BIOL 1123 Lecture 38: 32. Kingdoms
13 Apr 2018
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Document Summary
Mammals evolved during the triassic period from mammal-like reptiles, known as therapsids. The earliest mammals present where shrew-like mammals that lived inconspicuously in an age dominated by dinosaurs. Convergent evolution: marsupials and placental mammals that have evolved separately to occupy very similar niches on different continents, known as ecological equivalents. Ecological equivalents: unrelated organisms that occupy similar habitats and resemble each other. For example, sharks (fish) and dolphins (mammals) live in a marine habitat and superficially resemble each other. Mammals are divided into three groups based on the way they reproduce: Marsupials: embryo born early and grown in pouch. All mammals have hair and a range of glands including mammary glands. Mammals have a diversity of teeth which are adaptive for the types of diet they consume. Mammals fall into one of three diet categories: herbivores, carnivores or omnivores. For flight, they have hollow pneumatic bones, wings and feathers, which is unique to birds.
