Paleontology: Earliest Modern Bird Discovered in Spain

September 1996

from:
Microsoft Corporation. 1996. "Paleontology: Earliest Modern Bird Discovered in Spain" in September 1996 Update to Microsoft® Encarta® 96 Encyclopedia.

The fossilized remains of a tiny bird has provided evidence that birds flew as nimbly 115 million years ago as their descendants do today, solving a major puzzle in the evolution of flight in birds. The fossilized bird, named Eoalulavis hoyasi, was found entombed between two slabs of rock in a limestone quarry in central Spain. The fossil was so perfectly preserved that the bird's feathers and its last meal of tiny shrimp can be seen, the science journal Nature reported August 1, 1996.

About the size of a goldfinch, the bird sports a tuft of feathers technically known as an alula, or bastard wing, that would have helped it stay aloft at slow speeds. Airplanes use a similar device, called leading-edge flaps, to keep from crashing when they land. Eoalulavis is the most primitive bird found with an alula, which would have allowed it to fly between tree branches as effortlessly as a sparrow, according to Luis Chiappe, one of seven paleontologists who described the fossil in the Nature article.

The bird, which lived during the Cretaceous Period (about 138 million to 65 million years ago), provides the first evolutionary explanation for the aerodynamic wing structure of modern birds. Most paleontologists agree that birds evolved from small, meat-eating dinosaurs like the Velociraptor, which ran along the ground, snatching up their prey in their outstretched claws. From there, many paleontologists believe, it was a short jump in evolution to the Archaeopteryx, the oldest known bird, which lived about 150 million years ago. Many scientists believe Archaeopteryx probably flapped and glided, but the ancient bird is not believed to have had an alula.

The fossil of the Eoalulavis provides scientists with the next piece of the evolutionary puzzle. Researchers concluded that some 30 million years after the Archaeopteryx, at least one group of early birds had developed the feathery alula and were able to fly easily. That same feature is now shared by all flying birds today.

The alula, a tuft of feathers attached to each side of the outer wing bones, enabled the Eoalulavis to brake its flight without creating a burst of turbulence in the air above its wings, which would cause it to crash to the ground. This would allow it to fly and maneuver at low speeds. The bird also had claws suited for perching in trees.

Eoalulavis hoyasi, which means "dawn bird with a bastard wing from Las Hoyas," was discovered at a fossil site in Cuenca province, where a freshwater lake existed millions of years ago. The bird may have hunted by wading in shallow water the way plovers and other shorebirds do today. The fossil, found by José Sanz, a paleontologist at the Universidad Autonoma de Madrid, provides the first direct evidence of this kind of aquatic bird life.

Eoalulavis belonged to the group Enantiornithes, which died out at about the same time the dinosaurs went extinct-65 million years ago. Modern birds are descended from another group, the Neornithes, which first appeared about 65 million years ago.

The University of California at Berkeley, maintains a Web site at

http://www.ucmp.berkeley.edu/diapsids/birds/birdfr.html with a complete guide to birds and bird fossils, including the fossil record of the class, the ecology of bird species, and other resources. Also from UC Berkeley,

http://www.ucmp.berkeley.edu/vertebrates/flight/enter.html provides an overview of vertebrate flight, especially the flight of birds. A privately maintained site called "Birding on the Web" is located at

http://compstat.wharton.upenn.edu:8001/~siler/birding.html and includes information about birds and recreational activities, as well as links to ornithological and environmental resources.

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