Category: A to Z Challenge

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K is for the K-Pg Boundary

An image from a simple Google search for “dinosaurs.” From earthspacecircle.

You probably have heard about the asteroid. Big BOOM. You can’t really look at a generic picture of dinosaurs on the Interwebs without seeing them fleeing from hellfire and brimstone. But the asteroid involves two parts. The latter part is what happened after the BOOM, and I’ll tell that story toward the end of the alphabet. You’ll have to guess what letter.

But the first part of the scientific part of the story is how did they know? How could scientists tell that there was a big giant asteroid that eliminated all the dinosaurs? Maybe they could figure out from the fossil record that the dinosaurs disappeared. But how did they know it was caused by an extraterrestrial event? Particularly when the impact crater was, as it turns out, deep under water?

They didn’t know at first. The scientific method triumphed in the end. And fathers and sons.

The Old Ideas of Catastrophe

Before 1980, paleontologists did know that dinosaurs disappeared, around 64 million years ago, in fact. The end of the Cretaceous period was set at 64–and not 100 or 150–precisely because that was when all the dinosaur fossils disappeared.  It was somewhat handy that it happened during a chalky geological period since that made it easy to spot on the sides of cliffs.

The layers of geology. White is the KT boundary. Graphic from geowyoth.
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J is for Jurassic

Jurassic Park OG Velociraptor, photo from Filmexperience.net.

Scientists are actually preoccupied with accomplishment… focused on whether they can do something. They never stop to ask if they should do something.

Ian Malcolm, Jurassic Park

Chances are that you have seen Jurassic Park or one of its sequels. Chances are that you found some part of it exciting. Perhaps you found other parts to strain credulity. That’s ok. The Jurassic Park franchise is not entirely accurate. At first, I thought it was too pandering, too dumbed-down to create realistic dinosaurs. But I was wrong. At least about the relative realism of the dinosaurs.

No, they weren’t exactly Jurassic. The dinosaurs named and depicted did not completely act like their namesakes should have acted. The velociraptor and the dilophosaurus in the first movie were particularly off. But Spielberg got a lot of other things right. And he made dinosaurs really popular, which probably led to more people studying dinosaurs and more funding for dinosaur studies. Well played, Mr. Spielberg, well played.

Not Especially Jurassic

So what exactly is Jurassic? It’s a geological time period. Geologic time is divided up into eras and periods, chiefly to provide names for future geologists and paleontologists to memorize. Also, it’s shorter to write Jurassic than it is to write 200 to 145 million years ago. The entire era of the dinosaurs is called the Mesozoic, which means the middle (meso) era that had animal fossils (zoic), as opposed to the Paleozoic, which means older time of fossils, and the Cenozoic, which is the recent era, i.e. now.

The Mesozoic also had three divisions: Triassic, Jurassic, and Cretaceous. Triassic was called that because the Germans wanted that time period to have another three categories that they called the Trias. Kind of like the basic rule of magic; if you say a thing three times, then it becomes real.

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I is for Iguanodon

Author’s Note: I just realized that I have an excellent book that covers the story of Gideon Mantell and the iguanodons. This book, Terrible Lizard by Deborah Cadbury, contains all sorts of juicy details about the scientific rivalries, the tooth, and the horn. Unfortunately, I haven’t read it entirely yet, so this post will be based on bits and pieces of what I have cobbled. They’re still tasty bits. Dinosaur Cobbler.

Model of the originally envisioned Iguanodon, in a Dinosaur Museum in Colorado. Photo by kajmeister.

Gideon Mantell was thrilled to find the palm-sized rock that seemed unnaturally pointed and curved. He knew it came from an animal–probably an ancient animal. It seemed logical that it might be similar to a horn, like the one on a rhinoceros.

Oh, what a howling error! Mantell would be known forevermore for his mistake. Was it his fault, given that the foremost naturalist of his day insisted the animal was a rhinoceros? He also was pooh-poohed by the other scientists, only to have them become famous for his initial ideas. Maybe history should be kinder to Gideon. Still, he also dissed his wife. It was Mary who found the fossils, let him fill their dining room with samples, organized his papers, drew illustrations for his book, raised his children … and then was forced to move out when the house was turned into a museum. On second thought, let’s not cut him any slack.

Who Found the Tooth?

Iguanodon was only the second dinosaur to be discovered and named formally by the scientific community that runs such things, which in the early 19th century was in England. The idea of dinosaurs, the extent of dinosaurs rule over the planet, and their huge variation in function and design was all yet to be discovered in 1820. When the quarry near Gideon’s medical practice started revealing unusual fossil bones, there was some ambiguity about what animal it might have come from.

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