Fossilized Horn Welcome! You are encouraged to register with the site and login (for free). When you register, you support the site and your question history is saved.Fossilized remains of a horn thought to be of a triceratops found in sedimentary rock in 2011 has been dated to be 65.5 million years old and thus is evidence that dinosaurs existed shortly before the asteroid impact that is believed to have made them extinct. has been dated to be 65.5 million years old and thus is has been dated at 65.5 million years old and thus have been dated to be 65.5 million years old and thus are have been dated as being 65.5 million years old and thus have been dated at 65.5 million years old and thus are Review Answer