Around 95 million years ago, the landscape of Patagonia was home to some of the largest dinosaurs ever known, including towering predators and massive plant-eaters. But new research shows that this prehistoric world was not ruled by giants alone.
Scientists have uncovered a remarkably complete fossil of one of the smallest dinosaurs ever identified, a species named Alnashetri cerropoliciensis. Roughly the size of a modern crow, the animal likely preyed on small creatures such as lizards, snakes, early mammals and insects.
What makes the discovery extraordinary is the fossil’s condition. The skeleton was preserved almost exactly as the animal lay in life, offering rare insight into a group of dinosaurs known as alvarezsaurs — small, agile members of the meat-eating theropod lineage.
Nicknamed “Alna,” the specimen was found at La Buitrera, a sandstone-rich fossil site in Argentina’s Rio Negro Province. The region has become famous for yielding fossils of smaller prehistoric animals often overlooked in dinosaur research.
Researchers determined that Alna was a nearly full-grown female that lived in a harsh desert environment. After dying at about four years of age, her body was quickly buried by shifting sand dunes, a process that helped preserve even the most fragile bones.
Apart from birds, which evolved from feathered dinosaurs, Alnashetri ranks among the smallest dinosaurs ever discovered in South America and rivals the tiniest species found anywhere in the world.
Lead author Peter Makovicky of the University of Minnesota said the dinosaur weighed less than a kilogram — lighter than a chicken — and would not have reached an adult human’s knee in height. The findings were published in the scientific journal Nature.
Although no feathers were preserved, scientists believe Alnashetri was likely feathered, based on related fossils. Its body shape resembled a rooster with a long tail, slender legs and well-developed arms that were strong but unsuitable for flight.
Study co-author Sebastián ApesteguÃa explained that unlike later alvarezsaurs — which evolved specialized claws for digging into insect nests — Alnashetri retained sharp teeth, suggesting a more general hunting lifestyle.
The discovery challenges popular images of dinosaur ecosystems dominated solely by colossal creatures. Instead, researchers say it highlights a vibrant prehistoric world filled with small and medium-sized animals that played crucial roles in maintaining ecological balance.
