Fish first appeared around 425-500 million years ago, with the earliest fossils coming from an Ostracoderm. Ostracoderms lacked jaws and fins but were the first vertebrates. They eventually went extinct, giving rise to two groups - Placoderms and Acanthodians. Placoderms had thick bony plates and jaws fused to their skulls while Acanthodians evolved movable jaws and later became bony fish.

1. Fish History
By Mr. “I love fish” Chapman

2. Fish History
• First fossils were found about 425-500 MYA
• First fish fossils came from an Ostracoderm.
• “Plate skin”

3. Ostracoderm
• Poorly developed fins
and no jaw.
• First animal with a
backbone.

4. More Info
• Ostracoderms become
extinct and two
groups of fish evolved
from them.

5. Placoderms
• First group was the Placoderms, which
appeared about 395 MYA.
• They had thick bony plates with paired
fins.
• Their upper jaw was fused to the skull and
the lower jaw was hinged to the skull.

6. Placoderms

7. Placoderms
• Placoderms became extinct about 396 MYA
• Class: Chondrichthyes evolved from Placoderms.
• Chondrichthyes
– Chondra means ”cartilage”
– Ichthyic means ‘fish”
• Cartilaginous fish: 350 species
• (most sharks)
• Ex. Sharks, Rays, Skates

8. Info
• The 2nd group to
evolve from
Ostracoderms was the
Acanthodians.
• The appeared about
410 MYA
• First fish with both
jaws are movable

9. Acanthodians
• Acanthodians evolved
into Class:
Osteichthyes.
• Osteichthyes “Bony
Fish”