T29 - Tetrapods Flashcards
What phylum are tetrapods classified under?
Chordata
What are the three parts of tetrapod limbs?
- upper, single long bone
- pair of parallel long bones
- terminal hand/foot
Benefits to transitioning to life on land
- abundant food (plants, arthropods, other invertebrates
- continental drift and **land-locking **
- increasing competition and predation in aquatic environments
Explain the following challenges to terrestrial life. what could be beneficial to counteract these challenges?:
- gravity
- water conservation
- gas exchange
- reproduction
- locomotion
- sensory perception
- temperature
- gravity: more support, in the form of tissues and endoskeletons
- water conservation: protective skin to avoid desiccation
- gas exchange: avoiding desiccation of respiratory systems through internal lungs
- reproduction: from external fertilization in water unaided by air
- locomotion: inefficient historical side-to-side swimming motion
- sensory perception: different ways light, sound, and smell transmit in air vs. water
- temperature: air has higher temp fluctuations
What were body characteristics of transitional tetrapods?
- mobility?
- only lungs? only gills?
- mostly land or mostly aquatic?
- has legs
- has BOTH lungs and gills
- primarily aquatic
What were critical traits in transitioning to land?
Which clades did these traits come from?
- vertebral column (clade vertebrata)
- mineralization of skeleton, two pairs of lateral appendages (clade gnathostomes)
- simple lungs (clade osteichthyans)
- bony, muscular pectoral/pelvic fins (clade lobe-fins
- internal nostrils (early aquati tetrapods)
who were the tiktaalik? how long ago were they found?
transitional tetrapods found 375 mya
What were some of the tetrapod features of the tiktaalik?
neck, ribs, limb skeleton, flat skull, eyes on top of the head
Explain the following findings in tiktaalik fossils that link fish and tetrapods:
1. neck
2. fishapod bones and joints
3. pelvis
- allows head to move independent from body
- half-fish half-tetrapod limbs to allow for propping itself up, but not walk
- shape and size of pelvis shows capability for a wide range of movements
Who were the Acanthostega? How long ago were they found?
earliest transitional tetrapods found around 365 mya
Explain the following body plans of the acanthostega:
1. appendages
2. pelvis
3. fin-rays
4. streucture of knee and ankle joints
5. internal gills and lungs (limitations)
- numerous limbs with bony digits
- weak attachment to vertebral column
- long fin-rays near tail
- not weight-bearing
- ribs were too short to support the chest cavity on land
What is the habitat of the acanthostega?
aquatic environments
What are (5) the shared, deirved traits of calde tetrapods?
- 4 limbs that have feet with digits
- neck
- fusion of the pelvic girdle to the backbone
- no gills (with some exceptions)
- ears for airborne sounds
