What came after the dinosaurs? Giant penguins, of course

Plus, giant sharks, otters, sloths and dragonflies

Can you imagine a world where penguins are as tall as you?

This summer, scientists reported on the discovery of a monster penguin fossil in a New Zealand riverbed.

The huge prehistoric penguin weighed about 176 pounds — that’s about the same as a dishwasher — and, at five feet three inches, it was about as tall as a human.

Thanks to this discovery, scientists have slowly been piecing together the story of these giant birds.

The good old days

About 60 million years ago, after ocean dinosaurs went extinct, the sea was a much safer place.

Marine reptiles no longer dominated, so there was lots of food around, and birds like penguins had room to evolve and grow.  

Eventually, penguins morphed into tall, waddling predators.

In other words, they were at the top of their game.

A fossilized ankle from a giant penguin, left, compared to a similar bone from the largest living penguin: an emperor penguin. (Mark Baker/The Associated Press)

Bye bye birdies

But the glory days didn’t last.

After 30 million years, the giant penguins were gone.

Gerald Mayr, a paleontologist who studies these birds, suggests this is because of the rise of marine mammals like toothed whales, walruses, sea lions and seals.

It’s possible the marine mammals both preyed on the penguins and competed with them for food and breeding territory, which eventually drove the mega-birds to extinction.

A mystery

But consider this: Why did penguins, who once thrived as giants, evolve into the small, waddling birds we are familiar with today?

Did they need to be smaller and faster in order to avoid predators?

Or could they not find enough prey to sustain their large bodies once they were forced to compete?

It’s a mystery concerning not just penguins, but also other prehistoric giants.

Megalodon

Take the megalodon, for example.

With a name meaning giant tooth and a length of almost 60 feet, the megalodon was the largest fish to ever swim the oceans.

And though sensationalized by the media and Hollywood, don’t get too worried — megalodon is definitely extinct.

But while you might have expected that sharks would have a big, scary ancestor, would you expect the same of otters, sloths and dragonflies?

Early otters looked a lot like today’s river otters, except for the fact that they were the size of a wolf and weighed almost as much as one, too.

Some prehistoric dragonflies had wingspans that were two to three feet across.

And giant ground sloths were roughly the size of elephants!

Yet all of these giants met similar sticky ends: outcompeted by other animals, killed by a changing atmosphere and possibly even — in the case of the supersized sloths — being over-hunted by early humans.

Whatever the case, discoveries like that of the giant penguin fossil in New Zealand are filling in our understanding of prehistoric life.

Not to mention providing inspiration for your next Halloween costume!