ZOO 2090 Lecture Notes - Lecture 11: Eutheria, Xenarthra, Odd-Toed Ungulate

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Jinzhong Fu

Document Summary

Early groups evolved in the early permian and radiated in the late. They were dominant throughout the world until the end of the triassic. Some groups re-radiated after the end permian mass extinction event (the boundary between paleozoic and mesozoic faunas) Earliest therapsids known (biarmosuchia) displayed enlarged temporal fenestrae and reduction of palatal teeth: dinocephalians. Some authors consider cynodontia as a clade that includes mammals: arose in late permian and radiated mostly in the triassic. Mammals: arose in late triassic from small synodont ancestors. Integument glands in mammals are very complex: 2 basic types that are both limited to mammals: Sebaceous glands alveolar glands, oily/waxy secretion, often with hair. Function: dress hair (water proof); protect thin skin from drying. Sweat glands tubular glands, secret water, salts, urea. Function thermoregulation: mammary glands, may be specialized sebaceous gland, developed along the milk line during embryonic development, nipples number and location varies across species. Function nutrition to the new-borns: scent glands, many variations.