Mammal Comparative Skeletal

Question 0

In the mammals skull, the prearticular contributes a process to the _______ and the angular has contributed to a unique structure, the _______

Answer 0

Malleus, tympanic membrane

Question 1

What bones have been lost in the mammal skull?

Answer 1

Prefrontals, postfrontals, post orbitals, ectopterygoids, quadratojugals, parasphenoid, and all of the lower jaw except the dentary

Question 2

The large nasal chamber of mammals is filled with ______ bones, otherwise known as _______

Answer 2

Turbinate bones, nasal conchae

Question 3

Describe similarities between beaver skulls and wombat skulls

Answer 3

Both have powerful incisors at the front (on the premaxilla) with all other teeth at the back of the mouth. They both have a very large, strong lower jaw, with large attachment sites for muscles.

Question 4

True or false - explain why:

In carnivores, the temporal muscle and Coronoid process are small. In herbivores, they are large.

Answer 4

False. Carnivores need a large temporal muscle to power the chopping motion of their teeth.

Question 5

True or false - explain why:

The masseter muscle of carnivores is smaller than the temporal muscle. In herbivores, it is much larger.

Answer 5

True. The masseter muscle in carnivores functions only to stabilize jaw articulation.

Question 6

True or false - explain why:

In carnivores, the pterygoid muscle is large. It is small in herbivores.

Answer 6

False.
In carnivores, the pterygoid is small and doesn’t help the bite much.
In herbivores it is much larger because it works with the masseter to make the grinding motion of the teeth.

Question 7

Is the jaw joint in herbivores positioned above, below, or in line with the teeth? Why is this?

Answer 7

Jaw joint is positioned above the teeth because it gives more leverage to the masseter muscle, and allows the teeth to slide against each other perpendicularly.

Question 8

Is the jaw joint in carnivores positioned above, below, or in line with the teeth? Why is this?

Answer 8

In line with teeth. This allows the upper and lower teeth to approach each other at an angle, slicing up food.

Question 9

What are the four type of mammal teeth? Briefly describe each

Answer 9

1. Incisors - At the front of the mouth, used in nipping, cutting
2. Canines - Long, spike-like teeth used for holding and piercing
3. Premolars - All replacement teeth behind canines
4. Molars - Permanent teeth

Question 10

Premolars and molars are collectively referred to as ______

Answer 10

Cheek teeth

Question 11

Explain how someone writes out a dental formula for an animal

Answer 11

1.2.3.4
An animal with this formula above the line would have 1 incisor, 2 canines, 3 premolars, 4 molars on ONE SIDE OF THE UPPER JAW.

Question 12

What is strange about the dentition of the hyrax? What about cows and sheep?

Answer 12

The hyrax has no canines, but the incisors look like canines.
Cows and sheep have no incisors or canines in the upper jaw

Question 13

Mammals typically have __ cervical vertebrae

Answer 13

7

Question 14

What identifies thoracic vertebrae?

Answer 14

They bear ribs

Question 15

The thoracic rib consists of two parts, the _____ and the _____

Answer 15

Sternal rib (ventral, cartilaginous segment), and costal rib

Question 16

How can you tell the difference between marsupials and placentals based on their bones?

Answer 16

Marsupials typically lack auditory bulla, and have more palatine vacuities and a small, narrow brain case.