Extinct Marine Crocodiles Resemble Killer Whales

Jurassic crocodile fossils have generated a confusing array of classification schemes among paleontologists. Researchers comparing the jaws of two of these fearsome creatures—Dakosaurus maximus and Dakosaurus manselii—have discovered differences prompting them to “unbundle” the beasts, each into its own distinctive genus. They also discovered surprising similarities between the crocodiles and marine mammals.

The extinct crocodiles, now renamed Dakosaurus maximus and Plesiosuchus manselii, had large bodies and large mouths. By analyzing the shape and size of their mouths as well as the shape, arrangement, and wear patterns on their teeth, the researchers suggest what feeding options would have been available to these animals. Each had notable similarities to certain types of modern killer whales.

Plesiosuchus manselii takes the prize for size. “The largest known skull of Plesiosuchus manselii was approximately four feet, three inches long, putting it in the size range of adult T. rex skulls,” according to lead author Mark Young. The largest known sea crocodile, “It was bigger than living salt water crocodiles and great white sharks.” This animal’s jaw was able to achieve “a very large optimum gape (gape at which multiple teeth come into contact with a prey-item).”1 The tooth placement and the snout shape, however, suggest this huge animal’s teeth couldn’t withstand a fight with a struggling reluctant victim. But like “type 1” North Atlantic killer whales, it was well-equipped to open wide and gulp down whole fish.

Dakosaurus maximus, though possibly smaller than Plesiosuchus by over six feet based on the size of known fossils, was equipped for more adventuresome eating.

Dakosaurus maximus, though possibly smaller than Plesiosuchus by over six feet based on the size of known fossils, was equipped for more adventuresome eating. Biomechanical analysis of its snout and teeth suggest it could withstand forceful torsion. It also appears to have been able to generate a good deal of suction, something juvenile killer whales also do. Furthermore, the extreme enamel fragmentation and patterns of crown breakage on this animal’s teeth are reminiscent of that seen in another modern killer whale, Orcinus orca. This particular species of killer whale preys on sharks, presenting its teeth with frequent abrasive challenges. The researchers therefore suspect Plesiosuchus preferred the same sort of prey. It could handle food of its own size mechanically and may have been able to suck in its victims. Its teeth suggest it was not averse to a raspy, abrasive meal.

The evolutionary explanation for the remarkable similarity of feeding equipment between these extinct reptiles and modern marine mammals is convergent evolution. “Convergence is the evolution of a similar body plan, feeding mechanism (or other characteristic or behavior) in two different and not closely related groups, in this case crocodiles and mammals,” Young says. “The continual evolution of these morphologies in distantly related groups could be telling us something about the limits and optimal method of underwater feeding in vertebrates.”

Paleontologists draw conclusions about extinct animal diets primarily from analyzing their teeth. This approach clearly has limits, as we have often noted in discussions of the pre-Fall vegetarian design of all animals. The Bible indicates the original animals were not carnivorous.2 Nothing about strong sharp teeth and big gaping jaws proves they evolved in order to eat big prey. In this case, of course, the fossils being examined belonged to animals alive at the time of Noah’s Flood, almost 1,700 years after God created the animals. Therefore, the similarity of the tooth wear patterns to modern killer whales and the variety of feeding design capabilities present in these animals may well reveal not only what they were capable of eating but also what they had been eating.

Common designs in reptiles and mammals are no surprise, for a wise common Designer—our Creator God—would use useful designs in a variety of contexts. Nothing in this research demonstrates evolutionary relationships or proves convergent evolution occurred but rather shows the variety that can exist within a particular kind of animal, equipping it to care for itself in many habitats.

While sharp teeth and gaping jaws could be used for non-carnivorous purposes, we do not know what the teeth and jaws of the originally created ancestor of these animals looked like. Today's discussion of the way the same genetic information can be applied to produce a wide variety of finch beaks calls attention to the sort of variation possible within a created kind of animal. After man's sin brought the curse of death into the world, many animals developed the variations needed for both defense and attack.3