Chapter 36: Comparing Vertebrates
Section 1: Evolution of the Vertebrates
Evolution of the Vertebrates

Ever since the first vertebrates appeared more than 500 million years ago, they
have been _______________________________
o Have developed many new and unusual features

_______________________________________

_______________________________________

_______________________________________

_______________________________________
The Vertebrate Family Tree

Most scientists agree that:
o __________________________________ evolved from ______________
_______________________________ ancestors
o _________________________ evolved from _______________________
ancestors
o _____________________________________ evolved from
_________________________ ancestors
Trends in Vertebrate Evolution

Two general trends appear repeatedly during the course of vertebrate evolution
o If closely related evolutionary lines are subjected to
___________________________________________________________,
they tend to become ________________________________________ as
they evolve
o If evolutionary lines encounter extremely _______________________
____________________________________________, they tend to
become _____________________________________________________
as they evolve

As different vertebrate groups evolved, they utilized the same basic sets of body
parts for many uses

The pattern of evolution known as adaptive radiation is also known as
______________________________________________
o One species gives rise to many species that appear different externally but
are similar internally

______________________________________________ is just the opposite
o Adaptive radiations among different organisms produce species that are
similar in appearance and behavior
Body Temperature Control

Many chemical reactions work better at certain temperatures

When the body temperature is _____________________, animals slow down and
become immobile

When the body temperature is _____________________, body systems are
stressed and fail to function properly

Many techniques of temperature control have appeared in vertebrates
o Incorporate three important features

A source of ___________________ for the body

A way to ___________________________ that heat

A method of ___________________________________________
when necessary