Bicharracosaurus dionidei: 155-Million-Year-Old Patagonian Giant Bridges Two Famous Sauropod Lineages!

Paleontologists have announced Bicharracosaurus dionidei, a remarkable new sauropod from Patagonia whose 155-million-year-old fossils provide the first direct anatomical link between the two most iconic long-necked dinosaur lineages of the Late Jurᴀssic — the diplodocoids and the macronarians.

Described June 2026 in Scientific Reports, the partial skeleton was recovered from the Cañadón Calcáreo Formation in Chubut Province, Argentina. The specimen includes a complete neck with 13 vertebrae, a partial skull, and limb bones, revealing a 22-meter-long animal with a strikingly intermediate morphology.

The neck vertebrae combine the elongated, lightweight construction typical of diplodocoids with the more robust, pneumatized centra and complex laminae of macronarians. This “mosaic” anatomy proves the two groups diverged from a common ancestor later than previously thought and shared a transitional phase in southern Gondwana.

Lead author Dr. José Carballido (Museo Paleontológico Egidio Feruglio) states: “Bicharracosaurus is the missing link we have been searching for. It shows that the great sauropod radiation of the Late Jurᴀssic began in Patagonia and quickly spread across the globe.” The name honors both the local Tehuelche word for “long neck” and Argentine paleontologist Rodolfo D. D’Angelo.

The discovery also pushes back the origin of macronarian traits by at least 10 million years and suggests that the famous North American and African sauropods descended from Patagonian ancestors. As more material is prepared, Bicharracosaurus dionidei promises to redraw the family tree of the largest land animals that ever lived — proving that Patagonia was the true cradle of the long-necked giants.