Lecture 8 Flashcards
1
Q
What Needed to Evolve During Transition From Water to Land
A
- Movement
- Respiration
- Sensing the environment
- Feeding and reproduction
- Overcoming obstacles related to gravity and air
2
Q
What Structure Defines a Tetrapod:
A
Vertebrates that possess a Chiridium
3
Q
What is a Chiridium?
A
Muscular limb with well-defined joints and digits
4
Q
Defining Structures in Early Tetrapods: Tiktaalik
A
- Limb-like pectoral fins for support while standing and functional wrist joint
- Mobile neck allowing flexible head movement
- No bony gill covering suggesting increased use of lungs for respiration
5
Q
Defining Structures in Early Tetrapods: Acanthostega
A
- Limbs have digits (8 fingers and 8 toes)
- Girdles are designed to bear weight (reinforced pelvic girdle)
- Tail with fin rays and internal gills suggest it was aquatic
6
Q
Defining Structures in Early Tetrapods: Ichthyostega
A
- Limbs have digits (7 fingers and toes)
- Lacked internal gills
7
Q
Defining Structures in Early Tetrapods: Temnospondyls
A
- Gave rise to modern amphibians
- Semi-aquatic
- Robust bodies with flat skulls
- Fossils known from larval stage through metamorphosis
8
Q
Defining Structures in Early Tetrapods: Lepospondyls
A
- Occupied specialized niches on land and water
- Eel/Snake-like forms = aquatic
- Lizard/Newt-like forms = more terrestrial
9
Q
Seven Major Changes from Fishes to Tetrapods:
A
- Fin -> Chiridium
- Fused Shoulder -> ‘True’ Neck
- Reinforced Vertebral Column and Girdles
- Skull Shortening and Lost Hyomandibula Attachment
- Snout Elongation and Eye Location
- Reduction of Skull Bone Pattern
- Integument Modifications
10
Q
- Transition From Fin to Chridium:
A
- Elements distal to base of fin expand
- Modified to bear digits in early Tetrapods
- Change in angle between humerus and radius/ulna
11
Q
- Transition from Fused Shoulder to ‘True’ Neck:
A
- Loss of bone covering gill chamber (operculum) in fishes
- Loss of bones that joined the shoulder to the back of skull roof in fishes
- Evolution of the atlas vertebra
12
Q
What is the Atlas Vertebra:
A
First cervical vertebra
13
Q
- Reinforced Vertebral Column and Girdles
A
- Centra become more ossified (changes in vertebrae)
- Zygopophyses appear so that the ventral column can help keep the body off the ground (changes in vertebrae)
- Changes in bones supporting the appendages (Changes in girdles)
- Physical connection with a vertebral column for both girdles (Changes in girdles)
- Points of attachment for muscles used in new mode of locomotion (Changes in girdles)
14
Q
- Skull Shortening and Lost Hyomandibula Attachment
A
- Back part of the skull is shortened
- Hyomandibula is no longer attached to the otic capsule (‘nose’)
- Hyomandibula becomes stapes (‘ear’)
- Braincase now supported by connection with roof of mouth
15
Q
- Snout Elongation and Eye Location
A
Eyes move to the tip of head
