Gates: I'M IN BAJA, MEXICO TO SOLVE A PREHISTORIC MURDER MYSTERY --

WHAT DROVE THE MEGALODON SHARK,

THE BIGGEST, MOST POWERFUL PREDATOR OF ALL TIME,

TO EXTINCTION?

PALEONTOLOGIST DR. ROBERT BOESSENECKER

BELIEVES THE ANSWER MAY LIE IN THE MEG'S FOSSILIZED TEETH,

AND WE JUST FOUND ONE.

OH, MY GOD! Boessenecker: WHOA.

LOOK AT THAT! BEAUTIFUL.

ARE YOU KIDDING ME?

LOOK AT THE SIZE OF THIS THING!

THAT IS A MASSIVE TOOTH.

THAT'S UNBELIEVABLE!

SO, THIS IS A FULL ADULT MEG TOOTH?

YEAH, THIS IS FROM A SHARK THAT WAS ABOUT

50 TO 60 FEET IN LENGTH.

THAT IS HUGE.

AND IT'S JUST ONE OF THE ESTIMATED

276 SUPER-SIZED CHOMPERS

THAT LINED THIS SUPER-SHARK'S 11-FOOT MOUTH.

SO, WHAT CAN WE LEARN FROM A TOOTH LIKE THIS?

SO, THIS TOOTH IS REALLY BIG, IT'S TRIANGULAR,

IT'S THICK, IT'S GOT SERRATED CUTTING EDGES.

THIS IS AN ANIMAL THAT HAD TEETH ADAPTED

FOR FEEDING ON QUITE LARGE PREY.

AND IN FACT, I BROUGHT SOMETHING ALONG TO SHOW YOU.

WHAT IS THIS?

THIS IS A FOSSIL WHALE RIB

WITH MEGALODON BITE MARKS ON IT.

AND ON THIS SIDE,

THE MEGALODON BIT ALL THE WAY THROUGH THE RIB.

THAT'S INSANE.

FOSSIL EVIDENCE INDICATES

THAT THE MEG'S PRIMARY DIET WAS WHALES.

BUT AROUND 3 TO 4 MILLION YEARS AGO,

THE NUMBER AND SIZE OF WHALES BEGAN TO DECLINE.

BECAUSE OF THIS, THE MEG HAD TO TURN TO SMALLER WHALES

AND PERHAPS ANOTHER MORE PLENTIFUL FOOD SOURCE.

THE PROBLEM WAS THEY WEREN'T THE ONLY ONES

WHO HAD A TASTE FOR SEAL.

OKAY, SO, IF IT DIDN'T DIE OUT FROM SOME MASS EXTINCTION EVENT,

WHAT KILLED THE MEG?

COULD HAVE BEEN OUT-COMPETED BY A NUMBER OF DIFFERENT SHARKS.

AND ONE OF THEM IS STILL ALIVE RIGHT HERE IN BAJA TODAY.

IT'S STILL ALIVE? YES.

SO, SHARK SPECIES THAT ARE ALIVE TODAY

ONCE WENT HEAD-TO-HEAD WITH MEGALODONS

IN THE HUNT FOR SMALLER PREY.

IN FACT, ONE OF THE BIGGEST, STRONGEST, AND FASTEST

CAN BE FOUND IN THE WATERS OFF BAJA CALIFORNIA --

THE MAKO SHARK.

TO LEARN IF THE MAKO COULD HAVE GIVEN MEGALODONS

A RUN FOR THEIR MONEY,

I'M MEETING WITH SHARK BEHAVIOR ECOLOGIST TRISTAN GUTTRIDGE.

JUST PUT THAT ON THE BUCKET THERE.

TRISTAN. HEY.

JOSH. HOW ARE YOU, MAN? HOW ARE DOING?

NICE TO MEET YOU. NICE TO MEET YOU, TOO.

I HEAR YOU'RE THE MAN TO SEE ABOUT A MAKO?

YES. LET'S GO FIND SOME.

LET'S DO IT.

WE MOTOR OUT THREE MILES WITH THE FINEST SELECTION

OF SHARK CAVIAR ABOARD,

AND IT TURNS OUT SHARKS AREN'T THE ONLY CREATURES OUT HERE

WITH A TASTE FOR THE FINER THINGS.

♪♪

[ SEAL BARKING ]

♪♪

HOW CAN YOU DENY A SWEET LITTLE FACE LIKE THAT?

♪♪