New finding challenges belief birds evolved from dinosaurs

A sparrow-sized fossil from China challenges the commonly held belief that birds evolved from ground-dwelling theropod dinosaurs that developed the ability to fly. Instead, the fossil – a Scansoriopteryx - is the remains of a tiny tree-climbing animal that could glide say researchers from the Dinosaur Museum in Blanding and the University of North Carolina. Using advanced 3D microscopy, high resolution photography and low angle lighting, the researchers revealed an absence of fundamental dinosaurian characteristics. The scientists believe the research shows dinosaurs are not the primitive ancestors of birds. Instead, the Scansoriopteryx should be seen as an early bird whose ancestors are to be found among tree-climbing archosaurs that lived long before the dinosaurs. “The identification of Scansoriopteryx as a non-dinosaurian bird enables a re-evaluation in the understanding of the relationship between dinosaurs and birds,” said Stephen Czerkas. “Scientists finally have the key to unlock the doors that separate dinosaurs from birds.” The investigations – published in Journal of Ornithology - found a combination of plesiomorphic or ancestral non-dinosaurian traits along with highly derived unambiguous birdlike features. The researchers specifically note the primitive elongated feathers on the fore- and hind limbs, suggesting Scansoriopteryx is an ancestral form of early birds that had mastered basic aerodynamic manoeuvres of parachuting or gliding from trees. These findings fulfil a prediction first made in the 1900s that the ancestors of birds didn’t evolve from dinosaurs, but instead from earlier arboreal archosaurs which originated flight according to the tree-down scenario. These small tree-dwelling archosaurs had improved ability to fly, with feathers that enabled them to at least glide. This ‘tree-down’ view is in contrast with the ‘ground-up’ view many palaeontologists side with. “Instead of regarding birds as deriving from dinosaurs, Scansoriopteryx reinstates the validity of regarding them as a separate class uniquely avian and non-dinosaurian,” said Alan Feduccia. Jurassic archosaur is a non-dinosaurian bird