Rodentia and Lagomorpha

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Rodentia and Lagomorpha

• The Last of the Taxonomohegans!

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Rodentia and Lagomorpha

• Hawks, John D., Department of Anthropology,
  University of Michigan
• PHYLOGENETIC RELATIONSHIPS OF THE ORDER
  LAGOMORPHA (RABBITS, HARES, AND PIKAS)
• The taxonomic position of rabbits and their
  relatives (Order Lagomorpha) has been changed
  several times since Linnaeus classified them as a
  family within the Order Rodentia.
• The close relationship between lagomorphs and
  rodents has been supported by numerous studies of
  morphological characters.

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Rodentia and Lagomorpha

• Recently, molecular studies have cast doubt on
  this relationship, most notably suggesting that
  Lagomorpha is most closely related to Primates.
• In this study, thirty-six diverse species of
  lagomorphs, primates, rodents, and other mammals
  are sampled at up to three mitochondrial DNA
  loci, including the 12s rRNA, cytochrome C
  subunit II and cytochrome B genes.
• Parsimony analysis of these gene sequences
  supports the sister group relationship of
  Lagomorpha and Rodentia.

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Rodentia

• Largest mammalian order - 28 families and 2016
  currently recognized species
• Cosmopolitan distribution native everywhere
  except Antarctica, New Zealand, and a few oceanic
  islands
• Adapted to a wide range of habitats terrestrial,
  arboreal, scansorial, fossorial, and semiaquatic
• Found in all biomes, often commensal with humans

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Rodentia

• Most rodents are small (20-100 g), but one is
  large, capybara (Hydrochoerus hydrochaeris) - up
  to 50 kg
• Systematics is complex and confused - this is
  putting it mildly!
• All things considered, they still have some
  general morphological characteristics.

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Rodentia Morphology

• Diagnostic feature - single pair of upper and
  lower incisors
• Incisors are open-rooted and ever-growing used
  for gnawing (Rodentia from Latin rodere - to
  gnaw)
• Anterior side is enamel and wears slower than
  posterior side - forms a chisel!
• Rodents have a diastema!
• Lips can close in front or behind teeth.
• External or internal pouches

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Rodentia Morphology

• Teeth greatly reduced from the primitive
  eutherian number
• Typical - 1/1, 0/0, 0/0, 3/3 16
• Never have more than two premolars
• No species has more than 22 teeth, except the
  silvery mole rat 1/1, 0/0, 3/3, 3/3 28
• Herbivorous or omnivorous
• Coprophagy reported in 11 families
• Females have a duplex uterus and males, a baculum

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Aplodontidae

• Monotypic family - the mountain beaver
• Aplodontia is endemic to the Pacific northwest
  British Columbia to northern California
• Most primitive living rodent
• Associated with areas of heavy rainfall
• Not a beaver and does not live in the mountains!

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Sciuridae

• 50 genera and 273 species
• Everywhere except Australia, Madagascar, and
  southern SA
• Two families
• Sciurinae - tree and ground squirrels
• Petauristinae - flying squirrels

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Sciuridae

• Tree squirrels den in trees or leaf nests
• In boreal or cool temperate areas, most species
  hibernate
• Diurnal and arboreal
• Ground squirrels are terrestrial and burrow, and
  many aestivate and hibernate

Squirrel Fishing
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Sciuridae
Red Squirrel
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Sciuridae
Fox Squirrel
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Flying Sciuridae

• Flying squirrels have a furred Patagium between
  front and hind limbs
• Some can glide up to 450 m and turn 90o
• Flying squirrels and Australian gliders -
  convergent evolution!

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Geomyidae

• 5 genera and 35 species
• North and Central America
• In soil conducive to digging
• Visual and auditory ability reduced
• Thick, chunky bodies
• Small eyes and pinnae
• Eat subterranean parts of plants- roots and
  tubers
• The pocket gophers

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Heteromyidae

• Kangaroo rats, kangaroo mice, pocket mice - 59
  species and 6 genera
• SW Canada, Central America, NW SA
• Look similar to kangaroos!
• Bipedal jumpers
• Externally opening, furred cheek pouches - carry
  seeds back to burrows for storage - eat
  perishables!

