Mammal Basics Flashcards
What evolutionary group did mammals evolve from (what is the line that branched into mammals)?
Therapsid reptiles
What group did therapsids descend from?
Synapsid reptiles
How long ago did mammals evolve?
300 mya to 190 mya
What four evolutionary characteristics were involved in the evolution of mammals?
- Brain grew
- Ears more complex
- More advanced jaws
- Differential teeth
What 6 characteristics did the therapsids have?
- Robust skull
- Single large canine
Cynognathus: - Limbs beneath trunk
- Jaw similar to modern animals
- Possibly endothermic
- Possibly had hair
Describe the 9 unique characteristics of mammals.
- Hair
- Mammary glands
- 3 middle ear bones
- Deciduous (fall out) and permanent teeth
- Marrow in bones
- Non-nucleated red blood cells (no nucleus)
- Muscular diaphragm
- Heterodont dentition (many different teeth)
- Endothermic (body heat from within)
What are the 3 subclasses of the class mammalia?
- Prototheria
- Metatheria
- Theria
What are characteristics of the subclass Prototheria, and what species are in it?
- Lays eggs
- Platypus, echidna
What are characteristics of the subclass Methatheria, and what species are in it?
- Born very young, develop in mother’s pouch
- Marsupials
- Kangaroo, koala, opossum
What are characteristics of the subclass Theria, and what species are in it?
- Live young
- All other mammals
About how many species of mammals are there?
5000 species
About how many orders of mammals are there?
19 to 26 orders
What causes the biggest change in classification of mammals and what is an example of this?
DNA Technology: Whales have now been put in Artilodactila with deer and elk because of DNA findings.
What are the ranges in sizes of mammals?
- Shrews and bats: as little as 3 grams
- Blue Whale: 170 metric tons
What are 3 different characteristic varieties of mammals?
- Variety of niches
- Life history strategies
- Modes of locomotion
