Gansus Bird-Dino Connection - Penn Press Release

[Patti Kane-Vanni <pkv1@erols.com>]

Thought you'd all want to see the story as issued from a close source, The 
University of Pennsylvania Press Release
http://www.upenn.edu/pennnews/article.php?id=969

The Early Bird Caught the Fish: Fossils Depict Aquatic Origins of 
Near-Modern Birds 115 Million Years Ago
June 15, 2006

PHILADELPHIA -- Five fossil specimens of a near-modern bird found in the 
Gansu Province of northwestern China show that early birds likely evolved in 
an aquatic environment, according to a study reported today in the journal 
Science.  Their findings suggest that these early modern birds were much 
like the ducks or loons found today.  Gansus yumenesis, which lived some 105 
to 115 million years ago during the Early Cretaceous period, took modern 
birds through a watery path out of the dinosaur lineage.
The report was co-authored by Peter Dodson of the University of Pennsylvania 
and his former students Hai-lu You of the Chinese Academy of Geological 
Sciences, Jerald Harris of Dixie State College of Utah and Matthew Lamanna 
of Carnegie Natural History Museum in Pittsburgh.
"Gansus is very close to a modern bird and helps fill in the big gap between 
clearly non-modern birds and the explosion of early birds that marked the 
Cretaceous period, the final era of the Dinosaur Age," said Peter Dodson, 
professor of anatomy at Penns School of Veterinary Medicine and professor in 
Penns Department of Earth and Environmental Sciences.  "Gansus is the oldest 
example of the nearly modern birds that branched off of the trunk of the 
family tree that began with the famous proto-bird Archaeopteryx."
Gansus yumenensis takes its name from the Gansu region, where it was found, 
and the nearby city of Yumen.  According to Dodson, Gansus is something of a 
lost species, originally described from a fossil leg found in 1983, but 
since largely ignored by science.  The five specimens described by Dodson 
and his colleagues had many of the anatomical traits of modern birds, 
including feathers, bone structure and webbed feet, although every specimen 
lacked a skull.
"It appears that the early ancestors of modern birds lived lifestyles that 
today we would stereotype as being duck-like, heron-like, stork-like, 
loon-like, etc.," said Jerald Harris, director of paleontology at Dixie Sate 
College of Utah.  "Gansus likely behaved much like its modern relatives, 
probably eating fish, insects and the occasional plan.  We won't have a 
definitive dietary answer until we find a skull."
The skeletons, headless as they are, offer plenty of evidence for a life on 
the water.  Its upper body structure offers evidence that Gansus could take 
flight from the water, like a modern duck, and the webbed feet and bony 
knees are clear signs that Gansus swam.
"Webbed feet is an adaptation that has evolved repeatedly in widely separate 
groups of animals, such as sea turtles, whales and manatees, and would only 
hinder climbing or landing in trees," Harris said.  "The big bony crest that 
sticks off the knee-end of their lower leg bones are similar to structures 
seen in loons and grebes.  These crests anchor powerful muscles needed for 
diving under water and swimming."
According to Harris, these adaptations all demonstrate how the Gansus branch 
of the family tree, the structurally modern birds called ornithuromorphs, 
split from the enantiornitheans (or "opposite birds").  Enantiornitheans 
were among the feathered fossils found in northeastern China during the 
1990s.
"The enantiornitheans had the best adaptations for perching, so they were 
able to dominate the ecological niche that we would associate with 
songbirds, cuckoos, woodpeckers or birds of prey," Harris said.  "Gansus 
appears to have had adaptations for a lifestyle centered around water, based 
on things like the proportions of the leg and foot bones."
While the enantiornitheans are now long gone, their perching lifestyle has 
now been taken over by the descendents of birds like Gansus.  What remains a 
mystery for now, according to the researchers, is how the amphibious 
lifestyle of birds like Gansus helped enable them to survive the cataclysmic 
end of the dinosaurs 65 million years ago.
Funding was provided by the Discovery Channel (Quest program) and the 
Science Channel, the Carnegie Museum of Natural History, Dixie State 
College, the Chinese Geological Survey of the Ministry of Land and Resources 
of China and the Gansu Bureau of Geology and Mineral Resources.

Contact: Greg Lester
215-573-6604
glester@pobox.upenn.edu

Copyright © 2006, University of Pennsylvania
Office of University Communications
200 Sansom Place East, 3600 Chestnut Street, Philadelphia, PA 19104-6106
Copyright Information | Contact U s | Privacy Policy | Disclaimer