Origin of Vertebrates Flashcards
What are the 5 major innovations of vertebrates?
- vertebral column
- head: cranium and brain
- jaws
- paired limbs
- cleidoic egg
T or F: All vertebrates display all five chordate characters AND all five innovations
False
All vertebrates display the chordate characters but not all will have innovations 3-5 (jaws, paired limbs, cleidoic egg)
Briefly explain the structure of the vertebral column
- replaces notochord for support
- bone/cartilage blocks
- centrum: cylinder enclosing/replacing notochord
- dorsal neural arch encloses nerve cord
- ventral hemal arch encloses blood vessels
What is the head in vertebrates derived from?
- neural crest cells
- ectodermal placodes
Which group did jaws and a muscular group evolve first?
Gnathostomes
What is the significance of the evolution of jaws?
-changes in feeding and respiration
What is the significance of the evolution of limbs?
-changes in movement, plus habitat/niche
What are the three steps in the process of development in diversity?
- Cleavage (make cells from zygote to multicellular blastula)
- Gastrulation, neuralation
- Differentiation, organogenesis (cells to organs)
In differentiation and organogenesis, what does the ectoderm go on to form?
- nervous system
- eye parts
- epidermis
In differentiation and organogenesis, what does the endoderm go on to form?
- pharynx
- digestive tract
- liver
- pancreas
- urinary bladder
In differentiation and organogenesis, what does the mesoderm go on to form?
- dermis
- bones
- muscles
- blood vessels
- heart
- kidney
- gonads
What’s the difference in how neural crest cells arise versus ectodermal placodes?
Neural crest cells: arises by delamination from neural tube and peripheral migration (4th germ layer?)
Ectodermal placodes: arise from thickenings of surface of ectoderm and cavitation
