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 16 th – Dec. 31 st 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 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 • 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