.
BIOLOGY:
- ANATOMY -
SKULL AND SKELETON: SKULL (page 1)
.

 
.
    The skull of the thylacine is variable with respect to both its absolute size and the proportion of its separate parts, but to no greater extent than that found in the placental wolf (Canis lupus).  The thylacine however, exhibits a far greater degree of sexual dimorphism in its cranial and dental characters than is the case in any other marsupial species.
 
    There is a marked difference in the skull size between the sexes, the male thylacine having a proportionally larger skull with a longer face.  The skull of the female is distinguishable from that of the male by its smaller size, shorter muzzle, less expanded zygomata, and with respect to its dentition, smaller but proportionally larger teeth.

    It was Thomas Oldfield (1888) who provided the earliest published range for both male and female thylacine skulls.

    Historically, Temminck (1824, pp. 60-65) made the following remarks regarding the skull of the thylacine:

comparison of male and female thylacine skulls
.
Comparison of male and female thylacine skulls.
* range from 205mm to 226, t range from 179mm.  Oldfield (1888).
.
.
    "By comparing the cranium of this animal with those of dogs one must agree at first glance the resemblance seems striking but is easy to see that on the whole they are completely different in a way very marked by the form and the number of teeth.  It is true, that the lengthened shape of the muzzle and strong conical curved canines give the head of this animal a resemblance to that of dog's but one can still notice that independently of the disparity of the teeth, the zygomatics are much more strongly arched than in any species of dog.  The thylacine also differs from the true Dasyurids with which it was joined not only by the number of true molars but by the lower form of those on the jaw, size and force of the canines, the length of the muzzle (and cranial changes) which results in forward placement of the eyes whereas true Dasyurids have eyes on the sides of their head".
.
    In comparing the skull of a thylacine with that of a placental carnivore, one of the most obvious evolutionary similarities is in the carnassial (=sectorial) teeth.  Other features are the palatal vacuities (holes in the palate) like those found in the skulls of primitive mammals, posteriorly expanded nasal bones, an alisphenoid tympanic wing flooring the middle ear, the involvement of the jugal at the edge of the glenoid fossa for articulation of the lower jaw, broad extension of the lachrymal bone onto the face of the skull and mesially enlarged angular process of the dentary (lower jaw); features the thylacine shares with most other marsupials.
.
palatal vacuities
.
The palatal vacuities.
brain case
.
The brain case is small and narrow.
.
lachrymal foramen
.
The lachrymal foramen is anterior to the orbit so that it opens onto the surface of the face, rather than the inside of the orbital space.
jugal
.
The jugal (also known as the zygomatic or malar bone) is large.  View a graph demonstrating jugal width vs. skull length between T. cynocephalus and C. lupus.
.
angular process of dentary
.
The angular process of the dentary is inflected medially in almost all marsupials.
nasal bones
.
Flared (diamond-shaped) nasal bones as opposed to the rectangular nasal bones of placental carnivores.
.
Photos: International Thylacine Specimen Database 5th Revision 2013.
.
.
References
.
return to the subsection's introduction forward to: Skull (page 2)


Search the Thylacine Museum
Site Map
Website copyright © C. Campbell's NATURAL WORLDS.
Photographs and other illustrations (where indicated) are © C. Campbell's NATURAL WORLDS.
Other photos and images are © their respective owners.