The Internal Anatomy of the Thylacine
- A Historical Perspective
(continued)
Much of what we know
today about the internal anatomy of the thylacine is derived from the meticulous
anatomical dissections performed by Professor D. J. Cunningham and
published as part of the HMS Challenger report in 1882.
Cunningham was Professor
of Anatomy at the Royal College of Surgeons in Ireland. The HMS Challenger
expedition brought a male and female thylacine back to England in 1876
preserved in barrels of spirit. Both specimens were sent to HMS Challenger
whilst berthed in Sydney by Sir Charles Du Cane, the then Governor of Tasmania.
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| The
Red-tailed Phascogale (Phascogale calura), as depicted by Henry
C. Richter, one of John Gould's illustrators. This painting was presented
as plate 32 in "The Mammals of Australia - Vol. 1", 1863.
A small member of the marsupial family Dasyuridae, it has apparently occurred
only in the southwestern Western Australia wheatbelt since the late 1950s
or earlier. |
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Cunningham notes:
"The
male had manifestly been received in a very putrid state, but its long
immersion in strong spirit had considerably improved its condition.
The female was in an admirable state of preservation, and it is consequently
from it that the majority of the drawings have been taken and the description
framed.
A special
interest is attached to the anatomy of this animal, from the very prevalent
belief that the genus of which it is the sole member is rapidly becoming
extinct. Thus Owen, writing in 1842 speaks of it as a species "whose
term of existence seems fast waning to its close".
The remains of the skeletal
and soft tissue parts from both of these animals are now preserved in the
collection of the Natural History Museum in London (Source: ITSD 2005).
Cunningham opens his
report with a detailed comparison of the musculature of the fore and hind
limbs of the thylacine (Thylacinus cynocephalus) with that of a
specimen of the Spotted cuscus (Phalangista maculata
=Spilocuscus
maculatus) and of the Red-tailed Phascogale (Phascogale
calura) highlighting both their structural similarities and
differences. He details the origin and insertion of the various muscle
groups with respect to the three species. |
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Due to the reduction of the clavicle in the thylacine, a rerouting of the
muscles normally attached to it has been necessary. The cleido-mastoid
is partially inserted into the inner portion of the clavicle and partly
joins the clavicular area of the deltoid muscle. The scapular section
of the deltoid muscle is enlarged, and unlike the case in dasyurids, there
is no spinal section. The subclavian muscle cannot be inserted into
the upper margin of the clavicle. Instead, it runs beneath the clavicle,
changes direction, and inserts into the fascia which covers the supraspinatus.
The supinator longus is not well developed, and the anconeus externus is
absent. As an adaptation to a running, however, the triceps is quite
large. Also, the pectoralis minor is rather well developed compared
to its usually small size in dasyurids. The pectoralis quartus is
small and quite basic. |
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| Marsupialia
Plate IV - Thylacine, from "The Voyage of H.M.S. Challenger"
(1882). Fig. 1 - Internal aspect of the thigh. Fig. 2 - Dissection
to show the gluteus quartus muscle. Fig. 3 - Marsupial pouch of the
female. Fig. 4 - Dissection of the marsupial pouch - teats left in
position. Fig. 5 - Gluteal region and outer aspect of the thigh. |
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