Mosasaur fossil proves the early lizards had tails like sharks

(Phys.org) —A trio of researchers studying a mosasaur fossil found in Jordan report in their paper published in the journal Nature Communications, that the late cretaceous period reptile clearly had a hypocercal (shark-like) tail fin. The fossil was first discovered in 2008 by workers digging at a quarry—it then sat unstudied in Eternal River Museum of Natural History in Amman for four years before this new team of researchers from Sweden, Jordan and the U.S. discovered its existence and began giving it a closer look.