Flashcards in Herbert Deck (45)
What is the difference between prototheria, metatheria, and eutheria?
Prototheria- egg layers (monotremes)
Metatheria- embryonic young (marsupials)
Eutheria- birth more developed young
Four traits that distinguish mammals from reptiles?
Suckling of young
What are the origins of marsupials and monotremes?
Breaking off from Antarctica 35-40 million years ago
What are the origins of Australian eutherians?
Island hopping 5-6 million years ago
What are the most easily recognisable differences between ameridelphia and australidelphia?
Structure of the tarsal bones
Also blood proteins, DNA and sperm morphology
What are the four orders of marsupials?
What is the name of the opposable 1st digit on the hind foot present in some marsupials?
Multiple pairs of lower incisors
One pair of incisors in the lower jaw.
Normal occurrence of having two or more fused digits in a mammal species.
Between what two digits is syndactyly most common?
II and III
What is the dentition of dasyuromorphids?
Would a spotted quoll have one or more digits fused together naturally?
No, it is a dasyurid, they do not have any syndactyly
Bandicoots have three pairs of equal sized lower incisors.
Yes they are of the order peramelemorphia which are polyprotodonts
Syndactyly is a defining aspect of peramelemorphia
What does the order notoryctemorphia include?
All diprotodonts have one pair of lower incisors
True or false?
What order do koalas belong to?
All diprotodonts have syndactyly
What is the significance of the path of the ureters in marsupials?
Prevents the fusion of the vagina into a single structure
Multiple cycles in breeding season
How is ovarian activity modulated in marsupials?
Describe the placenta of bandicoots koalas and wombats
Structure and function of the pouch?
Invagination of skin of ventral abdomen through a gap in cutaneous muscles, interior skin is hairless, coated by a brown secretion
High humidity and stable temperature for growing young
Mammary glands with long nipples to suckle young
What is embryonic diapause?
A female mates while a young is in her pouch. The conceptus is suspended until the first young has finished suckling.
How does embryonic diapause work?
Corpus luteum develops and is then inhibited by suckling stimulus
Solitary marsupials are usually...
Small nocturnal carnivores/omnivores
Exceptions include brushtails and koalas
What is sexual size dimorphism?
Significant difference in size between the sexes within a species
How do marsupials cope with cold conditions?
1 increase metabolic rate
2 huddling in groups
3 torpor (pseudo hibernation)