2. Osteichthyes Osteichth ancestor Acanthodians Actinistia - Coelacanth
Actinopterygii
Sarcopterygii
Osteichth
ancestor

3. Latimeria chalumnae

4. need africa-indian ocean map here

6. Osteichthyes Actinistia - Coelacanth Dipnoi - lungfishes
Sarcopterygian
ancestor

7. Dipnoi

8. Osteichthyes Actinistia - Coelacanth Dipnoi - lungfishes
Osteolepiformes
Sarcopterygian
ancestor

9. I am often nervous when I fly…

11. Evolution of tetrapods
Ichthyostega
Eusthenopteron
“50 things…”
Osteolepiform
ancestor

12. Evolution of tetrapods
Eusthenopteron
bones of dermal skull roof
bones of appendicular skel
labyrinthodont teeth
palatine fangs
Osteolepiform
ancestor

14. Ichthyostega

15. Evolution of tetrapods
Ichthyostega
Eusthenopteron
Osteolepiform
ancestor

16. appendicular skeleton… labyrinthodont teeth palatine fangs terete
Eusthenopteron:
dermal skull roof…
appendicular skeleton…
labyrinthodont teeth
palatine fangs
terete
large, predatory, freshwater
well-developed median fins
occipital condyles, notochord
vertebral centra (PC and IC)
ribs…
bones of dermal skull roof similar in shape and pattern to early tetrapods
no occipital condyles
notochord remains and extends into braincase
vertebral centra: a dorsal and posterior pleurocentrum and a ventral and anterior intercentrum
laterally or dorsally directed ribs associated with pleurocentrum
bones of appendicular skeleton similar in arrangement to early tetrapods (“labyrinthodont amphibians”)

17. Evolution of tetrapods
a fish!!!!
Panderichthyes
Eusthenopteron
dorsoventrally flattened
dorsal orbits
reduced median fins
frontal bones (!)
Osteolepiform
ancestor

19. Evolution of tetrapods
Tiktaalik
Panderichthyes
Eusthenopteron
head…
pectoral girdle…
pectoral fin…
dorsoventrally flattened head
disassociation of pectoral girdle from head skeleton
bones of pectoral fin articulate and have postures similar to those of early tetrapods
shorter, thicker digits on pectoral appendage; fewer lepidotrichia
Osteolepiform
ancestor

20. Evolution of tetrapods
Acanthostega
Tiktaalik
Panderichthyes
zygapophyses
iliac crest…
ribs…
Eusthenopteron
Osteolepiform
ancestor

21. Acanthostega

22. Ichthyostega

23. Evolution of tetrapods
Ichthyostega
Ichthyostega
Acanthostega
Tiktaalik
olecranon process
Panderichthyes
Eusthenopteron
Osteolepiform
ancestor

24. Evolution of tetrapods
Tulerpeton
Ichthyostega
Acanthostega
Tiktaalik
reduction of digit #
Panderichthyes
Eusthenopteron
Osteolepiform
ancestor

25. Evolution of tetrapods
“crown tetrapods”
Tulerpeton
Ichthyostega
Acanthostega
Tiktaalik
occipital condyles
notochord…
Panderichthyes
Eusthenopteron
notochord excluded from braincase
Osteolepiform
ancestor

26. 50 things… Tournasian… the tournasian gap - 10 my or so
Devonian was the age of fishes, but early evolution of tetrapods occurred during the later part of the Devonian
by the Tournasian (early carboniferous) early tetrapods were well established
few fossils from early carboniferous…
Tournasian…

27. Lepospondyls:
an unresolved polychotomy…
Batrachomorphs
intercentra
cheekbones firmly attached
toes 4/5
Reptilomorphs
pleurocentra
cheekbones loosely attached
toes 5/6
crown tetrapods

28. Problems posed by the terrestrial environment

31. problems posed by the terrestrial environment
H20 in terrestrial environment…
O2 in the terrestrial environment…
these affect…
water balance (organisms are…)
gas exchange – mechanism, rate
internal transport mechanisms
metabolic rate…
% of o2 in air ; in water at sea level and 0oC mg/l or ppm
– presence of lots of oxygen allows higher metabolic rate

36. problems posed by the terrestrial environment
specific heat capacity?
water = 1.0
air = 0.24
thermoregulation
difficult…
necessary…
thermoregulation
difficult in the aquatic environment - high heat capacity of water
thermoregulation is necessary in the terrestrial environment - great temperature fluctuation

38. problems posed by the terrestrial environment
density…
viscosity…
better support
different locomotion patterns
buoyancy: (go swimming in the ocean…)
viscosity: dictates/allows changes in locomotion

39. problems posed by the terrestrial environment
Reproduction…
fertilization (deposition/transport of gametes)
development
dispersal