Huayracursor jaguensis: The Oldest Long-Necked Sauropod Ancestor from the Andes That Rewrites the Dinosaur Family Tree

Paleontologists have unveiled Huayracursor jaguensis, the earliest known sauropodomorph with clear signs of neck elongation and increased body size, discovered high in the Andes of northwestern Argentina. This 230-million-year-old fossil from the Late Triᴀssic Carnian stage pushes back the origins of the iconic long-necked giants like Argentinosaurus by millions of years and forces a major revision of early dinosaur evolution.

The nearly complete skeleton was excavated in 2023–2024 from the newly identified Santo Domingo Formation at Quebrada Santo Domingo, La Rioja Province. Published October 15, 2025, in Nature by Martín Hechenleitner and an international team, the specimen reveals a medium-sized herbivore with elongated cervical vertebrae—an “incipient” long neck—far exceeding the short-necked, small-bodied Carnian relatives previously known.

Huayracursor (“wind runner”) combines primitive traits with advanced features that bridge the gap between early Triᴀssic dinosaurs and the mᴀssive Norian sauropodomorphs. Its discovery in a remote Andean basin also documents one of the most complete Carnian dinosaur skeletons ever found, alongside rhynchosaurs, cynodonts, and aetosaurs.

This find demonstrates that key sauropod traits—larger bodies and longer necks—emerged synchronously at the very dawn of the dinosaur era, reshaping our understanding of how the largest land animals in Earth’s history first evolved. The holotype is now housed at Argentine insтιтutions, promising further surprises as the new basin is explored.