BIOL 123 Lecture Notes - Lecture 1: Eutheria, Theria, Marsupial
Document Summary
Prototherian (e. g. platypus, echidna) lay eggs but are suckled by mother after hatching. Therian: marsupial (e. g. kangaroo, koala) the baby is attached to mother through placenta in uterus and fed through blood system. Baby only develops to small size, then crawls into pouch and attaches to teat with milk. Therian: eutherian (most mammals) baby develops to fairly advanced stage in mother to avoid predation. Mammals evolved form a separate group of reptiles. Became dominant after meteor wiped out all animals >25kg. Single jaw bone, and bones to amplify sound in the ear. Opposing, specialised teeth (e. g. molars, canines, etc. ) Endothermic with fair/fur insulation, sweat glands. Most mammals: a placenta to feed the young in the mother. Subclass theria: marsupials vs subclass eutheria: young fed by placenta to an advanced stage. Primates (order) of class mammalia of phylum chordata. 4th largest of 18 orders of eutheria. Evolved into primates around time dinosaurs disappeared.
