Two years later, Osborn took a special course of study in anatomy in the College of Physicians and Surgeons and Bellevue Medical School of New York under Dr. William H. Welch, and subsequently studied embryology and comparative anatomy under Thomas Huxley at London, as well as Francis Maitland Balfour at Cambridge University, England.

In 1891, Osborn was hired by Columbia University as a professor of zoology; simultaneously, he accepted a position at the American Museum of Natural History, New York, where he served as the curator of a newly formed Department of Vertebrate Paleontology.

As a curator, he assembled a remarkable team of fossil hunters and preparators, including William King Gregory, Roy Chapman Andrews, Barnum Brown, and Charles R. Knight.

[11] (Modern researchers use computed tomography scans and 3D reconstruction software to visualize the interior of dinosaur endocrania without damaging valuable specimens.

)[12] On November 23, 1897, he was elected member of the Boone and Crockett Club, a wildlife conservation organization founded by Theodore Roosevelt and George Bird Grinnell.

[13] Thanks to his considerable family wealth and personal connections, he succeeded Morris K. Jesup as the president of the AMNH's Board of Trustees in 1908, serving until 1933, during which time he accumulated one of the finest fossil collections in the world.

[19] But his decision to invest heavily in exhibition also alienated certain members of the scientific community and angered curators hoping to spend more time on their own research.

[20] Additionally, his efforts to imbue the museum's exhibits and educational programs with his own racist and eugenist beliefs disturbed many of his contemporaries and have marred his legacy.

Writing before Piltdown was exposed as a hoax, the Eoanthropus or "Dawn Man" Osborn maintained sprang from a common ancestor with the ape during the Oligocene period which he believed developed entirely separately during the Miocene (16 million years ago).

Therefore, Osborn argued that all apes (Simia, following the pre-Darwinian classification of Linnaeus) had evolved entirely parallel to the ancestors of man (homo).

He also held the view that mutations and natural selection play no creative role in evolution and that aristogenesis was the origin of new novelty.

[citation needed] Due to this, he endorsed Madison Grant's The Passing of the Great Race, writing both the second and fourth prefaces of the book, which argued for such views.