Small Mammals Flashcards
What are the distinguishing characteristics common to all mammals
All mammals have mammary glands and hair, although hair may be drastically reduced or present only in foetal stages before birth.
What are common characteristics common to most mammals
- Viviparous: the young are developed in-utero.
- The only exceptions are the monotremes which include echidnas and platypus.
- heterodont
What are the distinguishing characteristics of the Order Lagomorpha (lagomorphs: rabbits, hares, pikas)
- They have two pairs of upper incisors, with one pair being directly behind the other
- Both their upper and lower incisors have longitudinal grooves on the anterior surface
- 26-28 teeth depending on species, compared to 16-22 in rodents
What are the distinguishing cranial characteristics of the Family Leporidae (hares & rabbits)(2) (Lab)? a. Name 2 species that are red- or blue-listed (sub)species. b. Name two introduced species in this family
- distinctive skulls with well-developed supraorbital processes and lattice-like fenestration.
- Two species which are red-listed are Lepus americanus (snowshoe hare, subspecies) and Lepus townsendii (white-tailed jackrabbit).
- Two introduced species of Leporidae in BC are Oryctolagus cuniculus (European rabbit) and Sylvilagus floridanus (eastern cottontail).
What isthe distinguishing cranial characteristic of the pika family (Ochotonidae) ((Lab)? i. Name a listed (sub)species.
- skulls lack supraorbital processes.
- Ochotona collaris (collared pika) is a blue-listed subspecies of pika.
What are the 2 distinguishing cranial characteristics of the order Rodentia (Rodents)
- 2 upper and lower ever-growing incisors and a lack of canine teeth.
- distinguished by a layer of hard, yellowish enamel which is harder than the dentine surface of the tooth.
What are the 2 distinguishing cranial characteristics of the mountain beaver family
- distinct projection on upper cheek teeth
- flask-shaped ear.
What is a distinguishing cranial characteristic of the squirrel family
All species of squirrels have well-developed postorbital processes.
What are the 2 distinguishing cranial characteristics of the pocket gopher family
- The lower mandible has a small shelf
- hourglass shaped chewing surface of 1st upper cheek tooth
What are 4 distinguishing cranial characteristics of the pocket mouse family
- Easily visible external, furlined pocket on either side of mouth,
- infraorbital opening on the side of the rostrum,
- upper incisors grooved,
- auditory bullae huge.
How do you identify a skull belonging to the beaver family (Castoridae)
Auditory bullae are elongated for aquatic life.
How do you distinguish between a lagomorph skull and rodent skull
Lagomorphs have the following distinguishing characteristics:
They have two pairs of upper incisors, with one pair being directly behind the other
Both their upper and lower incisors longitudinal grooves on the anterior surface
They have 26-28 teeth depending on species, compared to 16-22 found in rodents.
Rodents are distinguished by only 2 upper and lower ever-growing incisors and a lack of canine teeth. These incisors are distinguished by a layer of hard, yellowish enamel which is harder than the dentine surface of the tooth.
Lagomorph skulls won’t have the same prominence of front teeth, while rodent skulls will lack the second pair of incisors behind the first. Rodent skulls will also commonly have a notch in the lower jaw which is missing in lagomorphs.
What is a distinguishing cranial characteristic of the voles & lemming subfamily (Arvicolinae)
- complicated patterns of tooth enamel that form closed triangles or transverse folds.
What is a distinguishing cranial characteristics of the old world rats and mice (Murids) family
- Molar teeth with 3 rows of tubercles
- palate extends far posterior to the level of the last molar.
What is a distinguishing cranial characteristics of the North American rats & mice (Neotominae) family
The tubercles (cusps) on the molar teeth are arranged in two longitudinal rows rather than three rows (see figures 68 & 94 in R & L of B.C.) and do not appear as closed triangles (compare with the subfamily Arvicolinae)
What are the 2 best distinguishing cranial characteristics of the jumping mice family
- Upper incisors are narrow and grooved in front.
- Infraorbital opening on the side of the rostrum is large.
What four families of rodents and lagomorphs have grooved front upper incisors? Would you change your answer to question 17 with this in mind
Dipodidae (jumping mice)
Heteromyidae (pocket mice)
Leporidae (hares and rabbits)
Ochotonidae: (pikas; 2 species).
What is a distinguishing cranial characteristic of the porcupine family
The infraorbital foramen is large
How do you distinguish between a beaver skull and porcupine skull
Beaver skull is massive with a relatively narrow braincase, auditory bullae are elongated, and cheekbone is expanded.
Porcupine skull has large infraorbital foramen, a large jaw process, and a forward-projecting tooth-bearing bone structure.
What are the distinguishing cranial characteristics of the order Insectivora (insectivores)
All are essentially insect eaters, small in size, and usually have molariform teeth (like that of a molar; premolars and molars when similar in shape) distinctly ‘W’ shaped, primitive in nature.
What are the 3 distinguishing cranial characteristics of the shrew family
Skull lacking either complete zygomatic arch or auditory bullae. Teeth with dark red pigment on cusp tip.
What are the 2 distinguishing cranial characteristics of the mole family
- Skull with complete zygomatic arch and auditory bullae;
- 11 teeth.
What is the distinguishing cranial characteristic of the marsupial order? What other features are unique to this order
Skull unique in shape with 50+ teeth.
Marsupials also have either pouches or only two longitudinal folds of skin enclosing the teats located near midline of the abdomen.
List as many red- and blue-listed (sub)species of small mammals as you can
Lepus americanus: snowshoe hare (R-listed subspecies).
Lepus townsendii: white-tailed jackrabbit (R-listed).
Sylvilagus nuttallii: Nutall’s cottontail (B-listed).
Ochotona collaris: collared pika. (B-listed subspecies)
Neotamias minimus: least chipmunk (R- & B- listed subspecies)
Neotamias ruficaudus: red-tailed chipmunk (R- & B- listed ssp)
Marmota vancouverensis: V-Island marmot (R-listed)
Thomomys talpoides: Northern pocket gopher (R-listed ssp.)
Perognathus parvus: Great Basin pocket mouse (B-listed)
Myodes gapperi: southern red-backed vole (R-, & B-listed ssp.)
Synaptomys borealis: northern bog lemming (B-listed ssp.)
Microtus townsendii: Townsend’s vole (R-listed ssp.)
Reithrodontomys megalotis: western harvest mouse (B-listed)
Zapus hudsonicus: meadow jumping mouse (B-listed ssp.)
Sorex bendirii: Pacific water shrew (R-listed)
S. merriami: Merriam’s shrew (R-listed)
S. navigator brooksi: Western water shrew (B-listed)
S. rohweri: Olympic Shrew (R-listed)
S. palustris: American water shrew (B-listed)
S. preblei: Preble’s shrew (R-listed)
S. trowbridgii: Trowbridge’s shrew (B-listed)
S. tundrensis: tundra shrew (R-listed)
Scapanus townsendii: Townsend’s mole (R-listed)
