clade afrotheria: orders lagomorpha and rodentia through heteromyidae

infraclass eutheria/placentalia

• jugal typically doesn’t form part of mandibular fossa

• angular process of dentary usually not inflected

• palate usually not fenestrated

• no marsupial pouch

• epipubic bone absent

orders/families in clade afrotheria

• order tubulidentata/family orycteropodidae (aardvark)

• order macroscelidea/family macroscelididae (elephant shrew)

• order tenrecoidea/family chyrsochloridae (golden mole)

order tubulidentata/family orycteropodidae

• aardvark

• cheek teeth homodont, columnar, consisting of numerous vertical tubres of dentine matrix with no enamel

• no interparietal bone

• no incisors

order macroscelididae/family macroscelididae

• elephant shrew

• palate usually fenestrated

• auditory bullae enlarged

• long proboscis

• no external cheek pouches

• quadritubercular and bunodont teeth

order tenrecoidea (aka afrosoricida)/family chrysochloridae

• golden mole

• skull strongly triangular in shape

• eyes covered with skin

• upper molars tritubercular

• teeth and crowns with V-shaped ectoloph

orders/families in clade paenungulata

• order hyracoidea/family procaviidae (hyrax)

• order proboscidea/family elephantidae (elephant)

• order sirenia/family dugongidae (dugong)/family trichechidae (manatee)

order hyacoidea/family procaviidae

• hyrax

• ½ incisor count, upper incisors ever-growing and tusk-like

• cheek teeth lophodont and relatively simple

• postorbital process well developed (often forming complete bar)

• specialized elastic pads on soles of feet

• jugal forming part of mandibular fossa

• interparietal well developed

order proboscidea/family elephantidae

• elephant

• upper incisors ever=growing, long and tusk-like

• cheek teeth polyphyodont and lophodont with many transverse ridges

• long proboscis

• limbs pillar-like

• sole of feet with large elastic pad

• no postorbital bar or interparietal bar

order sirenia

• pachyostoic (thickened and dense) skull

• modified forefoot into a paddle-like flipper

• no hindlimbs

• includes families dugogidae and trichechidae

• absent or reduced nasal bones

family dugongidae

• dugong

• tail fluke “dolphin-like”

• premaxilla large and bent sharply downward

• jugal broaden below orbit and in contact with premaxilla

• cheek teeth with simple columns

• big incisors

family trichechidae

• manatee

• tail fluke rounded

• premaxilla small and only slightly bent downward

• jugal broadened behind orbit and not in contact with premaxilla

• cheek teeth with two transverse ridges

• no incisors

orders/families in clade euarchontoglires

• order lagomorpha/family ochotonidae (pika)/family leporidae (hare/rabbit)

• order rodentia/family aplodontiidae (mountain beaver)/family sciurdae (squirrels)

• suborder castorimorpha/family castoridae (american beaver)/family geomyidae (pocket gopher)/family heteromyidae (kangaroo rat/pocket mouse)

clade glires

• orders lagomorpha and rodentia

• ever-growing incisors and no canines

order lagomorpha

• pikas and hares/rabbits

• 2/1 incisor count

• fenestrated maxilla

• cheek teeth transverse bilophodont

• 2 pairs of upper incisors (2nd pair small and peg-like; located directly behind the enlarged anterior pair)

family ochotonidae

• in order lagomorpha

• pika

• no supraorbital process

• maxilla with single (or 2-3) perforations

• soles of feet covered in fur but naked digital pads

• round ears

family leporidae

• in order lagomorpha

• hares, rabbits

• surpaorbital process present and fan-shaped

• maxilla with numerous perforations (web-like fenestration)

• soles and digital pads covered in thick hair

• elongate ears

order rodentia

• families aplodontiidae and sciuridae (mountain beaver and squirrels etc)

• 1/1 incisor count

• teeth are ever-growing

• no canines; have broad diastema instead

• no fenestrations

• unique infraorbital foramen conditions

family aplodontiidae

• in order rodentia

• mountain beaver

• protrogomorphous, skull flattened

• crowns of teeth ringlike and each with small projection

• auditory bullae not inflated but flask-shaped with a long tympanic tube

• body is blocky with vestigial tail

• most primitive rodent

• angular process strongly inflected on lower jaw

family sciuridae

• in order rodentia

• squirrels, marmots, prarie dogs

• sciuromorphous, postorbital processes present

• crowns of cheek teeth usually with distinct cusps or ridges and valleys (“hand peace sign” in teeth cheek

• auditory bullae not flask shaped withotu a long tympanic tube

• large postorbital process

familes in suborder castorimorpha

family castoridae (american beaver), family geomyidae (pocket gopher), family heteromyidae (kangaroo rat, pocket mouse)

family castoridae

• american beaver

• sciuromorphous skull

• no postorbital process

• basioccipital depression

• crowns of cheek teeth flat with narrow inner and outer lateral enamel folds

• auditory bullae not inflated but somewhat flask-shaped with tympanic tube

• tail large, broad, and flat

• incisors stained

family geomyidae

• pocket gopher

• myomorphous infraorbital foramen compressed against side of rostrum (does no perforate through maxilla)

• crowns of cheek teeth simple

• auditory bulla small

• tubular body with small ears and short tail

• external fur-lined cheek pouches

• no postorbital process

• broad zygomatic plate

• nasal bones do not extend beyond incisors

family heteromyidae

• kangaroo rat and pocket mouse

• myomorphous and rounded skull

• infraorbital foramen entirely piercing the rostrum perforates through maxilla

• crowns of cheek teeth simple

• auditory bulla can be slightly inflated to greatly inflated

• limbs modified for saltation

• external fur-lined cheek pouches

protrogomorphous

• only observed in mountain beavers (family alpodontiidae)

• only lateral and superficial masseters

• both masseters originate on zygomatic arch

• small infraorbital foramen

• no zygomatic plate

sciuromorphous

• note tiny roundish hole

• zygomatic plate

• lateral masseter originates on zygomatic plate

• small infraorbital foramen and canal

myomorphous

• zygomatic plate

• larger infraorbital canal

hystricomorphous

• no zygomatic plate

• huge infraorbital foramen

• lateral masseter originates from zygomatic arch

what type of molars are these

tritubercular or zalambdodont

in which families do we observe polyphyodonty

elephantidae (elephants) and trichechidae (manatees)