10. Tanystropheus
This freakish looking creature is literally half neck. It's entire body was 20 feet long, but 10 feet of that was its neck. Despite its giant size, paleontologists think that this Triassic beast could detach its tail if caught by a predator and then regrow it later like some small lizards today. Tanystropheus ate small fish and insects, so wouldn't exactly be a threat to Jurassic World's humans, but this slightly odd animal, who lived both on land and in the water, would make an interestingly unusual background creature to populate the dino world. Generally suspected to have been quite a poor swimmer, Tanystropheus would, instead, have walked along the bottom of the sea, using its incredibly long neck to catch its prey. None of the Jurassic Park films thus far have spent much time in water, possibly due to the complications it creates with producing good effects, so this fourth installment has that as a whole new area to explore. A creature like Tanystropheus could lead nicely from land animals to undersea ones as an early introduction, if the film is looking to bring in some sea monsters at some point.