Canis lupus hominis

From Live Science:

The extinct thylacine, more commonly known as the “Tasmanian tiger” or “marsupial wolf,” hunted more like a cat than a dog, meaning the tiger moniker may be the more appropriate nickname.

The thylacine had the striped coat of a tiger, the body of a dog and like other marsupials (including kangaroos and opossums) carried its young in a pouch. These carnivores were last seen in Australia 3,000 years ago, having died out after the introduction of dingoes by humans. The last remaining populations were sheltered by their isolation on the island of Tasmania, surviving until the 1900s, when a concentrated eradication effort wiped the thylacine out.

Researchers hypothesized that the dingoes were a main cause of the thylacine decline in Australia, because the two species were in direct competition — using the same hunting strategies to hunt the same prey.

Dingoes are a species [sic] of wolves, they are runners,” study researcher Borja Figuerido of Brown University said. “If the thylacines are ambushers, the hypothesis of the extinction of the thylacine outcompeted by dingoes is less probable.”

The elbow joint of the thylacine and the modern tiger, top, is wider and more rectangular than the dog-like wolf and fox, bottom, which are more toward the square. This suggests different styles of catching and subduing prey, cat-like or dog-like.

By looking at the elbow joint bones of the thylacine and 31 other mammals, the researchers noticed they resembled those of cats, which can rotate their paws upward to pounce and attack prey. Dogs and wolves don’t have this rotation capability.

“These anatomical characters reveal something about the hunting strategies of the thylacine. They are more ambushers than previously suspected,” Figueirido said. “Ambush predators usually manipulate the prey with the forearms, they have very good mobility. Running predators lack this ability, because the elbow is locked.”

The limited rotation of their arm bones makes dogs and wolves (including dingoes) faster runners, which changed their hunting behaviors. Dogs and wolves hunt in packs, following their prey over longer distances. The researchers determined that the thylacine was more of a solitary, ambush-style predator, similar to cats.

Marsupial mammals, found mainly in Australia and other areas of the Southern Hemisphere, are similar to placental mammals (such as humans, dogs and cats), but their evolution diverged from ours during the Cretaceous Period, the earliest example of a marsupial appearing about 125 million years ago.

The evolution of these two groups of mammals is an example of convergent evolution, where two separate groups in different locations evolve similar morphologies to deal with similar habitats. The thylacine was thought to be the marsupial equivalent, or ecomorph, of the wolf, with similar body size and eating habits.

Now, Figueirido said, “this designation will need to be revised.”

The study was published today (May 3) in the journal Proceedings of the Royal Society B: Biology Letters.

All of this information has been discussed before, so I don’t know why it’s making news now.  The convergence is in phenotype, not behavior or hunting style. I don’t think anyone ever made that claim.

The dingo outcompeted the thylacine because it was a pack-hunter. It was smarter, and it could attack both large and small prey.

It’s very similar to what happened to Hyaenadon when bear-dogs arrived in North America.

The notion of convergent evolution isn’t that animals from different ancestries evolve to be exactly the same. That’s a bizarre standard– and the one that seems to be put forth here.

But it is remarkable that the bulk of this animal’s adaptations– even if it were an ambush predator– closely resemble that of a dog.

It’s still convergent evolution. You’re never going to find convergent evolution that is 1:1 anywhere. Even with golden and marsupial moles, which are probably the closest anyone will ever get to that 1:1 convergence.

Convergent evolution can mean that only one trait is similar, such as the retractable claws in both modern cats and the thylacoleo, the extinct “marsupial lion,”  or the fact that koalas have the fingerprints, which are essentially a primate trait.

By this metric, the thylacine and the dingo are pretty strong examples of convergent evolution, for they share many traits, including the head shape, and the fact that both were digitigrade. Both use strong jaws that have evolved into the shape of a muzzle.

And a dingo isn’t a “species of wolf.”  Is is a subspecies that is sometimes called Canis lupus dingo or Canis lupus familiaris, which is probably more accurate, seeing as dingoes are more closely related to East Asian and Indonesian dog breeds than they are to wild wolves.