Scientists have uncovered the fossilize remains of an strange species of dolphin that live 30 million years ago in what is now South Carolina . These nonextant aquatic mammals measured just three groundwork in length , they featured little schnoz , and perhaps unusual of all , they had no teeth .
Asdescribedtoday in Proceedings of the Royal Society B , this freshly identify brute represents both a newfangled species and an solely new genus . Its name , Inermorostrum xenops , means “ defenseless snout”—a address to its toothless constitution . The lead author of the new study , Robert W. Boessenecker from the College of Charleston , says this animal belongs to the Xenorophidae kinfolk — an ancient radical of echolocating dolphins that present the earliest evolutionary offset from jagged hulk . As the discovery of Inermorostrum evoke , an interesting set of evolutionary experiment run this aquatic mammal down a very unknown course .
Boessenecker ’s analysis was based on the discovery of a exclusive Inermorostrum skull , which was recently found in a limestone outcrop by a diver in South Carolina ’s Wando River . Like other Xenorophids , its facial characteristic paint a picture it had the power to echolocate , but that ’s where the similarity end . Inermorostrum had a tiny body , a snout about three times forgetful , and a back talk completely destitute of teeth ( other Xenorophids had a complete dental profile , featuring at least 11 teeth in its upper jaw ) . clear , this ancient dolphinfish had follow a different evolutionary path — but to what end ?
Modern dolphin , with their farsighted toothy snouts , are well at catching Pisces , but as Boessenecker points out , little snouts , which typically seem in toothed whales , are good for suction feeding .
“ The smaller the oral opening , the keen the suction — fender whale , belugas , and porpoise all have similarly short honker and heavy , muscular lip , ” explained Boessenecker in an email to Gizmodo . “ The last feature is perhaps the most critical — toothlessness , or tooth simplification , [ as it describes ] suction feeding specialiser like the narwhal ( the tusk is the only tooth , and it is not used for feeding ) , spermatozoon whales ( which miss upper teeth ) , and beak whales ( which typically only have small tusks , also not used for feeding ) . ”
The compounding of a short snout and toothlessness , say Boessenecker , suggest Inermorostrum was not only adequate to of suction feeding — it was an “ obligate ” suction feeder , entail it could only apply sucking to feed . What ’s more , grooves and holes on its schnoz suggests it had elaborate lip or sensory hair , both of which are useful for sucking feeder . Based on these features , along with its flyspeck torso and downward slanting snout , Boessenecker speculates that Inermorostrum was a sucking feeding specialist , gobble up fish , calamari , and other soft - incarnate creatures from the seafloor much like modern walrus .
Interestingly , Inermorostrum appeared just four million old age after the emergence of its toothed hulk ascendant , which suggests this echolocating species evolved its suction - feeding machine characteristic rather quickly . But alas , this specialized feeder was not to be . Today , modern dolphins , like the bottlenose dolphin , feature a schnoz that ’s double as long as it is encompassing , allowing it to catch fish and enter in suction alimentation . As is so often in the case in biology , it ’s best to avoid over - specialization and not paint oneself into an evolutionary street corner .
[ Proceedings of the Royal Society B : Biological Sciences ]
EvolutionPaleontologyScience
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