Due to its massive size and the fact that its virtually unchanged in the fossil record for 23 million years, DeSouza says the arapaima has become known as the “dinosaur fish.” And while the species never actually lived during the time of the dinosaurs, its primeval appearance certainly brings the popular
Enter Leedsichthys problematicus. The extinct fish—thought to be the largest on record—lived about 165 million years ago in Europe and South America. It grew to at least 16.5 meters in length and might have weighed 45 metric tons, which means it was larger even than today's whale shark.
Coelacanths, which have been around for 400 million years, were thought extinct until they were found alive in 1938 off South Africa. The coelacanth a giant weird fish still around from dinosaur times can live for 100 years, a new study found.