Sunday, October 30, 2011

Zygodactyl: One of Our Favorite Words


 adj \ˌzī-gə-ˈdak-təl\

Definition of ZYGODACTYL

: having the toes arranged two in front and two behind —used of a bird


International Scientific Vocabulary zyg- + Greek daktylostoe
First Known Use: 1831

Our Greenwing macaw and Diva parrot Roxanne
shows off her zygodactyl feet

We know that many dinosaurs were feathered. There is considerable scientific debate regarding the age of avians, and when birds first appear in the paleontological record. 

Fossil of feathered Sinosauropteryx from Inner Mongolia, China

Some paleontologists claim Archaeopteryx as the oldest bird, dating 150 million years ago.

Berlin specimen fossil of Archaeopteryx

The feathers of Archaeopteryx can clearly be seen in this fossil specimen. There is no dispute that birds lived among dinosaurs, and may be descended from dinosaurs. Parrots, however, are living dinosaurs. No word says living dinosaur like zygodactyl! It is known that parrots are among the oldest of the avians. Fossilized zygodactyl tracks have been found dating to 120-110 million years ago (early Cretaceous period), 50 million years before the first identified zygodactyl fossils.

We know that the thing that makes parrots different from other avians is that they are zygodactyl. That is: Parrots have two toes forward, and two toes backward. Surprisingly however, parrots are not the only zygodactyl birds. Woodpeckers (including flickers), cuckoos (including roadrunners), and some owls are also zygodactyl.

We have fossil evidence that parrots lived among dinosaurs. Identified by a University of California-Berkeley graduate student, the oldest known fossil of a modern land bird in North America is a jawbone believed to be from a parrot found in eastern Wyoming in 1960, and reported in the British journal Nature in 1998:

The fossilized jaw of a parrot dating from the last days of the dinosaurs is the earliest known fossil of a modern land bird, says Thomas Stidham, a graduate student in the Department of Integrative Biology. The find provides the strongest evidence to date that modern birds evolved long before most scientists thought.
An analysis of the find, excavated from Cretaceous deposits in eastern Wyoming, appeared in the Nov. 5 issue of the British journal Nature.
"This find suggests that by the end of the Cretaceous period, around 65 to 70 million years ago, modern birds were an important group, at least in North America," said author Stidham.
"These data also indicate that modern bird groups, including parrots, may have been relatively unaffected by the mass extinction at the end of the Cretaceous period," he wrote in a scientific correspondence in Nature.

Potential morphologically modern psittaciform mandible fragment of fused dentaries, from a find in the Hell Creek Formation of Wyoming. This jaw is remarkably parrot-like.

While some paleontologists dispute the identification of the Wyoming fossil as a parrot, the oldest undisputed parrot fossil ever found was located on Denmark's Isle of Mors, and nicknamed Danish Blue in honor of the Monty Python Ex-Parrot sketch.

Artist conception of the 54 million year old Danish Blue parrot

Reported by National Geographic in 2008, this find is important because it suggests that parrots evolved in the Northern Hemisphere before branching into widely diverse species in the Southern Tropics.

Scientists speculate what dinosaurs may have sounded like. We have no doubt what dinosaurs sounded like! Anyone who lives with macaws or cockatoos knows exactly what dinosaurs sounded like. The full-throated honking of a Hyacinth macaw would probably scare a Tyrannosaurus rex!

A living honking modern dinosaur, our Hyacinth macaw Princess Tara

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