part 5 – living on land from fish to (terrestrial) tetrapod

Part 5 – Living on Land

From fish to (terrestrial) tetrapod

“fishes” tetrapods

The Transition

Challenges of terrestrial living

“Fishes” Tetrapods

The players …..

Aquatic tetrapods

† Shallow water, freshwater aquatic tetrapod (lobe-finned fish)

Aquatic tetrapods

Icthyostega

Internal choanae

Internal choanae

Aquatic / terrestrial tetrapods

† Primitive aquatic tetrapods

† Primitive terrestrial tetrapods (on the way to amphibians)

Terrestrial tetrapods

2 terrestrial tetrapod groups

Amniotes (reptile/bird, mammal)

(Lepospondyli)

1.

† Primitive amniotes (pre- reptile/bird, mammal)

(Lepospondyli –

husk vertebrae)

1.

Temnospondyli

2.

Amphibians + (many) extinct things

Temnospondyli2.† Proto-Amphibians

(split vertebrae)

2 terrestrial tetrapod groups

Tetrapods

† aquatic

tetrapods

† semi-terrestrial

tetrapods

† Lepospondyli

Amniotes

† Temnospondyli

Amphibians

Terrestrial tetrapods

lobe-fin fish

†early tetrapods

Lepospondyli

Amnoita

Temnospondyli

Class Amphibia

† various dead ends

† various dead ends

† various dead ends

aquatic

terrestrial

fish

tetrapod

Some time scale

6 billion years

Cenozoic

Mesozoic

Paleozoic

600 million years

Paleozoic

Fish Events

Paleozoic

Tetrapod events (early)

Paleozoic

Tetrapod events (late)

Paleozoic Earth

Paleozoic Earth

Ordovician terrestrial habitats

Devonian terrestrial habitats

Carboniferous terrestrial habitats

Carboniferous millipede tracks

Meganeura

Carboniferous dragonfly

75 cm wingspan

Permian – cooler and drier

Permian Volcanism

Devonian – First tetrapods

Panderichthys

Tiktaalik

Acanthostega

Ichthyostega

Carboniferous – tetrapods diversify and move onto land

Pederpes

Loxomma

Amphibamus

Tuditanus

Permian – it all almost ends

Living on land

Pre-adaptations

Lungs

Limbs

Internal choanae

Pre-adaptations

Support and Movement

Fish

primitive (terrestrial) tetrapod

Terrestrial tetrapods

Vertebral innovations

Vertebral Columnfishes, pre-terrestrial tetrapods

Vertebral Column

terrestrial tetrapods

Terrestrial tetrapods

zygapophyses

Early Tetrapods

Terrestrial

Aquatic

Limb Girdles

Fishes

opercular bones present

pectoral girdle skull connected

*

Panderichthys

Lobe-finned Fish

Tiktaalik

Basal tetrapod = “fish-o-pod”

Opercular bones lost

Vantastega

Skull / girdle connection lost

Tetrapods have necks

“fish”

tetrapod

“fish”tetrapod

Pelvic girdle

“Fishes”No connection to vertebral column

Lobefin fish

Primitive tetrapod

no connection

connection

Pelvic girdle

Eryops

Pectoral

Pelvic

Eryops

Pre-amphibiansTemnospondyli

living amphibian pelvic girdle

Appendicular Skeleton

lobe-fin fish

aquatic tetrapod

Appendicular Skeleton

early terrestrial tetrapod

later terrestrial tetrapod

“fish”

tetrapod

“fish”tetrapod

How many digits?

Physiology and soft anatomy

Switching from gill breathing (with lungs) to lung breathing

“Fish” – gills with lungs

Tetrapod – lungs with gills

Gill breathing – with lungs

Gill breathing – with lungs

Lung breathing

lobe-fin fish

†early tetrapods

Lepospondyli

Amnoita

Temnospondyli

Lissamphibia = Class Amphibia (s.s.)

† various dead ends

† various dead ends

† various dead ends

aquatic

terrestrial

fish

tetrapod