Mammal overview

Question 1

Give the 2 subclasses of the mammal class.

Answer 1

Prototheria (Monotremata)

Theria (Metatheria)

Question 2

Give the 2 infraclasses of the subclass Theria.

Answer 2

Marsupialia

Placentalia

Question 3

What is the difference between organisms in the subclass Prototheria and Theria

Answer 3

Prototheria- Lay eggs

Theria- Have live young

Question 4

What has caused drastic changes in the mammalian phylogeny ?

Answer 4

Fossil findings

Molecular analysis

Question 5

How many mammalian orders are there ?

Answer 5

27
1 Prototherian
7 Marsupial
19 Placental

Question 6

How many species exist in the mammalian order ?

Answer 6

5,488

Question 7

Give a broad description of a mammal.

Answer 7

Group of animals with;
Backbones
Bodies with fur (?) 
Nurse infants with milk
Unique jaw articulation

Question 8

What is the mammae ?

Answer 8

Mammary gland, where milk production takes place

Question 9

What is a mammillae ?

Answer 9

A nipple/teat, delivers milk to the infant

Question 10

How many mammaries will an organism have ?

Answer 10

Generally twice as many mammaries as the average litter size.

Question 11

What are the benefits of feeding via the mammary system ?

Answer 11

Guarantees constant supply of food
Female can redistribute energy into milk production

Little energy required for offspring to feed.

Question 12

What one species has paternal lactation ?

Answer 12

Dayak fruit bat

Question 13

What bone has articulated to form the mammalian jaw ?

Answer 13

Dentary bone

Has met with the squamosal bone in the skull to form jaw.

Question 14

Which ancestral bones are responsible for an increase in the acuteness of mammalian in hearing ?

Answer 14

The quadrate and Articular bone.

Question 15

The quadrate bone has become the….

Answer 15

Incus of the inner ear

decreased in size

Question 16

The articular bone has become the….

Answer 16

Malleus of the inner ear

decreased in size

Question 17

How many jaw joints do mammals have in the present day ?

Answer 17

One jaw joint, giving more efficient chewing.

Question 18

How do mammalian teeth differ from shark teeth ?

Answer 18

They do not continuously grow.

Will replace them once or never.

Question 19

Give cycle of placental mammal teeth.

Answer 19

2 sets
Milk teeth
Adult teeth

Question 20

Which teeth remain constant throughout a placental mammals life ?

Answer 20

Molars, only one set.

Question 21

Give the cycle of marsupial teeth.

Answer 21

1 set

Only last premolar will be replaced

Question 22

What enamel is found on mammalian teeth ?

Answer 22

Prismatic enamel

Question 23

What is an occipital condyle ?

Answer 23

Where the skull meets the top of the neck vertebrate.

Question 24

How many occipital condyles do mammals have ?

Answer 24

2

Question 25

What is the advantage to mammals of having 2 occipital condyles ?

Answer 25

Decreases tension on skull | Allows greater control of head movement

Question 26

How many occipital condyle do birds have ?

Answer 26

1

Question 27

What is the disadvantage of 2 occipital condyles ?

Answer 27

Decreased lateral head movement

Question 28

Give the earliest fossil evidence of mammals.

Answer 28

160 million years ago

Question 29

Who do mammals share there AMNIOTE common ancestor with ?

Answer 29

Reptiles, Dinosaurs, Birds,

Question 30

Give the groups which this amniote ancestor diverged into.

Answer 30

Anapsids Diapsids Synapsids

Question 31

How can you identify the difference between the Diapsids and Synapsids ?

Answer 31

Temporal fenestra ``` Di= 2 Temp Fen. Syn= 1 Temp fen. ```

Question 32

What is a temporal fenestra ? What is its function ?

Answer 32

Large holes in the sides of the skull. Enable muscles to expand and lengthen

Question 33

Which group went on to form the mammals, 300 mya ?

Answer 33

Synapsids

Question 34

Give the first order of dinasours which mammalian charecteristics.

Answer 34

Pelycosauria E.g Dimetrodon.

Question 35

Describe the limb arrangement of Pelycosaurs.

Answer 35

Limbs were sprawled out to the sides | like reptiles

Question 36

What were the pelycosaurs replaced by and when ?

Answer 36

Therapsids- More advanced synapsids | Late Permian

Question 37

What occurred in the Triassic to threaten Therapsid survival ?

Answer 37

Huge increase in number of other dinosaurs. | Managed to survive

Question 38

Give the key beneficial adaptions of the Therapsids

Answer 38

Limbs beneath the body (rapid locomotion) Secondary palate Separate mouth and nasal passage, (eat and breath at same time.)

Question 39

Describe the positon of the Articular and the Quadrate in the therapsids.

Answer 39

Remain in lower jaw | Not incorporated into malleus an incus of ear

Question 40

What other adaptions took place between the Therapsids and the mammals of today ?

Answer 40

``` Became endothermic Live young birth Heterodont teeth (diff.) Development of temporal fenestra Zygomatic arch Hair and fur ```

Question 41

What is the zygomatic arch ?

Answer 41

A cheek bone- Enables | more efficient chewing

Question 42

What is the advantage of heterodont teeth ?

Answer 42

Enable specialisation of organism, can eat diff prey items

Question 43

When did the First mammals separate from the Therapsids ?

Answer 43

In the late Triassic, | 240 million years ago

Question 44

What feature separated the 1st mammals from the Therapsids ?

Answer 44

Dentary bone fused to squamate skull, to form jaw.

Question 45

Give the original niche thought to be occupied by these animals.

Answer 45

Nocturnal and insectivores | Only niche left available by dinasours

Question 46

The first mammals actually occupied a wide range of niches. How do we know this ?

Answer 46

Jaw analysis. | Comparing jaws of fossils to modern day mammals.

Question 47

Give the progression of mammals from Synapsids.

Answer 47

Synapsids Pelycosaurs Therapsids Cycodonts

Question 48

When did the split between marsupial and placental occur ?

Answer 48

168 million years ago

Question 49

When did the split between protherian and therian occur ?

Answer 49

200 million years ago