PHILADELPHIA -- When a French count claimed the damp North American climate made the continent's wildlife degenerate, Thomas Jefferson responded with a "megalonyx."
The nearly foot-long "great claw" found in what is now West Virginia indicated an animal maybe two or three times the size of a lion, he wrote in a 1796 letter.
The "megalonyx" was eventually determined to be a giant ground sloth, but to Jefferson it still proved that fauna in the largely unexplored new continent rivaled the animals of Old Europe.
The bones and letter are part of the American Philosophical Society's new exhibit, "Stuffing Birds, Pressing Plants, Shaping Knowledge," examining 130 years of natural history in North America.
The exhibit includes some of the earliest examples of taxidermy, dried plants and seeds from Lewis and Clark's expedition and illustrations drawn by such naturalists as John James Audubon and Alexander Wilson.
In the 18th and 19th centuries, natural history was a new science pursued like a hobby. Dabblers such as Henry David Thoreau and Edgar Allan Poe published their research in botany and the study of seashells.
Believing in man's dominion over nature, and that understanding and organizing living things brought mankind closer to God, people set out to explore the world around them, curator Sue Ann Prince said.
Many naturalists were physicians curious about the new American wilderness. Some - most notably Lewis and Clark - were sponsored by the government and sent to hunt new species.
More than 230 specimens collected between 1730 and 1860 - including a turtle with notes scrawled on its shell, a now-extinct Carolina parakeet, and handwritten journals - are on display in the society's Philosophical Hall, near Independence Hall, through December 2004.
Although arranged in glass cases like modern natural science exhibits, showmanship influenced this exhibit's historical presentations, Prince said.
For example, painter and naturalist Charles Willson Peale pioneered the use of arsenic in preserving birds, but he posed them for dramatic effect.
A sleek bald eagle prepares to launch from its perch next to two more of Peale's birds, a strutting wild turkey and two preening golden pheasants. They are quite lifelike, but Prince said Peale manipulated them to showcase their colorful feathers and, in the eagle, sharply focused glass eyes.
The naturalists also fed a philosophical struggle emerging in the 19th century to rationalize religious conviction with scientific discovery, Prince said. The public celebrated Jefferson's megalonyx for its huge size; the problem was, no one had ever seen one.
"But Jefferson didn't believe in extinction. Nor did a lot of other people at the time," Prince said. "There was an order in nature that God had created, and it was mankind's duty to sort that order out. ... But it was fixed - if there was a divine creator, then nature was fixed and that didn't change."
Jefferson "just assumed maybe they were out West somewhere. It was not at all silly because you didn't have this notion of the evolution of species," she said.
The handwritten title page of Charles Darwin's "The Origin of Species," which introduced his theory of evolution and the natural selection of species, closes the exhibit.
Benjamin Franklin founded the American Philosophical Society in 1743 "to promote useful knowledge." It served as a national library, patent office, museum and academy of science before the federal government established these institutions in Washington, D.C.
The society continues to be a source of research in biology, genetics and other evolutionary sciences. Invitation-only members from a variety of fields include Sandra Day O'Connor, Yo-Yo Ma, I. M. Pei and 93 current Nobel Laureates.
"Stuffing Birds, Pressing Plants, Shaping Knowledge," is only the second public show in the society's history, after it established a public outreach program in 2001.
Prince said the specimens on display continue to contribute "useful knowledge."
Two guitar fish and a Warsaw grouper preserved in alcohol in large glass jars are "type specimens" for the species, against which all others are compared. Scientists still use Carolus Linnaeus' 1735 "Systema Naturae," which opens the exhibit, to classify living things by kingdom, genus and species.
Even the things early naturalists got wrong - such as rattlesnakes depicted as medieval serpents - helped advance our scientific knowledge because they show the scientific process of trial and error, said Dr. Baruch Blumberg, who shared the 1976 Nobel medicine prize and is on the society's official board.
"Strangely, some of the hypotheses that subsequently prove to be wrong move you forward because you have to come up with a new hypothesis," he said.
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