Last week the long running PBS series, Nature, showed an episode entitled: “Supersize Crocs”. The premise was to follow croc conservationist, Rom Whitaker as he attempted to see if any 20+ foot crocodiles survive today.
Unfortunately, much like the Discovery Channel’s “In Search of the Giant Squid” documentary, the results garnered from this doc were inconclusive at best. By the end of the show, the largest croc actually found, was 18ft long. Compared to the late, great Steve Irwin’s attempts at finding giant crocs, it would appear that Whitaker was short by 1 foot. There was some allusion to a 20 foot beast that was seen briefly before it ran into the water. Unfortunately Whitaker could only give a guestimate of its size based of its slide print (which was not all that clear).
Overall, the documentary made for a nice hour long diversion. There was a lot of crocodile measuring, and some unecessary CGI used to explain crocodylian anatomy. It also featured Croc biologist, Adam Britton, though only for about 10 seconds.
There were, however, some problems with the program that bugged me.
First, was the purported maximum size. Whitaker wanted to find a 20 ft croc. During the program he ran into a person who said that he had seen a 22ft individual. He said that this was 2ft longer than the longest individual ever recorded. The problem with this is that there have been reports of saltwater crocodiles (Crocodylus porosus) reaching sizes of 23 ft. While not all these reports may be valid, there are enough credible ones to suggest that they once could reach this size (Ross, and Magnusson, 1989).
My second qualm comes from Whitaker’s statement that crocodiles grow slowly. In the documentary, Whitaker states that the largest crocodiles (the 20+ footers) would have taken 80 years to reach that size. That is a completely unrealistic statement. Most crocodylians studied to date, tend to take between 10-15 years to reach sexual maturity. At this point they are often very close to their maximum size. From this point on, growth slows substantially (though never completely stops). Large crocodiles might live to 80 years old (some may be centennial), but they don’t take 80 years to get there.
My final problem with the program was that it continues to promote the myth that crocodylians have remained unchanged for over 200 million years. Crocodylians (i.e. Eusuchia) weren’t even around 200 million years ago. In fact, true crocodiles are a fairly recent group, having evolved around 80 million years ago (something that the Nature website gets correct, but the actual documentary does not). They are but one branch of a highly successful group of animals called crocodyliformes; which in turn are a branch of the highly successful crocodylomorphs. Finally, all are members of the Dinosaurian sister group: Crurotarsi, or Pseudosuchia (for those who would like to continue the croc naming trend).
The only reason why crocodiles always get lumped into the “living fossil” category, is because the bodyplan that they do have, happens to have been a popular bodyplan for the past 200 + million years. Crocodylians are just the latest group to use it. Before them, there were pholidosaurs, and way before all that, we had phytosaurs.
Calling crocs living fossils, is doing a disservice to their lineage. Just among the Crocodylia, we had such out there animals as the land dwelling, panzercroc Pristichampsus, and the weird Australian mekosuchines (e.g. Quinkana, Mekosuchus, Trilophosuchus, to name a few).
Not to mention strange behemoths such as the “duck billed” Purussaurus.
Regardless, the point is that crocs are way more diverse than they are ever given credit for.
Overall, I’d say the best part of the entire documentary would be the scenes of freshwater crocs (C.johnstoni) galloping into the water.
Oh, and the only reason I’m bringing this up now is because I just saw it last night.
Refs:Ross, C.A. and Magnusson, W.E. 1989. “Living Crocodilians” in Crocodiles and Alligators. Ross, C.A. ed. Facts on File pg: 68