Tu

be

rcula

r vs. Prism

atic Te

eth

Ne

w W

orld

Ra

ts & M

ice(P

eromyscus m

aniculatus shown)

Old

Wo

rld R

ats &

Mice

(Mus m

usculus shown)

Prism

atic cu

sp p

atte

rn in

mu

rids, vo

les a

nd

lem

min

gs (note alternating triangles)

(Right upper m

olariform toothrow

of Microtus ochrogaster show

n) A

= anterior, P

= posterior, B

= buccal surface, L =

lingual surface

A

L

P

B

Alte

rna

ting

en

am

el (w

hite

ridg

es)

an

d d

en

tin (lig

ht b

row

n m

ate

rial)

ma

inta

ins o

cclusa

l surfa

ces a

sth

e to

oth

we

ars d

ow

n; e

na

me

l is m

uch

ha

rde

r tha

n d

en

tin

** In each

of th

e follo

win

g p

lates the u

pp

er righ

t mo

lariform

too

thro

w is sh

ow

n w

ith th

e anterio

r-m

ost to

oth

at the to

p an

d th

e last mo

lar at the b

otto

m o

f the p

ho

to. T

he b

uccal su

rface (adjacen

t to

the ch

eek) is to th

e left and

the lin

gu

al surface (ad

jacent to

the to

ng

ue) is to

the rig

ht.

Plate 6

Tu

be

rcula

r

Sou

thern red-backed vole

(Clethrionom

ys gapperi)

Meadow

vole

(Microtus pe

nnsylvanicu

s)

Abru

pt p

alate

-T

ransve

rse sh

elf

Pala

te slop

ing

d

ow

nw

ard

Plate 7

Inferorbital foramen

Gen

us Tam

ias (T

amias am

oen

us)

Inferorbital foramen situated in the

Zygom

atic plate

Black-tailed

prairie d

og

(Cyn

om

ys lud

oviscian

us)

Inferorbital foramen situated in projection on

maxillary bone (Tree squirrels, ground squirrels,

and prairie dogs)

Western harvest m

ouse (R

eithrodontomys m

egalotis) V

entral view of upper grooved incisors

Northern bog lem

ming (S

ynaptomys borealis)

Very deep reentrant angles: (a) upper teeth cut inw

ard from

buccal surface, (b) lower teeth cut inw

ard from lingual surface

ab

Sagebrush vole (Lem

micus

curtatus) 3 lingual projections on last upper m

olar

Northern red-backed vole

(Clethrionom

ys gapperi) 4 lingual projections on last upper m

olar

Prairie vole (M

icrotus ochrogaster) R

eentrant angles of upper molariform

teeth equal on lingual and buccalsurfaces

Heather vole (P

henocomys interm

edius)

Reentrant angles of both upper (a) and

lower (b) m

olariform teeth m

uch deeper on lingual surface than on buccal surface

ab

Plate 8

Meadow

vole (Microtus

pennsylvanicus)W

ater vole (Microtus richardsoni)

Montane vole (M

icrotus montanus)

M2 4 closed triangles and posterior

loop (arrow)

M2

loop

M3 w

ith 2 deep reentrant angles onlingual side

M3 w

ith 3 deep reentrant angleson lingual side; no loop on M

2

M2

M3

Montane vole (M

icrotusm

ontanus)

Incisive foramina constrict

abruptly and narrowposteriorly (bracket)

Long-tailed vole (Microtus

longicaudus)

incisive foramina parallel throughout,

only slighlty narrower posteriorly

Red squirrel (Tam

iasciurushudsonicus)

Anterior m

arginof orbit opposite P4

(arrow)

P4

M1

Plate 9

M3

Plate 10

Co

lum

bia

n g

rou

nd

squ

irrel (S

pe

rmo

ph

ilus co

lum

bia

nu

s)T

he thirteen-lined ground squirrel (S. tridecem

lineatus) has similar characteristics; these tw

o species can be separated by greatest length [G

L] (SP

CO

> 45m

m, S

PT

R <

45mm

)

Higher pow

er

P3

P4

M1

M2

M3

Pronounced anterior valley on P

4 - M3 passes

completely across the tooth (arrow

s)

Higher pow

er

Go

lde

n-m

an

tled

gro

un

d sq

uirre

l (Sp

erm

op

hilu

s late

ralis)

Anterior valley on P

4 - M3 does not pass com

pletely across the tooth (arrow

s)

Ridge of enam

el rises up at lingual side of cusp

No ridge of enam

el rises up at lingual side of cusp