Dinosaurusten

Dinosaurusten refers to the diverse group of Mesozoic reptiles commonly known as dinosaurs. They inhabited almost every continent and occupied a wide range of ecological roles, from small insect-eaters to gigantic herbivores and apex predators. They first appeared in the late Triassic period and dominated terrestrial ecosystems for about 165 million years, until their extinction at the end of the Cretaceous.

Taxonomy and evolution follow two traditional, widely accepted clades: Ornithischia and Saurischia. Saurischia, meaning lizard-hipped, includes the theropods—many of which were carnivorous and bipedal—and the sauropodomorphs, which gave rise to the largest land animals. Ornithischia, meaning bird-hipped, comprises primarily herbivorous groups with a wide range of herbivorous adaptations. Modern birds are considered by most scientists to be the surviving lineage of theropod dinosaurs, making dinosaurusten effectively the ancestors of all today’s birds.

Morphology and behavior varied greatly. Some species were feathered, particularly among the theropods, and feather impressions have been found in numerous non-avian groups, suggesting a progression toward flight in certain lineages. Body sizes ranged from small, bird-sized species to massive sauropods. Diets included plants, small animals, and carrion, with numerous specialized teeth and jaw structures corresponding to different feeding strategies.

Fossil evidence is found worldwide, including skeletal remains, trackways, and, in some cases, preserved soft tissues. The end-Cretaceous mass extinction, around 66 million years ago, wiped out the non-avian dinosaurusten, while the avian lineage survived and diversified into the birds seen today. Paleontology continues to study their diversity, evolution, and ecological roles across the Mesozoic world.