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Flashcards in Marsupials Deck (30)
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1

Where are marsupials found ?

In Australia and the southern hemisphere (New Guinea)

2

Where are the oldest marsupial fossils found ?

In present day china and north America.

3

How have we documented the ancestral spread of marsupials ?

Through molecular analysis, Studying the fossil record and use of tectonic models

4

Describe the relationship between the Australian and south American marsupial groups.

A Single South American marsupial became the ancestor of the Australian marsupials
(Australian marsupials, within wider group of SA marsupials)

5

When did marsupials evolve ?

168 ya, In the early cretaceous period.

6

Describe the adaptive radiation of marsupials.

Evolved in Laurasia (Europe, asia, N America)
crossed from S America to Antartica and then Australia
Continents then began to split leading to considerable adaption of marsupials in isolated habitats.

7

How were marsupials able to cross from South America to Australia ?

Gondwana, giant land mass linking South America, Antarctica and Australia

8

How many species exist in the modern day ?

300 species of marsupial

9

How many orders of marsupial ?

7

10

Give the causes of marsupial extinction 3 million years ago

Placental mammals are thought to have hunted some marsupials to extinction

11

Give an example of the extreme diversity found within the marsupials.

Planigale and Adult red kangaroo
(20,000 times heavier)
Huge weight difference!

12

Give an ecological equivalent of the marsupial Sugar glider, from Australia

Eutherian
Northern flying squirrel,
North America

13

Give an ecological equivalent of the Eutherian Spotted hyena

Marsupial
Tasmanian Devil

Both have sloped hindquarters, Big jaws

14

Give the ecological equivalent of the marsupial Kangaroo

Eutherian
Patagonian Mara

15

Give the ecologically equivalent mole species

Southern Marsupial Mole
European Eutherian Mole

16

Why are marsupial and eutherian equivalents, analogous not homologous ?

They are not ancestral features
Instead characteristics due to CONVERGENT evolution

17

Define analogous

Are comparable due to similar morphological features

18

Define Homologous

Shared ancestry between species

19

When did the Eutherians evolve from the Marsupials ?

In the late Jurassic, 140 million years ago

20

Describe the difference in uterus horns between Eutherians and marsupials.

Eutherians have a 1 horned uterus
Marsupials have 2, 3 horned uterus

21

To fully fertilise the 2 horned uterus, what have some marsupial males evolved ?

Doubled lobed penis
e.g. Kangaroos

22

Describe a marsupials placenta.

Short lived
Not intricate
Nutrients are exchanged via the egg sac

23

What are the Bandicoots ?

A marsupial group consisting of 20 species who have developed placentas
However they are much smaller and lack villi

24

Describe the gestation period of marsupials in comparison to that of the eutherian

Much shorter (13-35 days)
Eutherians much longer
(45-650d)

25

Give the longest eutherian gestation period

650 days, 2 years

26

Describe the life cycle of the new-born marsupial

Crawls up female to pouch
Attaches to nipple (by smell?)
The nipples swell, new born able to move until jaw muscles developed
Released when comparatively same size as placental offspring

27

After giving birth to offspring when are marsupials again able to reproduce ?

Immediately- Postpartum estrus
However if fertilised the zygote will be arrested at the blastocyst stage until current offspring die or develop further

28

Give the advantage of this rapid reproduction
(arrested blastocyst stage)

Enables rapid generation of offspring in breeding season

If nipple feeding offspring die, new offspring to take place.

29

What was the first marsupial to have its genome coded ?

Opossum

30

What were the immune findings of the first marsupial genome sequence ?

The common ancestor of E & M; M had the basic building blocks for the human immune system

Modern day eutherian genetic invention is mostly due to changes in regulatory DNA and non-coding sections rather than new genes