Archaeopteryx, Was It a Bird or Dinosaur?

Examining the Bird-Like Dinosaur to Understand Evolution

Nov 11, 2009

There has long been a debate over the evolution of birds, though when faced with the histology of the Archaeopteryx, dinosaurs are birds' most likely ancestors.

Birds, when examined with an objective eye, are very strange-looking compared to the many other types of living animals. They characteristically have beaks (features which only really appear elsewhere with anapsids and squid), feathered bodies, and scaly, reptilian feet.

It has long been popularly believed that birds are the result of one evolutionary thread of dinosaurs. This was postulated to the masses, partly in thanks to paleontology consultant James Horner, in Jurassic Park, as Dr. Grant explains to a young boy how a velociraptor was similar to a large turkey. Hyperbole, perhaps, but recent research only supports the ideas behind this statement.

Recently in a paper published in the journal PLoS ONE ("Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx") , a group of paleontologists, led by Gregory M. Erickson of Florida State University, explain some remarkable findings that emerged from intensive histological scrutiny of several skeletons of Archaeopteryx, whose name translates to “old bird.” Archaeopteryx is the oldest specimen of bird-like creature that has been discovered (belonging to a group called Avialae), which makes it a great starting point for determining where modern birds may have come from.

Erickson and his associates describe the bone structures of Archaeopteryx by highlighting the similarities that exist between their long, parallel-fibered bones and the similar bones of non-avialan (not bird-like) dinosaurs. Based on this histological discovery, the bones of the Archaeopteryx were slow-growing, unlike modern birds, and more along the lines of the growth rates of non-avialan dinosaurs.

Archaeopteryx has often been coined, due in part to its name, as the oldest known bird. Even with its long, bony tail, and its mouth full of teeth, it is still often considered a prehistoric version of living avian creatures. However, it seems based on this research, that this creature wasn’t really a bird at all, rather just a dinosaur that flew and had bird-like characteristics, placing it into that Avialae group previously mentioned.

Erickson and the other researchers conclude, based on the histological and anatomical breakdown of Archaeopteryx's skeletal remains, that the “oldest bird” was a primitive precursor to birds, but cannot correctly be considered a bird in the modern sense.

Flighted, avialae dinosaurs may have been the precursors to modern birds, but they must be considered only that: precursors. To refer to the Archaeopteryx and other avialae dinosaurs as “birds” would be erroneous and misleading.

While their study with Archaeopteryx does not lend too much to the wide-scale debate on the origins and evolution of birds, it seems the Archaeopteryx can, with conviction, be removed from the equation.

Erickson GM, Rauhut OWM, Zhou Z, Turner AH, Inouye BD, et al., 2009. Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx. PLoS ONE 4(10): e7390. doi:10.1371/journal.pone.0007390

The copyright of the article Archaeopteryx, Was It a Bird or Dinosaur? in Evolution is owned by Kristina Bjoran. Permission to republish Archaeopteryx, Was It a Bird or Dinosaur? in print or online must be granted by the author in writing.