They’re Calling This Adorable Creature The ‘Platypus’ Of Dinosaurs

Illustration for article titled They’re Calling This Adorable Creature The ‘Platypus’ Of Dinosaurs

Meet Chilesaurus diegosuarezi, a newly described dinosaur discovered by a seven-year-old boy in Chile. The theropod was related to famous meat-eaters like T. rex, but researchers think it was a vegetarian. Stranger still: It possessed a mixture of anatomical features unlike anything researchers have seen before.


Illustrations by paleoartist Gabriel Lio via University of Birmingham

This new dinosaur is not only a new species, it’s an entirely new genus. Called Chilesaurus diegosuarezi, it’s named after the country where it was discovered and in honor of the boy, Diego Suárez, who found the remains while visiting the Toqui Formation in Aysén with his parents. The bones of several individuals, including four complete skeletons, were analyzed by paleontologists from the University of Birmingham and the Bernardino Rivadavia Natural Sciences Museum, in Buenos Aires, Argentina. The results of their work now appear in the journal Nature.

Illustration for article titled They’re Calling This Adorable Creature The ‘Platypus’ Of Dinosaurs

Chilesaurus was a theropod, a group of dinos that included the meat-eating Velociraptor, Carnotaurus and Tyrannosaurus. Until this discovery, the only known plant-eating theropods were those closely related to birds.

“The discovery of Chilesaurus lends support to the interpretation that dietary diversification towards herbivory was more common-place among basal theropods than previously thought,” write the researchers in the study.

Chilesaurus is interesting in other ways as well. Dating back 145-million years to the Jurassic Period, it was about the size of a turkey, with some individuals growing as long as 10 feet (3 meters). It featured a proportionally small skull and its feet resembled those of more primitive, long-necked dinosaurs. It’s also the first complete Jurassic-era dinosaur ever found in Chile.

Illustration for article titled They’re Calling This Adorable Creature The ‘Platypus’ Of Dinosaurs

Chilesaurus possesses physical characteristics similar to those observed in a variety of other species—an observation that led paleontologists to refer to the dinosaur in a statement as a kind of “platypus.” Indeed, this creature is an excellent example of convergent evolution at work, or in this particular case, an example of mosaic convergent evolution.


Chilesaurus represents an extreme case of mosaic evolution among dinosaurs, owing to the presence of [certain] dental, cranial and postcranial features,” write the scientists.

Mosaic convergent evolution happens when a single species evolves multiple characteristics that also appear independently across different species. For example, the newly described dinosaur had strong forearms like the Allosaurus, but a pelvis similar to ornithischian dinosaurs, such as Stegosaurus and Ceratopsians.


Chilesaurus illustrates how much relevant data on the early diversification of major dinosaur clades remain unknown,” conclude the authors. “It also provides an important cautionary benchmark in our attempts to gain a reliable view of the overall evolutionary history of Dinosauria.”

Read the entire study at Nature: “An enigmatic plant-eating theropod from the Late Jurassic period of Chile”.


Image credits: University of Birmingham

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Zach Miller

Having now read the paper (and skimmed the supplementary info), I can attest to the bizarreness of Chilesaurus. It's got a mix of characteristics from all over the Dinosauria but also from different tiers of Theropoda. I'm particularly flummoxed by the structure of the hand. It is functionally didacyl, as in tyrannosaurs, but the first digit has a distinct "twist" that is characteristic of basal sauropodomorphs. Similarly, the feet are functional tetradactyl as in basal saurischians and, later, therizinosaurs.

The pubis resembles that of ornithischians in that it is rod-like and points the wrong way. The ischium is fairly robust and elongate, also like ornithischians. This suggests an herbivorous diet (the pubis turned back to allow an expanded gut).

The skull is actually not well-represented. The tooth-bearing bones, some pieces of the top of the skull, and some pieces of the back of the skull were found. All point to a short-snouted skull with chisel-like dentition and a large eye socket. The premaxillae bones are rugose, implying the presence of a beak (although I note, personally, this is not a sure thing).

And let's not overlook that this was a good-sized animal—even without a complete tail, the largest specimen is estimated to be just over three meters long.

It shakes out to be a basal tetanurine in phylogenetic analysis. I do not advocate the presence of feathers until we have feathers on non-coelurosaur tetanurines.