1 - Vertebrates Flashcards
What lead to the vertebrates
Phylum chordata, subphylum craniata, infraphylum vertebrata
Vertebrate 5 characteristics
- Largest, most successful chordates
- Bony/cartilaginous vertebrae replace notochord
- 3 part brain
- Skull/cranium
- abundant fossil record
Why study vertebrates
- Earth’s fossil history
- conservation issues
- human ancestry/biology
- intricate design questions
8 classes
- mammalia
- aves
- reptilia
- amphibia
- sarcopterygii (may contain the first 4)
- actinopterygii
- chondrichthyes
- Petromyzontida
Phylum chordata 3 subphyla
- lancelets/cephalochordata
- urochordata
- craniata
Subphylum craniata 2 infraphyla
- hyperotreti (notochord)
- vertebrata
Phylum chordata 5 main characterisistics
- Notochord
- pharyngeal slits
- tubular nerve chord
- post-anal tail
- endostyle (thyroid gland)
Notochord
supportive/flexible rod dorsal to body cavity
Pharyngeal slits
- openings between digestive tract and outside of body
- form of pouches
- filter feeding or gills develop for gas exchange
Tubular nerve chord
dorsal notochord extended anteriorly into brain
Post-anal tail
extends posteriorly beyod anal opening
Endostyle (thyroid gland)
- ventral aspect of pharynx
- secretes mucus used in filter feeding
- transformed to thyroid gland in adult lampreys and other chordates
Evolution of humans
5 mya
Cambrian explosion/first chordates
490-543 mya
Jawed fishes diversity + first amphibians
400 mya
3 extra characteristics not just unique to chordata
- bilaterally symmetrical deuterostomes
- complete digestive tract
- heart (ventral, contractile blood vessel)
Subphylum urochordata 3 classes
ascidiacea, appendicularia, thaliacea
Subphylum cephalochordata
lancelets shallow marine substrates partially buried filter feeders notochord extends into head segmentally arranged muscles on either side of notochord oral hood with cirri
Oldest chordate fossil
- Haikonella
- from china
- 530 mya
Bigger + smaller compared to invertebrates
Smaller: less than 5% of species, diversity/biomass, breadth of distribution, number of niches occupied, evolutionary persistence
Bigger: body size diversity/max size, brain size/cognitive performance
