Vertebrates:Reptiles, Birds & MammalsBy: Aura, Megan, & Maura

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

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

Five Adaptations for Flying

1. Large pectoral muscles connecting to the sternum give flapping powers

2. Efficient respiratory and circulatory systems and a four chambered heart to keep tissues supplied with oxygen

3. No urinary bladder, females have one ovary to cut down on weight

4. Toothless to cut down weight of the skull

5. Hollow bones– help them fly

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.

Physical Features Unique to Mammals

Physical features of mammals:

1. mammary glands: produce milk for offspring

2. extra layer of fat beneath skin to retain heat

3. differentiation of teeth: come in a variety of shapes & sizes adapted for chewing many different kinds of foods