Mammalogy Lab Study Guide

MAMMALOGY LAB STUDY GUIDE: Rodentia & Lagomorpha (Michigan Species)

BIG PICTURE REMINDERS

Order Rodentia

• Characteristics:

  • One row of upper incisors.

  • Evergrowing incisors.

  • Diastema (gap) between incisors and cheek teeth.

Order Lagomorpha

• Characteristics:

  • Two rows of upper incisors (the second being a small peglike row behind the first).

  • Memory tip: LAGOmorph = extra LAYER of teeth OUTSIDE RODENTIA.

Know These Too

Virginia Opossum (Didelphis virginiana)

• Unique Features:

  • Only marsupial in Michigan.

  • Contains 50 teeth (most of any Michigan mammal).

  • Features a prominent sagittal crest.

  • Small braincase.

  • Range: Lower Peninsula (LP) and western Upper Peninsula (UP).

• Memory tip: "virginiana" = Virginia opossum.

Nine‑banded Armadillo (Dasypus novemcinctus)

• Unique Features:

  • Exhibits 9 bands.

  • Not present in Michigan.

• Memory tip: "novem" = nine.

ORDER RODENTIA

Family Sciuridae (Squirrels, Chipmunks, Marmots)

Least Chipmunk (Neotamias minimus)

• Features:

  • Skull size: < 34 mm.

  • Contains 5 upper cheek teeth.

  • Found only in the Upper Peninsula (UP).

• Memory tip: "minimus" = mini = smaller skull.

Eastern Chipmunk (Tamias striatus)

• Features:

  • Skull size: > 34 mm.

  • Contains 4 upper cheek teeth.

  • Found statewide.

• Memory tip: "striatus" = striped.

Woodchuck / Groundhog (Marmota monax)

• Features:

  • Large, blocky skull.

  • Heavy zygomatic arches.

  • Found statewide.

Thirteen‑lined Ground Squirrel (Ictidomys tridecemlineatus)

• Features:

  • Marked by 13 stripes.

  • Skull size: < 40 mm.

  • Found in the LP and western UP.

• Memory tip: "tridecem" = 13.

Eastern Gray Squirrel (Sciurus carolinensis)

• Features:

  • Contains 5 upper cheek teeth.

  • Skull size: < 60 mm.

  • Found statewide.

• Memory tip: "carolinensis" = from Carolina.

Eastern Fox Squirrel (Sciurus niger)

• Features:

  • Contains 4 upper cheek teeth.

  • Skull size: > 60 mm.

  • Found in the LP and east/central UP.

• Memory tip: "niger" = darker, larger fox squirrel.

Red Squirrel (Tamiasciurus hudsonicus)

• Features:

  • Characterized by a short rostrum.

  • Skull size: 40–50 mm.

  • Found statewide.

Northern Flying Squirrel (Glaucomys sabrinus)

• Features:

  • Belly fur gray at base.

  • Found in UP and the northern half of LP.

Southern Flying Squirrel (Glaucomys volans)

• Features:

  • Belly fur white at base.

  • Found in LP and west-central UP.

• Memory tip: "volans" = flying.

Family Geomyidae

Baird’s Pocket Gopher (Geomys breviceps)

• Features:

  • Possesses large claws.

  • Note: Not a Michigan species.

• Memory tip: "geo" = earth digger.

Family Castoridae

American Beaver (Castor canadensis)

• Unique Features:

  • Very large skull.

  • Tubular auditory meatus.

  • Infraorbital foramen smaller than foramen magnum.

  • Found statewide.

• Memory tip: "canadensis" = Canada.

Family Cricetidae (Mice, Voles, Lemmings, Muskrat)

White‑footed Mouse (Peromyscus leucopus)

• Features:

  • Found in the LP and parts of central UP.

• Memory tip: "leuco" = white; "pus" = foot.

Deer Mouse (Peromyscus maniculatus)

• Features:

  • Found statewide.

  • Often has a more clearly bicolored tail.

• Note: Very difficult to distinguish from P. leucopus morphologically.

Southern Red‑backed Vole (Myodes gapperi)

• Features:

  • Exhibits a reddish dorsal stripe.

  • Short tail.

  • Found in UP and northern LP.

Meadow Vole (Microtus pennsylvanicus)

• Features:

  • Found statewide.

Woodland Vole (Microtus pinetorum)

• Features:

  • Found in the LP.

Tundra Vole (Microtus oeconomus)

• Note: Not present in Michigan.

• Memory tip: "Microtus" = small vole group.

Common Muskrat (Ondatra zibethicus)

• Features:

  • Rectangular skull.

  • Long rostrum.

  • Laterally compressed tail.

  • Partially webbed hind feet.

  • Found statewide.

Southern Bog Lemming (Synaptomys cooperi)

• Features:

  • Very short tail.

  • Found statewide.

Family Zapodidae

Meadow Jumping Mouse (Zapus hudsonius)

• Features:

  • Long tail with white tip.

  • Long hind legs for jumping.

  • Found statewide.

• Memory tip: "Zapus" = jump.

Family Erethizontidae

North American Porcupine (Erethizon dorsatum)

• Unique Features:

  • Has quills.

  • No elongate auditory meatus.

  • Found in UP and north half of LP.

ORDER LAGOMORPHA

Family Leporidae

Eastern Cottontail (Sylvilagus floridanus)

• Features:

  • Found statewide except in the eastern half of UP.

Snowshoe Hare (Lepus americanus)

• Unique Features:

  • Turns white in winter.

  • Longer legs.

  • Flared postorbital processes.

  • Found in UP and north half of LP.

Family Ochotonidae

American Pika (Ochotona princeps)

• Unique Features:

  • Small, rounded ears.

  • Notable alpine species.

QUICK SKULL ID CHECKLIST

• Two rows of upper incisors → Lagomorph.

• One row of upper incisors → Rodent.

• Huge skull, aquatic features → Beaver.

• Laterally compressed tail → Muskrat.

• Skull < 34 mm (chipmunk) → Least chipmunk.

• 5 upper cheek teeth (Sciurus) → Gray squirrel.

• 4 upper cheek teeth (Sciurus) → Fox squirrel.

• Very short tail in small rodent → Bog lemming.

• Red dorsal stripe → Red-backed vole.

SCIENTIFIC NAME ROOT HINTS

• leuco = white.

• volans = flying.

• minimus = smallest.

• tridecem = 13.

• canadensis = Canada.

• americanus = American.

• novem = nine.

• Zapus = jump.