooth, and bore only one
precarnassial premolar. The latter is a characteristic not evident
in Thylacoleo species. Such dissimilarities, they gathered,
was a sufficient basis for constituting a new genus, Wakaleo.
The species name, W.
oldfieldi, was given to the South Australian specimen from lake
Ngapakaldi consisting of a left dentary which includes the incisor, P3
and M1. Also present are alveoli for P1
(or P2), M2 and M3.
Because of wear facets formed on an isolated M2, it
was presumed that there were two maxillary molars which were positioned
posterior to, and not lingual to, the carnassial.
The fossil from Bullock Creek, Northern Territory was a fragment of mandible
bearing a single molar, M1, alveoli for M2
and M3, and a partial alveolus for I1.
The dentary was somewhat larger than that of W. oldfieldi, and when
one takes into consideration the spatial separation as well as a possible
time difference between the two specimens, Clemens and Plane (1974) felt
well-founded in designating a second species, W.
A third species of this genus, W.
alcootaensis, from the Miocene Alcoota local fauna of the Northern
Territory (Archer & Rich 1982), would appear to be the largest member
of the genus yet found. This specimen, a fragment of a skull, retained
tribosphenic molars, a characteristic which implies secondary modification
of the ancestral quadritubercular molars for a life of carnivory.
Mention is made by Clemens and Plane (1974) of an edentulous (missing its
teeth) skull fragment from the mid-Miocene Ngapakaldi Fauna. Possibly,
it was a thylacoleonid, as it displays alveoli for an enlarged P3
and four molars.