MEANING: Chile lizard
PERIOD: Late Jurassic
CONTINENT: South America
Chilesaurus shows a bizarre mix of traits from various dinosaur groups. While nebulous taxonomic placement is usually the result of scant fossil remains, Chilesaurus has an almost completely known skeleton from multiple specimens. Originally thought to be a basal theropod, it had enlongated forward-facing facing teeth. These indicated that it was herbivorous, and suggested it could be a sauropodomorph. The pelvic arrangement closely resembles ornithischian dinosaurs, further confusing its evolutionary lineage. Other baffling traits include the fact that it had a beak, two-fingered hands, and weight-bearing hallux.
Chihlesaurus is from the Jurassic. The Jurassic is a geologic period that spanned from the end of the Triassic, 201 million y ears ago, to the beginning of the Cretaceous, 145 million years ago. It is the middle period of the Mesozoic Era. The start of the Jurassic was marked by the major Triassic-Jurassic extinction event. The end, however, has no clear boundary with the Cretaceous. By the beginning of the Jurassic, Pangea had begun rifting into two landmasses: Laurasia and Gondwana, and the climate was warm with no ice caps. Life on land was dominated by dinosaurs, and the first birds appeared, evolving from a branch of theropods. The oceans were inhabited by marine reptiles, while pterosaurs were the dominant flying vertebrates.
Chilesaurus is an enigma. Chilesaurus presents a taxonomic puzzle intriguing to paleontologists. Originally placed within the tetanurae within theropoda, its exact placement within this group has been a subject of debate. Subsequent analysis suggested a herbivorous diet, raising questions about its classification. Some researchers propose Chilesaurus as a basal member of the clade Ornithischia due to its peculiar combination of features resembling both theropods and ornithischians. However, others maintain its placement within theropoda. Despite ongoing discussions, Chilesaurus stands as a prime example of the complexity of dinosaur taxonomy and the continual refinement of our understanding of prehistoric life.
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