synapsidia - mammals Flashcards
look at phylogeny and early mammal pics
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what modifications in carnivorous pelycosaurs
- Modifications to jaws and teeth
a. Anterior teeth enlarged
b. Heterodont dentition- Arching of the palate
a. Creates strength and air space - Modification to post cranial skeleton
a. Legs longer/slimmer; vertebrae closer and rigid
b. Better speed/coordination overall - Thermoregulation
Large dorsal crest to boost body temp
- Arching of the palate
carnivorous cynodonts dentition?
- Well developed heterodont dentition
a. With cusps
carnivorous cynodont jaw bone modifications?
- Enlarged dentary bone
a. Articular quadrate forms dentary squamosal; bones play a role in sound transmission
• Articular formed malleus
• Quadrate formed incus
• Hyomandibular formed stapes
other carnivorous cynodont features !!!
- Ventral orientation of hindlimbs
a. Bounding gait evolved (flexing up/down)- Loss of ribs in lumbar region
• Diaphragm evolved - Turbinal bones in nasal passages
• Used to warm and humidify inhaled air
• Also evolved secondary palate - Hair (endothermy) evolved
Muscular lips (food manipulation)
- Loss of ribs in lumbar region
early “mamma”l characteristics?
• The non-mammalian synapsids (mammal like reptiles) 1. Larger brains 2. Spine that flexed up and down 3. Larger jaw muscles 4. Preciesly interlocking cheek teeth 5. Diphyodont (two sets of teeth) •
describe morganucodontids. dentition?
• Early well known mammals in late triassic • Based on molar cusp patterns • Shrew sized, nocturnal insectivores 2. Dichotomous radiation of this group • Tricondonts - 3 linear cusps • Tribosphenics - 3 triangular cusps
look at pics on early evolution page
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Multituberculates - describe
• Most diverse mammals of mesozoic (multicusped) ○ Small tree dwellers ○ Distinctive skulls and teeth § Rodents of the mesozoic § Now extinct but survived dinosaur ○ Euryphagous: diverse diet ○ Nocturnal ○ Gave birth to highly immature young
competition during mesozoic for niches? (3 points)
- The “players at this time period
• Archosaurs (dinosaurs;crocs)
• Lepidosaurs (sphenodonts; lizards)
• Living cynodonts
• Early true mammals - morganucodontids; multituberculates- Niche separation
• By temporal activity
○ e.g. diapsid reptiles were diurnal
○ Emphasis on vision evolution - Early mammals were nocturnal reducing competition
• Reliance on olfaction;hearing;endothermy - Interrelationships of structures evolved
• Changing jaw structure affected diet
• Post cranial skeleton changes improved:
○ Locomotion
○ Rates of food intake
○ Metabolism
• Endothermy evolved
- Niche separation
what are the four diagnostic features of mammals?
1. Mammary glands • Evolved from modified apocrine (sweat) glands 2. Hair • Present at some stages in life cycle 3. Diaphragm • First appeared in cynodonts endothermic
describe protheria - monotremes
- Protheria - order monotremata (monotremes)
• Egg laying • Pro = old/early, many extinct • Family ornithorhynchidae ○ Elongate bill (electroreceptors) ○ Fresh water
describe Family tachyglossidae
○ Spiny anteaters (echidnas)
○ Abdominal pouch only during breeding
Possibly from australia? Not conclusive
describe theria - reproduction?
- Theria
• Viviparous mammals
• “transitional” group
describe marisupials
a) Metatheria - superorder marsupialia • South/north america • Gestation and development: ○ Short gestation (less than 30 days) ○ Lecithotrophic (nutrition mainly yolk) ○ Young crawl to marsupium ○ Nipples swells in young's mouth - secure attachment ○ Young gestated > # of teats
hares vs rabbits
Social life + black tip on ears are easiest ways to tell them apart
