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Celebrate Fossil Day

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Trace-Fossil-DF-250

A trace fossil on display behind the Museum’s Apatosaurus mount in the Hall of Saurischian Dinosaurs.

 © AMNH/D. Finnin.


From 75-foot dinosaurs to saber-toothed tigers, an overwhelming number of animals stopped moving ages ago. But their remains are still talking.

At the American Museum of Natural History, scientists pore over nearly 5 million fossilized specimens across many different collections, looking back in time to piece together what these unique organisms looked like and how they behaved.

In celebration of National Fossil Day, marked today by the National Park Service and the American Geological Institute, dig into some of these fascinating specimens from the Museum’s fourth-floor Fossil Halls, highlighted below.

Piecing Together a Giant

Collected in the late 1890s, the Museum’s Apatosaurus skeleton was the first sauropod—an animal belonging to a group of long-necked, quadrupedal, and gigantic dinosaurs—ever mounted. Museum preparators labored over the specimen for several years before it went on view in 1905. Nearly 90 years later, the Apatosaurus was partly disassembled and remounted to reflect new findings about the giant animal’s posture. The first version of the mount featured the wrong head as well an incorrect tail length and configuration—showing the tail dragging on the ground instead of being held up in the air. The sauropods, the largest known animals ever to walk on land, are the focus of the Museum’s current exhibition The World’s Largest Dinosaurs.

Disappearing With a Trace

Fossils don’t need to be made of bones. A trace fossil on display behind the Museum’s Apatosaurus skeleton in the Hall of Saurischian Dinosaurs gives researchers some of the most important clues to the ways dinosaurs lived. Uncovered by Museum researchers in 1940 in Texas, this trackway shows the footprints of two types of dinosaurs—sauropods, gigantic vegetarian dinosaurs; and theropods, two-legged, primarily carnivorous dinosaurs. Besides illuminating the physical shape of these dinos’ feet, the site these tracks came from shows scientists that some dinosaurs may have traveled in herds and held their limbs directly below their bodies, like elephants. Because there is no groove between the footprints, researchers also have concluded that these dinos’ immense tails must have been carried completely off the ground.

The Mummy Returns

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The mummy, a type of duck-billed dinosaur called an Edmontosaurus, has led to some important discoveries. 

© AMNH/D. Finnin.


This remarkable specimen is called a “mummy” because in addition to fossilized bones and teeth, it also left impressions of skin in the surrounding rock. It is mounted in the Hall of Ornithischian Dinosaurs as it was found, lying on its back with the knees drawn up. The mummy, a type of duck-billed dinosaur called an Edmontosaurus, has led to some important discoveries. By studying the specimen, scientists learned that the animal’s skin was covered with tiny bumps called tubercles, similar to the skin on a bird’s feet. In its stomach, scientists found the animal’s last meal—pine needles, bark, and cones. This finding contradicted theories that the dinosaurs lived near swamps and lakes and ate soft water plants.

For more about the Museum’s fossil collections, take a look inside the Big Bone Room or watch this video on the challenges of preparing fossils.

Thumbnail image of Apatosaurus on homepage © AMNH/B. Blackwell.

Tags: Dinosaurs

American Museum of Natural History

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New York, NY 10024-5192
Phone: 212-769-5100

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