Assertion: plesiosaur's tail | /r/CapableOf | bear vertical fin
Facets:
Source sentences:
text: From such finds it is known that the skin was smooth, without apparent scales but with small wrinkles, that the trailing edge of the flippers extended considerably behind the limb bones; and that the tail bore a vertical fin, as reported by Wilhelm Dames in his description of Plesiosaurus guilelmiimperatoris (presently Seeleyosaurus).