1940 and indicated that the expansion of the distal (lower) ischial end may reflect a strong ischiocaudalis muscle, which together with the high tail neural spines were used for swimming. Barsbold in his brief 1974 description of the Fighting Dinosaurs specimen accepted this hypothesis and suggested that Protoceratops was amphibious (water-adapted) and had well-developed swimming capacities based on its side to side flattened tail with very high neural spines. Jack Bowman Bailey in 1997 disagreed with previous aquatic hypotheses and indicated that the high caudal neural spines were instead more reminiscent of bulbous tails of some desert lizard species (such as Heloderma or Uromastyx), which are related to store fat with metabolic water in the tail. He considered a swimming adaptation unlikely given the arid settings of the Djadokhta Formation. In 2008, based on the occurrence of some Protoceratops specimens in fluvial (river-deposited) sediments from the Djadokhta Formation and (vertebral centra that are saddle-shaped at both ends) caudal vertebrae of protoceratopsids, Tereshchenko concluded that the elevated caudal spines are a swimming adaptation. He proposed that protoceratopsids moved through water using their laterally-flattened tails as a paddle to aid in swimming. According to Tereschenko, Bagaceratops was fully aquatic while Protoceratops was only partially aquatic. Longrich in 2010 argued that the high tail and frill of Protoceratops may have helped it to shed excess heat during the day—acting as large-surface structures—when the animal was active in order to survive in the relatively arid environments of the Djadokhta Formation without highly developed cooling mechanisms. In 2011 during the description of Koreaceratops, Yuong-Nam Lee and colleagues found the above swimming hypotheses hard to prove based on the abundance of Protoceratops in eolian (wind-deposited) sediments that were deposited in prominent arid environments. They also pointed out that while taxa such as Leptoceratops and Montanoceratops are recovered from fluvial sediments, they are estimated to be some of the poorest swimmers. Lee and colleagues concluded that even though the tail morphology of Koreaceratops—and other basal ceratopsians—does not argues against swimming habits, the cited evidence for it is insufficient. Tereschhenko in 2013 examined the structure of the caudal vertebrae spines of Protoceratops, concluding that it had adaptations for terrestrial and aquatic habits. Observations made found that the high number of caudal vertebrae may have been useful for swimming and use the tail to counter-balance weight. He also indicated that the anterior caudals were devoid of high neural spines