Training Module 4 – Cretaceous Creatures

How would you describe your fossil?

1. Isolated teeth

2. Jaws and tooth plates

3. Vertebrae

4. Scales, shells, and plates

5. Bones and bone fragments

Try again! Vertebrae usually have a broad surface that is flat or bumpy.

Try again! Jaws and tooth plates usually have rows of repeating teeth or sockets for teeth that fell out.

Try again! Vertebrae usually circular cups at their ends and struts that stick out along the rim.

Try again! Bone fragments usually have broken cross sections that look like a hollow tube or like the end of a broken pencil.

ID Sheet 4

1. My tooth is shaped like a column or cone.

2. My tooth has multiple cusps that look like big bumps on it.

3. My tooth is shaped like a diamond or a leaf.

4. My tooth is flat and shaped like a triangle and may have tiny serrations along the edge.

5. My tooth is big at the top, shaped like a hexagon, and attached to two thick roots.

ID Sheet 4-B

1. My tooth has a single cusp (i.e. bump), fang, or saw blade on it, and it may have roots.

2. My tooth has multiple cusps (i.e. bumps) with roots on the bottom.

Try again! Focus on the top of your fossil. It should have multiple points.

Try again! Focus on the bottom of your fossil. It should have two roots.

ID Sheet 4-B-II

1. My tooth has a round base with multiple rows of cusps that look like bumps.

2. My tooth has one triangular part attached to one circular part with multiple cusps that are unevenly spaced out.

3. My tooth has one triangular part attached to one circular part with multiple cusps that are evenly spaced out.

4. My tooth is triangular, is not attached to a circular part, has three main cusps, and a row of small cusps along one side.

5. My tooth is triangular, is not attached to a circular part, has three main cusps, and does not have a row of small cusps along one side.

Try again! Focus on the top of your fossil. It should have multiple points.

You did it! You found a marsupial mammal lower molar!

Fun Facts!

1. Skin denticles (also known as placoid scales) are teeth-like scales that cover the body of rays, skates, and sharks.
2. In modern sharks and rays, the skin denticles all point toward the tail. This causes the skin to feel smooth in one direction and rough like sandpaper in the other, which helps them swim faster.
3. The placoid scales of sharks and rays do not grow bigger as the fish grows bigger. Instead, new scales are created in between the old ones to cover the animal’s increased body size.

Place your fossil in the correct box on the Fossil Training Sheet.

Click here to identify another microfossil.

Try again! Look at the flat side of your fossil and focus on how much it curves.

Try again! Look at your fossil from above and note the number of the shorter points.

Try again! Notice how the points on the top of your fossil are not all the same size.

Try again! Focus on the shape and symmetry of the serrations and the direction they point.