Edmontosaurus (Hadrosaurus) minor (Leidy)
Description: The teeth of the hadrosaurs were lined into a tooth battery for the grinding of plant material. As the teeth were
worn down, they were discarded and replaced with new ones, similar to a shark. Because of this, singular worn teeth are usually
found. The grinding surface is diamond shaped and may have a vertical ridge splitting the diamond into two triangles. The tooth
crown is covered with enamel and the root tapers from the crown to a blunt point.
Only a few isolated confirmed bones from this hadrosaur exist from this site. The best way to identify this hadrosaur, as well as
other dinosaur material is by size. Large sections of leg bone turn up very uncommonly but are for the most part unmistakable.
Typical large sections are about 15 cm (about 6 in) in length and 9 cm (about 3.5 in) wide. Much of the possible material from
this dinosaur is very beaten, worn, and scrappy. Most of the time, the spongy marrow (medullary cavity) has been eroded out
leaving the more dense outer bone. This is mostly due to conditions before and after fossilization. No doubt, a larger amount of
dinosaur material occurs but is to broken, worn, or too fragmentary to be recognized. Identification to the family of
Hadrosauridae is usually the best one can safely do.
Commonality: Scrappy bone material of the duckbills is uncommon. Teeth are very uncommon and other identifiable material is
Similar fossils: Teeth are distinctive and are hard to confuse with other locality teeth. Size should serve to differentiate bone
Size: Edmontosaurus is a typical member of the herbivorous duckbill family and reached 6 meters (about 20 feet) in length.
Notes: A close earlier relative (Hadrosaurus foulkii) has the distinction of being the first relatively complete dinosaur to be
discovered in North America and probably the world. A partial skeleton made up of 35 bones was found in Haddonfield,
Camden County, New Jersey in 1858. This partial skeleton was the first to be mounted and displayed in a bipedal stance. By
doing this, Dr. Joseph Leidy disproved a widely held belief of the time that dinosaurs were lumbering, lizard like reptiles. He
recognized that the hind limbs were longer than the front and should be mounted as a biped. From that day forward, the
American paleontologists, who during the 1800's were considered rank amateurs by the Europeans, took the lead in dinosaur
paleontology. This skeleton still remains at the Academy of Natural Sciences in Philadelphia.
Hadrosaurs are believed to have inhabited (at least for part of the year) the coastal lowlands. These dinosaurs were part of the
new breed of dinosaurs that were evolving during the Late Cretaceous. Their teeth were modified to eat grasses (another new
corner) and other low growing plants. Like the other dinosaurs, the hadrosaurs became extinct at the end of the Cretaceous.