22. Mammals Flashcards
What is a defining features of mammals?
They are amniotic that have hair and produce milk
What are five derived characteristics of mammals?
Mammary glands to produce milk Hair Four chambered heart Large brain Diaphragm
What phylum did mammals evolve from?
Synapsids!!
What are two features of synapsids?
No holes
Jaw joint evolved into the mammalian ear
When did the first truel mammals arise?
200-145 MYA, during the Jurassic period
What are the three lineages of mammals and when did they arise?
Monotremes
Marsupials
Eutherians
In the crustacean period
What is one feature of monotremes and what specie are they?
Egg laying mammals - platypus
What are three features of marsupials and what are three species?
Embryo develops within the placenta in the mothers uterus
Nursed in the maternal pouch called a marsupium
Born in early development
Possums, kangaroos, koalas
What is a feature of eutherians and name a species
Young eutherians complete development in the uterus - JOINED TO THE MOTHER BY THE PLACENTA
Primates
what are five derived characteristics of a primate?
Hands and feet Large brain Forward looking eyes Complex social behaviour Fully opposable thumbs
