Category: A to Z Challenge

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E is for Extinction

Cartoon by Bizarro.

The pop cultural perspective on extinction is filled with visions of failure. The extinction of the dinosaurs is frequently viewed through this lens. But consider the lengthy reign of dinosaurs on Earth. Dinosaurs spent more than 160 million years ruling Earth’s terrestrial ecosystems. And technically, when you consider those modern dinosaurs flying around today, it means that dinosaurs have been around for more than 230 million years.

Kristi Curry Rogers, “Dinosaurs.”

Dinosaurs are often used as the definition of old, dead, extinct. Blackberries are now dinosaurs. Baby Boomers are dinosaurs with modern devices. The moniker is somewhat unfair. After all, dinosaurs did spread and thrive across the globe longer than any other type of creature. Fish lasted for about 60 million years in the “Age of Fish,” and mammals have also only been around about 65 million years. Dinos are extinct, but it took a rather dramatic way to take them out. (Well, technically crocodiles have been around since the dinosaurs, so maybe…)

Still, for what it’s worth, before we get overwrought about dinosaurs disappearing and the horror of species vanishing, we should get straight how extinction actually works.

Extinction causes from Firesafe Council.

Two Flavors of Extinction

First off, there are two kinds of extinction:

  • Background Extinction
  • Mass Extinction

Species go extinct all the time, and they always have. Background extinction refers to a one-off event, where a species dies off because it can’t adapt to the existing conditions. They lose their habitat or food source. Predators adapt more quickly than they do. Climate change has occurred countless times across the earth, multiple ice ages and warm ups and volcanoes spewing sulfur and CO2, plants gobbling it up. Every time there is a significant climate change, species go extinct–we’ve already had two Ice Ages in human history.

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D is for Diplodocus

Diplodocus casts in the Carnegie Museum, photo from Carnegie museum.

Diplodocus was one of the oldest dinosaurs discovered. Language is so imprecise, though. Were they the bones of a 120-year-old? Was he from the Triassic, the earliest dino-era? Nope. He was among the first dinosaurs found by the dinosaur hunters during the late 19th century. So Dippy–that’s what that first skeleton came to be known as–Dippy was famous because he was one of the first, but he became more famous for a bigger reason. Dippy was copied.

Diplodocus was one of those “big” dinosaurs I mentioned back with the letter “B.” He is classified as one of the sauropods, those giant, the huge, long-necked, long-tailed dinos who were vegetarian and too humongous to be messed with. The family tree of the Diplodocus, (or the clade called Diplodocidae) groups the Apatosaurs with the Diplos. Both groups had long necks and tails, but the Apatosaurs were stockier, whereas the Diplos tended to be skinny in the front and all the way to the back, with an almost whip-like tail. (Like Anne Elk said, if you remember *ahem* Anne Elk, they were thin to start with, then much much thicker, then thin again. *ahem*.)

diplo (double) + docus (beam)

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C is for Clade

Dinosaur clade with timeframe, graphic from Fossil Wiki.

It’s all about the family trees. Today’s dinosaur-themed post is about how the dinosaur world is organized.

I know some of you are thinking, geez, don’t you know the names of any dinosaurs? Why isn’t A to Z going to be about Ankylosaurus to Zupaysaurus? I will have a few posts dedicated to specific dinosaurs, especially my favorites. But you can look up tons of dinosaur lists A to Z. There are kid’s alphabet books that do that. I promised to give you “all about dinosaurs,” not all about 26 dinosaurs. We need to round out this paleontological survey a bit more in order to achieve that goal.

How paleontologists organize the dinosaurs is quite important because it helps us understand how dinosaurs did what they did. As I mentioned in post “A,” the ankle bone structures differing from those of crocodiles urged scientists to think about why, and why was because dinosaurs stood upright. Hip-bone differentiation helped identify the two big groups — wait until letter “H”! And then… the birds. But we’ll get to that.

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