Agnatha

Question 1

Agnatha General Info

Answer 1

Grade:
- Cambrian stage 3 to recent
- all jawless fish
Clade:
- Late Devonian to recent
- debated
Have cartilaginous skeletons
Major groups - conodonts + ostracoderm

Question 2

Hagfish - Myxini

Answer 2

Penn. to recent
Very basal
Can defend themselves w/slime
Predators + detritovores + absorbers

Question 3

Lampreys

Answer 3

Late Devonian to recent
Ectoparasites, predators
Keratinous “teeth” in a sucker mouth
“Teeth” are not biominerals like ours

Question 4

Conodonts

Answer 4

Cambrian to early Jurassic
Calcium phosphate elements
Usually disarticulated
Many groups found in a single biozone

Question 5

Ostracoderms

Answer 5

Heavily armored dermal skeletons - bony plates on head
Way to group together the armored jawless fish - not monophyletic

Question 6

Thelodonti

Answer 6

Late Ordovician to Devonian
Scales disarticulate easily
Scales turned into “teeth” when they migrated to the mouth
Mostly marine - some could have been fresh
Pectoral + dorsal + anal fins