CRETACEOUS PERIOD: 110 - 65
million years ago
were the most common, varied, and well-adapted ornithopod (bird-hipped)
dinosaurs. The group probably evolved in central Asia and by the
Late Cretaceous Period, had spread all over the lands of the northern
hemisphere, migrating across a land bridge that existed at that time
connecting Asia to North America. From there, the group moved
eastward again to Europe. Remains of a certain type have even been
found in southern Argentina, believed to be from a migration from North
America across a volcanic island chain that once existed. Hadrosaurs
were the first dinosaur family to be described in North America.
The outward appearance
of hadrosaurs varied widely amongst the different species but
structurally, they were all the same. The most obvious common
feature was the elongated face ending in a broad, flattened
snout. The toothless beak of
the hadrosaur looked quite similar to the bill of a duck, hence the common
nickname of these dinosaurs, "duck-billed dinosaur".
herbivores (plant-eaters) and only had teeth in the cheek area, not the
front of the mouth. The many rows of teeth were perfect for
effectively grinding up rough vegetation for easy digestion.
This unique group of
dinosaurs grew in sizes over 40 feet and probably weighed over 5
tons! In-depth studies of a variety of duckbill remains indicate
that these were strictly land-based dinosaurs that walked predominantly on
all fours but had the ability to stand on their hind legs. In 1999,
a remarkable discovery was made from the Hell Creek Formation where a
mummified hadrosaur was discovered with skin, ligaments, tendons and
what appear to be some internal organs. CT scanning of the
specimen and further research will help scientists to further understand
this and even other, dinosaurs.
Hadrosaur remains have been found in
China, North America, South America (Argentina) and Europe.
Misspellings: hadrasaur, hadrasore, hadrysaur, hardosaur.
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