Prehistoric basking shark is smaller than thought
picture: For example, we know the megalodon monster from movies such as “The Meg”. Scientifically, however, it is highly questionable whether its colossal proportions always correspond to the facts.
The megalodon is such a archetypal prehistoric animal that it continues to stimulate imagination and fascinate science. Automatic image of this basking shark (Otodus megalodon) that lived around the world 1.5 to 3.6 million years ago comes from the movies. In particular, its colossal dimensions. However, anyone interested in paleontology knows there is a question mark. Scientists assume that the megalodon should have been at least fifteen to twenty meters in length, but this is not certain. Firm assumption: an account based on recovered individual fossilized teeth and vertebrae, in the absence of significant fossil remains.
Now a team led by paleontologist Kensho Shimada (DePaul University, Chicago) argues that we need to rethink: “Our research indicates an as-yet-unaccounted factor that indicates a geographically specific ecotype.” Concretely, this relates to the so-called Bergmann rule. This evolutionary law states that warm-blooded animals – such as today’s great white shark (Carcharodon carcharias) and its relatives – tend to be larger in cold regions than in warm regions. The reason for this is that the larger it is, the more efficiently it retains heat.
From there, Shimada & Co. Examined a number of sites that are potential breeding grounds for megalodon. The fossil teeth found there are on average smaller than those found in places to the north and south. Smaller teeth, the remains of young and developing sharks, is the cause. However, our research shows that they may have come from a mature megalodon, but on average, because they lived in warmer waters. Therefore, our conclusion is that not all megalodons have grown into giants. In other words, huge specimens twenty meters long were already present, but mainly in populations that lived in the coldest possible habitats.
Schematic image of megalodon’s body size pattern, based on this new research: The warmer the water, the smaller the prehistoric shark. Or vice versa: the colder it is. (© DePaul University / Kensho Shimada)
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