Section 4: The Paleontology Laboratory

What we know about dinosaurs, mastodons, and petrified forests depends on the work and study of paleontologists. The study of paleontology goes back more than 200 years. In that time, scientists have learned much about life in the very distant past.

Salamander vert
Image 28: These small vertebrae are from an ancient salamander. Each one lacks a few parts, so the paleontologist must study both to know what perfect salamander vertebrae (backbone) looked like. The vertebra on the left lacks the side processes, but the hole through which the spinal nerve passed is intact. ND Geological Survey collection.
Coprolite
Image 29: Coprolite. This is coprolite-the feces of an ancient animal that has become fossilized. A well-preserved coprolite might contain fossilized bones or plants that the animal ate which helps paleontologists to know what species co-existed with the animal that produced the feces. ND Geological Survey collection.

The State Historical Society of North Dakota houses the paleontology laboratory of the North Dakota Geological Survey. The storage cabinets in the laboratory hold thousands (See Image 28.) of pieces of bones and teeth and pieces of rock with fossilized plants and animals captured in them. (See Image 29.)

When someone finds a set of bones or a piece of bone, paleontologists carefully note the exact location and the formation (geological layer) it has been found in. The formation will help to identify the fossil because certain animals are associated with particular time periods. If the fossil is fragile, the bones will be covered in a “jacket” of Plaster of Paris to protect the bones and to make sure that each bone remains in the same place in relation to the rest of the bones. (See Image 30.)

Image 33: When the North Dakota Heritage Center was closed for new construction in 2012, the Highgate Mastodon had to be “de-constructed” and stored until its new gallery was ready. The process had to be done carefully so the bones would not be damaged. The Highgate Mastodon is mostly fossilized bone, though the tusks have been replaced by fiberglass models in order to prevent damage to the very heavy and fragile fossilized tusks.

 

Once the fossil has been excavated from the rocky formation where the animal died millions of years ago, it goes to a paleontology laboratory where it is cleaned and identified. Paleontologists examine the bones for identifying parts such as spinal processes which are bony points that stick out from the main part of a bone. (See Image 31.) They examine teeth to see if the animal was an herbivore with broad or flat teeth for chewing plants or a carnivore with sharp teeth or serrated edges. Once they have evaluated the fossils for all identifying characteristics, they might be able to name the animal the fossil came from. However, if the fossil does not have strong identifying characteristics, it might be difficult to name it.

In North Dakota, certain fossilized animals are fairly common. Fossilized parts of Edmontosaurus and Triceratops are relatively common, while Tyrannosaurus rex is pretty rare.  There are fewer examples of animals of the Oligocene Epoch.  It was a period of high erosion and few remains of animals were able to withstand the forces of erosion.

Because the fossils are fragile and a fossilized skeleton might be incomplete, one of the tasks of paleontologists might be to reconstruct fossils for display. (See Image 32.) The paleontologist may repair the fossil or replace it with a copy. There are several possible ways to present a fossil for display. The parts of the fossil that are sturdy enough to be on display in a museum might be joined with artificial parts that were sculpted by a skilled paleontologist. Sometimes fragile bones are encased in material to make a mold from which a perfect copy is made. Another method is to sculpt a new bone from foam or other materials. These sculptures and casts are lightweight and can be displayed without damaging the original fossil. (See Image 33.)

The rib cage of a Triceratops was excavated and wrapped in this jacket of cloth and Plaster of Paris. In the paleontology lab, the jacket is carefully removed. A rib is exposed along the top of the pile of bones and rock. The paleontologist holds a vertebra from the Triceratops, pointing to the parts of the bone that she can use to identify these bones as Triceratops. The size of the bone, the placement of its parts, and the location of the fossil help the paleontologist to identify this fossil as a Triceratops.
 
Identifying Fossils. One of the best ways to begin to identify fossilized bones is to examine any teeth that might remain with the fossil. Sharp teeth indicate a carnivore. Some carnivores (meat-eaters) had long sharp teeth that had a row of serration to help tear flesh. Broad, flattened teeth indicate an herbivore. Herbivores that ate brush or shrubs might have some pointy teeth to tear leaves off the limbs. Some dinosaurs, such as the Edmontosaurus, produced new teeth regularly. The dentary plate along the outside of the jaw produced new teeth which then appeared on the inside of the jaw. The dentary plate along the outside of the jaw produced new teeth which then appeared on the inside of the jaw.
 
Re-constructing Fossils. It would be very rare for scientists to have an entire skeleton of a dinosaur or other ancient animal to work with or to display. Parts of fossilized skeletons must be re-created. In the picture of the Mosasaur vertebrae, the section labeled Pre-hip 6 is part true fossilized bone and part re-constructed bone. If a fossil arrives in the lab as crushed as this crocodile skull, it may not offer much new information on crocodiles and probably cannot be re-constructed. Some bones can be made whole by adding molded or sculpted pieces to complete the bone. In this case, an Edmontosaurus tibia (back leg bone) that is missing the lower part will be completed by adding a carefully carved and colored foam piece. Sometimes, paleontologists want to make a cast of something so that people can touch it or view it more closely than they could with a fragile ancient fossil. This Equus tooth was re-constructed from a mold. It is made of rubber, but is an exact copy that can be touched without harming the original. When the painting is complete, you won’t be able to tell the difference. Some pieces are completely replaced for exhibit to protect the fossil from damage. This Mosasaur backbone will be completely replaced by carefully sculpted foam pieces so that the fossil can be preserved. The vertebrae to the rear of the photo are sculpted from foam. The vertebrae in the front of the photo are actual fossils.
 

Why is this important?  When we enter a museum where fossils of ancient animals are displayed, we would love to see the actual bones of a real dinosaur. However, the problems of display include the difficulty of supporting the weight of a fossilized dinosaur, the possibility of damage to a rare fossil, and the common problem of missing parts. Paleontologists would like you to enter a museum display to learn more about the animals and plants that inhabited Earth at different times. From those displays you can learn more about how the Earth has changed over the past 500 million years.