The thylacine is a fascinating creature. More commonly called the Tasmanian tiger, because of its stripes, or the Tasmanian wolf, this dog-like creature was once the largest predator marsupial. It became extinct in 1936 when the last known specimen died in captivity.
There are many interesting topics to discuss about the thylacine. One is its extinction. A bit like the dodo, the thylacine is a “poster boy” for animals that humans drove to extinction. In the case of the thylacine, it is because of hunting, spurned on by the belief that thylacines were hunting sheep, imported to Tasmania by ranchers.
Another topic is, are thylacine really extinct? Reports of thylacine sightings occur to this very day. Of course, none of them come with any kind of verification, such as a body or a clear photograph, but the reports spur on the hope that this unique and iconic creature may still be lingering somewhere.[1]
An oddity of these reported sightings is that they sometimes take place on the Australian mainland. This is odd because Europeans only encountered thylacines in Tasmania. However, it is known from fossils that thylacines used to live in Australia just a few thousand years ago. As creationist, we expected this: all creatures came off of the Ark about 4,500 years ago. It makes sense that thylacines would be found in Australia, as they would have to pass through that continent in order to reach Tasmania. Of course, the question is, why did they die out on the mainland? The standard answer is that they were outcompeted by dingoes, which were presumably brought to Australia by the Australian aborigines. However, that explanation has been questioned, leading to more speculation as to why thylacines lasted so much longer in Tasmania.
As interesting as these topics are, I want to focus on something else. That is, the convergence between thylacines and dogs. Note that by “dog,” I mean the dog kind, and not simply the domesticated pet.
The concept of convergence is strongly associated with the they of evolution. “Convergence” is typically defined as two creatures that look similar to each other but did not evolve from the same ancestor. You can see why the Tasmanian wolf would be used as an example of convergence: as a glance, it looks like a dog, but unlike dogs, which are placentals, the thylacine is a marsupial. The thylacine, according to the theory of evolution, evolved from a marsupial ancestor while dogs evolved from a placental ancestor. Thus, their similarities are coincidence, rather than indicating any shared ancestry.
The standard explanation for convergence is that two different animals ended up taking on similar body styles because they both evolved to live the same kind of lifestyle. To use an oversimplified example, since there are no placentals in Australia (aside from a couple species of bats and mice, and the aforementioned dingo which was apparently imported by humans), wolves couldn’t evolve in Australia. Thus, as predatory marsupials evolved and were subjected to the same evolutionary pressures that created the wolf found in the rest of the world, the Tasmanian wolf, the marsupial answer to the placental wolf, was created.
As creationists, we do not accept this idea of convergence. Since we believe that God created creatures according to distinct, separate kinds, any similarities between two different kinds of animals would be because God created them that way. God created the dog kind, and He also created the thylacine kind, and He intentionally, for one reason or another, decided to make the two look like each other. The explanation that dogs and thylcaines look similar because they both lived similar lifestyles can still be used as an explanation: perhaps God created the thylacine because the dog body “worked so well,” it was just the best thing to use for a marsupial carnivore. In this manner, we can still talk about convergence while divorcing it from an evolutionary worldview.
While it may be convenient to talk about convergence, it is not nearly as descriptive as we may think. Sure, the thylacine looks like a dog, so we call it a marsupial wolf, but is it truly like a dog?
The first thing that we need to understand is that the thylacine does not exist in a vacuum. It is the marsupial predator most people know about, aside from the Tasmanian devil, and even then, people usually think about the cartoon character as opposed to the actual animal. In fact, there is a whole group of marsupial carnivores. The order Dasyuromorphia contains the marsupial carnivores, and it is divided into a few families, including Dasyridae and Thylacinidae. Most of these animals are small, between the size of a mouse and the size of a cat, and thus often get overlooked as interesting or notable. However, it is important to note that thylacines did not “pop out of nowhere”: they belong to a group of marsupials with similar designs and lifestyles.
Here are some examples of Dasyuromorphia. First, we have the more familiar Tasmanian devil, which belongs the family Dasyridae. This animal would be about the size of a badger.
Then we have the tiger quoll, sometimes also called the native cat, because it is about the size of an actual cat. It also belonged to the family Dasyridae.
Now, the thylacine belongs to the family Thylacinidae, rather than Dasyridae, so it may not even belong to the same kind as the devil and quoll. Nevertheless, you can see that there is a resemblance between these animals. Sure, their proportions are different, and the thylacine has more dog-like proportions and size, but it could just as easily be called a large, lanky quoll as a marsupial dog. We call the thylacine dog-like because we are familiar with dogs. If quolls were more familiar to us, we may have called the thylacine quoll-like. Our perception of convergence is just that: a perception based on our experiences.
Even though Europeans lived alongside thylacines and hunted them to extinction, they were not studied very much before they went extinct. We actually lack a good amount of scientific observations of living thylacines in the wild. This means that their natural behaviors have been, and still are, a bit of a mystery. Thus, it is pretty easy to take their comparison to a dog and presume that thylacines must have behaved like dogs. In fact, there are recent studies to indicate that such is not the case.
Studies of the limbs, especially the fore-limbs, of thylacines have indicated that they had very different behaviors compared to dogs. Dogs, and especially large dogs like wolves, are pursuit predators. That is, they run well. They are not only fast, they are also endurance runners. Wolves typically hunt in packs, and when they do, they run down their prey. Deer, elk, and other prey may be able to run fast, but wolves can run longer, and they eventually run their prey to exhaustion. This design for running is found in the structure of the forelimbs. As it turns out, thylacines lack these structures. In fact, their limbs can be best described as unspecialized:[2] they were not designed for running after prey, like a wolf. In fact, their limbs do not appear to be designed for any special type of hunting: they may have been able to pounce on prey, like a fox, or stalk and ambush their prey like a cat. Even so, they were not specialists for either of these lifestyles, and probably hunted in whatever manner worked.
Moreover, their skulls appear to not have been designed for handling large prey. Their skull design is closest to a fox or jackal’s, which would make it best for handling prey items much smaller than its own body,[3] which even further separates the Tasmanian wolf from an actual wolf. It also calls into question just how dangerous they were to sheep and the reason for their extermination.
All in all, thylacines appear to have been their own unique creature. They were not dogs with pouches welded to their undersides, but contained their own designs for their own lifestyles. Can we say that they are convergent on dogs? Of course we can, provided we understand that convergence simply means similar designs given by God, and not similar designs created by evolution. Also, we must always keep in mind that despite how much two animals may appear similar to each other, they are not carbon copies of one another. Rather, each kind was a special creation, designed for its own place in the world God created.
Thoughts from Steven
[1]To be clear, there is no credible evidence that thylacines are still living. It has been nearly ninety years since there has been a living, or even a body, of a thylacine, and despite attempts to actually find and collect a living specimen, none has every been found.
[2]Janis, Christine and Borja Figueirido (2014) “Forelimb Anatomy and the Discrimination of the Predatory Behavior of Carnivorous Mammals: The Thylacine as a Case Study” Journal of Morphology 275: 1321-1338
[3]Rovinsky, Douglass; Alistair Evans; and Justin Adams (2021) “Functional ecological convergence between the thylacine and small prey-focused canids” BMC Ecology and Evolution 21: 58
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