Jawed fish Flashcards
(14 cards)
What defines gnathostomes as the first true vertebrates?
They possess a lower jaw, cranium enclosing a tripartite brain, and complex sense organs.
What key respiratory and feeding innovation did gnathostomes develop?
Muscular pharynx for active water intake; gills used solely for respiration.
What lifestyle did these traits enable in early gnathostomes?
Active swimming predation, rather than sessile filter feeding.
Why is it important to study extinct prehistoric fish in zoology?
To understand modern animal relationships and vertebrate evolution.
What field of study focuses on prehistoric fish?
Paleoichthyology.
When did prehistoric fish live?
From the Cambrian to the Tertiary period.
What is a living example often considered a “living fossil”?
The coelacanth.
What time period did Placoderms live in?
From the Silurian to the end of the Devonian period.
What physical feature defines Placoderms?
Armoured plates covering the head and thorax (“plate skin”).
Why are Placoderms evolutionarily significant?
First fish to develop pelvic fins—precursors to tetrapod hindlimbs.
What were Acanthodians?
Extinct fish with traits of both bony and cartilaginous fish.
What feature gives Acanthodians their name?
Fins with bony bases and dentine spines on the anterior edge.
: Were Acanthodians true sharks?
No, they were not true sharks or cartilaginous fish.
How did their habitat change over time?
Originated in marine environments, adapted to freshwater in the Devonian.
