Arthropods
They have skeletons with jointed bodies and legs. Modern arthropods include insects and crustaceans like shrimp and crabs. Among ancient creatures, trilobites, which flourished in the Paleozoic Era, are famous.
Paleontology Encyclopedia
Creatures other than dinosaurs
Life on Earth began about 3.8 billion years ago. Early life forms were single-celled organisms called prokaryotes, which lacked a distinct nucleus. Over a long period, they evolved into eukaryotes, multicellular organisms, and vertebrates, with the sea as the stage for this evolution. Here, we introduce prehistoric creatures other than dinosaurs.
Molluscs
This is the second largest phylum of animals after arthropods. It includes shellfish, squid, and octopus. Among ancient creatures, ammonites belong to the phylum Mollusca.
Echinoderms
This phylum includes starfish, sea urchins, sea cucumbers, and sea lilies. Although there are exceptions, their bodies have a five-fold radial symmetry (a special structure in the animal kingdom).
Fish - Pisces
About 524 million years ago, the first vertebrates were born. It was Myllokunmingia, the oldest jawless fish. Currently, fish account for more than half of all vertebrate species.
Amphibians
It is believed that amphibians made the transition to land in the Late Devonian, about 365 million years ago. Introducing extinct amphibians.
- (No corresponding creatures at present)
Plesiosaurs
Plesiosaurs are not dinosaurs by scientific definition. They are often mistaken for dinosaurs due to the tendency to think of all large animals of the Mesozoic Era as dinosaurs.
Ichthyosaurs
An extinct marine reptile resembling a dolphin. It is thought to have evolved from terrestrial reptiles and become aquatic in the Early Triassic. They particularly flourished in the Jurassic.
Pterosaurs
Like plesiosaurs and ichthyosaurs, pterosaurs are not scientifically dinosaurs. They did not have feathers and glided with wings made of a membrane.
Other Reptiles
Reptiles are thought to have appeared about 300 million years ago. They were resistant to dryness and expanded their habitats inland. Lizards, turtles, snakes, and crocodiles existed.
Synapsids (Mammal-like Reptiles)
Synapsids are the group that would later lead to the evolution of mammals. They were once called "mammal-like reptiles." Representatives include Dimetrodon and Edaphosaurus.
Mammals
Like humans, mammals. The first mammals existed in the Late Triassic. Throughout the age of dinosaurs, these small, mouse-sized creatures awaited their chance to flourish.