April 28, 2015 | David F. Coppedge

Platypus Dinosaur: A Vegetarian T. Rex

A new dinosaur from Chile is as unbelievable as the first reported platypus was to English zoologists: a crazy mix of animals.

Meet Chilesaurus: a theropod from Chile that looks like a combination of other dinosaurs: a small vegetarian T. rex with a long neck and two-fingered arms. Martin Ezcurra, one of the paleontologists who announced the find in Nature, explains in The Conversation how they identified this “weird and wonderful” dinosaur as a new species:

Its skull and neck look like those of primitive long-necked dinosaurs like Plateosaurus; the vertebrae resemble those of primitive meat-eating theropods such as Dilophosaurus; the pelvis is very similar to that of ornithischian dinosaurs such as Iguanodon; and the hand has only two well-developed fingers as in Tyranosaurus [sic] Rex, but with a longer arm.

However, there is no possibility that Chilesaurus is simply made up of different dinosaur bones, because we found four partial skeletons. Working partly in Buenos Aires, Argentina, and partly in Birmingham, our team compared the bones to those of other dinosaur groups. Eventually we decided through different analyses that Chilesaurus belongs to a completely unknown lineage of dinosaurs that acquired herbivore habits from carnivorous ancestors. Chilesaurus is the first herbivorous theropod (a lineage that includes mainly predatory dinosaurs) from the southern hemisphere.

Ezcurra likens it to the famous platypus that had some incredulous zoologists thinking at first it was a hoax. How can evolution explain such a mosaic of features?

A bizarre combination of features like that seen in Chilesaurus can also be seen in living animal species, such as the platypus, which is a mix of duck, beaver and otter. Some naturalists even considered it a hoax. But animals such as Chilesaurus and the platypus can be explained by an evolutionary process called convergence evolution, in which two unrelated species or groups acquire similar characteristics because of living in similar environments or having a similar behaviour.

Similarly, the bizarre anatomy of Chilesaurus will probably open a heated discussion about its relationships. Ultimately, the discovery reveals how much data is still completely unknown about dinosaurs and that there is still much waiting to be discovered in the rocks that tell the story of our planet in deep time.

The new dinosaur was also reported by Live Science, Science Daily, and Science Magazine, complete with colorful artwork.

How do they know that carnivorous dinosaurs did not get their meat-eating habit from vegetarian ancestors? How do they know the coloration of its skin? If there is “much data still completely unknown about dinosaurs” then we don’t need the fake confidence about this one, or about “the story of our planet in deep time.” Did Ezcurra see deep time? Did he see “convergence evolution”? No. He saw beautifully designed bones embedded in rocks. Spare us the storytelling.

For more on the improbability of convergent evolution, see the 4/20/15 entry.




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