Name: Sthenurus
(Strong tail).
Phonetic: Sten-u-rus.
Named By: Richard Owen - 1873.
Classification: Chordata, Mammalia, Marsupiala,
Diprotodontia, Macropodidae, Sthenurinae.
Species: S. andersoni, S. atlas,
S. browneorum, S. gilli, S. maddocki, S. occidentalis,
S. oreas, S. orientalis, S. pales, S. stirlingi, S.
tindalei.
Diet: Herbivore.
Size: 3 meters long.
Known locations: Australia.
Time period: Zanclean of the Pliocene through to the
end of the Tarantian of the Pleistocene.
Fossil representation: Several specimens.
Sthenurus
was a large kangaroo, similar to the better known Procoptodon.
Analysis of Sthenurus fossil locations combined
with carbon dating has
yielded the conclusion that Sthenurus was a
generalist herbivore that
adapted to whatever plants were available. This is because analysis
shoes that at some times and locations Sthenurus
would be a browser of
vegetation and at others a grazer of grass, but most importantly
these times form up a mixed sequence that does not support the
progression from one kind of foraging to another. Additionally there
are other deposits that hint that Sthenurus browsed
and grazed at the
same time.
Part
of this dietary adaptability came from the teeth which had a thick
covering of enamel. Although better suited for tougher vegetation,
these teeth would have worked perfectly fine upon softer plants too.
As a kangaroo Sthenurus would have also been
flexible enough to get
down low for grazing, or rising up on its legs to reach vegetation
that was beyond the reach of smaller herbivores. When doing so
Sthenurus may have relied more upon its tail to act
a makeshift
‘third leg’ since while the tail was shorter than in some
kangaroos, it was especially robust in its makeup. This might have
been to compensate for the extra weight of the body of Sthenurus
which
overall also seems to have been of a strongly robust build. Sthenurus
also possessed a degree of stereoscopic vision which would have helped
it with depth perception (the ability to judge distances),
something that would help it reach out at branches with its arms.
One
difference between Sthenurus and the modern red
kangaroo (Macropus
rufus) is that the feet of Sthenurus
were formed from a single
(fourth) toe, rather than the three toes of the red kangaroo.
This single toe ended in a nail that was more like a hoof, and was
probably formed because a single toe would have been better able to
support the extra weight of the larger body, especially when
Sthenurus was travelling at speed. These enlarged
single toes can
also be seen on other large kangaroos like the aforementioned
Procoptodon.
Further reading
- A new species of Sthenurus (Marsupialia,Macropodidae) from the
Pleistocene of New South Wales. - Records of the Australian Museum
25(14):299-304. - L. F. Marcus - 1962.
- Sthenurus (Macropodidae, Marsupialia) from the Pleistocene of Lake
Callabonna, South-Australia. - Bulletin of the American Museum of
Natural History (225): 23. - Roderick Tucker Wells - 1995.
- Systematics and evolution of the sthenurine kangaroos. - UC
Publications in Geological Sciences, University of California Press
146:1-623. - G. J. Prideaux - 2004.
- Role of development in the evolution of the scapula of the giant
sthenurine kangaroos (Macropodidae: Sthenurinae). - J. Morphol. 265
(2): 226–236. - K. E. Sears - 2005