.
MODERN RESEARCH PROJECTS:
- THE THYLACINE CLONING PROJECT -
(page 3)
.

 
.
    Riversleigh provides a rare view of what animals existed in Australian rainforests between about 12 million and 25 million years ago, when the predecessors of the modern-day fauna, along with some now lost marsupial groups which left no descendants, resided in a much warmer and wetter Australia.

    The teeming life of Riversleigh's rainforests supplied abundant prey for meat eaters, which included a number of thylacine species as well as early dasyurids.

    The Dasyuridae are a diverse group which includes specialized carnivores such as the Tasmanian devil (Sarcophilus harrisii), and the quolls (Dasyurus spp.), as well as smaller predators and insectivores such as the Brush-tailed Phascogale (Phascogale tapoatafa), dunnarts (Sminthopsis spp.) and tiny Planigale species which weigh less than 10 grams.

.
Prothylacynus patigonicus reconstruction
.
A life reconstruction of the prothylacynine borhyaenid marsupial Prothylacynus patigonicus from the Early Miocene of South America (illustration by Michael R. Long).  It was somewhat similar to the thylacine in form, but not ancestral to it.
    It wasn't until the early 1980s that the thylacine's position within Australian marsupial taxonomy became truly clear.  Morphologically, the thylacine bears a striking resemblance to the borhyaenids, an extinct family of large, wolf-like marsupial predators from South America.  However, in 1982, a comparative study of blood proteins called albumins indicated that the thylacine is in fact a close relative of the dasyurids, and suggested that it had branched off from the main dasyurid line of evolution approximately 12 million years ago.
.
    A decade later, analysis of DNA recovered from a preserved thylacine skin provided an even stronger confirmation of this evolutionary affinity.  The borhyaenid link was simply another deceptive case of evolutionary convergence: similar lifestyles create similar physical forms.  However, the albumin study also misled evolutionary biologists by underestimating how long ago the thylacinids and dasyurids had diverged from an early proto-dasyurid predecessor.  The recent discoveries of a number of fossil thylacinid species and at least one ancestral dasyurid at Riversleigh from approximately 22 million years ago suggest a minimum divergence time of 25 million years, and possibly even as far back as 30 to 40 million years ago.
.
    Among marsupials, the evolutionary relationship between thylacines and dasyurids such as the Tasmanian devil, quolls and phascogales is no closer than that of the wolf to its placental relations within the order Carnivora - bears, pandas and raccoons.  Man's primate ancestors are thought to have diverged from monkeys only about 15 million years ago.

    The wide genetic gap that exists between the thylacine and modern dasyurids may possibly be one of the most significant obstacles to cloning a thylacine.

Borhyaena skull
.
The skull of Borhyaena, a carnivous marupial from the Miocene Santa Cruz Formation of Patagonia, Argentina.

    Should the final hurdle of cross-species mitochondrial recognition be cleared, then the carrying of the thylacine embryo would not pose a significant problem as either the Tasmanian devil or Tiger quoll would technically be able to carry the mammary foetus full term.  Marsupial young are born at a very early stage in their development, and the only foreseeable problem with either mother would be pouch space, as the thylacine pup would be larger than either of their natural young as it matures.  However, as with orphaned kangaroo joeys, artificial pouches could be utilised as a substitute in the later stages of pouch development.

.
.
References
.
back to: The Thylacine Cloning Project (page 2) return to the section's introduction forward to: The Thylacine Cloning Project (page 4)


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.
.