Hadrosaurs
Hadrosaurs are some of the best known and most diverse (many
different species) types of dinosaurs. There have even been large
skin impressions found showing that hadrosaurs had small, button-like
scales all over their bodies. They seem to be the deer of the
Late Cretaceous. They were probably the prey of choice of the large
meat-eating dinosaurs (the tyrannosaurs). They divide into two
different groups, with the biggest difference between the groups being
what their head looks like. The heads of the hadrosaurines were flat
or had small spikes on the top. The heads of the lambeosaurines had
big crests on them. Hadrosaurs had the most complicated, best designed
teeth of all of the plant eating dinosaurs. They had up to 1200 teeth
in their mouth at the same time. With all of these teeth, they could
chew any plant material. This made them very successful as a group.
Hadrosaurines
The "flat headed" dinosaurs were very common. They came in large
varieties that fall into different groups. Some had very wide mouths
with very long, flat heads (edmontosaurs), some had little spikes on
the tops of their heads (saurolophs), and some had bumps on their noses
(gryposaurs). It was the discovery of the hadrosaur Maiasaura
that let palaeontologists know that hadrosaurs looked after their young
in nests. Eggs, babies, and nests of Maiasaura were all found
in the late 1970's in Montana showing a little bit about how baby
dinosaurs grew up. Huge bonebeds have been found for several of the
hadrosaurs, often with 10000 or more different dinosaurs in each!
Hadrosaurines ranged from 8 meters (Gryposaurus) to about
15 meters (Shantungosaurus) in length. They have been found in
Asia, South America, North America, and Europe. True hadrosaurs
include Gryposaurus, Maiasaura, Prosaurolophus, Shantungosuarus,
Edmontosaurus, Saurolophus, Brachylophosaurus, Anatotitan, and
Hadrosaurus.
Lambeosaurines
Lambeosaurines are easy to spot when you are in the museum. They are
the "duck-billed dinosaurs" with the big crests on their heads. There
were not as many types of these, but they were quite plentiful. Some
of the crests looked like big, flat, round disks on their heads. One
was a great big long tube that faced backwards on the top of the head.
These crests have been a mystery for years. At first, when people
thought that hadrosaurs lived in the water, they were thought to be for
breathing underwater. But, when they realised that hadrosaurs lived
on land, ideas have changed. Some scientists think that they were
used for smell. Some think that they were for making noise. Others
think they were used for both. New clues from new specimens may help
solve this mystery.
Lambeosaurines ranged in size from 6 meters (Bactrosaurus) to
about 9 meters (Lambeosaurus). They have been found in Asia and
North America. This group includes Lambeosaurus, Hypacrosaurus,
Corythosaurus, Parasaurolophus, and Bactrosaurus.
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