V1 Introduction to Vertebrates Flashcards
Why do we study them?
To understand ourselves better and they dominate ecosystems.
How many species of vertebrates exist?
50 000 species (only 1% of all organisms on earth)
Myxini
Hagfishes
Petromyzontida
Lamprey
Chondrichthyes
Sharks/ skates/ rays
Actinopterygii
Ray-finned fishes
Sarcopterygii
Lobe-finned fishes
Amphibia
Frogs/ salamanders/ caecilians
Reptilia
Crocodilians/ lizards/ snakes/ turtles/ tartua
Aves
Birds
Mammalia
Endothermic amniotic
Craniata
All vertebrates: Myxini Petromyzontida Chondrichthyes Acteropterygii Sarcopterygii Amphibia Reptilia Aves Mammalia
Vertebrata
Petromyzontida Chrodrichthyes Actinopterygii Sarcopterygii Amphibia Reptilia Aves Mammalia
Gnathostomata
Jaw mouthed
Chondrichthyes Actinopterygii Sarcopterygii Amphibia Reptilia Aves Mammalia
Agnatha
No jaw mouth
Tetrapoda
4 legged Amphibia Reptilia Aves Mammalia
Amniota
Reptilia
Aves
Mammalia
Pikaia gracilens
The first fossil evidence of Chordates 550 mya
Burgess Shale
Survival of the luckiest
Vertebrate origins involve HOX genes
A duplication of HOX genes (12 instead of 6) May have originated during paedomorphosis - sexual maturation of a larval form of a urochordate-like ancestor. HOX genes regulate development and so an increased number may give rise to a more complex organism.
