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Scientists Rethink the Chicken and the Dinosaur

Which came first: the chicken, or the dinosaur? What, not the old childhood riddle you remember? Weird…

Contrary to what some might think, not all creatures from Jurassic Park were dinosaurs. Definitional, dinosaurs are land dwelling diapsid reptiles descended from Archosaurs. Meaning that their limbs descended downward, were land-dwelling, had two large holes directly behind their eyes and two other large holes in their skull to allow for a stronger/bigger bite, and numerous other identification markers best left to professionals. But basically, Ichthyosaurs: not a dinosaur. Loch Ness Monster: not a dinosaur. Thunderbird: not a dinosaur.

Archaeopteryx_lithographica_(Berlin_specimen)

Fossilized remains of archaeopteryx, found in Southern Germany, with clearly defined wing structure

But, birds are dinosaur descendants. Well, maybe not…

The general consensus on the part of the scientific community for the past 150 years has been that members of the avian species were descendants of small ground dwelling theropod dinosaurs that survived the mass extinction of 65 million years ago. Thomas Huxley, the bulldog supporter of Charles Darwin’s theories of evolution, widely promoted the notion beginning in the 1850’s. Huxley observed the avian traits in the skull of the large predator Megalosaurus and in the hip of the small herbivore Hypsilophodon, as well as many other similarities in the fossil specimens available at the time.

The real bombshell came with the discovery of the fossilized remains of an Archaeopteryx in 1861. Found within limestone quarries in Southern Germany, this fossilized creature was seen as a transitory species between dinosaurs and birds. With much of the same skeletal structure as dinos, it easily could be mistaken as a dinosaur with wings.

Further discoveries were made over the next 150 years, reinforcing the view that dinosaurs were an original ancestor of the birds we know today.

However, new technology has allowed paleontologists a new birds eye view onto the debate.

The developments began with the fossilized remains of Scansoriopteryx, removed from Inner Mongolia between 2005 and 2012, in cooperation with the Chinese Academy of Geological Sciences. Small, sparrow-sized, with wings and fur protruding from its limbs, this creature was thought to be a coelurosaurian theropod dinosaur, which many scientists see as later developing into flying dinosaurs, and then birds.

Scansoriopteryx_by_Andalgalornis

Artists rendition of the Scansoriopteryx

The fossilized remains of Scansoriopteryx showed unambiguously bird like traits upon its discovery; wings coming out of its fore and hind limbs, wing membranes in front of its elbows, bird-like perching feet, and claws that make tree climbing possible. Jumping, gliding and parachuting from tree to tree, Scansoriopteryx was seen as an evolutionary stepping-stone for flight.

A new paper, published in the Journal of Ornithology by Stephen Czerkas of the Dinosaur Museum in Blanding, Utah, and Alan Feduccia of the University of North Carolina, offers new insight into the debate.

Utilizing advanced 3D microscopy, high-resolution photography, and low-angle lighting, they began to notice some suggestive facts. Namely, that the skeletal structure of the Scansoriopteryx lacked the fundamental skeletal structure to call it a dinosaur.

The research team further theorizes that birds did not descend from dinosaurs at all, but from a separate, tree climbing archosaur that lived long before the dinosaurs.

“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 American researcher Alan Feduccia.

This recent finding validates predictions from the early 1900’s that birds actually descended from small, tree dwelling creatures that could glide. This “tree down” view is the polar opposite of the “ground up” view that has been adopted by paleontologists in recent years.

“The identification of Scansoriopteryx as a non-dinosaurian bird enables a reevaluation in the understanding of the relationship between dinosaurs and birds. Scientists finally have the key to unlock the doors that separate dinosaurs from birds,” explained Czerkas.