Vertebrates: Reptiles, Birds & Mammals

1. Vertebrates:Reptiles, Birds & Mammals By: Aura, Megan, & Maura

2. Reptiles -three chambers in the heart [w/ a small fourth] -lungs -scales -external fertilization -oviparous [lays eggs] -reptiles lay amniotic eggs with shells -reptiles have scales with protein keratin in them to create a waterproof barrier which also prevents dehydration. -the scales help separate them from amphibians; prevents breathing through their skin -reptiles are ectothermic: they absorb external heat as a main source of insulation -conserve energy by basking in the sun when cold, and finding shade when too hot -birds and reptiles both have vertebrates and both have the ability to lay eggs

3. Birdies -four chambers in the heart -lungs -feather/skin -external fertilization -oviparous [lays eggs] -wings are remodeled from tetrapod limb. Shape and arrangement of feathers form the wing into airfoils. Bones are hollow and have honeycomb structure that’s filled with air -birds believed to have evolved from certain species of dinosaurs that also are related to reptiles -feathers are produced by similar tissues that produce scales; birds have scales on their feet -flightless birds have no sternal keel and pectoral muscles are undeveloped; feet made to walk on land and usually heavier in weight

4. Five Adaptations for Flying • Large pectoral muscles connecting to the sternum give flapping powers • Efficient respiratory and circulatory systems and a four chambered heart to keep tissues supplied with oxygen • No urinary bladder, females have one ovary to cut down on weight • Toothless to cut down weight of the skull • Hollow bones– help them fly

5. Mammals • four chambers in the heart • lungs • skin, hair • internal fertilization • viviparous [live birth] • jaws of later evolved mammals had less bones and jaw joint bone has changed; in fish & reptiles, jaws are composed of several fused bones and two small bones • like birds, mammals are endothermic, and most have a high metabolic rate. Reptiles, though, are considered “cold-blooded” because they do not use their metabolism extensively to control their body temperature.

6. Physical Features Unique to Mammals Physical features of mammals: • mammary glands: produce milk for offspring • extra layer of fat beneath skin to retain heat • differentiation of teeth: come in a variety of shapes & sizes adapted for chewing many different kinds of foods