Lec 4 Sarcop & Early Terrestrial Verte Flashcards
What are the 3 Sarcopterygian groups?
Actinistia, Dipnomorpha, Tetrapodomorpha
When is Sarcopterygian originated?
Silurian
What are the features of Sarcopterygian?
- lobed fins
- 1 main bone proximally that forms joint with girdles
- 2 dorsal fins
- cosmoid scales
- diphycercal tail
- intercranial joint
What are the characteristics of Coelacanths?
usual stuff: diphycercal tail, 2 dorsal fins, lobed fins
midline fins
What are the characteristics of Lungfish?
- Symmetrical array of supports in fins
- Loss of marginal tooth bearin elements and skull roof elements
- nostrils both inside oral cavity
- triangular, crushing tooth plate
What is used to describe Sarcopterygian with limbs with digits?
Stegocephalia
What are the features of Tetrapodomorpha?
Choana, 1 proximal radial and 2 radials, mandibular fossa, contact b/w otic and supraorbital canals
When is the critical period for fin-to-limb transition?
Late Devonian
What are the groups involved in fin-to-limb transition?
Eusthenopteron, Panderichthys, Tiktaalik, Acanthostega, Ichthyostega, Dendrerpeton
Anatomical changes in fin-to-limb transition?
Head
- longer snout, skull shorter behind orbits
- orbits back and more dorsal
- Hyomanidbula shorten and oriented laterally
Anatomical changes in fin-to-limb transition?
Neck region
- Loss of opercular bones
- Loss of extrascapular and supracleithrum
- Gular elements reduced
- gill regions reduced and missing
- Cleithrum reduced
- Capulocoracoid and interclavicle increase!
- girdle decouple from skull -> neck
Anatomical changes in fin-to-limb transition?
Limbs
Longer limbs, stouter, more separate
Digits (carpals, tarsals)
articular surfaces -> greater range of motion
Anatomical changes in fin-to-limb transition?
Body and fins
tail elongated
flattened body
missing anal and dorsal fins
Purpose of internal choana in fishes
Create a water current without having to move -> smell -> ambush prey
Why early tetrapodomorpha went onto land
a) temp
b) O2
c) avoid predators
d) repro
e) unexploited food sources
When did fully terrestrial vertebrates evolve?
Carboniferous
What are some terrestrial features in later tetrapodomorpha?
robust pelvic girdle and limbs
pentadactyl pes
metatarsals distinct from phalanges
digits face forward, not laterally
hook-like process on humerus for latissimus dorsi
