Unicorns as our stories tell of them never existed to begin with. There are a number of ideas of where the myth originated including sightings of still-living creatures such as Narwhals, rhinos, or the oryx (a type of antelope). Other suggestions of extinct animals include elasmotherium (a rhinoceros relative) and possibly an extinct species of goat. Sill, others have suggested that the myth comes from deer that, due to a genetic defect, only have one horn or antler.
opossum
Alligators and Crocodiles lived in prehistoric times, however are not considered proper dinosaurs. Most prehistoric creatures were made extinct many years ago.
The Caribbean Monk Seal and the the Icthyosaurus are two modern sea creatures that are currently extinct but there have been many more in prehistoric times.
Because they found a white horse and strapped a horn to its head. Although there are goats out there that were born with one horn. Really unicorns only existed in prehistoric times, but their not real now-a days.
The axe became a weapon in prehistoric (neolithic) times.(Things usually become weapons as soon as they are developed).
Dinosaurs and birds lived in North Carolina in prehistoric times
in prehistoric times, ichthyosaurs lived in Nevada.
Yes, in prehistoric times they wrestled nude.
Unicorns have been around for a long time, so they were around in medieval times, but no, they were not and are not just imaginary.
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No. If unicorns were real, they would be mammals."Unicorns" were actually single-horned rhinos, which were used as beasts of war in ancient times. They were misinterpreted as a mythical creature.See this related question: Do Unicorns Exist?
The early man in prehistoric times they were called prehistoric.