By Kate Findley, Wondrium Staff Writer
When and where were the first dinosaur bones discovered? And how were they actually classified as fossils belonging to dinosaurs? The story of dinosaurology and its evolution takes over a century to unfold.
Modern paleontologists know how to recognize and uncover dinosaur bones. But before paleontology developed as a field—and a common lexicon for fossils was established—how did scientists know what they were looking at?
In her video series Rediscovering the Age of Dinosaurs, Dr. Kristy Curry Rogers, Professor of Biology and Geology at Macalester College, heads back to the 17th century, when the first diagram of a dinosaur bone appeared in published literature.
First Dinosaur Bone Found
Robert Plot—a naturalist, a chemistry professor, and the first keeper of the Ashmolean Museum at the University of Oxford—was fascinated by the burgeoning study of natural history. He was especially interested in strange rocks that bore resemblances to animals and human body parts.
One of the most unusual pieces in Plot’s collection resembled a femur, which is the knee joint of a human thigh bone. But this bone was large, and Plot struggled to understand the implications of his find. In the end, he concluded that the bone must have come from the leg of a giant human.
Plot included an illustration of this mysterious “giant’s bone” in a report that he published in 1677. He supported his contention with examples drawn from the work of Greek and Roman philosophers, who’d written on the evidence for giant humans.
Almost a century later, Plot’s original illustration was redrawn in a scientific treatise by English physician Richard Brookes that included the use of natural objects—including fossils—in medicine. Brookes believed that Plot’s specimen bore a striking resemblance to a pair of giant testicles. He included a Latin description that identified the fossil as Scrotum humanum.
“Once humans finally uncovered the existence of dinosaurs, paleontologists would realize that this was the femur from a large-bodied carnivorous dinosaur,” Dr. Rogers said.
Plot’s Discovery Receives Proper Designation
More than a century would pass before Plot’s Scrotum humanum would be associated with Megalosaurus and given its proper genus and species designation.
In 1815, the study of dinosaurs began to take off. Reverend William Buckland—an Oxford professor and one of England’s most prominent geologists—built his own collection of fossil bones of some large, unknown animals from rock quarries near Oxford.
These included part of a large lower jaw full of sharp, terrifying teeth; a handful of vertebrae; some pieces of a pelvis and shoulder; and a few bones from a hind limb. They were all enormous and seemingly from a group akin to modern lizards.
Buckland wrote a report that featured the first formal description of a dinosaur—though that word was not yet coined. He named his newfound beast Megalosaurus, or “big lizard.” He believed that the animal may have been more than 40 feet long and heavier than an elephant.
Buckland used the anatomy of the jaw—with large, serrated teeth set into sockets—to interpret this creature as a carnivore. He also noted key differences that set Megalosaurus apart from an overgrown lizard: The thigh bone of Megalosaurus was shaped so that its hind legs would fall directly underneath its body. This arrangement is distinct from living lizards, whose limbs sprawl out to the side.
“The handful of bones that Buckland described for Megalosaurus provided a first glimmer that something was different about this ancient, giant, land-living reptile,” Dr. Rogers said.
Second Dinosaur Discovered
Meanwhile, Dr. Gideon Mantell— an obstetrician, geologist, and palaeontologist—and his wife, Mary Ann, were making discoveries of their own in the English countryside. Allegedly, their first truly notable dinosaur discoveries occurred in 1822, when Mary Ann was killing time while her husband treated patients.
The couple had recently completed work on a collaborative volume on the marine fossils they’d been finding in the area. Gideon was responsible for the descriptions and Mary Ann provided the scientific illustrations.
One day, Mary Ann spotted a couple of strange teeth in the gravel along a countryside lane. Gideon returned repeatedly over the next months in search of more fossils. A few more teeth, along with a couple of bones, came to light. These turned out to be the teeth and bones of a second type of giant reptile, fundamentally different than the Megalosaurus.
Gideon spent several years tracking down data and consulting with the expert comparative anatomists and geologists of the day. He noted the similarities of these teeth to those of living herbivorous iguanas, extrapolating that an iguana with teeth of similar size would have been gigantic—perhaps more than 60 feet long.
Finally, in 1825, Gideon named his new fossil reptile Iguanodon, or “iguana tooth.” With the naming of Iguanodon, it became known that herbivorous giant reptiles had lived alongside the ferocious, carnivorous Megalosaurus.
The field of dinosaurology had officially begun.