page_title: American Museum of Natural History
section_title: Fossil halls
hierarchical_section_title: American Museum of Natural History / Fossil halls
caption_attribution_description: English: Mounted skeletons of Tyrannosaurus rex (left) and Apatosaurus excelsus (right) at the American Museum of Natural History in New York City.
context_page_description: The American Museum of Natural History, on the Upper West Side of Manhattan, New York City, is one of the largest natural history museums in the world. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 interconnected buildings housing 45 permanent exhibition halls, in addition to a planetarium and a library. The museum collections contain over 34 million specimens of plants, animals, fossils, minerals, rocks, meteorites, human remains, and human cultural artifacts as well as specialized collections for frozen tissue and genomic and astrophysical data, of which only a small fraction can be displayed at any given time, and occupies more than 2 million square feet. The museum has a full-time scientific staff of 225, sponsors over 120 special field expeditions each year, and averages about five million visits annually.
  The one mission statement of the American Museum of Natural History is: "To discover, interpret, and disseminate—through scientific research and education—knowledge about human cultures, the natural world, and the universe."
context_section_description: Most of the museum's collections of mammalian and dinosaur fossils remain hidden from public view. They are kept in many repositories deep within the museum complex. Among these, the most significant storage facility is the ten-storey Childs Frick Building which stands within an inner courtyard of the museum. During construction of the Frick, giant cranes were employed to lift steel beams directly from the street, over the roof, and into the courtyard, in order to ensure that the classic museum façade remained undisturbed. The predicted great weight of the fossil bones led designers to add special steel reinforcement to the building's framework, as it now houses the largest collection of fossil mammals and dinosaurs in the world. These collections occupy the basement and lower seven floors of the Frick Building, while the top three floors contain laboratories and offices. It is inside this particular building that many of the museum's intensive research programs into vertebrate paleontology are carried out.
  Other areas of the museum contain repositories of life from the past. The Whale Bone Storage Room is a cavernous space in which powerful winches come down from the ceiling to move the giant fossil bones about. The museum attic upstairs includes even more storage facilities, such as the Elephant Room, while the tusk vault and boar vault are downstairs from the attic.
  The great fossil collections that are open to public view occupy the entire fourth floor of the museum as well as a separate exhibit that is on permanent display in the Theodore Roosevelt Memorial Hall, the museum's main entrance. The fourth floor exhibits allow the visitor to trace the evolution of vertebrates by following a circuitous path that leads through several museum buildings. On the 77th street side of the museum the visitor begins in the Orientation Center and follows a carefully marked path, which takes the visitor along an evolutionary tree of life. As the tree "branches" the visitor is presented with the familial relationships among vertebrates. This evolutionary pathway is known as a cladogram.
  To create a cladogram, scientists look for shared physical characteristics to determine the relatedness of different species. For instance, a cladogram will show a relationship between amphibians, mammals, turtles, lizards, and birds since these apparently disparate groups share the trait of having 'four limbs with movable joints surrounded by muscle', making them tetrapods. A group of related species such as the tetrapods is called a "clade". Within the tetrapod group only lizards and birds display yet another trait: "two openings in the skull behind the eye". Lizards and birds therefore represent a smaller, more closely related clade known as diapsids. In a cladogram the evolutionary appearance of a new trait for the first time is known as a "node". Throughout the fossil halls the nodes are carefully marked along the evolutionary path and these nodes alert us to the appearance of new traits representing whole new branches of the evolutionary tree. Species showing these traits are on display in alcoves on either side of the path. A video projection on the museum's fourth floor introduces visitors to the concept of the cladogram, and is popular among children and adults alike.
  Many of the fossils on display represent unique and historic pieces that were collected during the museum's golden era of worldwide expeditions (1880s–1930s). On a smaller scale, expeditions continue into the present and have resulted in additions to the collections from Vietnam, Madagascar, South America, and central and eastern Africa.
  The 4th floor includes the following halls:
  Hall of Vertebrate Origins
  Hall of Saurischian dinosaurs (recognized by their grasping hand, long mobile neck, and the downward/forward position of the pubis bone, they are forerunners of the modern bird)
  Hall of Ornithischian Dinosaurs (defined for a pubic bone that points toward the back)
  Hall of Primitive Mammals
  Hall of Advanced Mammals
caption: Hall of Saurischian Dinosaurs.
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