The Tasmanian tiger’s closest living relatives are the numbat and the members of the family Dasyuridae, a group that includes the Tasmanian devil, quolls, and dunnarts. Genomic analysis places the thylacine’s own family, Thylacinidae, as the sister lineage to both Dasyuridae and Myrmecobiidae (the numbat’s family), meaning these three families share a common ancestor that no other marsupial group does.1PubMed Central. A Chromosome-Scale Hybrid Genome Assembly of the Extinct Tasmanian Tiger (Thylacinus cynocephalus) That answer surprises many people, because the animal the thylacine most resembles in body shape and skull form is the gray wolf, a placental mammal separated from marsupials by roughly 160 million years of evolution.
Why Numbats and Tasmanian Devils, Not Wolves
Despite its canine appearance, the thylacine was a marsupial, part of the order Dasyuromorphia, which contains all of the carnivorous and insectivorous marsupials of Australasia. Within that order, three families matter here. Thylacinidae contained the thylacine and its extinct relatives. Dasyuridae is a large family of small to medium-sized predators, from the stocky Tasmanian devil down to mouse-sized planigales. Myrmecobiidae holds just one living species, the numbat, a small termite-eating marsupial found in Western Australia. Together, Thylacinidae sits as the closest sister group to both Dasyuridae and Myrmecobiidae.1PubMed Central. A Chromosome-Scale Hybrid Genome Assembly of the Extinct Tasmanian Tiger (Thylacinus cynocephalus)
So if you had to pick a single living species as the thylacine’s closest relative, the numbat and the Tasmanian devil both have roughly equal claim. Neither is dramatically closer than the other; the three families diverged from one another in the deep past, and whether Myrmecobiidae or Dasyuridae sits slightly closer to Thylacinidae depends on which dataset and which gene regions you consult. What all analyses agree on is that these three families form a clade to the exclusion of other marsupials. The thylacine is more closely related to a dunnart than it is to a kangaroo, a koala, or a wombat.
The Wolf Lookalike Problem
The thylacine and the gray wolf are one of the most famous examples of convergent evolution in all of biology. Place their skulls side by side and even trained anatomists have to look carefully to tell them apart, despite the two lineages having diverged around 160 million years ago.2PubMed Central. Ontogenetic origins of cranial convergence between the extinct marsupial thylacine and placental gray wolf The body proportions are strikingly similar too: long snout, lean build, digitigrade stance, a stiff tail. Early European settlers in Tasmania called it the “marsupial wolf” for good reason.
This resemblance is purely the result of natural selection converging on similar solutions for a similar ecological role, not shared ancestry. The thylacine evolved to be a pursuit predator in an environment where no placental carnivores existed, and it ended up looking like one. The gray wolf lineage did the same thing on the other side of the planet. When two unrelated animals face similar selective pressures over millions of years, they can wind up with eerily similar anatomy.
Interestingly, when researchers actually tested which canids the thylacine converged with most closely in terms of functional ecology, it wasn’t the gray wolf that came out on top. Convergence analyses found the strongest match between the thylacine and African jackals and South American “foxes,” with lesser support for the coyote and red fox.3PubMed Central. Functional ecological convergence between the thylacine and small prey-focused canids This makes sense given the thylacine’s body size, which was closer to a medium-sized canid than to a full-grown gray wolf. The “marsupial wolf” nickname, while evocative, probably overestimates the ecological similarity. In practice, the thylacine may have functioned more like a jackal or coyote.
How Two Unrelated Animals Built the Same Skull
The skull convergence between the thylacine and the wolf has been studied at a genetic level, and the findings are remarkable. Researchers identified candidate regulatory elements in the genome that control craniofacial development and compared how those elements evolved in the thylacine versus the wolf. They found abundant signatures of convergent positive selection, meaning both lineages independently experienced accelerated evolutionary change in the same regulatory DNA regions.4PubMed Central. Widespread cis-regulatory convergence between the extinct Tasmanian tiger and gray wolf
Those accelerated regions were enriched near genes involved in two major signaling pathways that shape the skull during embryonic development: TGF-beta and BMP signaling. Both pathways play critical roles in establishing the boundaries and identities of craniofacial tissues. The implication is that convergent evolution wasn’t just happening at the level of outward appearance; it was happening at the level of gene regulation. The thylacine and the wolf arrived at similar skulls in part by tweaking similar molecular switches during development.4PubMed Central. Widespread cis-regulatory convergence between the extinct Tasmanian tiger and gray wolf
A separate study looking at skull development from juvenile to adult stages found that the convergence between thylacine and wolf skulls followed patterns of mosaic evolution, with convergence concentrated in bone groups that share the same embryonic tissue origin, particularly tissues derived from neural crest cells. Neural crest cells are critical for skull patterning, and the researchers found homoplasy (independent evolution of similar traits) in the gene regulatory networks associated with those cells.2PubMed Central. Ontogenetic origins of cranial convergence between the extinct marsupial thylacine and placental gray wolf Put simply, the thylacine and the wolf didn’t just end up looking alike; they appear to have gotten there through overlapping developmental routes, which is a stronger form of convergence than scientists initially expected.
