What animals lived in the Tertiary Period?

The Tertiary Period: When the World Went Wild (and Mammals Took Over!)

Okay, picture this: the dinosaurs are gone – poof! – and the world is a blank slate. That’s pretty much what happened at the start of the Tertiary Period, a crazy-important chunk of Earth’s history that stretched from about 66 million to just 2.6 million years ago. Officially, scientists now call it the Paleogene and Neogene periods (started in 2008), but “Tertiary” still gives you a good idea of the massive changes that were happening. Think of it as the ultimate comeback story, where life as we know it really started to take shape.

Climate Chaos (and a Whole Lot of Cooling)

The Tertiary Period wasn’t exactly smooth sailing. The climate was all over the place! It kicked off super warm, like a never-ending tropical vacation. Palm trees? They were chilling in Greenland! But things started to cool down around the Oligocene Epoch, and that cooling just kept getting more intense. By the time we hit the Miocene and Pliocene, giant ice caps were forming, and we were heading straight for the ice ages. All that change meant the landscape changed too. Forests gave way to grasslands, which totally shook up the animal kingdom.

The Age of Mammals? You Bet!

Here’s where things get really interesting. With the dinosaurs out of the picture, mammals saw their chance and ran with it. This is why the Tertiary Period is often called the “Age of Mammals” – because they exploded onto the scene! They got bigger, smarter, and diversified like crazy, filling every niche imaginable. Seriously, from the oceans to the skies, mammals were making themselves at home.

• Early Days: In the Paleocene and Eocene epochs, we saw the first big mammals and some pretty funky-looking early primates. Think marsupials, insectivores, and those weird proto-primates.
• Hello, Modern Mammals! By the Eocene, the mammals we’d recognize today started showing up. Then, from the Oligocene onward, the landscape was dominated by the ancestors of horses, rhinos, antelopes, deer, camels, elephants, and, of course, those fierce felines and canines. It was like a mammal party, and everyone was invited.
• Enter the Hominids: And let’s not forget the Pliocene, when our own ancestors, the hominids, finally made their debut. We’re talking about Proconsul, that tree-swinging primate from way back when (around 23 to 17 million years ago), and Australopithecus. Pretty cool to think about, right?

Birds Take Flight (and Some Stayed Grounded)

Birds weren’t about to be left out of the fun. They also diversified like mad during the Tertiary. You had plenty of birds we’d recognize today, but also some seriously oversized, flightless oddballs.

• Flightless Giants: Picture this: a bird taller than you, stomping around and looking for a snack. That was Diatryma (or Gastornis), which showed up in the Paleocene and Eocene. These guys were huge and probably filled the predator role left open by the dinosaurs. And in South America, when it was an isolated continent, Phorusrhacos and its relatives were doing the same thing during the Oligocene.
• Little Songbirds: On the other end of the spectrum, the passerines – those little songbirds we see everywhere today – really took off during the Miocene.

Life Aquatic

The oceans were just as busy as the land.

• Marine Mammal Mania: Whales and seals started evolving during the Tertiary.
• Fish Frenzy: Fish were branching out, sharks were getting more common, and even trout and bass were making their first appearances.
• Creepy Crawlies: Crabs, bony fish, snails, and clams were all evolving like crazy, with many developing some serious defenses against predators.

Reptiles, Amphibians, and Bugs

While mammals and birds were stealing the show, reptiles, amphibians, and insects were still doing their thing. Reptiles gradually got replaced by mammals as the top dogs. And the insect world? It exploded, especially for bees and other pollinators that relied on all those new flowering plants.

The End of the Line (… for the Tertiary, Anyway)

The Tertiary Period wrapped up with another extinction event around 35 million years ago. It wasn’t as big as the dinosaur-killing one, but it still wiped out a bunch of marine life, thanks to changes in ocean currents, falling sea levels, and a generally cooler climate. And that cooling trend eventually led to the ice ages of the Quaternary Period.

So, there you have it: the Tertiary Period in a nutshell. It was a time of massive change, crazy diversification, and the rise of mammals to global dominance. It’s a reminder that life is always evolving, always adapting, and always finding a way.