Suddenly the ichthyosaurus and the plesiosaurus disappear below, leaving a whirlpool eddying in the water.

突然，鱼龙和蛇颈龙消失在了下方，留下了一个漩涡在水中旋转。

All at once an enormous head is darted up, the head of the plesiosaurus.

突然，一个巨大的头颅突然升起， 那是蛇颈龙的头颅。

The plesiosaurus, a serpent with a cylindrical body and a short tail, has four flappers or paddles to act like oars.

蛇颈龙是一种具有圆柱形身体和短尾巴的蛇，有四个拍板或桨， 就像桨一样。