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The origin and rise of mammals 1. Mammal-like reptiles - mammals 2. What is a mammal? 3. Mammal-like reptiles 4. Mam PowerPoint Presentation
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The origin and rise of mammals 1. Mammal-like reptiles - mammals 2. What is a mammal? 3. Mammal-like reptiles 4. Mammals and dinosaurs 5. Palaeogene radiation of mammals 6. Mammals on a cooling Earth. 1. Mammal-like reptiles - mammals. Mammals. Marsupials. Monotremes.

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PowerPoint Slideshow about 'The origin and rise of mammals 1. Mammal-like reptiles - mammals 2. What is a mammal? 3. Mammal-like reptiles 4. Mam' - Albert_Lan


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slide1

The origin and rise of mammals

1. Mammal-like reptiles - mammals

2. What is a mammal?

3. Mammal-like reptiles

4. Mammals and dinosaurs

5. Palaeogene radiation of mammals

6. Mammals on a cooling Earth

slide2

1. Mammal-like reptiles - mammals

Mammals

Marsupials

Monotremes

Triassic MLR

Mammals

By end Triassic

Cynodonts

Permian MLR

Therapsids

Gradual

acquisition

of mammalian

characteristics

Pelycosaurs

slide3

2. What characters make a mammal?

Suckle young,

but may still lay eggs

Furry

Ears with ear bones

Secondary palate

Specialised teeth -

usually grow once

Simple jaw, complex jaw muscles

Warm blooded

Diaphragm

Erect gait

slide4

2b. What skull characters

make a mammal?

Reptilian jaw

Simple teeth

Quadrate

Squamosal

Jaw hinge

Articular

Simple bite

Dentary

Mammalian jaw

Articular and

quadrate now

ear bones

Secondary palate

Squamosal

Jaw hinge

Complicated

bite

Dentary

Specialised teeth

Masseter muscle

slide5

3. Mammal-like reptiles

Thrinaxodon

Some tooth

specialisation

Secondary

palate

Rigid spine

Complex jaw,

no ear bones

?Fur

Chewing

muscle

Endotherm

?Diaphragm

Sprawling gait

Small size = small eggs, small hatchlings, much care,? suckling?

slide6

4. Mammals and dinosaurs

Limited Mesozoic radiation, all animals under 15kg. Mainly

small scavengers and carnivores.

Mammals

Cretaceous

origin. Evolved

on Laurentia

Marsupials

Cretaceous origin,

evolved on Gondwana

Monotremes

probably evolved near

Jurassic/

Cretaceous boundary.

Precise

ancestry uncertain

Multituberculates

successful

Mesozoic clade,

known principally

from teeth

Morganucodon

Lower Jurassic

tiny, agile carnivore

with complicated teeth

slide7

5. Palaeogene radiation of mammals

Large flightless birds

radiated to become top

terrestrial predators

Large crocodiles radiated

to become

top marine

predators

Mammals radiated

into a large range of other niches.

90% of mammalian groups

appeared within 10 Ma

of dinosaur extinction.

Initially herbivores, omnivores,

insectivores, scavengers.

Gradually replaced birds and reptiles

slide8

6. Mammals on a cooling Earth

Palaeogene Earth

Warm,wet,low ice,

abundant forests

Many isolated continents

promote intense speciation

Neogene Earth

Cool, dry, large icecaps,

evolution of grass,

formation of widespread

savanna

Himalayas rise

Americas collide

Continental collision and climate

change precipitate major extinction

modern mammals survive and radiate

slide9

6b. Dinosaurs arrive

Illium

Birds

Early

Jurassic

Ischium

and pubis

Sauropods

lizard-hipped.

Vegetarians

Evolved extremely large size,

often in excess of 20 m in length

and 50 tonness in weight.

Theropods

Late Triassic.

All theropods

were predators,

including

Tryannosaurusrex.

Ornithischians

bird hipped dinosaurs

All herbivores, including

armoured forms

Iguanadonts

and duck-billed dinosaurs.

Highly modified teeth and jaws

Illium

Pubis

Ischium

Archosaurs