suborder hystricomorpha
TRANSCRIPT
Suborder Hystricomorpha:
1) Angular process of jaw not in same plane as most of dentary
(hystricognathous; “gnath” = “jaw”)
2) Coronoid process more reduced than in sciurognaths
3) Often has prominent shelf projecting outwards from near base
of last molar
4) Hystricomorphous musculature means medial masseter
muscle passes through often enlarged infraorbital foramen
5) 18 families! Mostly African, South American, Caribbean, now
in tropical N Am, some in SE Asia (but you only need to know
9)
Family Bathyergidae (African mole rats)
• 6 genera, 17 species
• Sub-Saharan Africa
• Small, fossorial; reduced eyes and
external ears, loose skin, robust skull
• Dig using mostly incisors; incisors
procumbent, protrude from mouth even
when mouth is closed, roots extend
behind molars; cheek teeth are ring or
8-shaped
• Herbivorous, eat primarily underground
storage organs of plants; elaborate
burrows systems, some solitary, some
eusocial
Bathyergus
Heterocephalus
Family Hystricidae (Old World porcupines)
• 3 genera, 11 species
• Africa, Italy, southern and SE Asia
• Large (up to 27 kg), plantigrade,
terrestrial; covered in spines (which lack
barbs), inflated rostrum in some African
species
• Nocturnal, herbivorous, dig burrows
• Give birth once a year in an
underground chamber, young born fully
developed, but with soft spines which
harden after a couple of hours
Brush-tailed porcupine;
Atherurus
Crested porcupine; Hystrix
Family Erethizontidae (New World porcupines)
• 5 genera, 16 species
• Forests in N. America & northern S.
America
• Large (900 g-16 kg), terrestrial and
arboreal; covered in spines (with barbs)
mixed with hairs
• Herbivorous (esp. cambium in winter),
nocturnal, solitarily or in pairs (will share
winter dens) Coendou
Erethizon
Family Chinchillidae (chinchillas & viscachas)
• Southern S. America, high country of
Peru and Bolivia, through Argentina
• Medium to large (500 g-8 kg), 4 toes on
front feet, 3-4 on hind feet; dense fur;
long, well-furred tails
• Burrows & rock crevices; good jumpers;
Lagostomus highly cursorial
• Very vocal, vocalizations used in social
interactions, live in colonies;
herbivorous; diurnal
• Breed year round, usually twins, young
born fully furred with eyes open
• Hunted & farmed for fur
Mountain
viscacha;
Lagidium
Plains
viscacha
Chinchilla
Lagostomus
Family Caviidae (capybaras, maras, & guinea pigs)
• 6 genera, 18 species
• S. America in diverse habitats
• 400 g-79 kg, even larger forms (200 kg giant
capybara) existed during the Pliocene
• Diurnal, nocturnal, or crepuscular (varies by
species), herbivorous, rows of cheek teeth
converge anteriorly
• Mating & social systems vary: maras can be
monogomous, but most cavies are
promiscuous or live in groups dominated by a
top male
Capybara
Mara;
Dolichotis
Cavy; Cavia
Hydrochoerus
Family Dasyproctidae (agoutis & acouchis)
• 2 genera, 13 species
• Southern Mexico through the Amazon Basin,
mostly in tropical forest
• Up to 2 kg; digitigrade, slim legs, many
cursorial adaptations; toes are thick & hoof-
like, short tail
• Premaxillae & nasals extend past thin
incisors
• Herbivorous, scatterhoard fruits and nuts;
important seed dispersers
• Largely diurnal; solitary, but will group
around food resources
• Young born fully developed
• Fast runners & good swimmers Acouchi;
Myoprocta
Agouti
Agouti
Dasyprocta
Family Cuniculidae (Pacas)
Paca; Cuniculus
• 1 genus, 2 species
• Central Mexico to southern Brazil in
tropical forests along streams, rivers
• Up to 12 kg; nearly tailless; conspicuous
white stripes and spots; short legs and
blunt heads
• 4 digits on front feet, 5 on hind feet
(most others we discussed so far have 3
toes on hind)
• Resonating chambers formed by
maxillaries and greatly broadened
zygomatic arches
• Herbivorous, including fruit; single
young; hunted as food
Good to eat
Family Ctenomyidae (tuco-tucos) • 1 genus, 60 species
• Sandy/loamy soils in southern 2/3 of S. America
• Up to 700 g; fringe of stiff hairs on feet (used for
moving soil); long claws, procumbent stout
incisors, small external ears and other typical
fossorial adaptations; kidney-shaped cheek teeth
(3rd molar vestigial)
• Fossorial, herbivorous (esp. underground plant
parts), usually live in “colonies” of solitary
individuals, but at least 1 species social
• Same ecological role as gophers in N. America
(but no external cheek pouches)
Ctenomys
Family Myocastoridae (nutrias)
• 1 genus, 1 species
• S. & Central America, introduced to Europe &
the U.S. in fur farms
• Up to 8 kg; webbed hind feet, long & bare tail;
dense underfur
• Excellent swimmers (stay under water up to 5
min), live in burrows in river banks, eat
vegetation on land & in shallow water
• Breed year round & are prolific
• Nipples are high on females sides so young
can nurse while mother is in water
• Live in groups up to 10 individuals
Nutria; Myocastor
Family Echimyidae (spiny rats)
• 21 genera, 87 species
• Tropical regions of S. & Central America
(also West Indies until 1880s)
• Long tail which can break off (but
doesn’t regenerate), bristly hairs on back
& rump of most
• Nocturnal, can be fossorial, terrestrial, or
arboreal, most species are solitary
Family Capromyidae (hutias)
• Of 8 genera and 20 species, at least 8
species recently extinct
• Found in West Indies, most diverse in
Cuba
• Up to 7 kg, plantigrade, 5 toes on
each foot with strong curved claws
• Tail varies- vestigial to prehensile
• Mostly terrestrial, but some are
partially arboreal, nest in trees & rock
crevices
• Primarily herbivorous, but will eat
insects & even lizards
Order Lagomorpha
(rabbits, hares, & pikas)
• Unlike rodents, males have no baculum
• Like marsupials, testes are in front of penis
• Born with 3 pairs of upper incisors (evergrowing), but lose outer
pair with age
• 2nd pair of incisors found behind first pair & lack sharp edge
• Form 2 types of fecal pellets- 1 is re-ingested to extract nutrition
• 1 genus, 30 species
• Holarctic: N. America, eastern Europe, &
northern Asia
• N Am: rocky outcrops and talus; Eurasia:
variety of habitats, including steppe or
plains as well as rocky outcroppings
• 100-150 g; stocky bodies, short, round
ears; short limbs; hairy soles of feet; no
external tail; males lack scrotum
• Diurnal, herbivorous; steppe-dwelling pikas
prolific breeders like rabbits, but N Am
talus-dwellers only 1 litter per year
• Lay out vegetation to dry & store for use as
food & bedding in winter
• Social systems vary- solitary to large
colonies, communicate with loud whistles
Family Ochotonidae (pikas)
Ochotona
Family Leporidae (rabbits & hares)
• 11 genera, 61 species
• Found worldwide, but introduced in S.
America, Australia, New Zealand, Indonesia,
& Madagascar
• 300 g-5 kg (females larger than males);
elongated hind legs, short tail, ears longer
than wide
• Rabbits dig burrows for shelters, hares
typically do not; rabbits born naked/blind,
hares born fully formed
• Variety of habitats; herbivorous
Pygmy rabbit;
Brachylagus
Jackrabbit;
Lepus Sumatran striped
rabbit; Nesolagus