Fossils unearthed in Villa El Chocón, Argentina, have led paleontologists to identify a previously unknown sauropod species. Named Cienciargentina sanchezi, the dinosaur represents the earliest known member of the Rebbachisauridae family and shifts key perspectives on the Late Cretaceous dinosaur landscape in South America and beyond.
A Lost World Emerges From Patagonian Stone
The remains of Cienciargentina sanchezi were discovered at the base of the Huincul Formation, a geologic unit in the Neuquén Province known for its abundance of dinosaur fossils.
Dated to approximately 94 million years ago, the find places this new species firmly within the Cenomanian-Turonian stages of the Late Cretaceous. This timing is particularly significant because it positions Cienciargentina among the final diplodocoid dinosaurs before the group’s apparent extinction.
A Rebbachisaurid With A Twist
Rebbachisaurids are a subset of the broader diplodocoid lineage of long-necked, plant-eating sauropods. Unlike their more famous relatives like Diplodocus, many rebbachisaurids featured distinctive dental structures.
Some species had complex tooth batteries, a trait more commonly associated with hadrosaurs or ceratopsians. This newly identified species adds fresh evidence to the evolutionary timeline of the group.
As the authors note, “The rebbachisaurid materials from the Huincul Formation are especially relevant because, together with those of the Bajo Barreal Formation, correspond to the last indubitable diplodocoids before, presumably, they became completely extinct.”
Villa El Chocón’s Unique Fossil Record
The Huincul Formation, located in Patagonia, is central to understanding South American dinosaur evolution. Paleontologists have observed what they call a ‘faunal turnover‘ in this region during the mid-Cretaceous.
This shift affected not only sauropods, but a range of dinosaur groups. As researchers explain, “in Patagonia, particularly in the Huincul Formation, the hypothetical faunal turnover that occurred in the middle of the Cretaceous, which involved not only sauropods but other groups of dinosaurs, is observed, perhaps like nowhere else in South America”.
End Of The Diplodocoids, Rise Of The Titanosaurs
Following the Turonian stage of the Late Cretaceous, the global record shows a clear transition: diplodocoid dinosaurs vanish, and macronarian sauropods—especially titanosaurs—take their place in nearly all ecosystems. The emergence of Cienciargentina sanchezi in this transitional window offers critical insight into this pivotal evolutionary handover.
The authors stress the point: “from the Turonian onwards, sauropod communities are composed exclusively of macronarians, mostly titanosaurs.”
From Patagonia To The Global Dinosaur Record
The study, published in Cretaceous Research by María Edith Simón and Leonardo Salgado, provides new phylogenetic data that could refine the rebbachisaurid lineage. Beyond taxonomy, the discovery challenges established timelines and may prompt a reevaluation of dinosaur diversity in Gondwana during the Late Cretaceous.
Cienciargentina sanchezi not only fills a temporal gap, but also deepens understanding of ecological transitions during one of Earth’s most dynamic evolutionary periods.
Across South America, ongoing fossil discoveries continue to do more than illuminate the distant past—they reshape it. In this case, the bones of Cienciargentina may be whispering the final chapter of a dinosaur dynasty.
Source: The Daily Galaxy / Digpu NewsTex