Imagine wolf-sized prehistoric otters opening mollusks with their hands

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1 Imagine wolf-sized prehistoric otters opening mollusks with their hands By Smithsonian.com, adapted by Newsela staff on Word Count 678 Sugar, a North American river otter, swims in its enclosure at the Cincinnati Zoo. The ancient "badger otter" is a far cry from the modern river otters of today. AP Photo/John Minchillo Picture an otter and you ll probably imagine a peaceful creature playing in the calm seas. Otters are so adorable, in fact, it s easy to forget that they also use rocks to brutally bash open sea urchins and other mollusks. Now, paleontologists have uncovered a fossil from a 6 million-year-old ancient wetland. This ancient fossil brings the otter s true nature home: cute as they are, otters have been literally crushing it for millions of years. This new, burly otter has a bit of a mysterious backstory. In 1983, paleontologists described what they thought was a new fossil otter Siamogale thailandica from a single tooth found in Thailand. A later study suggested that the tooth was more likely from a European badger, and even the discovery of additional teeth did little to resolve where this mammal fit in. Now, thanks to expeditions in China, the mammal's true identity has been revealed. This article is available at 5 reading levels at 1

2 From the wealth of fossils found in the 6.2 million-year-old dirt of the Shuitangba coal mine in Yunnan, China, a team of Chinese and American scientists have now described Siamogale melilutra. There are parts of at least three skeletons from this new species of mammal. But it is a partly-crushed skull that solves the longstanding riddle once and for all: Siamogale is definitely an otter, although a badger-ish one. Tooth Of The Badger That Bit Ya The fossils show important traits that both demonstrate that it was an otter and explain why there was some confusion over its identity. Part of the rear of the skull bears some otter traits, Natural History Museum of Los Angeles paleontologist Xiaoming Wang writes. The first tooth of Siamogale thailandica found back in the 1980s does look like the same tooth in badgers. The end result is a bulky otter with a few hints of badger about it. It has the skull of an otter but shares many dental similarities with badgers, Wang says. That is why they are calling it melilutra, which is Latin for badger-otter. The results are published in the Journal of Systematic Palaeontology. Shuitangba's Wooded Wetland At the time Siamogale was alive, Shuitangba was a wooded wetland, says Cleveland Museum of Natural History paleoecologist Denise Su. At the time, the rest of the world was getting drier and colder, says Su, a co-author on the paper. This might explain why the mammals of Shuitangba seem to be different from those found elsewhere, including apes and tapirs that had vanished from other places. Shuitangba "allowed some of the mammalian species adapted for a warmer and stable climate to survive into the Pliocene, Su says. In other words, this strange creature may have been a straggler from an earlier time. It was preserved thanks to a protected environment that persisted while the rest of the world changed. Fossil Scans Reveal Bulky Beast Putting together the larger picture was no easy task, nor was getting a good look at the badger-otter itself. Siamogale melilutra is one of the best-preserved mammals from the Shuitangba site. However, Wang says, it has been badly crushed into a pancake-like shape. Study co-author Stuart White spent months putting together scans of each piece to try to figure out what the otter must have looked like. What s certain is that the new beast was a bulky one: With an estimated weight of 110 pounds, it was about the size of a modern-day wolf. The fossil otter is larger than all living otters, Wang says. Although many meat-eating mammals grew larger to tackle bigger prey, Wang says, he expects that Siamogale is large for a different reason. The mammal s This article is available at 5 reading levels at 2

3 teeth hint that Siamogale was a mollusk eater, similar to modern sea otters, Wang said. But while sea otters use rocks to crack open their hard-shelled food, it s unlikely Siamogale did the same. Perhaps our fossil otter has not learned to use rocks, Wang muses, and instead applied brute strength to crush hard shells? Future studies may answer this ancient puzzle. At least there is now more to study than the tooth, the whole tooth and nothing but the tooth. This article is available at 5 reading levels at 3

4 Quiz 1 Which selection from the article BEST supports the idea that more study is needed to understand how Siamogale is similar to modern otters? Part of the rear of the skull bears some otter traits, Natural History Museum of Los Angeles paleontologist Xiaoming Wang writes. This might explain why the mammals of Shuitangba seem to be different from those found elsewhere, including apes and tapirs that had vanished from other places. What s certain is that the new beast was a bulky one: With an estimated weight of 110 pounds, it was about the size of a modern-day wolf. The fossil otter is larger than all living otters, Wang says. The mammal s teeth hint that Siamogale was a mollusk eater, similar to modern sea otters, Wang said. But while sea otters use rocks to crack open their hard-shelled food, it s unlikely Siamogale did the same. 2 Which selection from the article BEST supports the idea that the Siamogale may offer insights into the evolution of the otter? In 1983, paleontologists described what they thought was a new fossil otter Siamogale thailandica from a single tooth found in Thailand. The fossils show important traits that both demonstrate that it was an otter and explain why there was some confusion over its identity. This might explain why the mammals of Shuitangba seem to be different from those found elsewhere, including apes and tapirs that had vanished from other places. Perhaps our fossil otter has not learned to use rocks, Wang muses, and instead applied brute strength to crush hard shells? 3 Which of the following sentences would be MOST appropriate to include in an objective summary of the article? There was an understandable mix-up when the first Siamogale fossils were discovered and some scientists said it was a badger. Scientists concluded that the climate in Siamogale's environment may have allowed it to survive as the world changed. There are some fascinating questions raised by the new discovery and scientists should work hard to get answers. Scientists had to work very hard and deserve a lot of credit for piecing together a fossil that was flat as a pancake. This article is available at 5 reading levels at 4

5 4 The central idea of the article is MOST developed by: comparing and contrasting the skeletal and environmental traits of Siamogale with its modern otter cousins describing the elements of Siamogale's life and its fossil that made it difficult to draw conclusions about its identity outlining the conditions at the Shuitangba dig site that damaged Siamogale's fossil and made its recovery difficult explaining that living otters use rocks to crack open their food but some scientists think Siamogale did not do this This article is available at 5 reading levels at 5