Joseph Leidy
Joseph Leidy was an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...


Leidy was professor of anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

 at the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...

, and later was a professor of natural history
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...

 at Swarthmore College
Swarthmore College
Swarthmore College is a private, independent, liberal arts college in the United States with an enrollment of about 1,500 students. The college is located in the borough of Swarthmore, Pennsylvania, 11 miles southwest of Philadelphia....

. His book Extinct Fauna of Dakota and Nebraska (1869) contained many species not previously described and many previously unknown on the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n continent. At the time, scientific investigation was largely the province of wealthy amateurs.


Leidy named the holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 specimen of Hadrosaurus
Hadrosaurus is a valid genus of hadrosaurid dinosaur. In 1858, a skeleton of a dinosaur from this genus was the first dinosaur skeleton known from more than isolated teeth to be found in North America. In 1868, it became the first ever mounted dinosaur skeleton...

, which was recovered from the marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...

 pits of Haddonfield, New Jersey
Haddonfield, New Jersey
Haddonfield is a borough located in Camden County, New Jersey. As of the 2010 United States Census, the borough had a total population of 11,593....

. It was notable for being the first nearly-complete fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

ized skeleton of a dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 ever recovered. The specimen was originally discovered by William Parker Foulke
William Parker Foulke
William Parker Foulke discovered the first full dinosaur skeleton in North America in Haddonfield, New Jersey in 1858....

. Leidy concluded, contrary to the view prevailing at the time, that this dinosaur could adopt a bipedal posture. He also described the holotype specimens of Arctodus
Arctodus — known as the short-faced bear or bulldog bear — is an extinct genus of bear endemic to North America during the Pleistocene ~3.0 Ma.—11,000 years ago, existing for approximately three million years. Arctodus simus may have once been Earth's largest mammalian, terrestrial carnivore...

(A. simus), the dire wolf
Dire Wolf
The Dire Wolf, Canis dirus, is an extinct carnivorous mammal of the genus Canis, and was most common in North America and South America from the Irvingtonian stage to the Rancholabrean stage of the Pleistocene epoch living 1.80 Ma – 10,000 years ago, existing for approximately .- Relationships...

 (Canis dirus), and the American lion
American lion
The American lion — also known as the North American lion, Naegele’s giant jaguar or American cave lion — is an extinct lion of the family Felidae, endemic to North America during the Pleistocene epoch , existing for approximately...

 (Panthera leo atrox), among many others.

The noted American fossil collector and paleontologist E. D. Cope
Edward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...

 was a student of Leidy's, but the enmity and ruthless competition
Bone Wars
The Bone Wars, also known as the "Great Dinosaur Rush", refers to a period of intense fossil speculation and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope and Othniel Charles Marsh...

 that developed between him and rival paleontologist O. C. Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...

 eventually drove Leidy out of western American vertebrate paleontology, a field that Leidy had helped to found. Leidy inadvertently contributed to the falling out of the two by showing Cope in the presence of Marsh that Cope had mistakenly placed the head of a fossil Elasmosaurus
Elasmosaurus + σαυρος sauros 'lizard') is a genus of plesiosaur with an extremely long neck that lived in the Late Cretaceous period , 80.5 million years ago.-Description:...

on the tail, rather than on the neck, and then publishing a correction.

Leidy was an early American supporter of Darwin's
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 theory of evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

, and lobbied successfully for Darwin's election to membership in the Academy of Natural Sciences
Academy of Natural Sciences
The Academy of Natural Sciences of Drexel University, formerly Academy of Natural Sciences of Philadelphia, is the oldest natural science research institution and museum in the New World...

 of Philadelphia.

Other scientific fields

Leidy was also a renowned parasitologist, and determined as early as 1846 that trichinosis
Trichinosis, also called trichinellosis, or trichiniasis, is a parasitic disease caused by eating raw or undercooked pork or wild game infected with the larvae of a species of roundworm Trichinella spiralis, commonly called the trichina worm. There are eight Trichinella species; five are...

 was caused by a parasite in undercooked meat. He was also a pioneering protozoologist, publishing Fresh-water Rhizopods
Amoeboids are single-celled life-forms characterized by an irregular shape."Amoeboid" and "amœba" are often used interchangeably even by biologists, and especially refer to a creature moving by using pseudopodia. Most references to "amoebas" or "amoebae" are to amoeboids in general rather than to...

 of North America
in 1879 - a masterpiece that is still referenced today.

Leidy collected gems as well as fossils, and donated his important collection of the former to the Smithsonian
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...

 before he died. At Swarthmore, he also taught a class on mineralogy and geology.


Joseph Leidy was born on September 9, 1823, to an established Philadelphia family of German extraction
The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

. His father, Philip, was a hatter; his mother, Catharine, died when he was young, during childbirth, whereupon his father remarried to his wife's first cousin, Christiana Mellick. Leidy also had a brother named Thomas Leidy. With the support of his stepmother, and after overcoming the opposition of his father (who wanted him to be a sign painter), Leidy studied medicine at the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...

. He graduated with his medical degree in 1844.

He married Anna Harden, a woman who took a serious interest in his work and helped him with it on occasion. Their marriage was childless, and they eventually adopted an orphaned seven-year-old girl.

Forensic innovator

In 1846, Leidy became the first person ever to use a microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...

 to solve a murder mystery. A man accused of killing a Philadelphia farmer had blood on his clothes and hatchet. The suspect claimed the blood was from chickens he had been slaughtering. Using his microscope, Leidy found no nuclei in these erythrocytes (human erythrocytes are anucleate). Moreover, he found that if he let chick erythrocytes remain outside the body for hours, they did not lose their nuclei. Thus, he concluded that the blood stains could not have been chicken blood. The suspect subsequently confessed.

External links

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