Week 2 Flashcards
Marsupials
Metatheria
Infra class for marsupials - that give birth to partially developed young ones
Eutheria
Placental mammals
!Marsupial origin
North America
!Convergent evolution between Australian marsupials and placental mammals, 6 examples. Kangaroos - Wallabies - Wombats - Koalas - Numbats - Diprotodonts (extinct) - What are the placental mammals equivalants?
Kangaroos - Antelopes Wallabies - Rabbits Wombats - marmots Koalas - sloth Numbats - Anteater Diprotodonts - Rhino and Tapir
!Marsupial 7 orders
Diprotodontia - diproyodonts Dasyuromorphia - marsupial carnivore Didelphimorphia - marsupial carnivore Paucitubercultata - opossums and the rest Microbiotheria - opossums and the rest Peramelemorphia - opossums and the rest Notoryctemorphia - opossums and the rest
!Why aren’t there marsupial aquatic mammals?
Marsupial young are often held in pouches and Martine mammals would struggle to have pouches. (However there is a semi-aquatic possum called Yapok)
!Economic importance of marsupials
Kangaroos hunted for hide and meat
Brush tailed possums are reared as fur bearers. They have become introduced pests, especially New Zealand, which has caused ecological and economical damage
Theria
Subclass containing the metatheria (marsupials) and eutheria (placentals)
Prototheria
Subclass for prototheria (monotremes)
!Evolution of pouches
Absence of pouch is the ancestral or primitive condition
Pouches have evolved independently many times
50% of marsupials don’t have a pouch
!Wombat pouch
Wombats have a backward opening pouch so that dirt doesn’t enter the pouch while digging.
!Distribution of marsupials
Mainly southern hemisphere
Australia and New Guinea (200 species)
North & South America (70 species)
!Lifestyle
Very diverse Adaptations for.. Fossorial - burrowing Ambulatory - walking Cursorial- running Saltatorial - leaping Semi-aquatic - frequently living in water Arboreal - inhabiting trees Gliding
!Diet
Very diverse Insectivorous Carnivores Omnivores Herbivores Nectarivorous Browsing and grazing
Differences between marsupial and eutherian skulls and brains?
In marsupials:
Palate of marsupials is fenestrated (2 extra holes)
Dentary angle is “bent”
Marsupials dentition
Upper jaw had more incisors than lower jaw (except wombats)
Cheek teeth typically 3/3,4/4
What orders have diprotodont dentition?
Diprotodontia
Paucituberculata
What is diprodont dentition?
Lower jaw shortens
Pair of lower incisors enlarge and elongate
Epipubic bone
A characteristic of marsupials.
A bone which project anteriorly (stick forward) from the pelvis
!Limb forms types
Marsupials show:
Plantigrade (majority) - walking on Palms/soles
Digitigrade - walking on fingers/toes
Water opossum has webbed hind feet to be semi-aquatic.
The hallux (big toe) is clawless
Syndactylous feet: what is it and in which orders?
Found in orders: Peramelemorphia Diprotodontia It is: 2nd and 3rd toes are fused. Separate sets of bones exist but are enclosed within a single skin sheath
Two most distinguishable features of marsupials from eutherians?
Syndactylous feet
Diprotodont dentition
!Marsupial reproductive development of young
Via lactation instead of placenta
Due to low birth weight of young and very short gestation
!Female marsupial reproduction
Have a double reproductive tract.
Birth takes place in median canal called the pseudovaginal canal
!Male marsupial reproduction
Scrotum anterior to the penis.
Penis bifurcates in majority of species
!Examples of marsupial species in the order Diprotodontia?
Possums
Kangaroos
Wombats
Koalas
!Diprotodontia distribution
Australian faunal region - included Tasmania & islands to the north of Australia e.g. new Guinea.
!marsupium
Pouch
Distinguishing characteristics of diprotodontia
syndactylous hindtoes
Diprotodont teeth
Schizodactylous forefeet
Arboreal diprotodonts (e.g koala) have forefeet where the first two digits oppose (face the other way) to the other 3
!Diprotodontia families
Pseudocheiridae - ring-tailed possums
Phalangeridae - cuscuses, brush-tailed possums
Burryamidae - pygmy possums
Petuaridae - striped possums, gliding possums
Potoridae - “rat” kangaroos
Macropodidae - kangaroos and wallabies
Phascolarctidae - koalas
Vombatidae - wombats
Tarsipedidae - honey possum/noolbenger
Acrobatidae - feathertail glider & feathertail possum
Ring tailed possum (order diprootodontia) adaptations
Ring tailed possum and greater glider
Arboreal folivores
Adaptation for folivory:
*Enlarge caecum for microbial fermentation of high cellulose diet
* Slow movement (because plant material doesn’t provide much energy)
*Coprophagy (helps with digestion)
!Pygmy possum (diprotodontia)
Pygmy possum
Arboreal nectivores
Adaptations:
*High nitrogen diet allows for large little sizes
*Extremely mobile to allow access to flowers
*Small size
Striped possums and gliding possums (order diprootodontia) adaptation
Striped possums and gliding possums
Arboreal
Adaptations:
*Use patagium to glide
Honey possum (order diprootodontia) adaptations
Honey possum
Nectar and pollen specialist
Because it eats pollen it had a reduced dental formula and a long tongue with brush-like tip.
Feathertail glider possum (order diprootodontia) adaptations
Feathertail glider possum:
- nectivore
- Brush-tipped tongue
- Highly mobile and can glide
!Phalangeridae (order diprotodontia)
Cuscuses and bushtail possum
Enlarged lower premolar (projects above the level of other cheek teeth)
!Phalangeridae (order diprotodontia)
Spotted cuscus and dwarf cuscus etc
!Potoridae (order diprootodontia)
Bettongs, potoroos, and rat kangaroos
!Macropodidae “big-footed” (order diprootodontia)
Kangaroos and wallabies
Largest and diverse marsupial family
Adapted for saltatorial (bounding) and ricochetal (jumping) locomotion
!Dendrolagus in family macropodidae (order diprootodontia)
Tree kangaroos
There was an arborial niche that was free to fill in terms of leaf eating and fruit eating
!Phascolarctidae (order diprootodontia)
Koala (monotypic family)
Feeds on eucalyptus
Wife distribution along the East coast of Australia.
Koalas from the south are much larger due to the cold.
!Dasyuromorphia “bushy tails” families
Dasyurodae - antechinus, quolls, devil etc
Thylacinidae - thylacine
Myrmecobiidae - numbat
Dasyuromorphia “bushy tails”
Order for marsupial carnivores
!Family Thylacinidae in order dasyuromorphia
Thylacine
Extinct
Numbat diet (order dasyuromorphia)
Numbat
Diet: termites
!Family dasyuridae in order dasyuromorphia
Antechinus, kowari, quolls, devil
Distribution: Australia and New Guinea - dry grassland to rainforest.
!Order Didelphimorphia
American opossum
Distribution: south, central, and north America
Habitat: grassland - rainforests
Lifestyle: arboreal, terrestrial, semi-aquatic
Diet: omnivores
!Order Paucituberculata
Marsupial shrews/rat opossum
Distribution: Andean region
Dentition: diprotodont
Monito del Monte (Order microbiotheria) adaptation
Monito del Monte
Adaptations: fat store in tail which provides energy to survive winter hibernation.
Marsupial mole (order Notoryctemorphia) adaptations
Marsupial mole
Adaptations:
Neck vertebra are fused which are adaptations to a fossorial lifestyle
