Based on the fossil record, ammonites came in a wide range of sizes and shapes, from smaller than an inch to as large as nine feet wide. Some ammonites had long, straight shells, while others had ...

Some ammonites had spines for defence and others would have had ornamentation that may have served to strengthen their shells. Around 180 million years ago in the Jurassic period, Dactylioceras lived ...

Ammonoidea includes a more exclusive group called Ammonitida, also known as the true ammonites. These animals are known from the Jurassic Period, from about 200 million years ago. Most ammonites died ...

This was the Jurassic, which took place 199 to 145 million ... Fishlike ichthyosaurs, squidlike cephalopods, and coil-shelled ammonites were abundant. Coral reefs grew in the warm waters, and ...