Monotremata, Didelphimorphia, Diprotodontia, Cingulata, and Pilosa (plus randomy

characteristics of class mammalia

• single dentary

• two occipital condyles

• secondary hard palate

• heterodont dentition

what subclass is the order monotremata in?

prototheria

characteristics of monotremata

• epipubic bones present

• complex pectoral girdle

characteristics of prototheria

• lack teeth, lacrimal bone, and auditory bullae

• small or absent jugal

• complex pectoral girdle (has extra elements) (pictured)

• only extant mammals that are oviparous (egg-laying)

• mammary glands but no teats

family tachyglossidae

• echidnas - includes genus Zaglossus, the long-beaked echidnas, and Tachyglossus, the short-beaked echidnas

• premaxillae expanded laterally and fused anteriorly

• body covered with spines

• feet with large claws, not webbed

family ornithorhynchidae

• platypus

• semiaquatic, semifossorial mammals

• bill is its main sensory organ

• premaxillae expanded laterally and separate anteriorly

• body covered by pelage of soft hairs

• feet webbed and furry

true or false: subclass theria includes monotremes

flase; theria includes the metatherians (marsupials) and the eutherians (placentals)

characteristics of subclass theria

• teeth (generally), lacrimal, jugal, and auditory bullae present

• simple pectoral girdle

• marsupium (pouch) in most species with short intrauterine gestation and prolonged lactation period

placental differences in marsupials

• choriovitelline placenta

• enlarged yolk sac

• relatively little attachment to developing fetus

placental differences in placentals

• chorioalltoic placenta

• chorionic villi extend deeply into the endometrium

• form a very tight connection between mother and fetus

infraclass metatheria (or marsupialia) characteristics

• jugal forms part of mandibular fossa

• inflected angular processes of dentary

• fenestrated palate (often)

• choriovitelline placenta

• epipubic bones present

order didelphimorphia characteristics

• the opossums

• about 20 geneara and 100 species

• diverse omnivores

• most are burrowers, some semi-arboreal

• one spp. is aquatic with webbed feet and watertight marsupium in females (yapok)

• lower incisors subequal in size and procumbent

order diprodontia characteristics

• about 155 species

• koalas, kangaroos, wombats, possums

• two procumbent lower incisors

• primarily herbivorous

• many arboreal species have schizodactylous feet, meaning they are adapted for grasping

family phalangeridae

• phalanger, brush-tailed possum, etc.

• 3/2 incisors

• canines reduced in size in upper jaw and absent in lower jaw

• molars bilobed transversely lophodont

• large masseteric fossa

which clade are orders pilosa and cingulata a part of?

clade xenarthra

order pilosa

• the sloths (two-toed and three-toed) and anteaters

• large recurved claws

• have anterior caniniform premolar (a premolar that looks like a canine tooth)

• incomplete zygomatic arch

• coarse hair

• long, tapered skull in anteaters

• sloth fur has greenish tint due to algae

family bradypodidae

• sloths

• cheek teeth homodont

• jugal bifurcated and projecting posteroventrally

• short rostrum

family myrmecophagidae

• anteaters

• no teeth (edentate)

• small jugal

• rostrum very long and curving downward

order cingulata

• armadillos

• has carapace and articulated skeleton

• ossified dermal scutes cover the head, body, and tail in most species

• nine-banded armadillo can contract leprosy

family dasypodidae

• the armadillos

• cheek teeth homodont

• body covered with keratin scutes overlaying bony plates

true or false: all marsupials have a tribosphenic molar

true

true or false: all marsupials have a tibosphenic molar

false

family didelphidae characteristics

• new world opossums

• 5/4 incisors

• canines well-developed in upper and lower jaw

• molars tritubercular (tribosphenic)

• polyprotodont

tribosphenic

molars with three main cusps (called the trigon) arranged in a triangular pattern; cusp patterns of many modern mammalian groups are derived from this pattern

which of these metatherians is a polyprotodont: phalangeridae, macropodidae, or didelphidae

didelphidae, the opossums

polyprotodont

dentition in several orders of marsupials in which the lower jaw is equal in length to the upper jaw and the lower incisors are small and unspecialized (as opposed to diprotodont)

family macropodidae

• kangaroos, wallabies

• 3/1 incisors; canines reduced or absent in upper jaw and absent in lower jaw

• molars bilobed (transversely lophodont)

• large diastema between canines and premolars

• large masseteric fossa

true or false: a diastema is a useful trait for identifying skulls of macropodidae

true

which family of mammals does this skull belong to?

tachyglossidae, the echidnas

in which families can you observe homodont cheek teeth?

bradypodidae (three-toed sloths); dasypodidae (long-nosed armadillos)

what type of molars are picture here? (kangaroo skull)

bilophodont

lophodont

occlusal pattern in which the cusps of cheek teeth form a series of continuous, transverse ridges, or lophs, as in elephants

what condition is depicted in the lower incisors of the skull?

diprotodonty - dentition in marsupials, specially the paucituberculata and diprotodontia, in which the lower jaw is shortened and the single pair of lower incisors is elongated to meet the upper incisors (as opposed to polyprotodont)

what family of mammals does this skull belong to?

bradypodidae (the sloths)

which of these are part of infraclass metatheria

• didelphidae

• bradypdidae

• macropodidae

• tachyglossidae

didelphidae (possums) and macropodidae (kangaroos etc.)

which of the following traits are useful for identifying infraclass metatheria?

• small auditory bullae

• inflection of angular process of dentary

• large paraoccipital process

• jugal as part of mandibular fossa

• fenestration of the palate

inflection of angular process of dentary, jugal as part of mandibular fossa, and fenestration of the palate

in which mammalian infraclass do we see an inflected angular process?

metatheria

which of these animals is diprotodont and which is polyprotodont?

A - diprotodont

B - polyprotodont