Mammals lab practical: skulls

Question 1

Virginia opossum

Answer 1

Prominent sagittal crest
five upper incisors per side
angular process projects medially

Question 2

masked shrew

Answer 2

tiny skull
red teeth
no zygomatic arch
lateral edge of braincase=smooth

Question 3

northern short-tailed shrew

Answer 3

red teeth
lateral braincase edge with prominent processes
no zygomatic arch

Question 4

eastern mole

Answer 4

weak zygomatic arch
90-degree rostrum and incisors
10 teeth per upper side

Question 5

star-nosed mole

Answer 5

sloping rostrum
11 teeth per upper side
weak zygomatic arch

Question 6

American pika

Answer 6

fenestrated maxillary bone
no boney latticework
2 pair upper incisors

Question 7

eastern cottontail

Answer 7

2 pair upper incisors
postorbital process not fused to skull
Maxillae fenestrated with boney latticework

Question 8

swamp rabbit

Answer 8

2 pair upper incisors
postorbital process completely fused to skull
Maxillae fenestrated with boney latticework

Question 9

plains pocket gopher

Answer 9

broad flat skull
broad zygomatic arch
each incisor has 2 grooves

Question 10

American beaver

Answer 10

large skull
orange incisors, no grooves
massive zygomatic arch

Question 11

meadow jumping mouse

Answer 11

extremely small skull
1 groove in each incisor
small premolar in front of 3 molars

Question 12

Ord’s kangaroo rat

Answer 12

enlarged auditory bullae
grooved incisors

Question 13

brown rat

Answer 13

paired parietal ridges
hard pallet extends beyond molars
front molar larger that other 2
no notch at bottom of upper incisor

Question 14

house mouse

Answer 14

no parietal ridges
notch on bottom of upper incisors
hard palate goes beyond molar
front molar larger than other two combined

Question 15

western harvest mouse

Answer 15

tiny skull
no peg premolar
cuspidate molars
grooved incisors
palate ends at or before back molars

Question 16

North American deer mouse/white footed deer mouse(Peromyscus)

Answer 16

smooth incisors
cuspidate molars
palate ends at last molar

Question 17

eastern woodrat

Answer 17

depression between orbits
semi-prismatic teeth
no parietal ridges on head
hard palate ends before or at back molar

Question 18

meadow vole

Answer 18

shorter rostrum
prismatic teeth
5 islands of dentine
constriction between orbitals

Question 19

prairie vole

Answer 19

shorter rostrum
prismatic teeth
4 islands of dentine
constriction between orbitals

Question 20

common muskrat

Answer 20

prismatic molars
significant zygomatic arch
flat head
constriction between orbitals

Question 21

southern bog lemming

Answer 21

prismatic molars
lateral groove on incisors
thick zygomatic plate
constriction between orbitals

Question 22

eastern chipmunk

Answer 22

4 upper cheek molars per side
Infraorbital aperture is a foramen

Question 23

woodchuck

Answer 23

post orbital processes projecting at right angles
5 upper check teeth per side’
white incisors

Question 24

thirteen-lined ground squirrel

Answer 24

5 upper cheek teeth per side
skull = 31 to 45 mm

Question 25

Franklin’s ground squirrel

Answer 25

5 upper cheek teeth per side
skull = 50 to 57 mm

Question 26

eastern gray squirrel

Answer 26

5 cheek teeth
first tooth very small, 5 total
look up length of skull

Question 27

eastern fox squirrel

Answer 27

4 upper cheek teeth
skull length 63-69mm

Question 28

North American red squirrel

Answer 28

3 transbullar septa visible as grooves
4 upper cheek teeth per side

Question 29

southern flying squirrel

Answer 29

interorbital region is relatively narrow and indented on each side. V shaped notch
5 upper cheek teeth per side

Question 30

eastern coyote

Answer 30

sagittal crest prominent
dorsal surface of post orbital process is convex

Question 31

red fox

Answer 31

paired ridge in a narrow V
dorsal surface of post orbital process has a shallow depression in it

Question 32

gray fox

Answer 32

paired ridges form a wide U
*****

Question 33

raccoon

Answer 33

broad and rounded
hard palate beyond last molars

Question 34

least weasel

Answer 34

long braincase, short rostrum
skull = 25-30 mm
last upper molar on each side is dumbbell shaped

Question 35

American mink

Answer 35

skull is 57-69 mm
long braincase short rostrum
last upper molar dumbbell shaped

Question 36

river otter

Answer 36

large skull with mustelid characteristics
orbits projected up

Question 37

striped skunk

Answer 37

area around eye sockets is well rounded with an arch
palate does not extend beyond molar
*******

Question 38

bobcat

Answer 38

very short rostrum
skull is broad and short

Question 39

bears

Answer 39

large thick skull

Question 40

elk

Answer 40

small canines
antorbital pits present

Question 41

white-tailed deer

Answer 41

no upper incisors
antorbital pit is shallow

Question 42

mule deer

Answer 42

no upper incisors
antorbital pit is deep

Question 43

moose

Answer 43

elongated maxillae and premaxillae
short nasal bones

Question 44

pronghorn antelope

Answer 44

long nasal bones
orbitals are large and set far back
no antorbital pit
horn core behind eye

Question 45

bighorn sheep

Answer 45

one lacrimal foramen
horn has boney core and is curved

Question 46

mountain goat

Answer 46

horn cores straight and round in cross section

Question 47

American bison

Answer 47

just a horn

Question 48

wild boar

Answer 48

Triangular
has tusks