Geology Home Page physical geology historical geology
Roger Weller, geology instructor regional geology planetary gems
by Sean Harvey
There are many types of dinosaurs and they can be broken down into numerous
categories. Dinosaurs are prehistoric animals that evolved over a time frame of
185 million years. Because the dinosaurs are extinct creatures now they are
ever changing discoveries that changes how dinosaurs are classified. The
following chart illustrates how dinosaurs are classified currently.
Dinosaurs evolved in a multitude of directions and with the many different
parallel, convergent and divergent evolutionary paths there are some species
that look completely different from one another, but are quite the same in many
aspects. There are many recognized dinosaurs when spoken of such as the
Tyrannosaurus Rex and the Triceratops; however, there are more then just these
nine or so common dinosaurs. In the following paragraphs some of these uncommon
dinosaurs will be uncovered with some interesting facts.
in Arizona there is a dinosaur discovery that much resembles a crocodile and
reached up to the length of ten feet. This dinosaur was called the
Arizonasaurus. The Arizonasaurus had a large fin on itís back to regulate the
body heat. This was thought to be a prehistoric predator and lived in hot
Shonisauarus is a swimming reptile that was considered to dolphin-like. This
animal grew to the amazing size of fifty feet! This reptile had four large
fins to help stabilize its body and had a small fin on top if its back. Not a
dinosaur, but from the age of dinosaurs.
that resembles the Velociraptor which was made famous through the movie Jurassic
Park is the Eoraptor. This dinosaur hunted in packs and is about the size of a
fox. It is about 3 and Ĺ feet long. This dinosaur was very dexterous and
worked well in the hunting environment. This dinosaur had very strong hind legs
and razor sharp teeth to shred through its prey.
The Corythosaurus had a large fin on the top of its head and stood on its
hind legs like many other dinosaurs. This was a very commonly found animal from
the Cretaceous period. This dinosaur was in Jurassic Park for a short scene or
two. This dinosaur had a large beak on the skull with many interlocking teeth in
the back of its jaw. This dinosaur was believed to be a herd dinosaur and able
to communicate to like animals through a uniquely designed nasal passage.
In great contrast to the Tyrannosaurus Rex there was one of the smallest
dinosaurs to ever exists, Nanosaurus. This dinosaur was approximately two feet
high and four feet long. This dinosaur was also a herbivore. Not much is known
about this dinosaur.
Lastly, the Guanlong which is related to the Tyrannosaurus Rex was a medium
sized dinosaur reaching about ten feet in length and also had a large protruding
head plate. It is made of a softer bone which may have been used to protect a
specialized organ. There is not much information on this dinosaur even though
there has been a full discovery of its bone structure. This dinosaur was found
in China. This animal was believed to have been carnivorous and very fierce
above are just the many hundreds of species the evolutionary path of life
traveled down. From big lizards to small - from flying, running and swimming
they conquered the world as their own. These dinosaurs came to be extinct with
the rest of their brothers and sisters by a nine mile thick meteorite striking
around the Gulf of Mexico. This meteorite has yet to be proven that it has made
the dinosaurs extinct; however, the evidence shows that this is a very logical
theory. This meteorite was believed to have stuck half on land and half on
This meteorite was believed to have killed all
large animals and the only survivors would be small mammals that lived off roots
under ground. These animals are responsible for the recovery of living life on
http://www.dinosaurfact.net/. Dinosaur Facts. 2007.
Reed, Wicander and Monroe, James. Historical Geology. Thomson Brooks/Cole. 2007. 5th ed.
http://www.sdnhm.org/kids/dinosaur/ Dinosaur Dig. San Diego Natural History Museum.
http://www.thedinosaurmuseum.com/html/dinosaur-facts.html Dinosaur Museum.
http://encarta.msn.com/encnet/departments/elementary/?article=10surprisingdinosaurfacts 10 Surprising Dinosaur Facts. MSN Encarta.
http://www.tooter4kids.com/DinosaurIndex/dinosaur_facts.htm Dinosaur Facts.