Sea Monsters (7 page)

The Mesozoic lasted for about 180 million years. There were no humans on earth
yet. But during this time and even before, fierce animals lived on the earth and in the seas. Much of what we know about them comes from their
fossils.

There was just one huge continent when the Mesozoic Era began. It is called
Pangaea
(pan-JEE-uh). Over millions of years, it broke apart into the continents we know today.

At this time, the earth was much warmer. There was little or no ice at the North and South Poles. The seas were higher. They covered much of the land that exists today. Giant ferns and flowering plants grew in the warm climate.
Dinosaurs roamed the earth. Large winged
reptiles flew in the skies overhead. Huge, dragon-like reptiles, monstrous
sharks, and other scary creatures filled the ocean.

The
marine reptiles that lived in the ancient seas were not dinosaurs. They were more closely related to lizards and snakes.

Dinosaurs ruled the land, but giant marine reptiles ruled the seas. Many had enormous bodies, heads, and teeth. They were deadly hunters, often moving at fast speeds.

When you see the
fossils of ancient sea creatures, you can hardly believe your eyes. Never in your wildest dreams could animals be so huge and scary!

Dunkleosteus
was part of a family whose name means “terrible fish.” And they were really
TERRIBLE
! These twenty-foot-long predators lived about 400 million years ago—long before the
Mesozoic Era.

Dunkleosteus
had the strongest jaws of any fish ever. If this monster bit you, 8,000 pounds of pressure per square inch would crush you like a bug. In fact,
Dunkleosteus
could cut a big shark cleanly in half!

You might think an animal this fierce had huge teeth. But
Dunkleosteus
didn’t have real teeth. Instead, it had two long, sharp, bony blades. The front of the jawbones came to a fang-like point.

Their mouths opened in a flash and sucked their prey right in. And guess what?
Fossils show that
Dunkleosteus
threw up a
lot as well. Fossil lumps of half-eaten prey appear to come from these terrible fish. It seems they ate many things that they couldn’t digest.

Yikes! Talk about colossal! This was the biggest carnivore ever.
Liopleurodon
could be over eighty feet long! Imagine an animal longer than the biggest trucks on the high-way. Imagine an animal twenty times heavier than a
T. rex.

These Mesozoic creatures had long bodies with two flippers on each side. Their huge heads were over ten feet long, bigger than many cars. They had super-strong jaws with powerful eight-inch teeth shaped like tigers’ fangs.
Liopleurodon
used their noses to smell prey underwater. Imagine if one of these monsters got a whiff of you!

Elasmosaurus
looks like a mistake. Nothing with such a small head could have a neck this long! Picture an animal that is forty-six feet long, and half of its body is its neck! The neck was made up of seventy vertebrae (VUR-tuh-bray), or back bones.

Elasmosaurus
ate squid and fish. It may have used its long neck to sweep the ocean floor for crabs and fish. Plus, it swallowed rocks. Piles of rocks are found in the stomachs of
Elasmosaurus
fossils. Maybe the stones helped grind up shells. Croco-diles swallow rocks to do this today.

When fossils of
Elasmosaurus
were first discovered over one hundred years ago, a famous scientist named
Edward Drinker Cope put them together. But he made a big mistake. He put the head on the tail end instead of on the neck!

When his mistake was discovered, Cope spent the rest of his life feeling bad about it—even though he was one of the best prehistoric marine-reptile experts of his day.

Xiphactinus
is nicknamed the “bulldog fish.” Its lower jaws jut out, showing rows of terrible sharp teeth. But another name for these big fish could be “speedy.”

Xiphactinus
swam really fast. Their powerful tails helped them reach speeds up to thirty-five miles per hour!

Xiphactinus
sometimes grew up to twenty feet long. Scientists have found their
fossils with much bigger animals inside their stomachs. Thanks to those fierce jaws and teeth, these bulldog fish weren’t afraid of anything!

Sometimes people find giant
sharks’ teeth along the Maryland, North Carolina, and California coasts. They’re as big as dinner plates! The teeth belonged to a huge shark called
Megalodon,
which means “giant tooth.” These massive sharks lived after the
Mesozoic Era had ended.

There are almost no
fossils of
Mega-lodon
skulls and skeletons. That’s because shark skeletons are made of
cartilage
(KAR-tuh-lidge), not bone. Cartilage rots after the animal dies. But teeth turn into long-lasting fossils.