(oh,but were is Prionosuchus, a little hard to find something here )
lion's mane jelly
It seems like the giant megalodon could have exceeded 18 m but for now this seems fine.
You should replace a Kronosaurus-like model instead of Pliosaurus. It is possible that Pliosaurus macromerus was not reaching 13 m and was about the size of Kronosaurus at 10-11 m. However, I suggest you to replace it with a kronosaur-like model because it seems that the Monster of Aramberri, a not yet named Mexican pliosaur, is related to kronosaurs and being between 12 and 14 m. In other words, this pliosaur, related to kronosaurs, is the most likely largest pliosaur to date.
I'm no amateur arguing without knowing, I can give you scientific ref. for this, the one about the pliosaur is very recent.