Fossils

Of all the preparations made by Meriwether Lewis for the epic continental journey then just coming together in the spring of 1803, none were more important than those made when he was in Philadelphia. Here he ordered many of the goods and supplies for the expedition, and here he received a hurried, informal schooling in a medley of topics—astronomy and celestial navigation, ethnography, botany, geology, and medicine. And yet, probably no subject was more unfamiliar to him than the lessons in paleontology (meaning “study of the prehistoric,” from the Greek words for “ancient” and “study”). Fossils, the remains of organisms that lived long ago (more than 10,000 years by modern geological definition), were part of the list of “objects worthy of notice” that Thomas Jefferson included in his long list of directives to Lewis, which itemized that the explorers should take special notice of “the animals of the country generally, & especially those not known in the U.S. [and] the remains or accounts of any which may be deemed rare or extinct.”^[1]Thomas Jefferson to Meriwether Lewis, 20 June 1803. Donald Jackson, ed., Letters of the Lewis and Clark Expedition with Related Documents, 1783-1854, 2nd. ed., 2 vols. (Urbana: University of Illinois … Continue reading In Jefferson’s day, “paleontology” was more subtly a part of geology overall; the term itself did not arise until about 1838 when English geologist Charles Lyell used it, and prior to that fossils were lumped together in a catch-all category, “mineral productions.”

Specimens of the fossil world are different from delicate flowers and plants waiting to be picked, or rocks gathered and bagged, all familiar in style and form even when new kinds are discovered in the wilderness. Nor are fossils like familiar or curiously new animals taken as prizes for their pelts or left alive for public display. Fossils can preserve bizarre forms that are unlike organisms living on earth today. They may be preserved as though they had just died or they may be wholly petrified; fragile or durable, complete or in fragments. But, at least at the turn to the 19th century, every one could be a vestige of an organism whose descendants may yet walk, skitter, swim, or fly. “Extinct” animals were not the exclusive subject of Lewis’s lessons, because in 1803 “extinction” was not a scientific certainty. Lewis and Clark’s Corps of Discovery could just as likely find “living fossils” as they could new kinds of animals and plants.

The Mammoth Mastodon

Under the supervision of Charles Willson Peale, leader of the first American scientific field expedition, two incomplete skeletons of mammoths were exhumed at John Masten’s farm—and duly dubbed mastodons—near West Point, New York, and on the nearby lands of Captain Joseph Barber and Peter Millspaw. By making wooden and papier mache replicas, bones missing from one skeleton were supplied by replicas from the other. This conjectural drawing, made by C.W. Peale’s son, served as a guide to the assembly of the bones for display at Peale’s Museum. Rembrandt took the other skeleton on a tour of England as well as the American Southland.^[2]Charles Coleman Sellers, Mr. Peale’s Museum: Charles Willson Peale and the First Popular Museum of Natural Science and Art (New York: Norton, 1980), 123-158.

Lewis had seen fossil bones in the President’s House in Washington and in a physician’s house in Philadelphia. What he had held in his hands might have been dead bones to one person, creatures “forgotten” to nature, but to Jefferson’s protégé they represented animals that might very well be walking, breathing, and reproducing beyond the western frontier. What would they find? At the time, mastodons were all the rage, but all manner of bones were pursued and perused by curious naturalists and displayed to an awed public—one standout specimen was a peculiar, scientifically significant creature called “the giant claw.” In this social milieu, Jefferson no doubt hoped that the explorers would find similar curiosities.

Geology

In the 18th and 19th centuries, geology—which by definition now includes paleontology—was strictly a relative science. That is, the absolute ages of rock layers were completely unknown, and geologists could only estimate whether rock layers were older or younger than each other. Geology still is a relative science in many ways, but because of our ability now to measure the abundance of radioactive elements in certain kinds of rocks, we have tremendous advantage over our ancestors in understanding absolute time. We can now measure how old things are in thousands or millions of years, and it turns out that the history of planet Earth is very long indeed; well over four billion years by current reckoning. This is orders of magnitude greater even than the daring first scientific estimates formulated two centuries ago.

The historical development of geology, especially at this critical period of the 18th and 19th centuries, is study that has spawned whole careers. This was when “deep time” (of millions of years at least) was first theorized and defended. It will suffice to say here that the development of modern geology, and its handmaiden paleontology, came neither easily nor quickly. And yet, as recently demonstrated by a geological historian, the idea that the “Genesis-busting” timeframe of modern geology drew the universal wrath of 18th century clergy just isn’t true.^[3]Martin J. S. Rudwick, Bursting the Limits of Time: The Reconstruction of Geohistory in the Age of Revolution (Chicago: University of Chicago Press, 2005), 115-131. His design of the (literally) … Continue reading

These centuries saw great developments that constructed precise understandings of the relationship of rock layers to one another. Likewise, the various physical and chemical processes at work in the earth were being much better understood. William Smith (1769-1839), known also as “Strata” Smith, pioneered the concept of the organization of rock layers into a recognizable, predictable record of earth history, demonstrating in the process how to ascertain which strata were older or younger. But whereas “younger” was distinguishable from “older,” the number of years was impossible to determine. The belief in catastrophic change during past epochs, promulgated by many of the day’s scholars, strongly influenced the analysis of fossils and their meaning to earth history. Men like the great French naturalist Georges Buffon (1707-1788) had some inklings that not all seemed to be as tidy as was represented by traditional scholarship, but they had not the field evidence and subjective analysis to take matters to the next stage.

