Lecture 16 Vertebrates Flashcards
Exam
What is a vertebrate?
Animal with a backbone
Key characteristics of vertebrate evolution
-skull and backbone
-Jaws and mineralized skeleton
- lobed fins
- limbs with digits
- amniotic egg
Vertebrates
all phylum chordata
Metazoa
Animal like
Eumatezoa
animals
Bilateria
L/R side
Deuterstomic
second mouth
BIlateria body plan
Anterior = before/ in front
Posterior = behind /after = end
Dorsal = back
ventral = from belly
Chordates shared features
Some may only exist in embryo
Notochord: skeletal support
Dorsal ( hollow never cord) : becomes brain+spinal cord
Pharyngeal slits: similar to gills and can develop into gills
Post anal tail: actual gills or head and neck, often lost
Vertebrates: chordates with a backbone
shared features
1. Increase genetic complexity: more genese=more features
2. neural crest: cells along neural tube (embryo) becomes early brain, spine, backbone> teeth bones and cartilage
Early vertebrate evolution
origin of a head: brain at the anterior end, eyes sensory organs, skull enclosing brain
Bony internal skeleton: initially unmineralized cartilage, began - 410 mya in skull and then spread as calcified cartilage
Gnathostomes: vertebrates with Jaws
Shared features
Jaws: unhinged structure allows for gripping
Increased genetic complexity
Enlarged forebrain: coincides with enhanced vision + sense of smell
Gnathostome lineages
- Sharks/rays: fish with cartilage skeleton
- ray-finned fish: Mineralized skeletons “fish” gills
lobe-finned fish: may have lungs
Tetrapods: gnathostomes with limbs
shared features:
fins> limbs with digits - to support weight on land
additional neck and vertebrae: allows side to side movement of head
adult lack gills > have lungs
Amniote: tetrapod withdry land-adapted egg
Shared features:
1 amniotic egg allows embryo to develop on dry land
2. Rib cage with Lungs reduced reliance on skin breathing
