The thylacine (Thylacinus cynocephalus) is the largest of modern-day carnivorous marsupials and was hunted to extinction by European settlers in Australia. Its physical resemblance to eutherian canids, such as foxes and wolves, is a striking example of evolutionary convergence to similar ecological niches. However, whether the neuroanatomical organization of the thylacine brain resembles that of canids and how it compares with other mammals remained unknown due to the scarcity of available samples. Scientists from the University of Queensland gained access to a century-old hematoxylin-stained histological series of an adult thylacine brain kept at private collections in Germany, digitalized it at high resolution, and compared its forebrain cellular architecture with 34 living species of monotremes, marsupials, and eutherians.
The thylacine was the largest of modern-day carnivorous marsupials, commonly known as the Tasmanian tiger, or Tasmanian wolf, because of its distinctive stripes and canid resemblance, and the island they inhabited by the time of British settlement in Australia.
Thylacines were distributed throughout New Guinea and continental Australia over 3,000 years ago, but human intensification, competition with dingoes, and climate change likely led to their mainland disappearance.
In Tasmania, their numbers had already reduced substantially by the 19th century with the introduction of farming, a hunting bounty, and disease, with the last recorded thylacine dying in Hobart Zoo in 1936.
Despite anecdotal accounts in historical records, very little is currently known about thylacine biology.
Such knowledge could help better understand the causes of their demise, refine conservation strategies of endangered species including extant carnivorous marsupials, and provide clues about general evolutionary processes.
The endocranial volume of 18 thylacine skulls was estimated at 51 mL and, assuming a body mass of 28.5 kg, an encephalization quotient of…
Read the full article here