A black woman shows off her muscles One-celled creatures don't have any muscles; the ones that can move themselves use flagellae instead. Even after living creatures evolved that had a [...]
Evolution of mollusks: Slugs are a kind of mollusk. When did the first mollusks appear? Mollusks are animals like mussels, clams, snails and slugs. Their name means "soft", because mollusks don't have [...]
A flatworm When did flatworms evolve? The first flatworms, or platyhelminthes, probably evolved from something like a hydra about 550 million years ago. What's a hydra? Proterozoic Eon All our [...]
Fish Stomach The first multi-cellular animals like hydras had no stomachs, or you could say they were all stomach, because they were shaped like a bag. Roundworms, a little later, [...]
Fish liver When did the first livers evolve? The earliest beginnings of what became the liver may have been relatives of segmented worms that lived about 600 million years ago. [...]
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 [...]
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 [...]
Eohippus - an early kind of horse When mammals first began to grow larger, after the dinosaurs became extinct about 70 million years ago, some of them evolved into the [...]
