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

Megalodon Exhibit Background Will be open at the Florida Museum of Natural History from June 16th – Dec. 31st 2007. Focal point of the exhibit is a 60-foot model of a Megalodon shark that visitors will be able to walk through.

Dr. Bruce MacFadden and Bob Purdy discussing the plans

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 Centrum with growth rings Shark centrum Tree 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 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?

MegaloMania Megalodon has intrigued people for thousands of years

Misconceptions about Megalodon Did Megalodon live at the same time as T-rex? 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 Animal Fatalities in the 1990’s 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