Lecture 11

Question 1

What percentage of UK mammals are in decline?

Answer 1

25%

Question 2

Give 4 defining features of mammals

Answer 2

. Mammillary glands
. Hair
. Specialised teeth
. Skull type

Question 3

What is an amniote?

Answer 3

A tetrapod (4 limbed vertebrate with a membrane shelled egg: Egg with a membrane (waterproof) that allows gas exchange

Question 4

What are the 4 types of amniote skull types?

Answer 4

. Anapsid
. Synapsid
. Diapsid
. Euryapsid

Question 5

Describe the amniote skull type anapsid and give examples

Answer 5

Has no temporal fenestra

Turtles- orbit at angle and no secondary hole

Question 6

Describe a synapsid amniote skull and give an example

Answer 6

Has a single fenestra

Mammal-like reptiles

Question 7

Describe a diapsid amniote skull and give examples

Answer 7

Double fenestra

Lizards/ snakes

Question 8

What defines the nodes in a cladogram?

Answer 8

Synapomorphies- shares derived character states

Question 9

Describe pelycosaurs (when they lived, what they were)

Answer 9

. Abundant terrestrial forms in late Carboniferous/ early Permian (320-265 mya)
. Herbivores and carnivores with primitive heterodonty
. Relatively long limbed with parasagittal gait= when opposite limbs move together (compared to other reptiles)
. Elongated neural spines on vertebrae (weight-bearing)
. Dorsal sail: temperature regulation device?
. Basic tail= not as well defined
. Competition= carnivore —> sharp teeth for ripping
. 1 metre in length
. 150 kilos

Question 10

What is meant by a parasagittal gait?

Answer 10

When opposite limbs move together

Question 11

Describe therapsids (when they lived, their build)

Answer 11

. Worldwide occurrence in late Permian (249 mya- came later than the others) before the break-up of Pangea- roamed all the land mass—> wide spread
. Longer-limbed, more upright stance, rib number reduction, diaphragm

Question 12

Describe Cynodonts (cynognathus crateronotus) (habitat, diet, looks)

Answer 12

. Cynognathus was a very fast and fierce hunter. It had a very large and powerful head, up to 40cm in length, filled with incisors, canines and cheek teeth made for a carnivorous diet. It is likely it was warm-blooded despite being classified as a reptile
. Lived in temperate woodlands of Sphth America, South Africa and Antarctica during the Triassic period when this area made up the south of the continent of Gondwana
. Main food source were herbivorous reptile therapsids (so it is a secondary consumer)
. Small, reduction in lumber ribs (gone in us as we only have thoracic ribs)

Question 13

Why do we only have thoracic ribs and not lumber ribs?

Answer 13

Because we have a diaphragm that allows us to be able to expand and contract our lungs

Question 14

What do lumber ribs do?

Answer 14

Maintain pressure within the body allowing early mammals to breath properly (ability to take deep breaths)

Question 15

What is a zygomatic arch? What does this along with a sagittal crest allow? Give an example of a species that has this

Answer 15

The formation of the cheek bone from the top of the ear along the top.
This along with a Sagittarius crest allows really strong muscle development allowing for really strong jaws to form as in large carnivores e.g. badgers- very strong bite

Question 16

What are defining nodes in cladograms called?

Answer 16

Synapomorphies

Question 17

What is the difference between the late and early cynodonts?

Answer 17

Their cheek teeth- precursors to our molar teeth

Question 18

What is a cusp point?

Answer 18

Where teeth collide when they slot into each other

Question 19

What does the change in cheek teeth between late and early cynodonts mean for the cynodonts?

Answer 19

Allows the animal to have a shearing point and a crushing point and this variation in the teeth opens up a huge variation in the diet- the teeth fit against each other which allow you to chew

Question 20

What are semi-circular canals in your ear/ how do they work/ what do they do?

Answer 20

They act as a gyroscope and if they move in a particular direction then the brain interprets which way up you are by the movement of the liquid

Question 21

What is the cochlea in the ear filled with?

Answer 21

Fluid and hairs

Question 22

What is the endolymph in the ear (of a mammal)?

Answer 22

Liquid moves and determines which way up you are

Question 23

What is embryology?

Answer 23

Looking at embryos developing

Question 24

What does mammal embryology show? (Bones)

Answer 24

Homologies: articulations=malleus, and quadrate=incus (so the bones that where in the jaw but aren’t in mammals jaw are because they have moved to form part of the ear derived from the same origin/ common ancestry but they have a different function)

Question 25

What makes characters homologous

Answer 25

Common ancestry (without the necessity for similarity of function

Question 26

What is Ontogeny recapitulates phylogeny?

Answer 26

The idea that while watching something develop you will see it go right through its ancestry form (not true because the same embryo can develop in different ways)