We’ve always imagined dinosaurs as gigantic beasts roaring across ancient landscapes, but ecosystems are all about balance, with players large and small keeping nature intact.Patagonia, Argentina’s fossil treasure trove, continues to amaze us with new discoveries, unearthing delicate bones that reveal the diversity of life beyond giants.Recently, scientists discovered dinosaur fossils of small size, which completely changed the way we look at dinosaurs.

fossil of a small predator

At the fossil-rich La Buitrera archaeological site in northern Patagonia’s Rio Negro region, researchers have discovered the nearly complete skeleton of Arnachetli cerropolisiensis, one of the world’s smallest dinosaurs.These crow-sized theropods lived 95 million years ago in a desert called Cococom, which means “desert of bones” in the Mapuche language, and hunted lizards, snakes, mammals, and insects.According to Reuters, the specimen, nicknamed Aruna, was a small female who died at the age of almost fully grown and was immediately buried in a sand dune to preserve it in pristine condition. Weighing only 0.7 kilograms, “Arnashetri is really small…smaller than a chicken. It wouldn’t even reach the knee height of an average adult,” lead author Peter Makowiecki, a paleontologist at the University of Minnesota, said in a Nature study cited by Reuters.

It was exactly the size of seven small centimeter scales.

Arunashetri belonged to the alvarezaurids, strange theropods with stubby, powerful arms, slender legs, and a light skull. It was about 70 centimeters long, with most of it being a tail, and probably feathered like its relatives. Its sharp and numerous teeth resembled a small velociraptor, which was better suited for small prey, unlike the insect-digging claws of later Alvarezsaurus.“Its body resembled a rooster, but it had a long tail…” said co-author Sebastian Apesteguia of Argentina’s Félix de Azala Foundation and CONICET. The arms were well developed, but not long enough to fly. ”Apesteguía said histological analysis of the fragile bones revealed exquisite details. “The level of histological detail is exquisite.” The first foot bones were discovered in 2004, leading to the latest discovery in 2014, which took more than 12 years to prepare.

Patagonia is a dinosaur fossil paradise

Among giants like the 8-ton Giganotosaurus and the 70-ton Argentinosaurus, Arnashetri stands out as a shining example of diversity. Apesteguia says, “When we think of landscapes with dinosaurs…these landscapes are almost always missing medium- and small-sized animals, which are important components of the ecosystem. That era…coincided with the ‘Age of the Southern Giants.’ Arunachetri shows that it was not an age of giants, but rather an age of vast biodiversity.”This discovery proves that size reduction repeatedly evolved in alvarezosaurs and expands our view of Cretaceous life.