The museum consists of organized into 20 galleries as well as research, library, and office space. It holds some 22 million specimens, of which about 10,000 are on view at any given time and about 1 million are cataloged in online databases. In 2008 it hosted 386,300 admissions and 63,000 school group visits. Museum education staff also actively engage in outreach by traveling to schools all around western Pennsylvania. The museum gained prominence in 1899 when its scientists unearthed the fossils of Diplodocus carnegii. Today its dinosaur collection includes the world's largest collection of Jurassic dinosaurs and its Dinosaurs in Their Time exhibition offers the third largest collection of mounted, displayed dinosaurs in the United States. Notable specimens include one of the world's only fossils of a juvenile Apatosaurus, the world's first specimen of a Tyrannosaurus rex, and a recently identified species of oviraptorosaur named Anzu wyliei. Research teams including former Carnegie scientists made critical discoveries such as Puijila darwini, Castorocauda lutrasimilis, and Hadrocodium wui. Other major exhibits include Hillman Hall of Minerals and Gems, Alcoa Foundation Hall of American Indians, Polar World: Wyckoff Hall of Arctic Life, Walton Hall of Ancient Egypt, Benedum Hall of Geology, Dinosaurs in Their Time, and Powdermill Nature Reserve, established by the museum in 1956 to serve as a field station for long-term studies of natural populations. The museum's active curatorial departments are: Anthropology, Birds, Botany, Herpetology, Invertebrate Paleontology, Invertebrate Zoology, Mammals, Minerals, Mollusks, and Vertebrate Paleontology. These departments work collaboratively under strategic centers created to re-frame how the museum leverages its research, exhibitions, and public programming to meet the challenges and issues of today. In late 2013, however, the museum's parent organization and interim administration eliminated multiple scientific positions, seriously affecting its capacity to conduct original research.
Scientific publications
Carnegie Museum of Natural History publishes scholarly journals and books including Annals of Carnegie Museum, which offers peer-reviewed articles in organismal biology, earth sciences, and anthropology; Bulletin of Carnegie Museum of Natural History, offering monographs or collections of related papers from symposia; and Special Publications of Carnegie Museum, documenting special topics or areas of research.