The Thylacine Family Tree Before the Last Survivor
The thylacine we know from photographs and museum specimens was the last of a once-diverse family. Thylacinidae had multiple genera stretching back millions of years, and the fossil record reveals a range of body sizes and ecological roles that the final species, Thylacinus cynocephalus, doesn’t fully represent.
One of the best-studied early thylacinids is Nimbacinus dicksoni, known from the Miocene of northern Australia. Its teeth were relatively primitive for the family: the stylar cusps, stylar shelf, and paracone were more reduced than in dasyurids (its cousins), but the elongated shearing blade on the upper molars that defines the later thylacine hadn’t developed yet. Its lower teeth still retained small metaconids and a relatively unreduced talonid basin, features that the modern thylacine had lost in its push toward a more specialized meat-slicing dentition.5PubMed Central. The pre-Pleistocene fossil thylacinids (Dasyuromorphia: Thylacinidae) and the evolutionary context of the modern thylacine In other words, early thylacinids were less specialized carnivores than the animal that went extinct in 1936. The family gradually evolved toward a more exclusively predatory lifestyle over millions of years.
This is worth knowing because it reframes the thylacine not as a one-off oddity but as the final representative of a long evolutionary lineage. The family had been evolving in Australia for tens of millions of years, and the last species was simply the one that happened to still be around when Europeans arrived.
How Its Brain Compared to the Tasmanian Devil’s
If the Tasmanian devil is one of the thylacine’s closest living relatives, you might expect their brains to be organized in similar ways. Researchers investigated this by reconstructing the cortical projection maps of preserved thylacine and Tasmanian devil brains using white matter tracing techniques. The results showed real differences. The thylacine’s cortex had a more modularized pattern of basal ganglia projections, while the devil’s cortex was dominated by the putamen. Similarly, the thalamic projections had a more orderly topography in the thylacine than in the devil.6PubMed Central. Reconstruction of the Cortical Maps of the Tasmanian Tiger and Comparison to the Tasmanian Devil
What does that mean in practical terms? A more modularized cortex is often associated with more complex or specialized behavior. The thylacine was an active pursuit predator that needed to track prey, coordinate complex movements, and navigate large home ranges. The Tasmanian devil, by contrast, is a more generalized scavenger-predator with a powerful bite but less reliance on pursuit. Their brain organization reflects those different ecological lifestyles, even though they share a relatively recent common ancestor. Being close relatives doesn’t mean being neurological clones.
Bite Force and Hunting Style
One persistent question about the thylacine is what it actually ate and how it killed its prey. Bite force studies found that the thylacine had a relatively high bite force quotient, a measure that adjusts raw bite strength for body size. The values put it in the range of large-prey specialists, alongside animals like the dire wolf, suggesting that despite its medium body size, the thylacine was capable of taking relatively large prey.7PubMed Central. Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa
This sits in some tension with the ecological convergence data showing the thylacine most closely resembled jackals and small canids ecologically. One plausible reconciliation is that the thylacine was a flexible predator: capable of taking larger prey when available, but often targeting smaller animals in practice. Its relatively fragile skull may have constrained how often it could safely take on large prey, even if its bite force was theoretically sufficient. Early film footage of a captive thylacine shows a wide gape that looks impressive, but gape width and bite force are different things, and looking scary doesn’t mean the skull could withstand the stress of bringing down large wallabies on a regular basis.
What Happened on the Mainland
Thylacines once roamed the entire Australian mainland. They disappeared from the continent around 3,000 to 3,500 years ago, surviving only on the island of Tasmania, where they lasted until the twentieth century. The timing of their mainland disappearance coincides with the arrival of the dingo, which was introduced to Australia by seafaring people and established wild populations. The dingo filled a very similar ecological niche: a medium-sized pursuit predator targeting small to medium prey.
