6.24 million year old otter was size of modern wolf
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.
|The large extinct otter, Siamogale melilutra (Lutrinae: Mustelidae: Carnivora), from the Miocene Shuitangba site|
in northeastern Yunnan Province in China [Credit: Cleveland Museum of Natural History]
"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.
"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.
Source: Cleveland Museum of Natural History [January 23, 2017]