These reconstructions of the two known Kronosaurus species (K. queenslandicus and K. boyacensis) demonstrate the tremendous variances between these killer cousins of the Cretaceous Period.
Although the upper size limit of macropliosaurs is speculative and Kronosaurus was only a medium-sized species, we know that, at a minimum, these two behemoths exceeded 11 meters (36 feet) and some 15 short tons.
What is of greater interest to me is the adaptive differences in the their skull designs. Whereas K. queenslandicus has sleeker, blade-like jaws with shearing teeth ( a design that allowed it to prey on fish and ichthyosaurs and slice larger prey into smaller pieces), K. boyacensis had larger, heavier jaws and longer fangs. The temporal fenestrae are also bigger, allowing for the attachment of enormous bite muscles.
This heavier skull design (built, ostensibly, to withstand the violent struggles of large prey items) and the bigger, slightly curved teeth would seem to indicate that K. boyacensis was more of a bolt-shake feeder and that it bit into its prey, twisting and writhing like a great white shark to rip away large chunks. (for the record, the Kronosaurus imperator from my novels is more similar to this creature)
It would also seem to indicate that there were very large prey items for this animal to feed upon. Whether it was a proficient shark killer like some sub-species of Orca (there were plenty of 20+ foot sharks present during the early Cretaceous period) or there were even larger, yet-to-be-discovered fish or primeval cephalopods on the big pliosaurs’ menus remains to be seen.
Max Hawthorne, author