Paleo Myth Number 1: The Past Was More Awesome Than the Present

Now I might get some slack for saying this, maybe some paleo-nerd rage directed my way, but I don't think Megalodon is worthy of all the bad-azzery attributed to it. Why would I say this? Well first of all, the morphology and physique given to Megalodon is basically a scaled up great white, a conjecture we have no proof of save the similar tooth design. Instead of the homocercal tail that great whites utilize for rapid cruising and sustained acceleration augmented by endothermy, how do we not know that Megalodon had a heterocercal tail for slow cruising and ocassional short bursts of speed? What if Megalodon was not, like the great white, endothermic at all? * But I am going to venture that the greatest weakness of all for Megalodon is in fact the accolade most generously heaped upon it- it's size.

Now it does not really matter where you end up on the spectrum between the grey and red one, you still have a very large fish- probably among the largest fish that ever existed. But this brings up an interesting pattern, why do all the largest fish cluster around this 40-60 foot range? The largest predatory sharks, the largest filter feeding sharks, Leedsichthys and it's ilk of Mesozoic filter feeders- they all seem to cluster around this size but fish never truly reach blue whale size despite having a much longer tenure in the ocean to do so.

Martill. 1986. Leedsichthys and Liopleurodon

The answer, as succinctly as I can put it, is that as size increases in an organism the volume increases disproportionately faster. And this holds true if you are a single cell organism trying to diffuse wastes across a permeable membrane or if you are 30 tonne shark trying to supply oxygen throughout your body with a limited surface area (gills) for gas exchange. As Megaladon, and other giant fish, got larger and larger they start running into problems. Their volume is increasing exponentially while their surface area is increasing linearly. And the amount of area they have for gas exchange, their gills, is a function of their surface area and therefore not increasing at the same rate as the volume. What you have therefore is a whale shark, or a Leedsichthys, or a Megalodon that is approaching a size of diminishing returns and eventually a glass ceiling for gill-breathing animals. These mega-fish, I would argue, are not  sustained aerobic fast cruisers, had minimal endurance, probably slow metabolisms and essentially became dead in the water if pushed too hard. If you want to picture how Megalodon swam around, the video below of a whale shark going after a bait ball offers more insight, I believe, than modern hunting 1 tonne great whites do breaching after agile pinnipeds.

Megalodon succeeded because it lived at a time when their was just enough slow swimming marine mammals, abundant carcasses, and lack of competition from derived predatory pack hunting toothed whales to exist. It was limited to probably warm temperate seas and was basically good for one or two quick lunges at prey, but not extended chases like modern great whites engage in. When derived, social, and intelligent toothed whales came on the scene it was in trouble. Unable to out-swim or out-manoeuvre a couple of well placed strikes at the gills by these marine mammals and a tip into tonic immobility spelled doom for the last Megalodon just as it does today for many sharks at the hands (flippers) of killer whales. The feasts of liver ripped from Megalodon must have been a sight!!

Killer Whale w/Mako Shark. Visser/Barcroft (c)

Ok I will stop savaging the myth of Megalodon, the supposed marine bad-ass of all time. Admittedly I am playing devil's advocate a bit here- of course I would love to see a Megalodon, it probably is near the top of my all time list of extinct critters I would love to see alive. It must have been an amazing spectacle. But what I am trying to illustrate here, what I am getting at, is that we often fetishize the past at the expense, or ignorance, of the present. We build up these monsters of the past into fantastical, mythical god-creatures- when in reality they were just animals, with strengths and weaknesses all of their own. I could have easily started by debunking pseudo-mythical velociraptors, tyrannosaurs, Sarchosuchus, or Spinosaurus. What you must keep in mind when comparing past organisms to present  ones, is that we tend to look at the whole pantheon of awesome extinct animals- and cherry pick the most outrageous ones- and then compare them to the small finite sample available in this little slice of geologic time. And although our land fauna is very impoverished compared to the Mesozoic or even 10,000 years ago- our marine megafauna, especially whales, dominate all other epochs in terms of size, growth, and amazing feeding styles- lunge feeding baleen whales, super intelligent pack hunters, sonar aided hunting.

I'm sure everyone remembers the hoopla surrounding that god-awful faux-documentary about a live Megalodon and all the blowback discovery channel got for it? You know when shark week, umm, jumped the shark (sorry)? Well at about the same time everyone was ranting and raving about that horrible show on Megalodon during shark week, for a critter I argue has been hyped up beyond recognition, real science about a real arch-predator of the ocean was being published that did not garner 1/100th the attention the Megalodon debacle did. And this was the revelation that a whole new species of killer whale, the type D genotype, is alive and well and swimming around the southern oceans as we speak. A whole new species of killer whale!!! No discovery channel special!! No nat-geo special!! No media hoopla!!! Hardly any fanfare to speak of for a whole new species of multi-tonne marine arch-predator!!

Type D killer whale. Jean Pierre-Sylvestre. Nat Geo (c)

And here is where I want to crystallize my argument. And this is the case that not only are orcas super awesome marine predators, they are the baddest of the bad when it comes to marine arch-predators of all time. A cultured, highly intelligent, pack hunting, echo-locating, tool using, matrilineal, fast, strong, and persistent cosmopolitan family able to launch attacks on everything from schooling fish to herds of sperm whales and even the largest animal ever, the blue whale. Adult males are as large as t-rex and at least as intelligent as the average Wal-mart shopper. I put them over Megalodon, over Pliosaurs, over giant extinct raptorial sperm whales, over great whites which they casually snack upon, over mosasaurs. I believe they would find a way to kill each and every marine arch-predaor that lived before them. And they live with us right here right now. Yet we stuff them into unnatural concrete enclosures and wonder why they go insane and kill us. And when a whole new species is discovered we hardly take notice and pay respect to the all time maritime king.

Shame on us.

* Amendment 9/9/13. It has come to my attention that there is a paper Dermal scales of Carcharocles megalodon from the Miocene Mizunami Group, Central Japan! Author Hiroyuki Nishimoto et al 1992. Bulletin of the Mizunami Fossil Museum that purportedly shows evidence of placoid scales suggestive of high speed, fast growth and perhaps endothermy. I have not seen/or read the paper but it does exist. I don't claim to be a specialist in shark evolution, merely a fan. However I don't think this invalidates one of the premises of my article concerning gill surfaces area versus volume increase and the possible eco-physio-behavioral constraints imposed upon such large fish.

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