Chapter 34: Origin and Evolution of Vertebrates Flashcards
Single hollow nerve chords
runs just beneath the dorsal surface of chordata.
What does the single hollow nerve chords differentiate into within mammals
brain and spinal cord
Notocord
a flexible rod that form on the dorsal side of the primitive gut in the early embryo and is present in some developmental stages in all chordates
What does the notochord differentiate into within mammals
spinal column that surrounds the nerve cord
Pharyhgeal gill slits
connect the pharynx to the external environment; maybe called pouches in terrestrial chordates because it does not connect it to the outside Pharyhgeal gill slits connect the pharynx to the external environment; maybe called pouches in terrestrial chordates because it does not connect it to the outside.
Post anal tail
extends beyond the anus, at least during embryonic development
What are the three subphylum of chordata?
cephalochordate
Urochordata
Vertebrata
What Cephalochordata is also commonly known as what?
Lancelot
Describe some of the most important characteristics of the Lancelot skin? (3) and other important characteristics? (2)
- no pigment
- 1 cell layer thick
- scaleless
- no distinguishable head
- pharyngeal slits used for filter feeding
What is the common name of Urochordata?
Tunicate
Urochordata are only considered chordates because of their _____ stage
larva
What adult stage of chordata have a sessile adult stage with no major body cavity or segmentation?
Urochordata
What clade has two or more sets of hoxgenes?
vertebrata
What is the synapomorphy of cephalochordate?
Notochord
What is the first clade to have a cranium?
vertebrata
