Dinosaurs » Dinosaur Anatomy
How do scientists know what the dinosaurs
looked like? No-one can say for sure, but there are some
lines of evidence in the fossil
record, and from studies of modern animals. Putting it all
together is like the detective work in solving a difficult
murder case.When you see a colour painting, or an animation,
of a dinosaur as a living animal, this has been based on
a series of steps in reconstruction:
The patches were bigger and more common on the back. On
the crest the impression was more like a rooster’s
comb. Horned dinosaurs had similar scales, but a little
larger. Instead of the patches that duckbills had, for a
change of pattern the horned dinosaurs had large rounded
scales with a rosette of polygonal scales making the change
back to the basic pattern.The big round scales were more
common on the back and sides. Long-necks like Seismosaurus
had large scales, about 2-3 cm, with small bumps, about
2 mm, all over them. They also had a fringe down the back
that stood up and were tall thin triangles. Dinosaurs could
have bony scales like the bumpy ones on alligators. They
could be scattered almost anywhere, but were more common
on the back and sides. In the Stegosaurus,
some of them formed huge plates that went down the back,
and even the spikes on the tail were these bony scales.
In the Ankylosaurs, they formed a “shell” over
the whole body. In the horned dinosaurs, they attached to
the skull and formed the ornate horns of the frills. Some
dinosaurs even appear to have had feathers!
The horned dinosaurs were from North America. There were two major types; the centrosaurines, like Styracosaurus and the chasmosaurines, like Triceratops. The centrosaurines generally had a big nose horn, although some just had a “nasal boss”. They had more ornate frills than the chasmosaurines. The chasmosaurine generally had the frontal horns (brow horns) as the major horns. The chasmosaurines had a hollow cup at the base of the frontal horns that must have given them a nice clacking sound when they fought with each other. Some of the skulls have holes in the bones that look like they were made by fighting with other horned dinosaurs. The horn had a bone core covered with chitin - like your fingernails. Cow Horn in cross section, showing the bone core and the chitinous sheath.
Chasmosaurine Frontal Horns.
Here are castings of two dinosaur brains. The one on the right is a Maiasaurua and the pictures on the left are a Tyrannosaurus. Wes cut a cow skull in half so that you can see where the brain would be. The cow brain is much bigger than any dinosaur brain. We have even bigger brains and feel that intelligence is very important. Dinosaurs did amazingly well with their little brains and never had to worry about global thermonuclear war or MAD - Mutual Assured Destruction. Of course, they couldn’t know about the comet that was on a path leading to a collision with the earth. After all, their best astrophysicist had a brain the size of a walnut.
Dinosaurs must have eaten something, and a lot of it. It is fairly easy to imagine that Tyrannosaurs ate other dinosaurs - and anything else that they wanted. But what did the plant-eating dinosaurs eat? Plants have been evolving for millions of years. When most of the dinosaurs lived, there were no grasses. Early in the age of dinosaurs there were no plants with flowers, but cycads seem to have been common. Cycad seeds would have been good and cycad trunks have a lot of starch in them . Some people eat cycads today. Another tree that was common was the Ginkgo. Ginkgo leaves are edible and the seeds are considered a delicacy in China. There is some evidence from gut contents and droppings that duckbills ate conifers - like Christmas trees.
Claws, like horns, have a bony core with a hard chitin sheath. Some claws allowed the predatory dinosaurs to tear into the flesh of their victims. Claws could also have been used to hold down prey while the dinosaur used its powerful jaws and serrated teeth to rip off large chunks of flesh. The foot seen at the left is from a small tyrannosaur. The claw in the middle is the killing claw from the back leg of Utah Raptor. It was used to rip a long deep gash in another animal, like a kick boxer with a switch-blade. The sharp curved claw of the Allosaurus was a meat hook. It allowed the Allosaurus, seen on the right to grab and hold on to another animal.
The large vertebra has a hole in the side. That is the opening to the air space in side of the vertebra. In many dinosaurs the back bone is hollow. This hollow space made the bones lighter. The back bone allows the body to bend while forming a strong support for the body.
A whip-tailed Seismosaurus
could possibly thrash a predator even approaching from the
front. Poor Allosaur.
One estimate based on Diplodocus is that
the tip of the tail could exceed the speed of sound. It
would have generated a sonic boom when it was whipped. So
much energy would be in the whip and released as a boom
that it would have been as loud as the blast of
a 16-inch gun from a battleship! Seismosaur is
even bigger - about 50% bigger. That is at least double
the power! Besides being a weapon, the sound may
have been used to communicate with other Seismosaurs.