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

Shark centrum Tree ringsCentrum 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

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

Shark tooth Identifications

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

Carcharoclesmegaolodon

Carcharoclesauriculatus

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