For 155 million years, enormous dinosaur bones lay hidden in the rock of Patagonia. Then a shepherd named Dionide Mesa noticed something unusual on his farm in Chubut Province, Argentina. Twenty-five years later, scientists have named the creature he found: Bicharracosaurus dionidei.
This long-necked dinosaur was roughly 20 metres long and lived during the Jurassic period. Researchers have recovered more than 30 vertebrae from its neck, back and tail, plus ribs and part of its pelvis. The skeleton shows this was a fully grown adult.
What makes Bicharracosaurus remarkable is its unusual anatomy. Its back vertebrae resemble those of Diplodocus from North America, but other parts look like Giraffatitan from Africa. After careful analysis, scientists confirmed it was a brachiosaurid, a family of enormous dinosaurs.
The discovery is historically important. For decades, scientists knew Late Jurassic sauropods mainly from the Northern Hemisphere. South America was largely unknown. Bicharracosaurus is the first brachiosaurid ever found from the Jurassic of South America. It proves these giant dinosaurs walked through what is now southern Argentina.
The research involved scientists from Germany and Argentina. The bones now rest in the Museo Paleontológico Egidio Feruglio in Trelew. The dinosaur's species name, dionidei, honours Mesa, the shepherd who first saw it.