Father of American Vertebrate Paleontology
Joseph Leidy is best known for his study of the dinosaur Hadrosaurus foulkii, which greatly advanced knowledge of these prehistoric giants and placed the United States at the scientific forefront of vertebrate paleontology. Leidy studied other fossil animals, including fishes and reptiles, but most of Leidy's paleontological work was on prehistoric mammals, especially those from the American West.
Leidy was the leading American expert on anatomy and vertebrate paleontology during the middle 19th Century. Because of this, fossil collectors from across the country sent their finds to his office at The Academy of Natural Sciences of Philadelphia. Liedy was thankful for these offerings and would acknowledge the collectors in print. Unfortunately, the state-of-the-art for the collection and care of fossils was so primitive that the specimens were usually badly damaged and seriously incomplete. Despite these limitations, Leidy's mastery of comparative anatomy and powers of observation enabled him to generate numerous major findings and discoveries.
Leidy wrote approximately 230 publications on paleontology. Many of these were short notes, but others were important contributions to science. Among these are his numerous descriptions of new species and his studies on fossil horses and extinct ground sloths. He also published four monographs: The Ancient Fauna of Nebraska (1853), Cretaceous Reptiles of the United States (1865), On the Extinct Mammalia of Dakota and Nebraska (1869), and Extinct Vertebrate Fauna of the Western Territories (1873). He described a total of 130 new genera and over 300 species of fossil vertebrates. (See Fossil Species for more on several of the more significant species studied by Leidy.)
The paleontological contributions of Joseph Leidy were highly regarded in both the United States and Europe. Leidy also helped the advancement of paleontology through the training and encouragement of others. Ironically, the reduction of Leidy's studies in paleontology was prompted by the actions of one of his proteges, Edward Drinker Cope, and one of his admirers, Orthniel C. Marsh. The bitter competition between these two rivals, known as the Bone Wars, disgusted Leidy and dried-up his sources for fossils from the American West. Although the quantity and quality of the fossils available to Cope and Marsh typically exceeded Leidy's, it is the quality of Leidy's work that has generally stood the test of time.