2 
SIR R. OWEN ON THE AFFINITIES OF THYLACOLEO CARNIFEX. 
The species of carnivorous Phalanger is not named. No evidence of such by fossil 
specimens has reached me, nor have I found such exceptional habit of an existing 
species of Plmlangista elsewhere noted. 
As the palseontogical survivors of Dr. Falconer and Mr. Krefft have not signified 
any opinion of the fossil evidences, more or less fragmentary, of Thylacoleo discovered 
subsequently to the papers above cited, I deem it due to them to make known the 
most complete and instructive example of the mandibular and dental structures of the 
mooted species which have yet reached me. 
The subject of the annexed drawings (Plate 1) is the right “ramus” of the lower 
jaw, which was extricated in the present year (188G) from breccia of the Wellington 
Valley cave. A careful cast of this specimen has been transmitted to me by 
G. P. Ramsay, F.L.S., successor to Mr. Krefft, and present Keeper of the Australian 
Museum of Natural History, Sydney, New South AVales, together with the three 
drawings of the original specimen, natural size, herewith annexed. 
The dentition of this specimen closely repeats the characters of the mandibular 
teeth described and figured in fragmentary specimens,* The additional characters, 
which I interpret as decisive of the carnassial nature of Thylacoleo, are those of the 
hinder end of the lower jaw, including the articular process. This part is a “condyle” 
transversely extended, antero-posteriorly convex, as in both Lion and Tiger. The 
angle, a, of the ramus is bent inwards as in other Marsupials, including the smaller 
existing pouched Carnivores. In Thylacoleo, to add to the force of the biting actions 
of the mandible, a subsidiary ridge ending in the process, figs. 1 and 3, h, is developed 
from the outer side of the broad angle of the jaw ; the homologue of this ridge and 
process, wanting in placental Carnivora, is developed in the largest of the existing 
marsupial ones, e.g., Thylacinus cynocephalus. The coronoid process of the mandible 
in Thylacoleo (figs. 1-3, d) rises high above the condyle, and broadens antero- 
posteriorly as in the feline placental Carnivores. The entry of the dental canal is 
shown vt e, fig. 2 ; the exit at f fig. I. 
As the figures in Plate 1 are of the natural size, descriptive dimensions are omitted. 
What to me is of most interest in this decisively instructive fossil are the evidences 
of carnivorous modifications superinduced upon the primitive, and at present prevailing, 
diprotoclont marsupial type. In the mandible of the vegetarian kangaroo (J Tacropus) 
the incisive part of the dental series is represented, as in Thylacoleo, by a single pair 
of large incisors ; but these, as in the allied genera Dendrolagus, Bettongia, Hypsi- 
prymnus, are procumbent, depressed instead of compressed, having a smooth flattened 
upper surface with lateral margins, instead of the sharp-pointed and hinder trenchant 
border of the corresponding tooth of Thylacoleo, 
The tooth answering to the trenchant carnassial premolar (figs. 1 and 2, p. 4) in 
Thylacoleo has also the largest crown of the molar series in the above-cited gramini¬ 
vorous Marsupials, but in them the margin of the crown is broken by notches in which 
* See ‘ Phil. Trans,’ 1871, p. 238, Plate 13, fig. 1, and Plate 14. . 
