Dr. Xiaoming Wang, Curator and Head of Vertebrate Palaeontology at the Natural History Museum of Los Angeles County and Dr. Denise Su, Curator & Head of Paleobotany and Paleoecology at the Cleveland Museum of Natural History have published a paper with colleagues in the Journal of Systematic Paleontology on the discovery of one of the largest otter species ever found. This discovery was made in the Yunnan Province, Southwestern China by an international team of scientists from the United States, France, and China. It represents groundbreaking research into the evolution of a little-known fossil genus of the otter family.
This newly discovered species of otter, Siamogale melilutra, belongs to an ancient lineage of extinct otters that was previously known only from isolated teeth recovered from Thailand. The discovery of a complete cranium, mandible, dentition and various skeletal elements at Shuitangba provides information about the taxonomy, evolutionary history, and functional morphology of this new species.
"While the cranium is incredibly complete, it was flattened during the fossilization process. The bones were so delicate that we could not physically restore the cranium. Instead, we CT-scanned the specimen and virtually reconstructed it in a computer," said Dr. Su. The CT restoration revealed a combination of otter-like and badger-like cranial and dental feature, hence its species name, "melilutra," which refers to meles, Latin for badger, and lutra, Latin for otter.
Siamogale melilutra was about the size of a wolf and weighed approximately 110 lbs., almost twice as large as the largest living otters. It had a large and powerful jaw, with enlarged, bunodont (rounded-cusped) cheek teeth. These characteristics appear to have been adaptations for eating large shellfish and freshwater mollusks, both of which were found in abundance at Shuitangba. "From the vegetation and other animal groups found at Shuitangba, we know that it was a swampy, shallow lake with quite dense vegetation," said Dr. Su.
"Multiple otter lineages have low-crowned bunodont teeth, leading us to ask the question if this was inherited from a common ancestor or if this was convergent evolution based on common dietary behaviors across different species," said Dr. Wang, lead author of the paper. "Our phylogenetic analysis suggests that bunodont dentition independently appeared at least three times over the evolutionary history of otters."
The completeness of the specimens from Shuitangba allows the scientists to better understand the evolutionary history of otters and specifically this enigmatic genus from the Miocene, of which there had been little information. The findings from Shuitangba reveal that Siamogale belongs to one of the oldest and most primitive lineages of the otter family, which goes back at least 18 million years in the form of Paralutra from Europe.
The scientists are working to understand other aspects of the life of Siamogale melilutra.
"The discovery of the otter helps solve some questions about otter relationships, but has opened the door to new questions," said Dr. Wang. For instance, why was it so large, how did it crack open mollusks and shellfish for food, and how did it move in the water and on land?
"Continued studies by our group will address these fundamental questions and give us a more complete picture of its paleobiology," said Dr. Su.
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Support funding was provided by the National Science Foundation, Yunnan Natural Science Foundation, National Natural Science Foundation of China, Government of Zhaotong, Government of Zhaoyang, Institute of Vertebrate Paleontology and Paleoanthropology.
Field research was a collaboration between Chinese and American Scientists. The Chinese team was led by Xueping Ji (Yunnan Cultural Relics and Archaeology Institute). The American team was led by Prof. Nina Jablonski (Penn State University), Dr. Jay Kelley (Arizona State University), and Dr. Denise Su (Cleveland Museum of Natural History).
To view a photo gallery and video interview, log on to cmnh.org/ancientotter.
About The Cleveland Museum of Natural History
The Cleveland Museum of Natural History, incorporated in 1920, is one of the finest institutions of its kind in North America. It is noted for its collections, research, educational programs and exhibits. The collections encompass more than 5 million artifacts and specimens, and research of global significance focuses on 10 natural science disciplines. The Museum conserves biological diversity through the protection of more than 7,300 acres of natural areas. It promotes health education with local programs and distance learning that extends across the globe. Its GreenCityBlueLake Institute is a center of thought and practice for the design of green and sustainable cities. http://www.cmnh.org
About the Natural History Museum of Los Angeles County
The Natural History Museum of Los Angeles County is located at 900 Exposition Blvd., Los Angeles. It is open daily 9:30 am to 5 pm. NHM was the first dedicated museum building in Los Angeles, opening its doors in 1913. It has amassed one of the world's most extensive and valuable collections of natural and cultural history--with more than 35 million objects, some as old as 4.5 billion years. The Natural History Family of Museums includes the NHM, the La Brea Tar Pits Museum (Hancock Park/Mid-Wilshire), and the William S. Hart Park and Museum (Newhall, California). The Family of Museums serves more than one million families and visitors annually, and is a national leader in research, exhibitions and education.
Journal
Journal of Systematic Palaeontology