Coelacanth

Late Late Jurassic, Tithonian Age. Solnhofen, Lithographic Limestone. Solnhofen, Bavaria, Germany. The fish known as coelacanths are the most famous “living fossils” in the world. Coelacanths disappeared from the fossil record around 80 million years ago in the Cretaceous Period, so scientists thought that they had gone extinct. That is, until fisherman hauled up living coelacanths from deep water near Madagascar. Not only are these fish living fossils, they are also cousins of the missing links between fish and amphibians. The thick, muscular fins of coelacanths look a little like stubby legs; the ancestors of land animals with genuine legs were close relatives of early coelacanths.
Coelacanths illustrate the rule that ancient families can die out in fresh water and most areas of salt water but still survive in the ocean depths.