🦴 What is this tiny feathered dinosaur?

About 90 million years ago, a very small feathered dinosaur, whose cousins evolved into modern birds, lived in Patagonia.

In Argentina, paleontologists have unearthed an exceptionally well-preserved fossil of a dinosaur named Alnashetri. This discovery, made at the La Buitrera site, provides a rare glimpse into a little-known group. Scientists from the University of Minnesota and their Argentine colleagues have been able to examine an almost complete skeleton for the first time. This specimen now serves as a benchmark for understanding the evolution of these animals.


Compared to its more recent relatives, Alnashetri has distinct traits. It has longer arms and larger teeth, indicating it was not yet specialized for feeding on insects like its descendants. This observation shows that the decrease in size in these dinosaurs preceded the appearance of adaptations related to a specific diet. The study of the bones also reveals that the individual was an adult and at least four years old.

These dinosaurs are among the smallest known, with Alnashetri weighing less than 2.2 pounds (1 kg). Their small stature likely influenced their lifestyle and survival. To trace their evolutionary history, researchers also examined other fossils.

The analyses indicate that alvarezsaurs appeared earlier than previously thought, at a time when the continents formed Pangaea. Their dispersal across the globe occurred as land masses separated, which explains their presence on different continents today.


The La Buitrera site thus continues to yield paleontological treasures. Work carried out over the past twenty years has transformed our understanding of small Cretaceous vertebrates. Thanks to ongoing excavations in this fossil-rich region, paleontologists already expect new discoveries about the history of alvarezsaurs.