Inawentu (meaning "imitator") is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous (Santonian age) Bajo de la Carpa Formation of Argentina. The genus contains a single species, I. oslatus, known from a partial articulated skeleton including the skull. The square-shaped jaw of Inawentu demonstrates convergent characteristics with rebbachisaurids.
Discovery and naming The Inawentu holotype specimen, MAU-Pv-LI-595, was discovered in sediments of the Bajo de la Carpa Formation (Neuquén Group) near Rincón de los Sauces in Neuquén Province, Argentina. The specimen consists of a partial articulated skeleton, including a nearly complete skull, all of the vertebrae from the atlas to the end of the sacrum (comprising twelve cervical, ten dorsal, and six sacral vertebrae), and both ilia. MAU-Pv-LI-595 is one of the few known titanosaur specimens to preserve a complete neck. In 2016, the find was presented at a conference in Argentina. In 2023, Filippi et al. announced Inawentu oslatus as a new genus and species of titanosaurian sauropod based on these fossil remains in a non-final preprint. The description was finalized the following year. The generic name, "Inawentu", is derived from a Mapundungun word meaning "mimic" or "imitator". The specific name, "oslatus", combines the Latin words "os", meaning "mouth" and "latus", meaning "broad".
Description
The skull of Inawentu showed several convergent similarities to rebbachisaurids such as Nigersaurus, such as a wide, squared-off snout that was deflected strongly downward. The neck of Inawentu consisted of only twelve vertebrae, fewer than in any other known titanosaur. MCT 1487-R, a specimen possibly referable to Uberabatitan, has thirteen, Futalognkosaurus has fourteen, and Rapetosaurus has seventeen. Thus, Inawentu may have had a proportionately shorter neck than most titanosaurs. The centra and neural arches of the neck and back vertebrae are highly modified, which suggests that the neck would have been capable of multidirectional movement. As in most titanosaurs, there were ten dorsal and six sacral vertebrae. The hips were narrower than in Saltasaurus and Neuquensaurus.
Classification Filippi et al. (2024) recovered Inawentu as the sister taxon to Antarctosaurus in a clade also containing the coeval Bonitasaura. This clade was found to be a member of a previously unrecognized clade of square-jawed eutitanosaurs, which the researchers referred to as "Clade A". Their results differ from those of many previous studies, which typically found a close relationship between lognkosaurs and rinconsaurs. However, similar results were previously reported by Gorscak and O'Connor in 2016. The results of this phylogenetic analysis are shown in Topology A below. In 2026, Filippi and colleagues described Yeneen, another titanosaur from the Bajo de la Carpa Formation. Using a novel phylogenetic matrix developed from their description of Inawentu, the researchers recovered a notably different arrangement of taxa, with the Inawentu + Antarctosaurus as the sister to Brasilotitan, and this clade instead placed as a basal lineage of the Colossosauria (the clade including the Lognkosauria). Yeneen was instead placed within 'Clade A'. These results are displayed in Topology B below.
Paleoecology The Bajo de la Carpa Formation, where Inawentu was found, preserves an ecosystem including other titanosaurs, including other members of "Clade A": Bonitasaura, Rinconsaurus, and Overosaurus.
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