Georges Cuvier Revolutionizes Paleontology

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Georges Cuvier Revolutionizes Paleontology

Overview

In the wake of the French Revolution (1789-99), young naturalist Georges Cuvier took up arms against conventional beliefs calling into question the accepted view of the history of Earth as well as the relatedness of fossil organisms to living species. Through extensive field collection and meticulous study of fossil specimens, Cuvier began amassing the evidence that would establish extinction as a biological reality. His methodologies, field practices and procedures, and groundbreaking work paved the way for future paleontologists.

Background

Fossils have fascinated and mystified humans for thousands of years. Collected, discussed, and described by such historical figures as Aristotle (384-322 B.C.), Leonardo da Vinci (1452-1519), and Martin Luther (1483-1546), fossil origins served as a source of speculation and debate. Once believed to form in Earth's crust by processes similar to the crystallization of minerals, by the late 1600s fossils were generally recognized as the remains of plants and animals. The realization that fossils were neither randomly distributed throughout the crust of Earth nor found in all rock types led naturalists to examine fossils more closely as they sought answers to age-old questions.

While many of his colleagues offered explanations for the occurrence of fossils and other natural phenomena, providing cursory observational evidence to support these explanations, Cuvier (1769-1832) carried out exhaustive field studies collecting evidence to support his position that fossils were the remains of species that no longer existed. He became a bold innovator offering what few before him had: physical evidence. For him, fossils became more than natural oddities but rather served as the crux for a different view of the history of Earth.

Cuvier entered the infant field of geology with questions and concerns. The predominant philosophy at the time held that fossil remains were the remnants of animals that still existed elsewhere on Earth. To suggest that they were the remains of animals that no longer existed was counter to religious creationist doctrine. Cuvier, a devout creationist, suspected that Earth was much older than suggested by the biblical interpretation. He challenged current Earth history view on the basis of the physical evidence provided by the fossils themselves.

A gifted comparative anatomist, Cuvier carefully reconstructed ancient animals, thereby documenting the past existence of large mammals that resembled no living species. Through detailed studies of elephant anatomy, he demonstrated beyond a shadow of a doubt that African and Indian elephant species were two distinct species. Additionally, he demonstrated that the fossil remains of elephant-like organisms recovered from Europe and Siberia belonged to neither species but rather to a species that no longer existed—woolly mammoths. In addition to mammoths, Cuvier published articles describing giant ground sloths, Irish elk, and American mastodons in addition to a number of invertebrate species.

Cuvier's work extended beyond the proof and naming of extinct species, as he proposed the mechanism for the demise for these species—most of which existed before man, a notion hotly debated in and of itself. His proposition that extinction resulted from geological "catastrophes" or sudden changes in Earth's surface provided a causal agent for mass extinction and a foundation for species transformation. Cuvier was a steadfast opponent of organic evolution, and his work significantly influenced future scientists.

Impact

With the advent of Cuvier's work and publication of his catastrophe theory, fossils were viewed with heightened interest. Students and disciples of Cuvier continued to seek fossil evidence and scientific explanations that supported Cuvier's theories of extinction and Earth history.

A renowned student of Cuvier and glaciologist, Louis Agassiz (1807-1873) employed both Cuvier's methodologies and his philosophies as he explored living and fossil fishes in addition to the potential effects that glacial episodes must have had on Earth's ancient populations and topography (land surface features). Agassiz made lasting contributions to evolutionary biology and systematics through his construction of classification based on morphological characteristics. Similar to Cuvier, Agassiz opposed evolutionary thought even as his work was used by biologists to support it.

Cuvier's influence extended well beyond his own students, impacting those who would throw the gates to the field of vertebrate paleontology wide open. While not the first to discover a reptilian fossil—that distinction belonged to William Buckland (1784-1856)—Gideon Mantell's discovery of fossil iguana-like teeth in Sussex, England, in 1822 and his subsequent discovery of Hylaeosaurus in 1833 promoted continued interest in fossils. Close examination of his finds led Mantell (1790-1852) to suggest that based on physiologic differences Iguanodon and Hylaeosaurus belonged to different genera.

Sir Richard Owen (1804-1892), a comparative anatomist in the style of Georges Cuvier and a staunch anti-evolutionist, studied the relationships between groups of organisms. Upon examination of the known reptile fossils, Megalosaurus, Iguanodon, and Hylaeosaurus, Owen concluded that these organisms were members of a group distinctly different from living lizard species. In 1842 Owen published the results of his study, naming this new grouping of large, extinct reptilian animals "Dinosauria"—which meant "terrible lizard" or "fearfully great reptile."

In 1863, as curator of the British Museum of Natural History, Owen acquired, named, and described Archaeopteryx lithographica, a crow-sized animal possessing morphologic features characteristic of both lizards and birds. Regardless of how much Archaeopteryx looked like the missing link between reptiles and birds, Owen rejected evolution as the causal agent of the bizarre appearance of this fossil specimen. In fact, in response to evolutionists claiming Archaeopteryx as a missing link between animal phyla, Owen demanded evolutionists produce more "missing links."

In 1868 the nearly complete skeleton Hadrosaurus foulkii, discovered 10 years earlier in Haddonfield, New Jersey, went on public display at the Academy of Natural Sciences of Philadelphia. Through comparative anatomy techniques, Joseph Leidy concluded that Hadrosaurus was closely related to the Iguanodon discovered 50 years earlier on the other side of the Atlantic Ocean.

Completion of the Transcontinental Railroad in 1869 geared the world of paleontology up for the first of several eras of dinosaur discoveries. Discovery of dinosaur fossils in Colorado in the late 1870s initiated the "First Great Dinosaur Rush" as paleontologists scrambled to identify previously unknown species of the extinct beasts. The public's fascination with dinosaurs grew with each new discovery and public display. Two paleontologists, Edward Drinker Cope (1840-1897) and Othniel Charles Marsh (1831-1899), became bitter rivals as each sought to be the first to unearth the most spectacular dinosaur fossils. Thus began one of the most well-known rivalries in paleontological history. The fierce competition between Cope and Marsh resulted in the discovery and identification of no less than 28 new genera of dinosaurs.

Paleontology today still bears some resemblance to the science founded on Cuvier's principle of hard evidence. Fossil organisms are still identified using morphological characteristics. However, modern paleontologists strive to do more than identify the organisms to which fossils belong. Modern paleontology often involves the fields of paleobotany—the study of fossil plants—and paleoecology—the study of ancient habitats. Anatomical studies and reconstruction of extinct species excavated from the Rancho La Brea tar pits, for instance, provides extensive insight into the population structure of animals that lived 10,000 to about 400,000 years ago, a period termed the "Rancholabrean Land Mammal Age."

As to the role fossils play in settling the ageold debate between creationists and evolutionists, fossils are proving to be invaluable resources for determining the relatedness between extinct and modern species. Multiple copies of ancient DNA obtained from fossils have been made through the duplicating process of polymerase chain reaction, or PCR. A determination and comparison of the nucleotide base sequences between extinct and modern species often shows that which Cuvier refused to consider—a relationship between extinct and modern species of animals.

MICHELLE ROSE