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Published byHelena Melasniemi Modified over 5 years ago
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1/31/12 Objective: Understand that the characteristics of organisms change over time Warm-Up: Give one example of how life on earth has changed since the formation of Earth
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Vertebrates over Time
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Background We know that the Earth is 4.6 billion years old!
We also know that there has been life on Earth for about 3.5 billion years The life that was around 3.5 billion years ago looked very different than the life on Earth today Humans were not around 3.5 billion years ago Humans are vertebrates, a group of animals that includes other mammals, fish, amphibians, reptiles, and birds
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More about Vertebrates
Most of the animals you are most familiar with are vertebrates Vertebrate means that the animal has a spinal chord protected by a backbone Some animals are invertebrates, which means that they do not have a backbone There are some characteristics that all vertebrates share, but there are some important differences The earliest characteristics, or traits, of vertebrates began to appear in animals about 530 million years ago
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Common Traits Vertebrae (spinal bones)
Spinal cord (part of the nervous system) Gills in embryos (an embryo is a developing organism) Every vertebrate embryo has gills! Including human embryos
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Vertebrae
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Spinal Cord
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Embryonic Gill Slits
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Special Traits: Fish Fish are vertebrates, so they have vertebrae, a spinal cord, and embryonic gills They also have some unique traits: Fins Gills (in adults) Scales
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Special Traits: Amphibians
Unlike fish, amphibians have four limbs and lungs Smooth, moist skin Jaw has 3 bones All teeth are the same type
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Special Traits: Pre-Mammals
Also have four limbs and lungs Eggs with special membranes Different kinds of teeth
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Special Traits: Mammals
Also have four limbs and lungs Jaw with only 1 bone Different kinds of teeth Fur Eggs with special membranes
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Special Traits: Reptiles
Four limbs & Lungs Scaly skin Eggs with special membranes Jaw with 3 bones
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Special Traits: Birds Four limbs & Lungs Feathers Hollow bones
Eggs with special membranes
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