Lab 5: Rodentia and Lagomorpha Order Rodentia (8 families in B.C.) Sciuridae – squirrels (16 species in B.C.) Muridae – mice, rats, lemmings, voles (16) Aplodontidae – mountain beaver (1) Castoridae – beaver (1) Dipodidae – jumping mice (2) Erethizontidae – N. American porcupines (1) Geomyidae – pocket gophers (1) Heteromyidae – kangaroo rats, pocket mice (1) Order Rodentia • Incisors – Single pair of upper, single pair of lower – Enamel on anterior surface, not posterior surface • Diastema • No canines Order Rodentia Family Sciuridae • Postorbital process well-developed • Infraorbital foramen reduced - usually small and round Order Rodentia Family Sciuridae • Postorbital process well-developed • Infraorbital foramen reduced - usually small and round • 4-5 cheekteeth – anterior premolar sometimes small and peg-like – usually with transverse ridges Order Rodentia Family Muridae • Infraorbital foramen usually V-shaped (wider above) Order Rodentia Family Muridae • Infraorbital foramen usually V-shaped (wider above) • 2-3 cheekteeth – Prismatic with folds of enamel or cuspidate with 2-3 longitudinal rows Order Rodentia Family Aplodontidae Aplodontia rufa (mountain beaver) Namanu Outdoor School Order Rodentia Family Aplodontidae Aplodontia rufa (mountain beaver) • Infraorbital foramen small and round • 5 cheekteeth – Prominent outer projections • Auditory bullae flask-shaped Order Rodentia Family Aplodontidae Aplodontia rufa (mountain beaver) • Most primitive rodent • Not closely related to the beaver, despite the name • Range: western B.C. Order Rodentia Family Castoridae Castor canadensis (American beaver) Order Rodentia Family Castoridae Castor canadensis (American beaver) • Infraorbital foramen small and slit-like • 4 cheekteeth – Distinctive transverse folds • Broad jugal • Incisors massive • Bony tube surrounding external auditory meatus Order Rodentia Family Castoridae Castor canadensis (American beaver) • Largest rodent in North America • Create extensive “lodges” • Range: throughout B.C. Order Rodentia Family Dipodidae (jumping mice) Order Rodentia Family Dipodidae Zapus spp. (jumping mice) • Greatly enlarged infraorbital foramen • 4 cheekteeth – Upper premolar small and peg-like • Grooved incisors Order Rodentia Family Dipodidae Zapus trinotatus (Pacific jumping mouse) • crescent-shaped fold on upper premolar Order Rodentia Family Dipodidae Zapus hudsonius (meadow jumping mouse) • No fold on upper premolar Order Rodentia Family Dipodidae Zapus spp. (jumping mice) • Most closely related to species in Europe, Africa, and Asia • Very long tail and hind feet • Range (Z. hudsonius): most of B.C. except the coast • Range (Z. trinotatus): extreme southwestern B.C. Order Rodentia Family Erethizontidae Erethizon dorsatum (N. Amer. porcupine) Order Rodentia Family Erethizontidae Erethizon dorsatum (N. Amer. porcupine) • Greatly enlarged infraorbital foramen • 4 cheekteeth – Wide re-entrant folds • Enlarged auditory bullae • Massive incisors Order Rodentia Family Erethiontidae Erethizon dorsatum (N. Amer. porcupine) • Spines! • Can survive up to 18 years in the wild. • Range: throughout B.C. Order Rodentia Family Geomyidae Thomomys talpoides (Northern pocket gopher) U.S. Forest Service Order Rodentia Family Geomyidae Thomomys talpoides (Northern pocket gopher) • Infraorbital foramen small and round on side of rostrum • 4 cheekteeth – Premolars 8-shaped • Massive incisors premolar Order Rodentia Family Geomyidae Thomomys talpoides (Northern pocket gopher) • External fur-lined cheek pouches • Fossorial • Construct one burrow per individual • Closed tunnel entrances • Range: southern B.C. Order Rodentia Family Heteromyidae Perognathus parvus (Great Basin pocket mouse) Mark Chappell Order Rodentia Family Heteromyidae Perognathus parvus (Great Basin pocket mouse) • Large infraorbital foramen on rostrum • 4 cheekteeth – 2-lobed pattern • Grooved upper incisors • Enlarged auditory bullae almost touch anteriorly Order Rodentia Family Heteromyidae Perognathus parvus (Great Basin pocket mouse) • External, fur-lined cheek pouches • Range: southern B.C. Order Lagomorpha www.borealphoto.com Order Lagomorpha • 4 upper incisors (2 pairs) • Diastema • No canines Order Lagomorpha Family Ochotonidae (pikas) • No supraorbital process • 5 upper cheekteeth on each side Order Lagomorpha Family Ochotonidae (pikas) • 2 species in B.C. – Ochotona collaris (collared pika) – Ochotona princeps (American pika) • Mountainous areas • Thought that local extinctions possible because of climate change • Range (O. collaris): extreme northwestern B.C. • Range (O. princeps): southern half of B.C. Order Lagomorpha Family Leporidae (rabbits and hares) • Supraorbital process • 6 upper cheekteeth on each side Order Lagomorpha Family Leporidae (rabbits and hares) Lepus americanus (snowshoe hare) Lepus townsendii (white-tailed jackrabbit) • No interparietal • Broader postorbital process Lepus americanus Lepus townsendii Lepus townsendii Lepus americanus Order Lagomorpha Family Leporidae (rabbits and hares) Lepus americanus (snowshoe hare) • Summer dorsal pelage brown, winter pelage white • Range: throughout B.C. Lepus townsendii (white-tailed jackrabbit) • Range: extreme south-central B.C. Order Lagomorpha Family Leporidae (rabbits and hares) Sylvilagus floridanus (eastern cottontail) Sylvilagus nuttalli (mountain cottontail) • Distinct interparietal • Narrower postorbital process Sylvilagus nuttalli Sylvilagus floridanus Order Lagomorpha Family Leporidae (rabbits and hares) Sylvilagus floridanus (eastern cottontail) • Range: extreme southwestern B.C. Sylvilagus nuttalli (mountain cottontail) • Range: extreme south-central B.C..