Researchers found a tiny skull with wide eyes and a cartoonish grin. It could help solve an evolutionary puzzle<\/span> <\/p>\n<\/div>\n What makes the find even more exceptional the insight it offers into the evolutionary history freshwater dolphins, as these creatures are extremely rare in the fossil record, the study authors wrote. This is because there tend to be fewer individual dolphins in freshwater ecosystems, and strong water currents typically prevent fossils from preserving well. <\/p>\n
They called the newfound species Pebanista yacuruna; the genus references Peru\u2019s Pebas Formation, where the fossil was found, and \u201cyacuruna\u201d is a term for mythical aquatic people of local legend, in the Indigenous\u00a0Kichua language. <\/p>\n
\u201cI think this is a remarkable discovery, particularly given that South America has one species of river dolphin that belongs to a completely different group of odontocetes (toothed whales),\u201d said Jorge Velez-Juarbe, an associate curator of marine mammals at the Natural History Museum of Los Angeles County, in an email. <\/p>\n
Modern freshwater dolphins are known for their highly elongated noses, compared with marine dolphins\u2019 stubbier snouts. There\u2019s the South Asian river dolphin (Platanista genus) and the Amazon river dolphin (Inia genus), also known as the pink river dolphin, and the two groups include several species and subspecies. <\/p>\n
China\u2019s Yangtze river dolphin (Lipotes vexillifer) represents a third genus, but the species hasn\u2019t been seen in the wild in 40 years and may be extinct, according to the International Union for the Conservation of Nature (IUCN). In fact, all extant river dolphin species are endangered or critically endangered, the IUCN says. <\/p>\n
\u201cI said: \u2018Hey, John, does this connect to this piece that I have in my hand?\u2019\u201d Benites-Palomino recalled. What he held turned out to be a rostrum \u2014 the rounded tip of a nose \u2014 from the embedded skull. As they cleaned it up enough to see the shapes of tooth sockets, Benites-Palomino realized that they were looking at something unusual. <\/p>\n
\u201cWe started screaming: \u2018It\u2019s a dolphin! It\u2019s a dolphin!\u2019\u201d Benites-Palomino said. <\/p>\n
At first, they thought it would turn out to be an ancient relative of modern Amazonian river dolphins. But further cleaning revealed that the size and shape of the eye socket resembled that of South Asian river dolphins, which have much smaller eyes than their South American cousins. <\/p>\n
\u201cThat was a moment where everybody freaked out, because it wasn\u2019t an Amazonian river dolphin,\u201d Benites-Palomino said. This told the scientists that two types of dolphins had independently and at different times moved inland in the region. <\/p>\n
Platanistoids \u2014 the group that includes P. yacuruna and South Asia\u2019s modern river dolphins \u2014 were widespread about 20 million years ago. The ancestors of modern Amazonian river dolphins were common in oceans about 10 million to 6 million years ago, Benites-Palomino said. <\/p>\n
Because both groups of cetaceans were so diverse, some species likely ventured into river and lake ecosystems, seeking less competition for food. This Amazonian freshwater environment was nutrient-rich and teeming with life, home to crocodilians, turtles and fish, as well as mammals such as sloths, rodents, ungulates and primates. <\/p>\n
\u201cOverall, in these ecosystems \u2018river dolphins\u2019 can be considered as apex predators,\u201d Velez-Juarbe said. <\/p>\n
P. yacuruna was among the first wave of dolphins to test the waters in Amazonian rivers and lakes; a lack of predators in its new home could explain how the species evolved to become so large, according to the study. But environmental changes like drought may have later doomed P. yacuruna and driven it to extinction, opening the freshwater habitat to the ancestors of extant pink river dolphins. <\/p>\n
\u201cWe now know that this species was living there in the past, but also the Amazonia is important for our extant Inia geoffrensis,\u201d Benites-Palomino said. \u201c[The discovery] highlights that this is a tremendously important environment for the evolution of freshwater cetaceans.\u201d <\/p>\n
P. yacuruna\u2019s disappearance is a grim reminder that this important environment is all too easily disrupted. Today, modern Amazonian river dolphins face an uncertain future, mostly due to mercury pollution from gold mining invading the food chain, according to the World Wildlife Fund. The newfound fossil hints at the fragility of freshwater ecosystems and the vulnerability of their inhabitants \u2014 past and present \u2014 to environmental changes, whether such changes are natural or human-made, Velez-Juarbe added. <\/p>\n
\u201cPebanista adds another layer to the intricate evolutionary history of cetaceans and particularly \u2018river dolphins,\u2019 the few species that survive to present day are but the last remnants of groups that were once more diverse.\u201d <\/p>\n
Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.<\/em> <\/p>\n\nThis post appeared first on cnn.com<\/div>","protected":false},"excerpt":{"rendered":"
Around 16 million years ago, a dolphin giant cruised the depths of its watery domain. But unlike most modern dolphins, its home wasn\u2019t an ocean; it lived in a freshwater lake in the Peruvian Amazon. And though there are Amazonian freshwater dolphin species alive today, they aren\u2019t close kin to that ancient cetacean. Its closest <\/p>\n","protected":false},"author":0,"featured_media":17312,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"class_list":{"0":"post-17311","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-world"},"_links":{"self":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/17311","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/comments?post=17311"}],"version-history":[{"count":0,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/17311\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media\/17312"}],"wp:attachment":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media?parent=17311"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/categories?post=17311"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/tags?post=17311"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}