Campananeyen.

(Braincase of Campananeyen fragilissimus [scale bar = 5 cm], from Lerzo et al., 2024)

Meaning of name: Campananeyen = Las Campanas air [in Mapudungun]; fragilissimus = the most fragile [in Latin]

Age: Late Cretaceous (Cenomanian)

Where found: Candeleros Formation, Neuquén, Argentina

How much is known: Partial skeleton of one individual including parts of the skull, some vertebrae, the hips, and the feet.

Notes: Campananeyen was a rebbachisaurid, a group of sauropods best known for including the bizarre Nigersaurus from the Early Cretaceous of Niger. The preserved portions of the skull in the Campananeyen type specimen had been previously described in a 2016 paper, but were left unnamed at the time. Like in birds, much of the skeleton in sauropods was hollowed out by a complex network of air sacs extending from their respiratory system. In Campananeyen, this hollowing appears to have been particularly extensive, as it exhibits air spaces in the braincase and hip bones that have not been observed in other rebbachisaurids.