Lol just to think tho. Reptiles originally came out of the water to start life on land, then some of em decided "nope f*** this s*** I'm going back to the big ol salty pond", and then the ones that went back to living in the water got really really big just before almost dieing out completely. Thus now-a-days we have a ton of land based reptiles and very few marine based ones.That's a big turtle, at over 4 meters in length; seems reasonable that they would manage to breed like today's biggest ones.
Mosasaurs were apparently capable of reaching something like 18 meters or more; that's a whole 'nother level of big.
O well just be glad that megalodon, helicoprion, edestus, mosasaur, and dunkleosteus don't exist anymore. Btw if ya don't know what all of em are I suggest googling the name(s) there's some real nightmare fuel put into these prehistoric predators lol.