Gnathostomata

Question 1

Gnathostomata General Info

Answer 1

Silurian to recent
Jaws derived from the first 1-3 gill slits/arches - now form parts of our ear

Question 2

Placoderms

Answer 2

Silurian to Devonian
Extensive articulated head plates
Could be scaled
Pectoral fins on head
Acted as predators

Question 3

Chondrichthyes - Cartilaginous Fish

Answer 3

Silurian to recent
Sharks, rays, skates, chimaeras
Predators, sometimes durophagous
Rough skin - dermal denticles - migrate to mouth cavity to form the teeth we have now
Can reach large sizes - whale sharks
Can be egg laying, egg retaining, or live birthing –> (parousness)

Question 4

Acanthodians - Spiney Sharks

Answer 4

Silurian to Permian
Rhomboid platelet scales
Multiple boney spines
Scales + spines are most fossils

Question 5

Osteichthyes - Boney Fish

Answer 5

Late Silurian to recent
Divided into ray finned + lobe finned

Question 6

Actinopterygians - Ray Finned Fish

Answer 6

Late Silurian to recent
Account for half of all extant vertebrates
Huge ecological + morphological diversity

Question 7

Sarcopterygians - Lobe Finned Fish

Answer 7

Late Silurian to recent
More muscular fin structure
Limbs built like ours

Question 8

Coelacanth

Answer 8

Thought to be extinct for millions of years - we just recently found one - lazarous taxon
Live only in deep waters - narrow taphonomic window

Question 9

Tetropodomorphs

Answer 9

Early Devonian to recent
Robust, stocky, wide, flat
Emergence of a tetrapod body plan
Radial neck + pectoral girdle
Maybe started eating bugs (?)