The Internal Anatomy
of the Thylacine - A Historical Perspective
Gregory S. Berns
and Ken W. S. Ashwell (2017), in a paper entitled "Reconstruction
of the Cortical Maps of the Tasmanian Tiger and Comparison to the Tasmanian
Devil", published in the journal PloS ONE, used magnetic resonance
imaging (MRI) and diffusion tensor imaging (DTI) techniques for the first
time to scan two 100-year-old thylacine brain specimens and two brains
(one preserved, one recent) from the Tasmanian devil (Sarcophilus harrisii).
Only 4 intact thylacine brain specimens still exist, the remaining 6 having
been dissected (Source: ITSD 5th Revision 2013).
The two thylacine brains used in this study came from the Australian Museum
in Sydney [AMS M18411] and the Smithsonian Institution in Washington, D.C
Reconstruction of the
neural pathways of the Tasmanian devil (left) and the thylacine (right).
Source: Berns & Ashwell
MRI scans use strong
magnetic fields, radio waves and field gradients to produce detailed images
of the inside of the body. They reveal detailed information about
the architecture of the brain known as grey matter. DTI is a magnetic
resonance imaging technique that enables the measurement of the restricted
diffusion of water in tissue in order to produce neural tract images, revealing
the connective pathways of a brain known as white matter. Using these
techniques, Berns and Ashwell compared the structure of the thylacine brain
to that of the Tasmanian devil and reconstructed the white matter tracts
or neural wiring between different parts of the brain. They found
that thylacines have larger caudate zones than devils, which is consistent
with complex cognition, a vital requisite in hunting.
Ashwell states: "The
technology for imaging the preserved brains of rare, extinct, and endangered
species is an exciting innovation in the study of brain evolution and will
allow us to track pathways and study functional connections that could
never be analyzed through older experimental techniques".
will assist scientists in gaining a better understanding of the evolution
of the marsupial brain, a subject which remains poorly understood.
We are fortunate, thanks to the foresight of collectors like Sir Colin
MacKenzie, to have "wet" specimens of all of the thylacine's internal organs,
together with the eviscerated carcases of five adults, preserved in museum
and university collections around the world (Source: ITSD 5th Revision
2013). These specimens provide us with us with an opportunity to
study in detail the internal anatomy of a species that may now be on the
brink of extinction. With the advent of new diagnostic and imaging
techniques, like those used by Berns and Ashwell, there is still much to
be learnt about the anatomy of the thylacine. It is somewhat ironic
that we have learnt more about the thylacine from its physical remains,
than we have from the living animal itself.