Phylum Chordata - Chordates Internal skeleton with muscle ...

Efficient circulationHas four-chambered heart -like mammals butindependently evolvedWall dividing ventricle iscomplete, two circulationsdo not mixFlight muscles get fullyoxygenated bloodEndothermyBirds maintain higher body temperatures than most mammalsMetabolism in flight muscles proceeds at faster rateFeathers provide insulation to conserve heatClass Mammalia - MammalsThe least diverse group of vertebrates -4100 speciesAlmost all large land vertebrates are mammalsMost mammals are not large3200 species are rodents, bats, shrews, molesGreatest diversity was reached about 15 myanumbers are declining due to relativelycool climate