Megalodon The Largest Shark that Ever Lived Dana

Megalodon: The Largest Shark that Ever Lived Dana J. Ehret Ph. D. Student University of Florida Museum of Natural History

If Shark Teeth Could Talk • Shark teeth can: – Identify the species Lemon Shark Mako Shark

If Shark Teeth Could Talk • Shark teeth can: – Sometimes indicate body size Megalodon Whale Shark

If Shark Teeth Could Talk • Shark teeth can: – Indicate prey or prey size Great White Shark Basking Shark

This Was One Big Shark! • Scientists still debate Carcharodon (or Carcharocles) megalodon’s size – Different analysis = Different size estimates – All studies conclude Meg was huge! – Most scientists feel Megalodon was between 45 -60 feet long

The Circle of Life • A shark’s skeleton is composed of cartilage, which does not preserve in the fossil record – However, shark vertebrae do calcify • Growth rings are preserved in shark vertebrae – Shark vertebrae are discs which are called centra – Growth rings are recorded in these centra – Number of rings indicates the shark’s age at death Shark centrum Tree rings Centrum with growth rings

What did Megalodon Eat? • Megalodon was the top predator of its time – It would need to eat a lot to survive • An adult female probably weighed over 100 tons – Megalodon most likely ate whales, large fish, seals, sea turtles, and whatever else it wanted! • Estimates show Megalodon would average 2, 500 lbs of food per day!

When Was Megalodon Alive? • Megalodon lived from about 20 to 2 million years ago – Fossil teeth and (rarely) centra are found in ancient marine sediments – Megalodon is extinct! • Meg evolved to eat giant whales that appeared as the oceans cooled in the Miocene and Pliocene

Where Did Megalodon Live? • Megalodon had a worldwide distribution – Cosmopolitan species – Adults lived offshore (pelagic) – Most likely had “nurseries” closer to shore The Earth during the Miocene

Where do we find teeth today? • North America – Florida, North and South Carolina • South and Central America – Peru, Chile, Venezuela, Costa Rica, Panama • Africa – Morocco • Europe – Belgium

Collecting Megalodon • Shark teeth, including Megalodon, are the most plentiful fossils collected worldwide – They are abundant because sharks continuously grow new teeth and shed old ones, one shark can have 20, 000 teeth in its lifetime – Megalodon teeth are coveted for their large size (up to 7 inches long)

All Different Sizes and Colors Ascending Megalodon tooth sizes Same shark different color fossil teeth

Shark tooth Identifications http: //www. nmnh. si. edu/paleo/sharkteeth/index. html

Who is Megalodon related to? • Megalodon is a “lamnoid” shark related to modern makos, porbeagles, great whites, and many extinct species. – Scientists debate if Megalodon is directly related to the great white or if it was an evolutionary “dead-end”

Megalodon’s Ancestors

Megalodon’s Ancestors Carcharocles megaolodon Carcharocles auriculatus

Why did Megalodon become extinct? • Megalodon became extinct 2 million years ago. – Climate change during the Ice Age – Reduction in the number of large whales – Competition from other predators (sharks) The Earth during the Pleistocene

Why is Megalodon Important? • Megalodon’s extinction carries a conservation message of relevance today – Understanding macroevolution of body size in sharks – Also understanding the extinction of top predators – Decline of modern shark species

Why is Megalodon Important?

Megalo. Mania • Megalodon has intrigued people for thousands of years

Misconceptions about Megalodon • Did Megalodon live at the same time as Trex? – No. Non-feathered dinosaurs went extinct 65 mya. Megalodon evolved 20 mya. • Did Megalodon live at the same time as humans? – No. Megalodon went extinct 2 mya. Modern humans have only been around for 100, 000 years

Misconceptions about modern sharks • Annual Human Fatalities in the 1990’s in Florida – – Deer – 130 Dogs – 18 Snakes – 15 Sharks – 0. 4 • Florida Tornadoes 1985 -2005 – 188 tornado fatalities vs. 5 shark fatalities • Florida Bicycle Fatalities 1990 -2005 – 1, 520 bicycle fatalities vs. 4 shark fatalities • Sharks Are A Minor Threat!!

Questions? © Jason Bourque , Florida Museum of Natural History