Vertebrates

3. type of fish that all vertebrates are theorized to have evolved from (2 words)
4. organisms that are capable of producing their own body heat
7. organisms who possess a single temporal hole in their skull
10. shape that a bird's wings form to produce lift
11. skeletal structure that protects the brain
15. first vertebrates that developed to live on both land and water
16. temporary organ formed during pregnancy to help deliver nutrients and remove wastes.
17. extinct reptiles that achieved flight
18. protein found in hair that binds the dead cells together
19. the underdeveloped young that mammals with pouches give birth to.

1. _____________ flow. The term that describes how a fish's blood flows in the opposite direction that water flows through their gills
2. organisms that lack temporal holes in their skull
4. an interior skeletal structure composed of bone or cartilage
5. type of cartilaginous fish that includes sharks, skates, and rays.
6. jawless, eel-like aquatic creatures
8. fused collarbone found in aves
9. last remaining synapsids in the modern day
12. reptiles that lay their eggs in an external nest.
13. vertebrates with four limbs
14. egg laying mammals