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Heteromyidae
Kangaroo Rat

• Skulls are distinctive
• Infraorbital foramen pierces the rostrum
• Several species have greatly inflated auditory
  bullae - increase auditory acuity - nocturnal
  predators - also better able to maintain balance

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Heteromyidae

• Live in arid areas
• Adapted to dry , desert conditions
• Can live without free water for long periods
• Produce concentrated urine
• Nocturnal, inactive in burrows during the day
• Several species endangered!

Banner-tailed Kangaroo Rat (Dipodomys
spectabilis Merriam)
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Castoridae

• Two extant species
• Northern hemisphere
• Canadian beaver (Castor canadensis)
• European beaver (C. fiber)
• Name from castor glands and anal glands near
  cloaca in both males and females

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Castoridae

• Adapted to aquatic life
• Large - lt35 kg
• Fine insulating underfur
• Spatulate tail
• Nictating membrane
• Valvular nostrils
• Ears close under water
• Webbed hind feet

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Pedetidae

• Single species - Pedetes capensis - springhare
• Sandy soils or cultivated areas in southern
  Africa
• Large hind feet and muscular hind limbs
• Bipedal locomotion
• Spring into the air from the exit of their
  burrows
• Nocturnal and herbivorous

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Pedetidae
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Anomaluridae

• Scaly-tailed flying squirrels
• West and Central Africa - tropical forests
• 7 species, 3 genera
• Almost all have well-developed patagium that
  encloses forelimbs, hind limbs, and tail

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Ctenodactylidae
Mahatmagundi

• 4 genera and 5 species
• Gundis - sparsely vegetated, rocky, semiarid
  regions of Africa from Morocco east through
  Somalia
• Similar to pikas
• Dense pelage - comb with comblike hind toes!
• Diurnal, colonial, herbivorous

(Ctenodactylus gundi)
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Muridae

• Muroid rodents a diverse group!
• Mole rates, New World mice, rats, voles,
  lemmings, and allies (formerly Cricetidae)
  bamboo rats, and spiny dormice Old World rats
  and mice

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Muridae
Southern Bog Lemming
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Dipodidae

• 11 genera of jerboas and 4 genera of birch mice
  and jumping mice
• Tail exceeds head and body length in all
• Dormant or hibernate in burrows during the winter
  - up to 9 months in some species
• Jerboas can enter torpor in the summer during
  very hot, dry periods.

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Myoxidae

• 8 genera and 26 species
• Dormice
• Europe east to central and southern Asia, Africa,
  and southern Japan
• Small to medium in size
• Fat or edible dormouse (Myoxis glis) up to 200 g
  considered a delicacy since early Roman times!

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Myoxidae
Edible or fat dormouse (Myoxis glis)
Yum yum!
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Myoxidae
Edible or fat dormouse (Myoxis glis)
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Bathyergidae

• 5 genera and 12 species
• All strictly fossorial
• Sandy soils in the hot, dry regions of Africa
  south of the Sahara Desert
• African mole rat tunnel over 300 m!
• Feed on underground bulbs and tubers
• Some colonial (80 individuals) and others
  solitary

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Bathyergidae

• Naked mole rat (Heterocephalous glaber)
• Bare and wrinkled with only a few tactile hairs
• Reduced metabolic rate naked body allows easy
  dissipation of body heat
• Greatest eusocial system!
• Similar to some insects small workers vs..
  Larger nonworkers

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Hystricidae

• 3 genera and 11 species of Old World porcupines
• Deserts, steppes, forests
• Africa, Middle East, India, Asia (Indonesia,
  Borneo and the Philippines), Italy (introduced
  1000s of years ago)

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Hystricidae

• Quills do not have barbs!
• Herbivorous, terrestrial, and nocturnal
• Considered pest throughout much of their range

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Erethizontidae

• 4 genera and about 12 species
• New World porcupines
• Mixed coniferous forests, tropical forests,
  grasslands and forests
• SA species have prehensile tails
• Heavy spines with barbs, works itself in and can
  cause death!

