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Marasuchus (meaning "Mara crocodile") is a genus of basal dinosauriform archosaur which is possibly synonymous with Lagosuchus. Both genera lived during the Late Triassic in what is now La Rioja Province, Argentina . Marasuchus contains a single species, Marasuchus lilloensis. Marasuchus lilloensis was originally designated as Lagosuchus lilloensis in 1972. It was considered a new species of Lagosuchus, a contemporary archosaur described the previous year. However, a 1994 study argued that the original material of Lagosuchus was undiagnostic. This would mean that Lagosuchus and its original species (Lagosuchus talampayaensis) could be considered nomen dubia. Specimens of Lagosuchus stored at a museum in San Miguel de Tucuman were considered to be more diagnostic than those of L. talampayensis, and thus they were given a new genus: Marasuchus. A 2019 study redescribed the original material of Lagosuchus and concluded that it was valid and not readily distinguishable from Marasuchus lilloensis. This suggests that Marasuchus lilloensis is a junior synonym of Lagosuchus talampayensis. Specimens referred to the genus Marasuchus possessed some, but not all of the adaptations which traditionally characterized dinosaurs. For example, its proportions indicate that it was likely bipedal as in early dinosaurs. Also, it shared certain specific characteristics with that group, most relating to the hip and the head of the femur. Nevertheless, it lacked certain dinosaur-like features such as a perforated acetabulum, and it had several plesiomorphic ("primitive") features of the ankle.
References
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- Romer, Alfred Sherwood (11 August 1972). "The Chañares (Argentina) Triassic reptile fauna. XV. Further remains of the thecodonts Lagerpeton and Lagosuchus". Breviora 394: 1–7. https://archive.org/details/cbarchive_40458_thechanaresargentinatriassicre1952/page/n2.
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