August 23, 2017 by Marlowe Hood A life restoration of Inermorostrum xenops dolphins <\/p>\n
Scientists on Wednesday unveiled an extinct species of toothless, whiskered and objectively cute mini-dolphin that plied Earth's oceans some 30 million years ago. <\/p>\n
With only a fossilised craniumfound in a river near Charleston, South Carolinato work with, the researchers were able to reconstruct the snub-nosed mammal's evolutionary saga, describe its facial features and figure out what it snacked on. <\/p>\n
Just over a metre (three feet) from snout to tail, Inermorostrum xenops was half the size of the common bottlenose dolphin. <\/p>\n
Ironically, the pint-size Flipper was an early offshoot from one of the two main groupings of cetaceans called Odontoceti, or \"toothed whale\", that includes sperm whales and orca. <\/p>\n
This group also developed a radar-like capacity to navigate and detect objects by emitting sounds, called echolocation. <\/p>\n
The other branch, baleen whales, are filter feeders that strain huge volumes of ocean water to net tiny, shrimp-like krill or planktonthink humpback or the gargantuan blue. <\/p>\n
\"Inermorostrum took only four million years to evolve from ancestral whales with precisely occluding teeth\"matching top and bottom\"into a toothless, suction feeding specialist,\" explained Robert Boessenecker, a professor at the College of Charleston and lead author of a study in the British Royal Society journal Proceedings B. <\/p>\n
During those four million yearsa brief interlude on the evolutionary clockI. xenops lost its pearly whites, saw its snout and mouth shrink and developed super muscular lips. <\/p>\n
\"This last feature is perhaps the most critical,\" said Boessenecker, who deduced the dolphin's powerful smackers from a series of deep artery channels clearly designed to nourish extensive soft tissue. <\/p>\n
\"Short snouts typically occur in Odontoceti that are adept at suction feedingthe smaller the oral opening, the greater the suction,\" he said in a statement. <\/p>\n
Absent dentition, I. xenops' diet would have consisted exclusively of small fish, squid and other soft-bodied creatures. Because its nose was bent downward, the researchers suspect it prowled the ocean floor in search of prey. <\/p>\n
The dwarf dolphins were not the only \"toothed whales\" undergoing rapid evolution at that time. <\/p>\n
During the Oligocene age, 25 to 35 million years ago, other echolocating cetaceans developed long, toothy snouts specialised in catching fish. <\/p>\n
The researchers also found that both short and long snouts evolved independently numerous times, suggesting that natural selection is not an arbitrary process. <\/p>\n
Some dolphins, such as the modern bottlenose, settled on a happy medium between the extremes, \"the optimum length as it permits both fish catching and suction feeding,\" Boessenecker added. <\/p>\n
Explore further: Ancient South Carolina whale yields secrets to filter feeding's origins <\/p>\n
More information: Proceedings of the Royal Society B(2017). Doi: 10.1098\/rspb.2017.0531<\/p>\n
2017 AFP<\/p>\n
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Toothless, dwarf dolphin, a case study in evolution - Phys.Org<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" August 23, 2017 by Marlowe Hood A life restoration of Inermorostrum xenops dolphins Scientists on Wednesday unveiled an extinct species of toothless, whiskered and objectively cute mini-dolphin that plied Earth's oceans some 30 million years ago. With only a fossilised craniumfound in a river near Charleston, South Carolinato work with, the researchers were able to reconstruct the snub-nosed mammal's evolutionary saga, describe its facial features and figure out what it snacked on. Just over a metre (three feet) from snout to tail, Inermorostrum xenops was half the size of the common bottlenose dolphin. Continue reading