The last known Tasmanian tiger in footage digitised by the National Film and Sound Archive of Australia.
Photograph: National Film and Sound Archive of Australia.
The thylacine, or Tasmanian tiger, has long been a textbook example of convergent evolution: a marsupial predator whose resemblance to a wolf evolved independently in a distant branch of the mammalian family tree. For creationists, such similarities offer an opportunity to invoke a designer reusing a successful design. But that explanation overlooks the more revealing question: how far does the resemblance go, and why do similarities in some features coexist with substantial differences in others?
New research led by Flinders University’s Professor Vera Weisbecker, published in Nature Communications, shows why describing the thylacine as a “marsupial wolf” can be misleading. Its skull combined features resembling those of different carnivores with an unusual specialisation of its own. As the university’s account explains, this animal was more closely related to kangaroos than to dogs, despite its superficially canine appearance.
Three-dimensional comparisons revealed a striking mixture. The back of the skull resembled that of larger canids, including wolves, while the long, slender snout looked more like that of smaller foxes and jackals. Yet the whole skull was disproportionately large for the animal carrying it. The researchers suggest that this combination supported rapid, forceful snapping bites at relatively small prey. Some features even invite comparison with crocodiles and other vertebrates that catch agile prey with elongated jaws. These are inferences from anatomy, rather than direct observations of hunting behaviour, but they undermine the familiar image of a predator equipped to overpower large animals in the manner of a wolf. The authors explain these findings in their article for The Conversation.
This is precisely where convergent evolution becomes more informative than a superficial resemblance. Natural selection acts on inherited anatomy, modifying structures already present in a lineage. Similar demands can favour similar features in distantly related animals, without producing identical bodies or requiring identical lifestyles. Each lineage brings its own evolutionary history, developmental constraints and available variation to the process. The result can be a mosaic of resemblance and difference.
Invoking a designer who sometimes copies a wolf, sometimes a fox and sometimes produces something quite different adds no testable explanation for that pattern. Descent with modification, by contrast, provides a framework for investigating both the shared features and the departures from them. The thylacine’s distinctive skull makes that investigation richer, while reminding us that evolutionary convergence need never amount to a complete anatomical duplicate.
The article in The Conversation is reprinted here under a Creative Commons licence, reformatted for stylistic consistency:


































