The fish - to - tetrapod passage has beendescribedas one of the fundamental problem in evolutionary biology . Over 350 million years ago , during the late Devonian stop , Pisces began to inhabit shallower and shallow water , until the four - limbed vertebrates ( tetrapod ) , of which humans belong , set out to roam across realm .
Many questions fence in this changeover , including at what degree one of the most significant evolutionary change , the development of vertebrate hand and feet , originated . However , an ancient Pisces fossil find in Canada has helped to uncover the mystery of how the human deal acquire from Pisces the Fishes tailfin .
The remarkably complete specimen ofElpistostege , measuring in at 1.57 meter ( 5.15 foot ) long , let in the first entire sleeve skeleton watch in this orderliness of fish . Using eminent energy CT scans , researchers were able-bodied to uncover the tetrapod - like arm features in the pectoral fivesome of the fossil . Some of the structures divulge in the bailiwick , published inNature , includes the comportment of a humerus ( arm ) , radius and ulna ( forearm ) , quarrel of carpus ( wrist ) and phalanges organized in digit ( fingers ) .
“ This is the first time that we have unequivocally pick up finger locked in a fin with fin - rays in any known Pisces , ” John Long , Professor in Palaeontology at Flinders University , Australia , said in astatement . “ The articulating digit in the Phoebe are like the finger bones found in the manpower of most animals . ”
Previous fossils from around the time of the fish - to - tetrapod transition have been study by paleontologists to aid us understand the phylogenesis from a fish fin to a tetrapod limb . Until now , most fossils of the lobe - fin fish that were around in this geological period ( elpistostegalians ) , between 393 and 359 million years ago , have been found incomplete . ThisElpistostegespecimen is not only crowned as the most ended elpistostegalian dodo to appointment , but it also has now overtaken theTiktaalikspecies , from Arctic Canada to claim the status of the nearest fish from the tetrapods .
“ Elpistostege is not needfully our ancestor , but it is closest we can get to a true ‘ transitional fossil ’ , an intermediate between fishes and tetrapods , ” subject Centennial State - author Richard Cloutier , from Universite du Quebec a Rimouski , Canada , said .
Cloutier also explained the necessity for the Pisces to develop finger when transitioning to the ground . “ The line of digits connect to developing the capability for the fish to support its weight in shallow water or for short trip out on land , ” Cloutier tell . “ The increased number of small pearl in the Phoebe allows more plane of flexibility to open out its weight through the fin . ”
verbalise to IFLScience , John Long , one of Cloutier ’s fellow co - source , accent the teamwork involve in “ showing on the nose how Fish gave us the finger’s breadth ! ”
“ For me , the most rewarding part of the enquiry was working with the intact team from Rimouski and at Flinders , as we slowly bring out the story of this incredible fogey , the first ancient fish to have digits present in its fin , ” Long told IFLScience .
