Week 7 Sarcopterygians and the origin of tetrapods Flashcards
Describe the characteristics of important extinct species of tetra-pods and how these characteristics allowed colonization of terrestrial environments
limbs and digits
- body support and locomotion
Describe the defense mechanisms of amphibians
-Toxic
-Aposematic
-(some salamanders) have regenerative abilities
- burrowing
Identify and describe the similarities between the 3 orders of amphibian
Similiarties between the 3 orders: Moist permeable skin and undergo metamorphosis
Anura differences from other amphibians
Anura: (1) lack tail (2) compact body, specialized hind limbs for jumping
Caudata difference from other amphibians
Caudata: (1) some can regenerate lost body parts
(2) some stay in their juvenile stage
Gymnophiona differences from other amphibians
Gymnophiona: (1)limbless (2) sensory tentacles used for chemoreception
Sarcopterygian synapomorphies
scales made of cosmine
monobasic paired fin
intracranial joint
What’s special about Tiktalik
It has many terrestrial and aquatic features/shares them. For example, it has a long trunk (fish-like) and it also has the ability to flex elbows (tetra-like)
Important Stem tetrapods
acanthostega
ichthyostega
How do basal tetrapodomorphs and tetrapods compare
-Tetrapodomorph fish- pectoral girdle is attached to the cranial skeleton (no motion in neck area)
-Fin to forelimb
-pelvic girdle, attached to vertebral column in tetrapod
Tetrapod synapomorphies
-hands and feet w/ digits
-loss of fin rays
-oleacranon process on ulna
-zygopophyseal articulations between vertebrae
- modified pectoral/ pelvic girdle—> enlarged to allow weight to be transferred to the limbs
Synap of extant tetrapods
-3 skeletal modifications (allow for greater mobility of the skull)
-Rib modifications that allow for more mobility in central part of the body
-dermal body armor is greatly reduced or absent
-muscular tongue
-eyelids
-middle ear components
Tetrapod is what
a four-footed animal, especially a member of a group which includes all vertebrates higher than fishes
Sarcopterygians are what
(lobbed fin fish) coelacanths and lung fish
What is a Lissamphibian?
-non-amniote tetrapod
-moist, scaleless skin
contains Gymnophiona (caecilians) caudata (salamanders) ans Anura (frogs)