Research supports the hypothesis that direct killing by the larger dingo contributed to the thylacine’s mainland extinction, though the picture is complicated. Modeling work found that dingoes, being somewhat larger and competing for the same resources, could have driven thylacines out through a combination of direct aggression and competition.8PLoS ONE. Could Direct Killing by Larger Dingoes Have Caused the Extinction of the Thylacine from Mainland Australia? But attributing the mainland extinction to just one cause is problematic, because the dingo’s arrival coincided with intensification of the human economy, including changes in hunting technology and growing human populations.8PLoS ONE. Could Direct Killing by Larger Dingoes Have Caused the Extinction of the Thylacine from Mainland Australia? Climate shifts during this period may also have played a role.9World Archaeology. The impact of the dingo on the thylacine in Holocene Australia
Tasmania, being an island that dingoes never reached, became a refuge. But isolation came at a genetic cost.
The Genetic Bottleneck That Preceded Final Extinction
When researchers sequenced mitochondrial DNA from museum-preserved thylacine specimens collected over a roughly 60-year span, they found strikingly little variation. All sequenced specimens were on average 99.5% identical in the mitochondrial control region, a stretch of DNA that normally accumulates mutations relatively quickly and should show at least moderate diversity in a healthy population.10PubMed. Limited genetic diversity preceded extinction of the Tasmanian tiger The Tasmanian thylacine population appears to have had very low genetic diversity well before European settlers began actively persecuting them.
The likely explanation is geographic isolation. Tasmania was cut off from the mainland by rising sea levels roughly 10,000 years ago, trapping a relatively small thylacine population on the island.10PubMed. Limited genetic diversity preceded extinction of the Tasmanian tiger That population then shrank or stagnated over millennia, losing genetic variation through drift. By the time the bounty system in the 1800s accelerated the decline, the species was already genetically impoverished. This matters for understanding the extinction: the thylacine wasn’t just hunted to death from a position of strength. It was a genetically vulnerable population pushed over the edge. The last known individual died in Hobart Zoo in 1936.
De-Extinction and the Role of the Closest Relatives
The thylacine’s closest relatives aren’t just an academic curiosity. They are central to the most ambitious project in de-extinction biology. Researchers aiming to bring back the thylacine, or something functionally close to it, need a living host species whose genome can serve as a scaffold. Because the numbat and the dasyurids are the thylacine’s nearest kin, they are the obvious candidates for providing both a reference genome and, potentially, egg cells or a surrogate womb.
A chromosome-scale genome assembly of the thylacine published in 2022 used modern dasyurid genomes as comparison frameworks, exploiting the close phylogenetic relationship to help place thylacine genetic sequences in the right chromosomal context.1PubMed Central. A Chromosome-Scale Hybrid Genome Assembly of the Extinct Tasmanian Tiger (Thylacinus cynocephalus) The idea behind de-extinction is conceptually straightforward, even if technically daunting: take the genome of the closest living relative, identify the differences between it and the thylacine, and then edit the living genome to match. The fewer the differences, the fewer edits needed, which is why the choice of closest relative matters so much.
The fat-tailed dunnart, a tiny dasyurid about the size of a mouse, has been proposed as a practical surrogate because its reproductive biology is well studied and its small size makes laboratory work easier. Whether a dunnart-based approach could produce an animal that genuinely functions like a thylacine in the wild remains deeply uncertain. The gap between a chromosome-scale genome and a living, breathing marsupial predator with the right instincts, microbiome, and social behavior is enormous. But without the close phylogenetic relationship between Thylacinidae and Dasyuridae, the project wouldn’t even be conceptually possible.
Why the Numbat Gets Overlooked
When people hear that the Tasmanian devil is one of the thylacine’s closest living relatives, it feels intuitive. Both are Tasmanian, both are carnivorous marsupials, both have a similar rugged mystique. The numbat, by contrast, seems like an odd match. It is a small, delicate, striped animal that eats termites. It lives in eucalyptus woodlands in southwestern Australia and is itself critically endangered, with a wild population of only a few thousand.
But phylogenetic closeness has nothing to do with lifestyle similarity. The numbat’s family, Myrmecobiidae, diverged from the thylacine’s family in the deep past, as did the dasyurids. All three families then went their separate ecological ways: the thylacines became large predators, the dasyurids diversified into everything from devils to planigales, and the numbat’s lineage became hyper-specialized termite eaters. The numbat even has unusual features for a marsupial, like being active during the day and having a reduced or absent pouch, that reflect its own evolutionary trajectory. None of that changes the underlying genetic relationship.
The numbat’s conservation status adds an ironic wrinkle. Efforts to de-extinct the thylacine rely partly on understanding the genomes of its closest relatives, but one of those closest relatives is itself at serious risk of extinction. Conservation biologists have pointed out that the resources devoted to thylacine de-extinction could, in some alternate universe, go directly to saving the numbat, a living relative that fills its own ecological role and is slipping away right now. That tension between reviving the dead and protecting the living isn’t unique to this case, but the thylacine-numbat relationship puts it in unusually sharp focus.