Sunday, August 10, 2014

Carcharocles: Prehistoric Animal of the Week

Welcome to Shark Week 2014, the one week per year the masses educate themselves by watching programs such as Sharknado and Sharknado 2: The Second One! (The second one actually was really fun to watch...but not educational)  Starting last year, I have been reviewing a prehistoric shark as Prehistoric Animal of the Week to go along with the trend.  Since there were so many cool sharks throughout prehisroric history, I decided to open this year's up to a vote on our facebook page.  Well the people have spoken and this week goes to Carcharocles angustidens!

Life reconstruction of a large Carcharocles angustidens attacking the Miocene dinosaur, Madrynornis.  The penguin will escape though.  How do I know that?  I freaking made the painting.  That's how.

Carcharocles lived in oceans all over the world, including what is now North America, South America, Europe, Africa, Eastern Asia, Australia, and New Zealand, during the Oligocene through the Miocene epoch.  The oldest fossils are about 26 million years old.  Carcharocles is mostly known from teeth and a few other isolated vertebrae. (Remember, shark skeletons are mostly made of soft cartilage so they rarely fossilize except for the teeth.)  Judging by the size of the teeth, which were triangular-shaped with very distinct serrations, it can be estimated that the largest specimens of this shark could grow to over thirty feet long.   That is larger than the biggest modern Great Whites!

Tooth from Carcharocles angustidens.

Carcharocles would have been very similar to a Great White Shark in life if you go off of the teeth.  The teeth of Carcharocles are a bit narrower in the middle, however.  Carcharocles was likely an open water predator, hunting large prey like fish, small cetaceans (whales and dolphins), penguins, and seals.  It likely hunted this prey the same way many large marine predators do, by cruising deeper waters, using its superior senses to target its future meal and ambushing it from below to deliver a crippling bite.  Sharks with teeth like Carcharocles' do not have crushing power to dish out damage to prey.  (That's more crocodilian style.)  Instead, they rely on the extreme sharpness of their teeth, aided by their serrations to slash and cut, removing body parts and causing severe bleeding instead.  When you see sharks bite into large food items, you will notice them shake their heads from side to side.  This is them using their teeth like the serrations on a knife to cut a bite-sized chunk off.  To see this behavior in action by a modern shark, check out the video I linked below from a Shark Week special on Discovery Channel that aired six years ago. 


There is some dispute as to exactly how closely related Carcharocles angustidens is to modern Great Whites to the point where some scientists argue it should belong to the Carcharodon genus with them, which would change its full name to Carcharodon angustidens.  The very famous, megalodon shark, also belongs to Carcharodon, but some scientists believe it belongs in the Carcharocles genus.  See how we went full circle there?  Taxonomy is annoying! 

That is all for this week!  Hope you enjoyed our Shark Week contribution!  Just like I said last year, you don't have to stop loving and learning about sharks and science when Shark Week is over!  In fact, it's encouraged to keep learning!  As always comment below or on our facebook page!

References

Acosta Hostpitaleche, Carolina, Claudia Tambussi, and Mariano Donato. "A New Miocene Penguin from Patagonia and Its Phylogenetic Relationships." Acta Palaeontologica Polonica 52 (n.d.): 299-314. Print.

Gottfried M.D., Fordyce R.E (2001). "An associated specimen of Carcharodon angustidens (Chondrichthyes, Lamnidae) from the Late Oligocene of New Zealand, with comments on Carcharodon interrelationships". Journal of Vertebrate Paleontology 21 (4): 730–739. doi:10.1671/0272-4634(2001)021[0730:AASOCA]2.0.CO;2.

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