So the question becomes, if Megalodon did not evolve into great whites ( i.e., if they were not a chronospecies) then what happened to cause them to go extinct? One site argues that it was competition with great whites. Specifically, early great whites were outcompeting/preying on juvenile Megalodon which caused Megalodon to go extinct. As the cheetah post, of a few days ago, shows high infant mortality came be overcome. It is adult survivorship that is important. Another theory has it that oceanic temperature cooled off around the end of the Pliocene. My own hypothesis on the subject is that they were outcompeted by early killer whales (which go back at least 5 million years). Killer whales are warm blooded and travel in packs – which makes them efficient predators. They frequently team up to kill larger whales (such as blue whales)and occasionally eat great white sized sharks. They are, approximately, the same size as Megalodon and would have been trying to fill the same niche. What would it take to confirm my hypothesis and how can I broaden it into a theory? That is a subject for another post.
In the meantime, awhile back I had written a post on killer whales. Killer whales (in the Pacific Northwest, that is) are divided into three different forms: residents, transients and offshores. These three forms differ in morphology, ecology, behavior, and genetic composition and,it should be added, cultural behavior. The resident population is divided into northern and southern residents and thes two populations are reproductively isolated from each other even though there is a partial overlap in territory. I am wondering if this is the beginnings of a sympatric speciation event?
Filed under: Sharks | Tagged: Great White Sharks, Megalodon |
Afarensis: Anthropology, Evolution, and Science 
This is quite an interesting discussion of the Megalodon and Great White. I haven’t read much about sharks, but I do know there was a place in Santa Cruz County (Scotts Valley) where it was pretty commonplace to find fossilized shark teeth. Even though we lived there fifteen years, we never went looking. Now that we are up here in the Pacific Northwest, we see that the Killer Whale is practically the totem animal. Haven’t seen one yet, but often there are articles in the newspaper about where fisherman and shrimpers shouldn’t go because of the presence of Orcas. Now I’m going to have to do a little research to find out if and where there are fossil beds are around here.
If you find any fossils take pictures! I would love to see a killer whale in its natural environment. The more I find out about them the more fascinating they become.
If you find any fossils take pictures! I would love to see a killer whale in its natural environment. The more I find out about them the more fascinating they become.
I see I should have read post 1 and 2 before reading the top post and commenting. The subject is very interesting. I’m like Rexroth’s Daughter, I haven’t read a lot about sharks.
I only read about the sharks that scare me – mainly ones big enough to make supper out of me. Shark evolution is difficult because you only get teeth (since they are cartilaginous).If I lived on the ocean I would definitely get a bigger sailboat. On the other hand, the more I read about killer whales the more fascinated I become, they are really extraordinary creatures!