Exam 2 - Teeth

Question 1

Importance of teeth

Answer 1

1. Durability
2. Adaptive
3. Relative stability in structure within a phyletic line (ex. carnacial teeth on all carnivores)
4. Evolution of teen can be traced within lineages
5. Origin is from dermal armor

Question 2

Basic anatomy

Answer 2

1. Crown
2. Root
3. Pulp cavity (center of tooth)

Question 3

Cartilaginous fishes

Answer 3

1. Teeth are attached by collagen fibers
2. Fibers originate in the dermis (weak tooth attachment, ex: shark teeth)

Question 4

Pleurodont

Answer 4

i. Side tooth
ii. Tooth touches the bone on the liter portion of the root
iii. Joined to bone by collagen fibers and cement
*Cement is a non-vascular bone that is acellular

Question 5

Aerodont

Answer 5

i. Summit tooth
ii. Tooth rests on top of huge bone
iii. Joined to the bone by cement

Question 6

Theodont (what mammals have)

Answer 6

i. Sheath tooth
ii. Roots of teeth are located in sockets
iii. Anchored by cement

Question 7

Polyphyodont

Answer 7

Polyphyodont

i. Teeth are replaced continuously
ii. Replaced in sets, every other tooth
iii. Half of the teeth are replaced at a time

Question 8

Diphylodont

Answer 8

i. Teeth are replaced once
ii. Most mammals

Question 9

Fishes

Answer 9

1. Usually teeth are:
   i. Numerous
   ii. Conical or blade like (mostly)
   iii. Homodont (same shape)
   iv. Found on the margins of jaws, roof of the mouth, 5th gill arch, and some on tongue
   v. Most fishes are acrodont
   vi. Modifications of teeth are related to diet
   vii. Some have heterodont teeth (different size and shaped teeth)

Question 10

Crossopterygians

Answer 10

i. Teeth resemble bony fish
ii. Labyrinthodont teeth
a. Teeth extensively folded
b. Strong tooth resistant to wear
c. Lasted ~100 million years

Question 11

Modern Amphibians

Answer 11

1. Extant have fewer teeth
2. Small and pleurodont
3. Not labyrinthodont

Question 12

Reptiles, extinct toothed birds

Answer 12

1. Extant birds and turtles are edentate (means no teeth)
2. Homodonts
3. Some groups, teeth are cusped
4. Most have simple, conical teeth
5. All forms of tooth attachment occur
6. Synapsid reptiles revolved heterodont teeth

Question 13

Mammals

Answer 13

1. Have heterodont teeth
2. Attached to the dentary, premaxilla and maxilla
3. Great variety of shapes which are related to the diet
4. Some have ever growing teeth or replace teeth

Question 14

Consequences of chewing food for non-mammals

Answer 14

1. Teeth are used to kill and hold food
2. Food may be crushed
3. Swallowed whole

Question 15

Consequences for chewing food for Mammals

Answer 15

1. Hold food, but also shear, crush and grind food
2. Permits an individual animal to eat many different kinds of food
3. Also speeds digestion
4. To masticate food, food must be retained in the mouth
   i. Modification of the jaw articulation (up and down movement of the jaws)
   ii. Development of palate
   iii. Cheeks
   iv. Tongue
5. Several different kinds of teeth with different functions
6. Heterodont teeth and thecodont

Question 16

Kinds of teeth

Answer 16

incisors, canines, cheek teeth

Question 17

Incisors

Answer 17

i. Nipping
ii. Securing food
iii. Grooming
iv. Conical spikes for fish
v. Simple blades for nipping single root
vi. Usually 3/3 (upper/lower) unless secondarily lost, though marsupials often have more

Question 18

Canines

Answer 18

i. Simple spike like tooth
ii. Usually longer and stronger
iii. Used for piercing iv. Feeding and fighting
v. 1/1 always
vi. May be secondarily lost

Question 19

Cheek teeth

Answer 19

i. Pre-molars and molars
ii. Distinction difficult
iii. Premolars are deciduous, molars are not
iv. Molars sprout when baby teeth are replaced.
v. Function in crushing and grinding
vi. 4/4, 3/3 but lots of modification

Question 20

Dental formula for wolf

Answer 20

3/3, 1/1, 4/4. 2/3 (icpm)

Question 21

Dental formula for deer

Answer 21

0/3, 0/1, 3/3, 3/3

Question 22

dental formula for humans

Answer 22

2/2.1/1.2/2.3/3