Palaeontologists Discover New Long-Necked Dinosaur in Patagonia

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A German-Argentine team of paleontologists led by dinosaur expert Oliver Rauhut, professor at LMU's Department of Earth and Environmental Sciences and Chief Conservator at the Bavarian State Collection for Palaeontology and Geology, has discovered a new long-necked dinosaur: Bicharracosaurus dionidei lived in Argentina during the Late Jurassic period, approximately 155 million years ago.

Long-necked dinosaur fossils from the Jurassic period in the Southern Hemisphere are rare, so the new fossil contributes to a better understanding of the evolution of these giant herbivores on the southern continents. The researchers have now published their findings in the journal PeerJ.

With their massive bodies, long necks and tails, and tiny heads, long-necked dinosaurs (sauropods) embody the image of a typical dinosaur for many people. Sauropods include the largest known land animals of all time, with body lengths of up to 40 meters; the best-known examples are Diplodocus and Brachiosaurus.

The new long-necked dinosaur from southern Argentina is not quite as large: the researchers estimate the length of Bicharracosaurus dionidei to be around 20 meters. Parts of its spine were recovered, including over 30 neck, back, and tail vertebrae, several ribs, and a fragment of the pelvic bone. The structure of the bones indicates that the remains belong to an adult animal that lived on the southern continent of Gondwana around 155 million years ago.

The fossil is interesting to researchers in many ways: it combines a mix of characteristics from both brachiosaurids and diplodocids. For instance, some skeletal parts of Bicharracosaurus show similarities to the African Giraffatitan, a brachiosaurid from Tanzania. Other features, particularly those of its dorsal vertebrae, resemble Diplodocus and its closest relatives from North America.

“Our phylogenetic analyses of the skeleton indicate that Bicharracosaurus dionidei was related to the Brachiosauridae, which would make it the first Brachiosauridae from the Jurassic of South America,” says LMU doctoral student Alexandra Reutter, the study’s first author. The paleontologist analyzed the remains of the new dinosaur as part of her doctoral thesis.

“Our knowledge of the evolution of sauropods from the Late Jurassic has so far been based almost entirely on numerous fossil findings from North America and other sites in the Northern Hemisphere. For a long time, there was only a single significant site on the southern continents, in Tanzania. The fossil site in the Argentine province of Chubut, from which Bicharracosaurus dionidei originates, provides us with important comparative material, allowing us to continuously supplement and reevaluate our understanding of the evolutionary history of these animals, particularly in the Southern Hemisphere,” says leader of the study and dinosaur expert Oliver Rauhut.

The first remains of Bicharracosaurus dionidei were discovered by shepherd Dionide Mesa on his farm, the researchers chose the species name of the new dinosaur in his honor. The genus name is derived from “bicharraco,” colloquial Spanish for “big animal”. The fossil comes from the Cañadón Calcáreo rock formation in the Patagonian province of Chubut and is housed at the Museo Paleontológico Egidio Feruglio in Trelew, Argentina.

Reutter A, Carballido JL, Windholz GJ, Pol D, Rauhut OWM.: Bicharracosaurus dionidei, gen. et sp. nov., a new macronarian (Dinosauria, Sauropoda) from the Late Jurassic Cañadón Calcáreo Formation of Argentina and the problematic early evolution of macronarians. PeerJ 2026