Ammonites, which evolved about 416 million years ago, were once the most abundant animals of the ancient seas. There are more than 10,000 ammonite species identified.

Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described. The earliest trilobites known from the fossil record is dated to around 520 million years ago. 

Orthocerases were squid-like animals and they are related to ancient ammonites as well as modern squids, octopuses, cuttlefish and nautiluses. They lived during the Jurassic period (started  201 million years ago) and Cretaceous period (ended 66 million years ago). 

Mosasaurus is the extinct group of aquatic squamate reptiles. it lived from about 82 to 66 million years ago. 

Ammonite fossil from Eskişehir / Turkey

Oyster fossil from Eskişehir / Turkey 

Coral

Leaf Fossil in clay

Leaf Fossil in Clay