Family comparisons

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Soricidae (shrews)

Shrews are small mammals with short legs, a long flexible nose, small ears, and tiny eyes. From van Zyll de Jong (1983): "Most soricids are terrestrial, some are semi-fossorial (Cryptotis, Blarina), and others are adapted to a semi-aquatic way of life (e.g. Sorex palustris). Shrews are active day and night and in all seasons. They are chiefly insectivorous; the large species, to some extent are also carnivorous and some are known to eat seeds seasonally. The semi-aquatic forms are more or less piscivorous."

The skull is recognized by an elongated rostrum (snout); lack of zygomata (or zygomatic arches); first incisor enlarged; tympanic bone is a simple ring; and lack of auditory bullae (Hoffmeister, 1986). This family includes the the smallest terrestrial mammals and the only venomous mammal in North America, Blarina brevicauda. Four genera are represented within the family Soricidae in the United States and all are within the subfamily Soricinae, the red-toothed shrews: Blarina, Cryptotis, Notiosorex, and Sorex.

  • Northern Short-tailed Shrew (Blarina brevicauda), the largest shrew in North America. Image by Gilles Gonthier.
  • Notiosorex observed by Naturegirlkh.
  • Sorex observed by Asmedley.
  • Lateral view of the skull of Blarina brevicauda, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors.
  • Lateral view of the skull of Cryptotis parvus, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors.
  • Lateral view of the skull of Notiosorex crawfordii, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors.
  • Lateral view of the skull of Sorex monticolus, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors.
  • Top (dorsal) view of a Sorex skull showing the location of the missing zygomata. All soricids lack zygomata.
  • Tympanic rings (bones) on underside (ventral side) of the skull of Sorex monticola, which are characteristic of members of the family Soricidae


Talpidae (moles)

From Naughton (2012): "Talpids (members of the family Talpidae) in the United States are dark gray or blackish animals with fusiform bodies; short appendages; manus (hand) rotated so palm faces outward; entirely white teeth; the skull is compressed dorsoventrally with a long rostrum; complete auditory bullae; complete but weak zygomata."

  • Townsend's Mole (Scapanus townsendii), the largest mole in North America.
  • Star-nosed Mole (Condylura cristata), showing its unique star nose. This is the only species with a star-shaped nose.
  • American Shrew Mole (Neurotrichus gibbsii), the smallest species of mole in the Americas. Notice the small size and relatively long and hairy tail.
  • Dorsal view of the skull of a Townsend's Mole (Scapanus townsendii), the largest mole in North America.
  • Lateral view of the skull of a Townsend's Mole (Scapanus townsendii).
  • Lateral view of the skull of a Star-nosed Mole (Condylura cristata).
Cricetidae (true hamsters, voles, lemmings, muskrats, and New World rats and mice)

Cricetidae is a large and diverse family of rodents and the second largest family of mammals. It includes true hamsters, voles, lemmings, muskrats, and rats and mice native to the Americas. The largest member of this family is the muskrat (Ondatra zibethicus). The smallest member of Cricetidae is the Northern Pygmy Mouse (Baiomys taylori).


Muridae (Old World rats and mice)

The largest family of rodents and of mammals.

Heteromyidae (pocket mice, kangaroo rats, kangaroo mice)

From Hoffmeister (1986): "Relatively small-bodied rodents with long tails, most modified for jumping, with hind limbs elongated and forelimbs shortened, cheek pouches fur-lined and open externally, interparietal reduced, auditory bullae greatly inflated, incisors thin and compressed, no post-orbital process." Except for spiny pocket mice (Heteromys), heteromyids have grooved upper incisors. Five genera can be found in the United States: Chaetodipus, Dipodomys, Heteromys, Microdipodops, and Perognathus.

Zapodidae (jumping mice)

Members of the family Zapodidae (jumping mice) have elongated hind limbs, remarkably long tails that are not well-haired (lack crests and tufts), dorsal coloration that ranges from dull yellow to bright yellowish orange with a darker mid-dorsal stripe, and a white venter. The upper incisors are grooved. Their skulls can be recognized by the presence of three or four cheekteeth.

The family Zapodidae contains two genera: Napaeozapus and Zapus. Napaeozapus typically have white-tipped tails whereas Zapus do not. Species in the genus Zapus have four cheekteeth, while species in the genus Napaeozapus have three.

  • Northern Meadow Jumping Mouse (Zapus hudsonius) observed in the United States by Josh Emm.
  • Northern Pacific Jumping Mouse (Zapus trinotatus) shown, representing members of the genus Zapus. Zapus typically lack a white tip at the end of the tail.
  • Western Woodland Jumping Mouse (Napaeozapus abietorum) shown, representing members of the genus Napaeozapus. Napaeozapus typically have a white-tipped tail.
  • Cheekteeth (molariform teeth) of Zapus
  • Cheekteeth (molariform teeth) of Napaeozapus
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