Unenlagia Characteristics

Unenlagia measured 10 feet (3 metres) in length and 4 feet in height. Weight is unknown. Unenlagia was very birdlike and its pelvic region was very similar to that of the early bird Archaeopteryx. It was the size of a large ostrich but resembled a Velociraptor. The first birds appeared 150 million years ago, evolving from dinosaurs long before Unenlagia lived. Therefore, it is not an ancestor of modern day birds, but was an evolutionary dead-end.

Unenlagia had an small, elongated head with a beak that contained rows of small sharp teeth. It had a feather crest on top of its head and a flexible neck. On each foot, it had 3 toes which were equipped with large, sharp claws. Unenlagia was an omnivore and would have fed up on prehistoric plant material, insects and small reptiles and mammals.

The shoulder structure of Unenlagia shows adaptations for flapping and, since it was 6 feet long, Unenlagia was probably too big to fly, this provides evidence that it evolved from flying ancestors. The shoulder structure that allowed its short arms to move forwards, backwards, inwards (for grasping prey), and up and down (for a flapping motion). This flapping motion was not used for flying, because its wing-like arms were too short to support the heavy dinosaur.

Perhaps these proto-wings were used for balancing, turning, and a bit of lift during high-speed running. Although there is no fossil evidence of feathers from Unenlagia, it may well have had them, further adding lift to each upstroke of the proto-wings.

Twenty fossilized bones from Unenlagia were unearthed in an ancient river bed in the Patagonia region of Argentina (southern Argentina) by Fernando Novas, of the Museum of Natural History in Buenos Aires. Bird fossils are rare because bird bones are hollow and fragile, but Jurassic, mid-Cretaceous, Eocene and Miocene-Pliocene bird fossils have been found.

Unenlagia was named by Novas & Puerta in 1997.