River Dolphin’s Ancestor Unearthed?
(Click to enlarge) The dolphin was about 2.85 meters (9.4 feet) long and is thus slightly smaller than its modern-day namesake. (Credit: Julia Molnar/Coastal Carolina University)
Paleontologists may have found an ancestor, or at least a long-lost close cousin, of the Amazon river dolphin. Despite its common name, that species (Inia geoffrensis) also inhabits several other river systems in northern South America, and its evolutionary origins are as murky as those sediment-laden waters.
(From Science / by Sid Perkins) — Its ancestors may have left the ocean for fresh water when sea-level rise opened up new habitats about 6 million years ago. But in 2011, researchers excavated the fragmentary fossil of a seagoing dolphin—one that anatomical comparisons reveal is, at the very least, closely related to Inia—at a site along the Caribbean coast of Panama. The preserved bits that hadn’t been lost to erosion include a partial skull, lower jawbones, a few scattered teeth, and a scapula (which in humans is commonly known as the shoulder blade).
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