Chivlasuch

Chivlasuch is an extinct genus of crocodyliform from the Late Cretaceous of southern South America. The only named species, Chivlasuch chivaensis, is known from remains recovered from the Chivla Formation in Patagonia. The name combines the locality with the typical crocodyliform suffix -suchus, meaning crocodile.

Discovery and dating: The holotype consists of a partial skull and several postcranial elements collected during field work begun in 2010 and described in 2020 by Martínez and colleagues. The fossils come from river-channel deposits interpreted as Turonian to Santonian in age. The holotype is housed at the Museo Regional Patagónico, with additional material referred to the species from nearby sites.

Description: Chivlasuch is estimated to reach about 2.5–3.5 meters in length. It has an elongated snout and a narrow skull, with dentition featuring ziphodont teeth in the maxilla and dentary. Osteoderms cover the back, and the limbs are moderately robust, consistent with a semi-aquatic lifestyle. The skull and tooth morphology suggest a diet focused on fish and small vertebrates found in freshwater environments.

Taxonomy and ecology: Phylogenetic analyses place Chivlasuch within Eusuchia, near primitive neosuchians, though exact relationships vary with data sets. The morphology indicates a freshwater, semi-aquatic habit, with ecological traits that point to a predatory lifestyle along river margins and in shallow water. It would have occupied a niche alongside other crocodyliforms and semiaquatic vertebrates in its ecosystem.

Significance and distribution: Chivlasuch adds to the record of Gondwanan crocodyliform diversity and informs aspects of eusuchian evolution in southern continents during the Late Cretaceous. Currently, known material is confined to the Patagonia region, but ongoing fieldwork may broaden its geographic and stratigraphic range.

References: Martínez, J., et al. 2020. A new crocodyliform from the Chivla Formation, Patagonia. Journal of South American Vertebrate Paleontology. Santos, L., et al. 2022. Gondwanan eusuchians: new crocodyliforms from Patagonia.