Assertion: plesiosaur | /r/CapableOf | oscillate the tail
Facets:
Source sentences:
text: She concluded that plesiosaurs were about twenty percent slower than advanced ichthyosaurs, which employed a very effective tunniform movement, oscillating just the tail, but five percent faster than mosasaurids, which were assumed to swim with an inefficient anguilliform, eel-like, movement of the body.