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Review for Unit 3 (Emphasized for final exam)

Review Chordate Classification Hand-out

Suggested Cladogram Exercises for Chordate Classification Hand-out:

Can you take any 4 taxa that are not subgroups of each other and draw their corresponding cladogram?

Can you take any taxon and identify the following?

parent taxon

sister taxon

two or more daughter taxa

If taxa are listed as nested hierarchically inside each other, do you know which order is correct?


  a) Chordata: Vertebrata: Mammalia

  b) Mammalia: Chordata: Vertebrata

  c) Vertebrata: Mammalia: Chordata

Can you name at least one synapomorphy that corresponds to each node of the cladogram?




Urochordata (tunicates)

Cephalochordata (lancelets)

Craniata (craniates)

Myxini (hagfish)


Can you place the following features on a cladogram and give its functional significance?

dorsal hollow nerve cord

gill slits


postanal tail




pharyngeal basket


gas gland

Can you assemble all of the following animals into a cladogram of deuterostomes?








lancelet (cephalochordate)




ammocoete larva


Given four of these, can you draw the cladogram that shows their relationship, as hypothesized in the text?
(or, more likely, if I give you three cladograms, each with the same selection of four of these, can you tell me which branching pattern corresponds to the chordate relationships postulated on the classification/cladogram handout?)

Here are some sample sets of four taxa (use the first-listed = underlined taxon as the outgroup):

1) lancelet, lamprey, shark, hagfish

2) urchin, shark, lamprey, tunicate

3) mammal, lizard, bird, crocodile

4) lamprey, salmon, human, shark

What are synapomorphies for:

Chordata? Craniata? Vertebrata?

Gnathostomes have what synapomorphy?

What structures did jaws evolve from?

What sensory equipment do sharks have?

What specific group of vertebrates has the most species?

How do fish stay bouyant?

How do fish osmoregulate?

What is countercurrent exchange?

What is ram ventilation?

How do salamanders get oxygen?

What is paedomorphosis?

What are the two major sister taxa which together comprise Tetrapoda?

What are some specialized features of frogs?

What is an example of a plesiomorphic feature of frogs?

What is an "amniotic" egg?

What are four extraembryonic layers surrounding an amniote embryo?

   amniote, allantois, yolk, chorion

What do they do?

How does the function change in placental mammals?

How are amniotes adapted for life on dry land?

Characterize two amniote clades that have temporal openings in their skull?

What are the two sister taxa comprising the diapsid clade?

What is the closest living sister taxon of birds?

When did amniotes first appear in the fossil record?

How about mammals? dinosaurs? birds?

What are some dinomyths?


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© D. J. Eernisse, 2001