Charles Lyell (1797-1875), however, openly objected to attempts to link catastrophic events to Biblical calamity, most notably William Buckland’s (1784-1856) geological interpretations of the Noachian Flood. Lyell had been aware of the observations and of James Hutton (1726-1797), who in the late 18th century dismissed the catastrophists’ perspective in favor of far slower processes. Hutton’s idea was novel, not so much for the idea that changes occurred slowly, but that, cumulatively, it implied a vastly longer time frame than that of traditional Biblical historiography. Lyell collected the field evidence for changing sea levels and the formation of the earth’s surface features, which indicated that catastrophism was rare, and that causal events usually proceeded with slow and methodical purpose.

Most remarkable of Lyell’s interpretations was that not only did geological change usually happen slowly, but the field evidence he found also showed that these processes worked in the same fashion at all times. This concept of steady-state change came to be known as uniformitarianism, one of the underpinnings of modern geology.

In Lewis and Clark’s day, not all of these grand geological theories were in place. Never-the-less it was a time of relatively rapid change in the worldview, from one that believed in the catastrophic creation to another that saw instead gradual modifications over a very long time. Yet not all ideas gained acceptance, and others lagged in transforming into the views we have today.

Lewis, Student Paleontologist

Just six years after Jefferson sent his Megalonyx bones to the American Philosophical Society, Meriwether Lewis came to Philadelphia. Lewis’s tutor in the science that thirty years later would be named paleontology was Caspar Wistar (1761-1818) who almost certainly used the Megalonyx bones and mastodon teeth as lecture props.^[4]This is information that was never recorded. There is much about Lewis’s program of instruction when he was in Philadelphia that was never written down or reported to another diarist or … Continue reading The experience must have inspired Lewis to start thinking about the importance of fossils as evidence of species possibly still to be seen alive in the plains, mountains and forests beyond the Mississippi River.

Caspar Wistar was a Philadelphia Quaker physician and educator who was an heir to the glass manufactory wealth amassed by his grandfather, Caspar (1696-1752). Young Caspar was educated in Edinburgh, where he received his medical degree in 1786. He would not officially become a professor of anatomy until 1808, but at the time Lewis arrived in 1803 he was already an accomplished comparative anatomist, studying and teaching about the differences between comparable organs and bones and their functions in different kinds of animals.

Perhaps Wistar himself thought that fossils were among the least likely targets of the travelers as they trekked to the Pacific Ocean. This stood to reason. Unlike the useful geological productions of the territory that Lewis was to observe and report upon, such as lead, coal and salt, fossils had no practical worth beyond that of anatomical study and scholarship. Nevertheless, the exploring or hunting parties just could be fortunate enough to track roaming mastodons, for example, known hitherto only by their mammoth-sized tusks and bones.

But what would be the prize in the American West? Mastodons or megalonyxes? Mastodons were of great interest to scientists and the general public alike. To the lay person they carried strange names, like “the incognitum“—”unknown”—or geographically specific names, such as in the case of one famous specimen called “the Ohio animal.” The excavation of one mastodon in particular was attended to in 1799 by Charles Willson Peale and his son, Rembrandt, at the farm of John Masten in the Hudson River valley of New York. The elder Peale publicized it and a few years later magnificently illustrated the scene in a painting. This was one of two mastodon skeletons collected by Peale along the Hudson River (the other in 1801), both of which were mounted and displayed in his Philadelphia museum.

Mastodons (and mammoths) were such enigmatic animals because they resembled elephants but were so much larger. Mastodons and mammoths sometimes are conceptually confused; they are quite different animals, which added to the confusion about them. Although their skeletons differ from each other as much as each differs from the modern elephant, the easiest distinction between them is in their teeth. Mastodons have teeth with blunted points, with which they easily crushed sticks and twigs in their diet–and for this reason some early paleontologists believed the mastodon to be a carnivore, and because of its great size, perhaps even a predatory one. The teeth of mammoths are flatter, with undulating, parallel ridges well suited for grinding the grasses that comprised its diet.

Still, the problem remained about where the remains of these elephant-like creatures were being found. Who in the world had heard of elephants living in such inclement climes as Ohio and New York—not to mention the mammoths whose bones (and whole frozen bodies!) were found in the Siberian tundra? And, being also very big, they were very popular with a paying museum public. Surely Meriwether Lewis visited Peale’s museum in 1803 and there saw the eleven-foot-tall incognitum in its reconstructed glory. A few years later, a number of fossils would be among the boxes of “natural productions” that were shipped from the West to Jefferson and awaiting scientists. What the boxes lacked, though, were mastodon teeth and bones.

Lewis and Clark’s View

So we see that by the time Lewis and Clark hit the trail, the “nuts and bolts” of geology—descriptions of rocks and minerals—were well established. Accordingly, the explorers would be looking more for the practical products of the American West, those of economic use, things recognizable anywhere.

But fossils were problematical; they were more of an intellectual exercise. Would Lewis recognize living animals, examples of which he had seen only as bones in Philadelphia? Would the hunting parties of the corps unexpectedly find herds of mastodons, and packs of stealthy predators, or a lumbering solitary grazer previously never seen by humans? They did find some—just the bones, though—just fossils, far older than even all of human history. Once boxed up and shipped to Philadelphia, the few silent relics of ancient life would not come directly to the attention of researchers for several years. Still, the explorers executed the instructions received from Thomas Jefferson: to observe and report.