Origin of Tetrapods Flashcards
What were some challenges in the transition to tetrapod vertebrates?
- movement
- respiration
- sensing environment
- feeding, reproduction
T or F: Tetrapods arose from Actinopterygii
False
Tetrapods arose from Sarrcopterygian fishes
What makes a tetrapod?
- vertebrates with chiridium
- muscular limb, well defined joints and digits
What are some brief characteristics of the early tetrapod Tiktaalik?
- intermediate characteristics of fish and tetrapods
- limb-like pectoral fins provide support and have wrist
- mobile neck
- no bony gill covering = more use of lungs for breathing
What are some brief characteristics of the early tetrapod Acanthostega?
- limbs with digits
- girdles designed to bear weight
- tail with fin rays, internal gills
What are some brief characteristics of the early tetrapod Ichthyostega?
- no internal gills
- similar to Acanthostega, robust
T or F: Temnospondyls are considered to have given rise to modern amphibians
True, Lepospondyls were originally thought to give rise to amphibians but is no longer supported
What were some changes in the structure from fins to chiridium?
- change in angle between humerus and radius/ulna
- elements distal to base of fin expand
What were two losses important to the evolution of the true neck?
- loss of bones covering gill chambers
- loss of bones joining shoulder to back of skull
What are 7 important structural changes from fish to tetrapods?
- Fins to limbs
- Fused shoulder/true neck
- Reinforced vertebral column and girdles
- Shortened back of skull, different hyomandibula attachment
- Longer snout, eyes on top of head
- Reduced skull bones
- Modified/movement/loss of scales on body
T or F: the hyomandibula becomes the stapes which is part of hearing when looking at structural changes from fish to tetrapods
True
