Fossil of one of the smallest dinosaurs found in Argentina

A nearly complete, well-preserved skeleton of a crow-sized alvarezsaur, Alnashetri cerropoliciensis, was found in sandstone at La Buitrera in northern Patagonia and published in Nature; the specimen was a small female that died at about age four and was rapidly buried by a sand dune.

Researchers have described a nearly complete, well-preserved skeleton of a very small dinosaur from northern Patagonia. The animal is named Alnashetri cerropoliciensis and was nicknamed "Alna." The specimen was recovered from sandstone at La Buitrera in Rio Negro Province and retains bones in the positions they held in life. Its preservation gives new anatomical detail about alvarezsaurs, a small-bodied branch of theropod dinosaurs. Key details: - The fossil is nearly complete and was preserved with bones in life position at the La Buitrera site in northern Patagonia. - Alnashetri was about the size of a crow, reported as weighing around 1.5 pounds and described as smaller than a chicken. - The specimen was a small female that lived in a desert environment and died at about four years old, so it was nearly fully grown when buried by a sand dune. - Alvarezsaurs are characterized by short, powerful forelimbs, long gracile hindlimbs and lightly built skulls; researchers suspect Alnashetri was feathered based on related fossils and note that alvarezsaurs are part of the theropod group but only distantly related to birds. Summary: The discovery adds a well-preserved example of a very small alvarezsaur to the South American fossil record and provides detailed anatomical information about this unusual group of theropods. The research describing the specimen was published in the journal Nature. Broader implications for alvarezsaur biology are reported by the authors. Undetermined at this time.