Fossils of hard mineral parts (like bones and teeth) were
formed as follows: o Some animals were quickly buried after their
death (by sinking in mud, being buried in a sand storm, etc.). o
Over time, more and more sediment covered the remains. o The parts
of the animals that didn't rot (usually the harder parts likes
bones and teeth) were encased in the sediment. o In the right
circumstances (no scavengers, quick burial, not much weathering),
parts of the animal turned into fossils over time. o After a long
time, the chemicals in the buried animals' bodies underwent a
series of changes. As the bone slowly decayed, it was replaced with
minerals. o This process results in a heavy, rock-like copy of the
original object - a fossil. The fossil has the same shape as the
original object, but is more like a rock! At times, it is possible
that some of the original bone may remain.
Slide 3
Why are Fossils Rock-Colored? Because they ARE rocks! A
fossilized object is just a rocky model of an ancient object. A
fossil is composed of different materials than the original object
was. During the fossilization process, the original atoms are
replaced by new minerals, so a fossil doesn't have the same color
as the original object. Fossils come in many colors and are made of
many different types of minerals. Also, some fossils of skin (and
other soft body parts) have been found. Again, the color of the
skin is not retained during the fossilization process, all that
remains today is a rocky model of the original.
Slide 4
So how do we know what color dinosaurs were? Or what their eyes
looked like? Who decides?
Slide 5
Paleoartists- Those who specialize in extinct animal
restoration
The skeleton is then studied to determine as much about the
animal as possible. Sometimes, fossilized skin impressions are
found with the fossil as well. Paleoartist such as Tyler then get
ideas about what the exterior of the animal looked like by looking
at the patterns, color, and camouflage of present-day animals.
Tyler sculpted this model of what Tiktaalik may have looked
like.
Slide 9
Herrerasaurus ischigualastensis was found in Argentina in 1958
by Victorino Herrera, for whom the fossil was named. This skeleton
was incomplete, but the discovery of a complete skull in 1988 and
additional fragments have provided enough information to make a
complete reconstruction.
Slide 10
This reconstruction was created to illustrate a section of a
paleoart book, Life Restorations of Dinosaurs (2008). Tyler used
the well-preserved skull as the starting point. An alert,
inquisitive appearance is suggested by the pose, with soft tissues
based upon reptilian (reptile) and avian (bird) references, and a
coloration scheme inspired by the Komodo dragon.
Slide 11
Article about how Tyler constructs his models:
http://www.tylerkeillor.com/pdfs/Muse%2
0magazine%20with%20Tyler.pdf
Slide 12
On left: Fossil specimen of snake in dinosaur egg nest. On
right: An illustrated diagram showing where the fossils of the
snake and hatchling dinosaur were located at in the nest.
Slide 13
Sketch what your model of this scene would look like. What
colors would you use? What position would the snake and baby
dinosaur be in? Why?
Slide 14
This hatchling reconstruction is based upon fragmented fossil
remains found in a nest of sauropod eggs, associated with the snake
Sanajeh. Paleontologist Jeff Wilson used limb bone lengths and egg
diameter to determine an estimated size for this dinosaur at
hatching. Fossilized embryonic skin from Argentinian sauropods
provided reference for the size and shape of scales on the
hide
Slide 15
Read an article about the find and related model at:
http://www.tylerkeillor.com/pdfs/Tyler's%20Deposits%20article.pdf
Slide 16
Paleoartists will at times get ideas for what dinosaurs looked
like by studying animal species that survived the great dinosaur
extinction, such as alligators and crocodiles: Alligators
Crocodiles
Slide 17
It is thought that these animals may have survived the dinosaur
extinction because they have the ability to self-heal, live in
water, adapt to changes in their environment fairly easily, are
cold-blooded, and extremely quick learners. They provide
paleoartists with hints about what animals from millions of years
ago may have looked like.