Paleontology remains an exciting field, where scientists learn more about dinosaurs and other ancient species every day. For instance, only recently have they determined that Earth’s most fearsome predators were likely adorned with flamboyant, feathery plumage rather than the more commonly imagined reptilian skin. It may be hard to top the latest discovery by researchers at the University of Birmingham, though: Chilesaurus diegosuarezi, a vegetarian cousin of t-rex that appears to be a hodgepodge of other species, not unlike a platypus.
“Chilesaurus can be considered a ‘platypus’ dinosaur because different parts of its body resemble those of other dinosaur groups due to mosaic convergent evolution. In this process, a region or regions of an organism resemble others of unrelated species because of a similar mode of life and evolutionary pressures. Chilesaurus provides a good example of how evolution works in deep time and it is one of the most interesting cases of convergent evolution documented in the history of life,” Martín Ezcurra, Researcher, School of Geography, Earth and Environmental Sciences, University of Birmingham.
The dinosaur, creatively named because it was found in Chile by researcher Diego Suarez, is categorized alongside theropods like velociraptor and tyrannosaurus and is the earliest-known example of an herbivorous theropod.
It’s appearance is indeed odd, with a disproportionately small head and feet that look more at home on some of the long-necked dinosaurs of the Jurassic age. In fact, when Suarez happened upon the specimen while studying rocks with his parents in the Toqui Formation in Aysén, south of Chilean Patagonia, he initially thought he’d happened upon the remains of several different dinosaurs. Since then, more than a dozen of the same species have been recovered.
For scientists, Chilesaurus represents the clearest example of something called “convergent evolution.” That is, the dinosaur’s seemingly disparate body parts are the result of adaptations unique to its environment, borrowed from sometimes unrelated species. It’s teeth, for example, resemble those of long-necked herbivores because they were selected as best-suited for the diet between those and Chilesaurus theropod cousins. It also has the stout hands and arms of allosaurus, and a pelvic girdle similar to those found on ornithischian dinosaurs.
For all of its weirdness, Chilesaurus piecemeal approach to evolution appears to have worked: The volume of recent excavations reveal that it was by far the most abundant species in southwest Patagonia 145 million years ago. Not bad for an odd-looking, vegetarian dinosaur that topped out at a little under 10 feet long but averaged the size of a turkey.
“Chilesaurus shows how much data is still completely unknown about the early diversification of major dinosaur groups. This study will force palaeontologists to take more care in the future in the identification of fragmentary or isolated dinosaur bones. It comes as false relationship evidence may arise because of cases of convergent evolution, such as that present in Chilesaurus,” said Ezcurra.