BIOL 4141 Chapter : Mammalian Characteristics Mammology 2014
Document Summary
Hair structure cortex: pigment medulla: dead cells containing air; variably present. cuticle. Our data show that cysteine-rich keratins are not restricted to mammals and suggest that the evolution of mammalian hair involved the co-option of pre-existing structural proteins. An integrated package: natural selection favors efficient use of energy, endothermy allowed nocturnal activity, endothermy is difficult for young, diphyodonty, lactation, social behavior. Teeth: high energetic costs associated with higher body t; increased selective pressure for efficient food processing, mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates, slice, dice, puncture, stab, grind, defend, Teeth: high energetic costs associated with higher body t; increased selective pressure for efficient food processing, mammal teeth---modified & specialized to far greater extent than in any other group of vertebrates, slice, dice, puncture, stab, grind, defend, display, Within species: fossilize; many fossil species described from teeth alone, often a single tooth! Dentine: same mineral composition, but 30% organic; softer.
