Marsupials (metatheria)

Question 1

when did metatheria seperate from eutherian

Answer 1

60 MYA

Question 2

where are they found

Answer 2

Australia and the Neotropics

Question 3

characterizing trait

Answer 3

a marsupium but not all have one

Question 4

Reproduction

Answer 4

variation in nipple # within species
females have a bifid reproductive system
females can do embryonic diapause during drought or when there is a lack of resources
short gestation
highly altricial young = long lactation period

Question 5

what was an inhibiting developmental feature that caused a like of diversification in marsupials?

Answer 5

the need for the ability to grasp at birth inhibited diversity of forelimb structure = less diversification in forelimb = not as good as competition against eutherians = got out competed.

Question 6

metatherians vs. eutherians

Answer 6

less diverse: eutherians have adopted highly productive food sources that Meta did not.
metatherians are more conservative morphologically
meta have not exploited greater size
meta have not evolved highly social behavior
meta are less diverse than eutherians

Question 7

lack of comparative success of marsupials

Answer 7

1) The cerebral cortex developed more rapidly and gets larger in eutherians than in marsupials
2) Eutherians have greater behavioral plasticity.
3) more developed anti-predator behavior
4) extended gestation of eutherians produced young that are more endothermic allowing them to better exploit colder climates.

Question 8

New world marsupials

Answer 8

Didelphimorphia, paucituberculata, microbiotheria

Question 9

australasian marsupials

Answer 9

dasyuromorphia, notoryctemorphia, perametemorphia, diprotodontia

Question 10

Didelphimorphia

Answer 10

North -> South America
18 genera, 111 species
Braincase is long and narrow
prominent sagittal crest
can have a marsupium
usually have a prehensile tail

Question 11

Paucituberculata: shrew opossum

Answer 11

3 genera, 7 species
disjunct distribution, on the andes mountains.
no marsupium
elongated head, small eyes, large olfactory bulbs
smooth brain

Question 12

microbiotheria: monito del monte/colocolo opossum

Answer 12

found in the southern Andes mountains
part of superorder australidelphia
scansorial (climbing)/ arboreal
originated in Australia and migrated through Antarctica into S.america

Question 13

Dasyuromorphia

Answer 13

carnivores and insectivores
3 families

Question 14

Notoryctemorphia: marsupial moles

Answer 14

2 species
adaptations: vestigial lensless eyes, ears lack pinnae, enlarged claws for digging.

Question 15

peramelemorphia: bandicoots

Answer 15

hindfoot modification for cursorial locomotion.
some adapted for burrowing
slender rostrum narrow head

Question 16

diprotodontia

Answer 16

large order, 11 families
must well know marsupials
a wide diversity of anatomy, ecology, and physiology.