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New round in the controversial battle over dinosaur genealogy

NOBU TAMURA / WIKIMEDIA COMMONSThe dinosaur family tree continues to divide opinion among experts. A team of nine paleontologists from South America and Europe recently published a study in response to a controversial paper from March this year that proposed an alternative phylogenetic classification for some of the most important dinosaur branches (Nature, November 2). The new article analyzed data from the controversial paper by three English researchers from the University of Cambridge and the Natural History Museum in London, and recalculated the genetic relationships between the earliest known dinosaur lineages. “It is still too early to rewrite the dinosaur textbooks,” says paleontologist Max Langer, from the Ribeirão Preto campus of the University of São Paulo (USP), the lead author of the responding study and coordinator of the initiative that reevaluated the ideas proposed by the British trio. Langer and eight colleagues worked with the same data set that the English scientists used to formulate their alternative phylogeny—457 anatomical characteristics from 74 dinosaur species—and concluded that the traditional genealogy is still the most likely. The classic division separates the dinosaurs into two large groups: the Ornithischia, which includes mostly herbivorous species with pelvis structures similar to birds, as well as horns, armor, or duck-like beaks; and the Saurischia, which includes the theropods (bipedal carnivores) and sauropods (large herbivores, usually quadrupeds, with elongated necks), with hip anatomies similar to lizards. The alternative phylogenetic classification proposed by the British group removed the theropods from the Saurischia group and classified them alongside the Ornithischia in a new group called the Ornithoscelida. The responding study also supports the prevailing belief that dinosaurs originated in the southern hemisphere, probably in South America, something that the English researchers questioned in their March 2017 article.