The question of why snakes lost their legs fascinates zoologists . Unfortunately , the best grounds we have comes from an extinct specie calledTetrapodophis , of which we have just one specimen , and it is n’t even in a public museum . Nevertheless , a re - test ofTetrapodophishas tilted the case towards snake ancestor being aquatic creatures that dump their limb to enable them to glide more easy through the water .
Our single preciousTetrapodophisspecimen come from Brazil and is 120 million years former . Professor Mike Leeof Flinders University , Australia , separate IFLScience : “ This is far more crucial thanArchaeopteryxwhere we have 11 specimens . ” Just asArchaeopteryxrepresents the point where dinosaurs were farm wings to become birds , Tetrapodophisis a shot of the point where the antecedent of snakes were misplace their limb , which had been reduced to pocket-size appendages of more and more little note value .
The one and only fossil of Tetrapodphis compared with an artist ’s impression of the life matter . Alessandro Palci and Michael Lee / Flinders University / South Australian Museum
foot and hand are so utile that no animal mother rid of them without evolutionary air pressure . One potential reason is to glide gracefully through weewee with minimal resistor . Another is to tunnel into low space without bulge getting in the way . Aprevious studysuggested thatTetrapodophislooked more like a burrower , but Lee disputes this .
Lee state IFLScience the burrowing conclusion was ground on “ a comparatively inadequate tail and the material body of the lynchpin . ” However , Lee concluded , Tetrapodophis ' tail has been badmouth and was actually “ average in duration . ” The near - absence seizure of a spinal crest , on the other hired man , does makeTetrapodophislook like some modern burrowing specie . As Lee explained : “ If that was the only grounds , I would say it has something to it . ”
Tetrapodophis had body proportions that do n’t match any modern reptile , although they are closer to burrowing mintage than bather . Lee et al./Cretaceous Research
However , inCretaceous Research , Lee and co - authors face several pieces of grounds mutually exclusive to the burrowing theory . Most potent of these , Lee told IFLScience , is that “ the first finger is very robust , ” compared to the rest of the digits onTetrapodophis ' atrophied tree branch . This is standard for flippers , providing financial support for a hydrofoil material body that assists swim , but serves no purpose underground .
Tetrapodophis had digits that looked far more like the social system of flippers than limbs designed to digest weight . Lee et al . Cretaceous Research .
In addition , Lee enunciate in a statement : “ [ Tetrapodophis ] has a long thin tail and four slender legs , something you do n’t see very often in burrowing snakes and lizard today . "
conscientious objector - authorDr Alessandro Palciadded that the limb element were “ weak , poorly - petrify , and rather fin - like . We see these traits only in ancient marine lizards calledmosasaurs . "
Lee also noted thatPachyrhachis , another primitive snake that post - datedTetrapodophisby 20 million year and only had two remaining arm , was definitely aquatic .
Nevertheless , Lee recognize to IFLScience , this may not be a simple pillow slip of aquatic versus burrowing . “ The common ascendent of snakes may have had minor legs , and these may have been lost several time in dissimilar environments , ” Lee said . “ Today there are also some snakes living in intertidal zones , and are practiced both at swimming and burrowing . Something similar would explain why snake conform so well to both environments . ”
