Sea Turtle Evolution Through Time
From Ancient Ancestors to Modern Ocean Dwellers A Journey Through 220 Million Years Year 7 Science - Evolution and Fossils
Meet Our Modern Species: The Green Sea Turtle
Scientific name: Chelonia mydas Lives in warm ocean waters worldwide Herbivorous - feeds mainly on seagrass and algae Can grow up to 5 feet long and weigh 700 pounds Excellent swimmer with powerful flippers Returns to beaches to lay eggs
Ancient Ancestor #1: Odontochelys (220 million years ago)
{"left":"Lived in ancient shallow seas\nHad teeth instead of a beak\nOnly had a bottom shell (plastron)\nNo top shell protection\nAbout 1 foot long\nAte fish and small marine animals","right":"Modern green sea turtles have:\nComplete shell protection (top and bottom)\nBeak instead of teeth for eating plants\nPowerful flippers for ocean swimming\nMuch larger size (up to 5 feet)\nSpecialized for plant-eating lifestyle"}
Ancient Ancestor #2: Proganochelys (210 million years ago)
{"left":"First turtle with complete shell\nStill had teeth and couldn't retract head\nLived on land near water\nAbout 3 feet long\nAte plants and small animals\nHad spikes on neck and tail for protection","right":"Modern green sea turtles have:\nSmooth streamlined shell for swimming\nNo teeth - beak perfect for cutting seagrass\nCan partially retract head into shell\nLive entirely in ocean water\nNo spikes - smooth body reduces water resistance"}
Evolution Detective Activity
Look at the three turtle species we've studied Identify 3 major physical changes that occurred over time For each change, explain how it helped sea turtles survive better in the ocean Think about environmental pressures that might have caused these changes Be ready to share your findings with the class!
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