September 17

Main Points
1) Diversity, Phylogeny, and Systematics:
--Subclasses Prototheria and Theria
--Infraorder Metatheria (Marsupialia)
--Orders Monotremata through Peremelimorphia
2) Modern distribution of monotremes and
marsupials:
--adaptive radiation of marsupials
--continental vs. oceanic islands
--Wallace’s line
3) Terms: sister group, oviparous, cloaca, altricial,
marsupium, adaptive radiation, syndactyly,
placenta (choriovitelline vs. chorioallantoic)
Zoogeographic Regions
Subclass Prototheria
Order Multituberculata:
the greatest mammalian success story ever told
--may be of Prototherian descent, but didn’t lay eggs
--may have been driven extinct by eutherians
Diversion:
body sizes of extant mammals
North American mammals north of Mexico
Brown and Nicoletto 1991
Log10 Mass (g)
Lyons et al. 2004
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
long-nosed echidna
short-nosed echidna
duck-billed platypus
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
Diagnostic characters:
1) oviparous
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
Diagnostic characters:
1) oviparous
2) cloaca
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
Diagnostic characters:
1) oviparous
2) cloaca
3) mammary glands lacking nipples
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
Diagnostic characters:
1) oviparous
2) cloaca
3) mammary glands lacking nipples
4) no teeth in adults
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
Diagnostic characters:
1) oviparous
2) cloaca
3) mammary glands lacking nipples
4) no teeth in adults
5) electroreceptors in snouts
Subclass Prototheria, Order Monotremata
Taxonomy: 3 species, 2 families
Distribution: Australasian, in coastal, southeastern
Australia and in New Guinea (echidnas only)
Diagnostic characters:
1) oviparous
2) cloaca
3) mammary glands lacking nipples
4) no teeth in adults
5) electroreceptors in snouts
6) no pinnae
Subclass Theria, Infraorder Metatheria
Subclass Theria, Infraorder Metatheria
Taxonomy: 7 orders
Distribution: 4 orders Australasian, 3 orders Neotropical
Wallace’s Line
Late Jurassic, ~150 MYA
Subclass Theria, Infraorder Metatheria
sugar glider
flying squirrel
red kangaroo
white-tailed deer
jackrabbit
rabbit-eared
bandicoot
marsupial cat
bobcat
Subclass Theria, Infraorder Metatheria
Taxonomy: 7 orders
Distribution: 4 orders Australasian, 3 orders Neotropical
Diagnostic characters:
1) dental formula = 5/4, 1/1, 3/3, 4/4 = 50 teeth
Subclass Theria, Infraorder Metatheria
Taxonomy: 7 orders
Distribution: 4 orders Australasian, 3 orders Neotropical
Diagnostic characters:
1) dental formula = 5/4, 1/1, 3/3, 4/4 = 50 teeth
2) brain and braincase are relatively small
Subclass Theria, Infraorder Metatheria
Taxonomy: 7 orders
Distribution: 4 orders Australasian, 3 orders Neotropical
Diagnostic characters:
1) dental formula = 5/4, 1/1, 3/3, 4/4 = 50 teeth
2) brain and braincase are relatively small
3) young are born altricial, and are carried in marsupium
Subclass Theria, Infraorder Metatheria
Taxonomy: 7 orders
Distribution: 4 orders Australasian, 3 orders Neotropical
Diagnostic characters:
1) dental formula = 5/4, 1/1, 3/3, 4/4 = 50 teeth
2) brain and braincase are relatively small
3) young are born altricial, and are carried in marsupium
4) cloaca
Subclass Theria, Infraorder Metatheria
Taxonomy: 7 orders
Distribution: 4 orders Australasian, 3 orders Neotropical
Diagnostic characters:
1) dental formula = 5/4, 1/1, 3/3, 4/4 = 50 teeth
2) brain and braincase are relatively small
3) young are born altricial, and are carried in marsupium
4) cloaca
5) scrotum anterior to penis
Order Didelphimorphia: opossums
Taxonomy: 1 family, 15 genera, 63 species
Distribution: Neotropical, 1 species Nearctic
Order Didelphimorphia: opossums
Taxonomy: 1 family, 15 genera, 63 species
Distribution: Neotropical, 1 species Nearctic
Characteristics:
--most generalized metatherians
--clawless hallux
--prehensile tail
Order Paucituberculata: shrew opossums
Taxonomy: 1 family, 3 genera, 6 species
Distribution: Neotropical (Andes mountains)
Order Paucituberculata: shrew opossums
Taxonomy: 1 family, 3 genera, 6 species
Distribution: Neotropical (Andes mountains)
Characteristics:
--no marsupium
--convergent with shrews
Order Microbiotheria: monito del monte
Taxonomy: 1 family, 1 genus, 1 species
(monotypic order)
Distribution: Neotropical (Andes mountains)
Order Microbiotheria: monito del monte
Taxonomy: 1 family, 1 genus, 1 species
(monotypic order)
Distribution: Neotropical (Andes mountains)
Characteristics:
--genetically similar to Australian metatherians
--hibernates
Order Notoryctemorphia: marsupial “mole”
Taxonomy: 1 family, 1 genus, 1 species
(monotypic order)
Distribution: Australasian
Order Notoryctemorphia: marsupial “mole”
Taxonomy: 1 family, 1 genus, 1 species
(monotypic order)
Distribution: Australasian
Characteristics:
--no pinnae
--eyes vestigal, ears reduced
--enlarged claws
--convergent with other
fossorial mammals
Order Diprotodontia: kangaroos, wallabies,
phalangers, possums, wombats
Taxonomy: 10 families, 117 species
spotted cuscus
Distribution: Australasian
hairy-nosed wombat
koala
red kangaroo
Order Diprotodontia: kangaroos, wallabies,
phalangers, possums, wombats
Taxonomy: 10 families, 117 species
Distribution: Australasian
Characteristics:
--diprotodont teeth
--syndactyly
Order Peramelina (Peremelimorphia): bandicoots
Taxonomy: 2 families, 21 species
Distribution: Australasian
rabbit-eared bandicoot
Eastern barred bandicoot
Order Peramelina (Peremelimorphia): bandicoots
Taxonomy: 2 families, 21 species
Distribution: Australasian
Characteristics:
--hind limbs specialized for hopping
--have chorioallantoic placenta, in addition to
marsupium