INAWENTU

By the mid-Late Cretaceous, many classic herbivorous dinosaur lineages had vanished from South America, but an unexpected sauropod stepped into a role once dominated by others. Inawentu oslatus, described from the Bajo de la Carpa Formation of Patagonia, is a titanosaur whose broad, flaring snout recalls the rebbachisaurids—diplodocoid sauropods known as classic low-level browsers, sweeping their wide jaws across ground-hugging vegetation. By the time Inawentu lived, true rebbachisaurids were gone from the region, yet here was a titanosaur echoing their feeding style through convergent evolution, where unrelated animals independently arrive at similar solutions to similar ecological problems.

Its skeleton adds another layer of surprise. Inawentu is one of the few titanosaurs known from a complete neck, a rare stroke of preservation in a group usually represented by scattered vertebrae. Even more striking, that neck contained only twelve vertebrae, the lowest count known for any titanosaur. Despite its short series, the vertebrae are highly modified, with joint structures interpreted by researchers as enabling multidirectional movement across the entire neck. This suggests a compact but flexible feeding reach—an anatomical configuration consistent with, though not direct proof of, a low-browsing lifestyle.

A 2024 phylogenetic analysis by Filippi and colleagues added yet another twist. They recovered Inawentu within a previously unrecognized cluster of square-jawed titanosaurs, a lineage they deliberately left unnamed and referred to simply as "Clade A". This hints that Inawentu was not a lone experiment but part of a broader, previously overlooked radiation of titanosaurs exploring unusual skull shapes and feeding strategies—which, funnily enough, had contributed to the previous owners of that very design becoming extinct.