by Perry McCarney

Created on: April 13, 2009   Last Updated: November 24, 2009

While there is still controversy and argument between scientists on whether the avian species of today are descended from the dinosaur species of 65 million years ago, popular opinion is embracing the concept. Dinosaurs capture our imaginations and many wish that they still existed. So it is quite reasonable that we would like to believe that the birds we co-habit this world with are their distant relatives. But how likely is that?

The taxonomy of today links the relationships of extant species by taking blood samples and comparing DNA (deoxyribonucleic acid), the macro-molecules of every organism's genetic code. Although DNA molecules are strong and durable, they can only survive the death of the animal or plant they provided the blueprints for by an estimated maximum of 10,000 years. So, despite the concepts of movies such as "Jurassic Park", obtaining viable dinosaur DNA from a blood-sucking insect fossilized in amber is not going to happen. But this does not mean that assessing the genetic code of dinosaurs, or at least parts of it, can not be done from non-viable DNA; effectively the broken pieces extracted from fossilized remains.

Prior to Watson and Crick's discovery of the structure of DNA in 1954, evaluating how closely related two species were depended on comparing their anatomy. Key anatomical traits could often be traced back to a progenitor species that both subsequent species were descended from. When survival oriented morphological structures occur in a species, they or at least signs of them, are found in the species that evolve from that species. While later evolutionary modifications can and do occur, they will at most mask such traits, rather than removing them completely from the subsequent species.

Therefore it is feasible to make comparisons between prehistoric dinosaurs, extinct ancient species of birds and the avian species we currently share the world with. We do need to recognize how few fossil remains of appropriate dinosaur species are available to us. Birds are believed to be descended from the suborder of dinosaurs called theropodia, that belonged to the taxonomic order saurischia and included, believe it or not, Tyrannosaurus Rex. But it does make sense that birds should be descended from a suborder of dinosaurs that walked on two feet.

It is also the fossilized remains of theropods that have most frequently shown indications of feathers. In 2002, Chinese paleontologists at the Jiufotang rock formations unearthed the fossilized

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