Whale intestines (from Medicine Chest) When did intestines evolve? The first animals to have anything like an intestine evolved around 548 million years ago. These were roundworms, just a few [...]
Digestive system: A hydra eating: the mouth is where all the tentacles come together,near the center of the picture.The hydra is eating the round bug in its stomach. Before digestive [...]
Circulatory system: A dog heart What is the circulatory system? The circulatory system takes food and air from outside your body and brings it all over your body so that [...]
Evolution of turtles: Seychelles tortoise (Jardin des Plantes, Paris) Evolution of turtles The first turtles began to evolve from earlier reptiles about 225 million years ago, during the Triassic period. [...]
Boa Constrictor snake Some kinds of amphibians evolved into reptiles about 300 million years ago. At this time, plate tectonics had moved more and more of the land on Earth into [...]
Duck-billed platypus swimming Probably the very first mammals that evolved from reptiles about 200 million years ago were small animals covered with fur that still laid eggs like reptiles, but [...]
Opossum The earliest mammals, about 200 million years ago, hatched from eggs and then got milk from their mothers, like the duck-billed platypus. But soon after that, about 125 million [...]
Rat from New Zealand - Evolution of mammals When did the first mammals evolve? About 200 million years ago, when all the land on Earth was stuck together in one [...]
Early humans: Skeleton of early human Lucy, from about 3.2 million years ago When did the first humans evolve? About six million years ago, the earliest people evolved from earlier [...]
What is a chimpanzee? Chimpanzees evolved in the Tertiary period, about five million years ago, when they split off from earlier primates in Africa. When did chimpanzees evolve? Chimpanzees are [...]
