The External Anatomy
of the Thylacine
and stripe pattern variation (continued):
A feature commonly overlooked in most descriptions
of the thylacine is the whitish blaze to its chest. This originates
from between the front legs and extends as far as the neck.
The characteristic stripe
pattern of the thylacine is shared with only four
other living species of mammals: the numbat (Myrmecobius
fasciatus), Banded hare wallaby (Lagostrophus
fasciatus), Banded palm civet (Hemigalus
derbyanus), and Zebra duiker (Cephalophus
zebra) (Renshaw 1938). A comparison between the stripe
patterns of the thylacine and Zebra duiker can be viewed here.
In the course of the
thylacine's evolution, both intraspecific and intersexual competition occurred,
and this is responsible for the sexual dimorphism in the species.
It was J. West (1852) who first noticed this disparity: "females are
smaller and more agile".
occurs when members of the same species vie for the same resources in an
ecosystem. The consequence of this enduring intraspecific competition
in the thylacine
Last known captive thylacine
showing chest blaze.
Beaumaris Zoo (QD) Hobart
Photo courtesy: David Fleay
|is as a result of the available prey resources.
The thylacine's smaller prey species (potoroos, bettongs, placental mice,
small dasyurids, bandicoots, lizards and birds) are good sprinters and
are likely to be the main prey of the smaller and more agile females.
The "big game", such as the large Forester
kangaroo, wombat and the Red-necked wallaby however, can only
be overwhelmed by the larger, stronger, but not so agile males. This
sharing of the available prey resources has two distinct advantages:
1. A wider reaching
palette of animals can be procured by one species with two specialised
2. The second
advantage is seasonal; in periods when prey resources are scarce, a high
percentage of a population can avoid intraspecific competition.
It is highly likely
that male size is directly related to intrasexual competition for access
to oestrus females; hence why males become older and larger before they
get the opportunity to reproduce. Charles Darwin (1859), in his book:
the Origin of Species", states:
"And this leads me to say a few words on what I call Sexual Selection.
This depends, not on a struggle for existence, but on a struggle between
the males for possession of the females; the result is not death to the
unsuccessful competitor, but few or no offspring".
Most of the available historical literature seems to suggest that an adult
thylacine has a total body length (inclusive of the tail) of between 1.4m
and 1.6m [62 inches], with the animal standing at around 60cm [24 inches]
at the shoulder.
G. P. Harris (1808), in his paper: "Description of two new Species of
Didelphis from Van Diemen's Land", published in the Transactions of
the Linnean Society of London, makes reference to the body measurements
of the type specimen:
"The length of this animal from the tip of the
nose to the end of the tail is 5 feet 10 inches (177.8 cm), of which
the tail is about 2 feet (60.96cm)".
sexual dimorphism animation by Arnfinn Holderer (2016), with technical
contributions from C. Campbell and Dr. S. Sleightholme. Click gear
button in lower right corner and select "?" to view control options for
changing viewing angle and distance. This animation is copyright
and unauthorized use strictly prohibited.
Edwards Crisp (1855)
published a paper in the Proceedings of the Zoological Society of London
in which he compared the anatomy of the thylacine with that of the Cape
hunting dog (Lycaon pictus). Crisp notes that his specimen
measured some 85 cm (2 ft. 9½ in.) from nose to base of the tail,
with a tail length of 38 cm (15 in.).
In the project summary to
the 5th revision of the International
Thylacine Specimen Database (Sleightholme
& Ayliffe 2013), there are several historical references to
the body measurements of thylacines. These were sourced from articles
in the Tasmanian press.
In the Mercury newspaper
of the 15th November 1889 (p. 3), it is stated:
"Last week two miners
at the Twilight succeeded in killing a fine native tiger. It was
caught in a snare, but on the approach of Messrs. George Ward and J. Smith
it broke away, but was soon overhauled by a kangaroo
dog. A grand tussle ensued, but the tiger was handicapped
by receiving the contents of four discharges from a gun, and after a game
struggle killed. It measured 6ft. from the nose to the tip of the
tail, 3ft in girth, and 2ft. 9in. high, and although the teeth were quite
competent to do any amount of damage amongst Messrs. McKenzie's and Hewitt's
flocks, their worn appearance testified to its great age. The head
and paws were taken to Fingal to claim the Government reward".
The Adelaide Register
dated 10th June 1904 (p. 4) reports:
"Recently as Mr.
H. Turner, of Cluan, on the outskirts of the Glenore district, was going
round his traps, he was surprised to find a large native tiger caught by
the toes of one hind foot (says The Launceston Examiner). Mr. Turner
was about to secure his prey, when the trap chain broke, but, being an
active man, he managed after a stiff chase to get hold of his quarry by
the tail, and, protecting himself with a stick, got the animal into a large
bag, which he fortunately had with him. The tiger measures about
5 ft. 4 in. from tip to tip, and its captor has it chained up dog-fashion.
It sulked for a couple of days, but then took to its food all right.
Mr. Turner values his capture at £5".