Earlier this week , scientists at the Smithsonianannounced in the journalPeerJthat they have identify the fossilized remains of a dolphin from a new specie and a new genus . Off the Caribbean coast of Panama they found half a skull , a lower jaw with almost an integral curing of cone-shaped teeth , a ripe shoulder joint vane , and two small fin bone . These indicate a dolphin specimen over nine feet long that lived around six million years ago . The new species , Isthminia panamensis , resemble innovative river dolphins but likely lived in salt water , illuminating what has long been a missing link in evolutionary understanding .
As land mammals moved into the piss some 50 million age ago , they evolve from amphibious to nautical , eventually moving out into the undecided ocean as whale . River dolphins — of which there are four endangered , if not extinct , modern species — symbolise something of an evolutionary whole tone back . They developed wide , boat paddle - alike flippers , flexible necks , and narrow-minded , extra - longsighted snouts that leave them to return to fresh water rivers . I. panamensiscould help bridge the gap in scientist ' sympathy of how and when dolphins made this move back inland .
" Many other iconic freshwater species in the Amazon , such as manatees , turtle and stingrays have marine ancestors , but until now , the fossil disk of river dolphins in this basinful has not uncover much about their nautical ancestry , " the study ’s lead author Nicholas D. Pyenson said in astatement . " Isthminianow give us a clear boundary in geologic metre for agreement when this lineage invaded Amazonia . "
The fossils are too frail to be mildew and shake off using traditional method , so the Smithsonian ’s Digitization Program Office has created detailed , 3 - five hundred scans of thejaw , skull , andscapula , which you could regard online .
[ h / tWashington Post ]
