Lec 12 - Mammals Flashcards
Final Exam (14 cards)
What group did mammals evolve from?
Theriodont synapsids (advanced mammal-like reptiles)
When did mammals first appear
Triassic period, ~230 mya
What are synapsids?
Vertebrates with one temporal skull opening; includes mammals and their ancestors
What is significant about Cynognathus?
A transitional theriodont with both reptilian and mammalian traits
Name three key skull adaptations seen in early mammals like Cynognathus
Large temporal openings, secondary palate, double occipital condyle
What type of jaw joint do mammals have?
Dentary–squamosal joint
What bones form the three middle ear ossicles in mammals?
Quadrate → Incus, Articular → Malleus, plus the Stapes
What is differentiated dentition?
Having different types of teeth: incisors, canines, premolars/molars
What are the three major groups of modern mammals?
Monotremes (egg-laying), Marsupials (pouched), Placentals (placenta-based)
What skeletal traits are unique to mammals?
Double occipital condyle, scapular spine, fused pelvis, phalangeal formula 2-3-3-3-3
What does a secondary palate allow mammals to do?
Breathe while chewing
Which direction did limb positioning evolve in mammals compared to reptiles?
Limbs moved under the body for efficient movement
What feature distinguishes mammalian skin?
Presence of hair and mammary (milk-producing) glands
How did metabolism change in mammals?
Became higher and more regulated (endothermy)
