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Scott Hartman's troodont in _Science_
Nice to see a little media play for our own HP Scott Hartman:
In case the link doesn't work, here's the text:
MESA, ARIZONA--There's no shortage of anatomical evidence that birds evolved
from dinosaurs. But paleontologists have still had to contend with a slightly
embarrassing gap in the fossil record: The oldest known bird fossil,
Archaeopteryx, is much older than fossils of its closest dinosaurian relatives.
Now, that gap has been plugged.
Archaeopteryx is known from several 150-million-year old specimens found in
Upper Jurassic limestone in Germany. Aspects of its skeleton--such as its bony
tail, claws, and teeth--are similar to those of a group of predatory dinosaurs
called maniraptorans. However, the oldest fossils of those agile dinos were
discovered in rocks only 125 million years old, leaving paleontologists to
infer that some older relatives of these maniraptorans gave rise to
Archaeopteryx and all other birds.
One of those older dinosaur relatives, a contemporary of Archaeopteryx, was
described here yesterday at the annual meeting of the Society of Vertebrate
Paleontology. Collected in 2000 from Upper Jurassic rock layers in eastern
Wyoming, the fossil's bones were so delicate that William Wahl, of the Wyoming
Dinosaur Center in Thermopolis, needed several years to prepare them.
About 60% of the skeleton is preserved, including the skull. A groove along the
jaw was one of several features that allowed Scott Hartman, also of the Wyoming
center, to identify the skeleton as that of a kind of maniraptoran called a
troodontid, but the researchers have not yet named the new species. They
estimate that the creature was about 1.5 meters long. Like the later
troodontids, the proportions of the feet and limbs suggest it was terrestrial
rather than tree-dwelling, further supporting the idea that flight evolved from
the ground up, Hartman says.
Paleontologists had expected such fossils would eventually be discovered, and
they're pleased that this one begins to fill the time gap between bird fossils
and their closest dinosaur relatives. "This is seriously cool," says Jim
Kirkland of the Utah Geological Survey, who has studied birdlike dinosaurs.
All in the family. A new dinosaur species helps connect birdlike dinos to
dinolike birds (such as Archaeopteryx, shown here).
CREDIT: Sally A. Morgan; Ecoscene/CORBIS]
Department of Linguistics
University of Michigan