Skulls & Jaws Lab

Question 1

Three main components of vertebrate head

Answer 1

1. dermatocranium
2. splanchnocranium
3. chondrocranium

Question 2

dermatocranium

Answer 2

dermal elements making up the external, outermost framework of the skull, surrounding the other components and contributing to the jaws, braincase, and teeth

Question 3

splanchnocranium

Answer 3

visceral skeleton

provides support for gill arches and gill arch derivatives

Question 4

chondrocranium

Answer 4

support for sense organs and brain

Question 5

Which component of the vertebrate head is not always present?

Answer 5

Dermatocranium

Components have been lost or fused in more derived animals

Question 6

Williston’s law

Answer 6

trend toward fewer bones

Question 7

Skull

Answer 7

Region enclosing the braincase and extending to the upper jaw

Question 8

Mandible

Answer 8

Lower jaw

Question 9

As the number of bones decreases, the number of ____ decrease and the structure becomes _____.

Answer 9

suture lines

stronger

Question 10

The ___ is anterior to the maxilla

Answer 10

Premaxilla

Question 11

Frontal is ____ to the nasal

Answer 11

posterior

Question 12

Why temporal fossae?

Answer 12

They give a more secure area for muscle attachment and allow more space for the jaw muscles to expand during contraction

Question 13

Anapsid

Answer 13

No temporal fossae

Question 14

Examples of anapsid skulls

Answer 14

Fish, turtle, tortoise skulls

Question 15

How does the snapping turtle have a powerful bite without temporal fossae?

Answer 15

otic/temporal notch on the dorsal posterior area of the midline is where muscles attach, increasing bite power

Question 16

Supratemporal fossa

Answer 16

upper

Question 17

Infratemporal fossa

Answer 17

lower

Question 18

Diapsid

Answer 18

both the supratemporal and infratemporal fossae

Question 19

Modified diapsid condition in some birds and lizards

Answer 19

the bar between the two temporal fossae is lost, decreasing the weight of the skull

Question 20

Synapsid

Answer 20

infratemporal, but supratemporal was lost

Question 21

What extant animals are synapsids?

Answer 21

mammals

Question 22

Modified synapsid condition

Answer 22

black bears

temporal fossa is continuous with the orbit

Question 23

_____, and some ____, show a decrease in size of the post-orbital bar to accommodate larger jaw muscles (increase bite power).

Answer 23

Carnivores

omnivores

Question 24

Saggital crest

Answer 24

temporal muscles can attach here, increases bite strength

Question 25

Animals with saggital crests

Answer 25

lions, polar bears, wolves

Question 26

Dentary

Answer 26

Most reduced form of mandible found in mammals- a single bone makes up each side of the jaw

Question 27

In amphibians and reptiles, the ___in the upper jaw and the ___ in the mandible form the hinge.

Answer 27

quadrate | articular

Question 28

In mammals, the hinge is formed between the ____ | and _____– it’s much stronger because larger bones are involved.

Answer 28

dentary | squamosal

Question 29

the _____ becomes the stapes

Answer 29

hyomandibular

Question 30

the _____ becomes the incus

Answer 30

quadrate

Question 31

the _____ becomes the malleus

Answer 31

articular

Question 32

the ____ becomes the tympanic

Answer 32

angular

Question 33

The dentary ____ in size moving from more ancestral to more derived animals.

Answer 33

increases

Question 34

nocturnal animals have ___ orbits

Answer 34

large

Question 35

Predators have eyes set to the ___ of the skull

Answer 35

front

Question 36

Prey have eyes set to the ___ of the skull

Answer 36

sides

Question 37

____ are shed in ____, after the mating season.

Answer 37

antlers | winter

Question 38

pedicel

Answer 38

bony base of the antler, supporting it as it grows

Question 39

___, providing nutrients and blood to developing antlers, cover the antlers as they develop.

Answer 39

velvet

Question 40

At the end of growth, the outer edges of antlers become ________ and the middles fill with ____ and ______.

Answer 40

compact bone spongy bone marrow

Question 41

Decrease in ______ and ______ allow antlers to shed by making the pedicel lose_____.

Answer 41

testosterone pituitary hormones calcium

Question 42

____ are found on both sexes, ____ are found only on males

Answer 42

horns | antlers

Question 43

____ never branch and don't shed.

Answer 43

horns

Question 44

Horns have a bony core covered by a ___ cone attached by ___ ____.

Answer 44

keratin | connective tissue

Question 45

The exceptional pronghorn.

Answer 45

- horns are a cross between antlers and horns - horns shed yearly like antlers - sheath is made of keratin like horns - branch like antlers

Question 46

occipital condyle

Answer 46

rounded projection at the back of the skull that articulates with the first vertebra