Page 139 - Prehistoric Animals

Trak-O-Don

Trachodon

What is a Dinosaur ?
Known as a Dinosaur

Trachodon (meaning
"rough tooth") is a dubious
genus and is based on teeth
examined and named by, Jo-
seph Leidy in 1856, who ini-
tially described them as be-
longing to a duck-billed dino-
saur. Since then many - even
Leidy himself - have expressed
caution and cast doubt on his
description of the teeth and the validity of this genus. However, the
genus has remained and over the years has had several species
added to it. Today, in hindsight, only one species, the original type
species named by Joseph Leidy as Trachodon mirabilis, is the only
acceptable species of this now marginalized genus.

Commentators when describing Trachodon, will probable
use Hadrosaurid* as their source for information about the
makeup of the duck-bill, which was a large herbivorous dinosaur
that, on average, was 4 metres in height, 10 metre in length and
could weigh around 4 tonnes. Hadrosaurid most noticeable feature
was its flat bony duck-bill snout. It had jaws at the rear of its bill
lined with an array of grinding teeth. It had four limbs with the
front limbs being slightly shorter than the rear ones. In adulthood,
Hadrosaurid, was thought to have been bipedal, (Walking on all
fours) whereas, in childhood stood upright on its rear limbs to
walk. Hadrosaurs were a dominant species across Asia and North
America during the Late Cretaceous, but were thought to have mi-
grated across Europe, Africa, and South America at the close of the
Cretaceous. They eventually disappeared around 65 million years
ago.

*Hadrosaurids (Wikipedia)
(from Ancient Greek ἁδρός (hadrós) 'stout, thick', and σαύρα (saúra) 'lizard'), or duck-
billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is
known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in
their snouts. The ornithopod family, which includes genera such
as Edmontosaurus and Parasaurolophus, was a common group of herbivores during
the Late Cretaceous Period.[1] Hadrosaurids are descendants of the Upper Jurassic/
Lower Cretaceous iguanodontian dinosaurs and had a similar body layout. Hadrosaurs
were among the most dominant herbivores during the Late Cretaceous in Asia and
North America, and during the close of the Cretaceous several lineages dispersed into
Europe, Africa, and South America.