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Petromuridae

• Monotypic dassie rat (Petromus typicus)
• Southern Angola, Namibia, and NW South Africa
• Small, squirrel-like, with soft, yellow-orange to
  brown fun without underfur
• Diurnal and feed on plant material coprophagous

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Thryonomyidae

• Cane rats or grasscutters
• South Africa south of the Sahara Desert
• Chunky body - greater cane rat up to 10 kg
• Three grooves on anterior surface of incisors
• Pelage is coarse and bristle like
• Damage cultivated crops
• Important food for natives hunted/farmed

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Thryonomyidae
Thryonomys swinderianus (greater cane rat)
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Chinchillidae

• 3 genera - colonial
• South America - Andes Mountains of Peru south to
  southern Argentina
• Large heads with large eyes and ears
• Dense, soft pelage
• Visachas, chinchillas
• Hunted for fur - endangered/threatened

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Dinomyidae

• Monotypic pacarana (Dinomys branickii)
• Columbia, Venezuela to Bolivia
• Look like huge guinea pigs
• Slow, lumbering, nocturnal herbivores
• Endangered!

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Caviidae

• 5 genera and 15 species
• Cavies, guinea pigs, and Patagonian hares
• Throughout SA, but not in the Amazon basin
• Most have short, robust body form, short limbs
  and ears and a vestigial tail
• Exception Patagonian hares or maras - long ears
  and long legs - runners!

Dolichotis patagonum (Patagonian mara)
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Dasyproctidae

• 11 species of agoutis and 2 species of acouchis
• Southern Mexico to southern Argentina
• Diurnal, solitary, burrowing herbivores
• Hunted for food
• Acouchis - rain forest - smaller with larger tail

Myoprocta acouchy (green acouchi)
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Dasyproctidae
So why is the wild color of the Mongolian Gerbil,
and many other animals, often described as
Agouti?
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Dasyproctidae

• The word "Agouti" used to describe a coat where
  the shaft of the hairs is one color, usually
  yellow or red, and the tips of the hairs are
  black.
• Gives animal a brownish gold color that is an
  effective camouflage when hiding in vegetation or
  on a range of soils.
• In some animals like the Chinchilla and the Grey
  Agouti Gerbil the yellow band is replaced by a
  white one giving a grey color - effective
  camouflage when hiding amongst rocks.

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Agoutidae

• 2 species of pacas
• Central Mexico to Paraguay and Argentina
• Forested areas from lowlands to high elevations
• Usually near rivers
• lt 10 kg

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Echimyidae

• Spiny rats - 16 genera and 71 species
• Honduras to central South America
• Spiny, stiff, bristle like pelage
• Ratlike with pointed rostrum
• Closely tied to water

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Myocastoridae

• Coypus or nutria
• (Myocastor coypus)
• Chile, Argentina, Brazil, Bolivia
• Webbed hind feet
• Sparsely furred tail
• Fresh or brackish marshes
• Introduced US EU

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Lagomorpha

• hare shaped
• 11 genera and 54 species in the Family Leporidae
• 2 genera and 26 species in Family Ochotonidae
• Worldwide except southern SA Australia New
  Zealand Madagascar Philippines Caribbean
• Introduced everywhere!

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Lagomorph Morphology

• Small to medium-sized
• Coprophagy is common
• Reingest hard and soft pellets
• Live on low quality veg.
• Diagnostic - peg teeth! A second set of small
  incisors behind the larger, rodent like first
  incisors.
• A third pair of lateral incisors lost at birth or
  soon after

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Lagomorph Morphology

• In leporids, but not in ochotonids, there are
  fenestrations (laticelike penetrations of the
  bone).
• Rabbits have a cotton-ball tail hare tails are
  longer
• Pikas are rodent like but have short limbs, small
  ears, and no tail
• Pikas are agile but cannot run like rabbits

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Gotta Run!
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Ochotonidae
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Easter Bunny
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