Kingdom - Animalia

Phylum - Chordata

Class - Mammalia







  • are vertebrates (have backbones).
  • have hair on at least part of the body.
  • nourish young with milk secreted by mammary glands

Mammalogy is the branch of zoology that deals with animals belonging to the class Mammalia, the mammals.  There are approximately 5,400 species of living mammals, divided into 30 orders and 149 families. 



Basic Mammalian Taxonomy

Illinois has approximately 60 species of mammals representing seven orders:


  • 4 large sharp incisors that continue growing
  • no canine teeth
  • 26 species in Illinois

Mice, Rats,Voles, Squirrels, Beaver, Muskrat, Gophers, Woodchuck, Porcupine


Gray Squirrel


  • insectivores
  • sharp pointy teeth
  • 7 species in Illinois

1 Mole and 6 Shrews

  • Illinois shrews have no zygomatic arches
  • Moles have a slender zygomatic arch and white teeth


Northern short-tailed shrew


  • No top incisors
  • Hard palate that bottom incisors grind food against
  • One species in Illinois


White-tailed deer


  • 4 sharp incisors that continue growing
  • no canines
  • 2 peglike incisors behind upper incisors
  • 2 species in Illinois



Eastern Cottontail Rabbit


  • marsupial
  • have more teeth than any other North American mammal
  • prehensile tail
  • partially opposable toe on hind feet
  • prominent sagittal crest
  • one species in Illinois


Virginia Opossum


  • no canines
  • no incisors
  • small, peg-like cheek teeth
  • one species in Illinois


Nine-banded Armadillo


  • Illinois bats are insectivores
  • sharp pointy teeth
  • incomplete palate resulting in U shape
  • only mammals capable of flight
  • elongated forelimbs, especially digits
  • skin membrane covering forelimbs down to hindlimbs and tail

 bat skeleton.png

Red Bat


  • large sharp canine teeth
  • last upper pre-molar and first lower molar are blade-like
  • 11 species currently in Illinois

Foxes, Coyote, Weasels, Otter, Badger, Raccoon, Bobcat, Mink, Skunk





Although most people think of the larger mammals, lions, tigers and bears, the small rodents are the most diverse group of mammals, making up approximately 40% of mammal species. 

Mammals possess morphological, physiological, and behavioral adaptations for an amazing variety of habitats and lifestyles. Some mammals spend most of their time underground or in trees, some are completely aquatic (whales and dolphins), some live in extremely arid deserts, and some can even fly (bats).


Some past articles published in INHS Reports:

Species Spotlight: Coyotes. Winter 2001

Cost and Controversy in Managing Urban Deer. March-April 2000

Species Spotlight: Little Brown Bat. November-December 1999

Deer in the Suburbs of Chicago. May-June 1999

INHS Mammal Collection. March-April 1999

Species Spotlight: Short-tailed Shrew. January-February 1999

Franklin's Ground Squirrel: An Increasingly Rare Prairie Mammal. January-February 1999

Don't Blame It All on the Raccoons. May-June 1998

Coyotes and Foxes in the Town and Country. March-April 1998

Species Spotlight: Eastern Moles. September-October 1997

What Color Are Your Squirrels. May-June 1997

Raccoon Health Watch. March-April 1997

Species Spotlight: Bobcats. September-October 1996

Can We Restore Elk in Illinois? September-October 1996

Indiana Bats in Illinois. March-April 1996

Species Spotlight: Beavers. March-April 1996

Species Spotlight: Plains pocket gopher. September-October 1995

Coyotes in Cornfields. July-August 1995

Human Noise and Wildlife. January-February 1995