Scientists described a new predatory dinosaur from Argentina after recovering a partial skeleton with powerful forelimbs and large claws. Named Joaquinraptor casali, the animal belonged to the megaraptorans, a still poorly understood group that lived in parts of South America, Australia and Asia.
The specimen was found in the Lago Colhué Huapi rock formation in Patagonia. Researchers uncovered part of the skull together with bones from the arms, legs and tail. Distinctive anatomical features led them to conclude that the fossils represented a new species rather than another known member of the group. The research appeared in Nature Communications.
Joaquinraptor casali may have reached about 23 feet, or 7 metres, in length. It lived between 66 million and 70 million years ago, placing it close to the end of the age of non-avian dinosaurs. Analysis indicated that the individual was at least 19 years old when it died, although the cause of death could not be determined.
Megaraptorans are known for elongated skulls and unusually strong, enlarged claws. Their hunting methods and precise evolutionary relationships remain uncertain because many previous fossil discoveries were incomplete. Federico Agnolin of the Argentine Museum of Natural Science Bernardino Rivadavia, who was not involved in the research, said the new skeleton filled an important gap because it is among the most complete examples yet recovered.
One detail may help scientists investigate the animal's diet. A front-leg bone from an ancient crocodile relative was pressed against the dinosaur's jaws. The association does not by itself establish exactly how the crocodile relative died or whether the dinosaur killed it, but it offers a possible feeding clue. Researchers said further study could bear on whether Joaquinraptor was the leading predator in the humid flood plains it inhabited.
The animal's long arms and claws may have helped it seize prey, but the evidence does not yet settle how megaraptorans hunted. Lucio Ibiricu of the Patagonian Institute of Geology and Paleontology, a member of the discovery team, emphasised both the group's characteristic claws and the unresolved questions surrounding its behaviour and place on the dinosaur family tree.
Ibiricu chose the genus name in memory of his son Joaquin. He said Joaquin had been very young and had not yet developed a particular interest in dinosaurs, but believed he would still have appreciated the association.
The discovery adds a comparatively complete individual to a fossil record dominated by fragments. Its skull, limbs and tail provide multiple parts of the body for direct comparison, while the crocodilian bone offers a rare but cautious line of inquiry into feeding.
