diplomystus and priscacara fish fossil

adpression age aged ancient animals authigenic bioimmuration bones carbonization casts clupeiformes clupeomorph dasyatidae deceased diplomystus eocene evolution evolutionary exoskeletons extinct fish fossil fossilization genus geological heliobatis herring history impression imprints living mineralization mineralized molds natural once organism paleontology past permineralization petrified preserved priscacara radians recrystalization remains replacement sardine shells stone trace