Sciency Words: Thagomizer (An A to Z Challenge Post)

April 24, 2017

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, T is for:


Once upon a time, there was a caveman by the name of Thag Simmons. According to Glen Larson’s Far Side comic strip, Thag met an unfortunate end when he was clubbed to death by the spiky tail of a stegosaurus. As a result, cavemen began to call the stegosaur’s spiky tail a thagomizer.

Larson’s thagomizer comic was originally published in 1982. Death by thagomizer may sound like a gruesome way to go, but based on my own research about cavemen/dinosaur interactions, I have reason to believe Thag Simmons had it coming.

Over the course of this Sciency Words: A to Z series, we’ve seen some scientific terms that were pretty clever, and some that were kind of dumb, and a few that are truly misleading. But until now, we haven’t talked about scientific terms that come from pop culture.

In 1993, paleontologist Ken Carpenter was makng a presentation about the most complete stegosaurus skeleton ever found, and he needed a tern for the dinosaur’s distinctive spiky tail. One of the spikes had apparently broken and healed, which was compelling evidence that stegosaurs really did use their spiky tails as weapons.

In homage to Glen Larson, Carpenter chose the term thagomizer, and the term has now become the proper, semi-official term for that part of stegosaurus anatomy.

I want to thank @breakerofthings for letting me know about this term. I’d originally planned to do something else for T, but I think this was much better. Be sure to check out A Back of the Envelope Calculation, where “breaker” is doing an A to Z Challenge series on materials science in Sci-Fi/Fantasy.

Next time on Sciency Words: A to Z, how do you pronounce Uranus?

Sciency Words: Dinosaur (An A to Z Challenge Post)

April 5, 2017

Programming note: If you’re here for today’s Insecure Writer’s Support Group post, please click here.

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, D is for:


When I was a kid, dimetrodon was my favorite dinosaur. It has a sail on its back. How cool is that?

Then I found out that dimetrodon is not a dinosaur. It’s just a lizard. Then I found out from this video that it’s not even a lizard.

Also, pterodactyls aren’t dinosaurs. Neither are plesiosaurs or ichthyosaurs. None of my favorite dinosaurs were actually dinosaurs! Frustrating, isn’t it?

So today, I thought I’d give you a quick tip on how to tell when a “dinosaur” is actually not a dinosaur. Sciency Words is all about defining scientific terms, and paleontologists use several key features to define what is or isn’t a dinosaur. For example: the number of openings in the skull, the shape of the hip bone, the type of joint at the ankle….

If you’re a professional dinosaur scientist, you need to know this stuff. But for the rest of us, the easiest way to tell (in my opinion) is by looking at the orientation of the legs. Dinosaur legs are vertical to the ground, not horizontal. They go straight up and down, rather than being splayed out to the sides.

So if you think it’s a dinosaur, but the legs are splayed apart, it’s not a dinosaur.

If you’ve ever seen a crocodile or salamander try to run, you can understand why having your legs splayed apart like that is a disadvantage.

Standing upright on their vertical legs, dinosaurs had a much easier time walking and running on land. Also, vertical legs can support more weight, allowing dinosaurs to become much bigger and much heavier than their cousins, the amphibians, reptiles, and whatever the heck dimetrodons were.

Next time on Sciency Words: A to Z Challenge, we’ll find out what our planet’s name is.

Sciency Words: Brontosaurus (An A to Z Challenge Post)

April 3, 2017

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, B is for:


I’ll never forget that sad moment in my childhood when I found out that brontosaurus is not a real dinosaur. Someone made a mistake, and we had to call brontosaurus apatosaurus instead.

Here’s a quick rundown of events in the brontosaur/apatosaur naming controversy:

  • 1877: A dinosaur skeleton is discovered and given the name scientific name (genus and species) Apatosaurus ajax.
  • 1879: Another dinosaur skeleton is discovered and given the name Brontosaurus excelsus.
  • 1903: Upon further examination, it’s determined that these two dinosaur specimens are too closely related and should be classified as the same genus. Since the genus Apatosaurus was identified first, Brontosaurus excelsus became Apatosaurus excelsus.

On a personal note, I was stunned to find out all this happened way back in 1903. When I was a kid, I was under the impression that this was a much more recent development.

Anyway, there’s some good news for brontosaurus fans. In 2015, Brontosaurus was reinstated as its own genus. Turns out that while those two skeletons are very similar, there’s enough of a difference in the structure of the neck to justify classifying them separately.

By the way, brontosaurus means “thunder lizard,” because of the sound it must have made when it walked. Apatosaurus apparently means “deceptive lizard.” I’m not sure why they called it that back in 1877, but after this case of attempted identity theft, I’d say the name fits.

Next time on Sciency Words: A to Z Challenge, we’ll head out into space and meet some centaurs.

Sciency Words: The K-T Event

May 20, 2016

Sciency Words MATH

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us all expand our scientific vocabularies together. Today’s term is:


You already know this story. It was 65 million years ago. There were dinosaurs, there was an asteroid…

It’s easily the most famous asteroid impact in Earth’s history, and it’s called the K-T Event, or sometimes the K-Pg Event.

In geology shorthand, the letters stand for:

  • K: the Cretaceous period, which is spelled with a K in German. This was the last period of geological history in which dinosaurs roamed the Earth.
  • T: the Tertiary period, which immediately followed the Cretaceous. According to the International Commission on Stratigraphy (ICS), we’re not supposed to use this name anymore, but people still do. It’s sort of like how some people keep calling Pluto a planet, no matter what the International Astronomy Union (IAU) says.
  • Pg: the Paleogene period, which is the period immediately following the Cretaceous according to the ICS’s new list of geological periods. Please note, the Tertiary and Paleogene are not really interchangeable terms. They have the same starting point, but different end points.

Geologists and paleontologists puzzled for decades over a layer of clay separating Cretaceous and Tertiary (or Paleogene) rock. They called it the K-T boundary. There were several competing hypotheses about what might have caused this boundary and how it related to the mass extinction event that killed off the dinosaurs.

Then in 1980, a paper came out entitled “Extraterrestrial Cause for the Cretaceous-Tertiary Extinction.” This paper reported the discovery that the K-T boundary contained abnormally high levels of the element iridium.

Platinum group metals like iridium are extremely rare on Earth (except in the planet’s core) but common in asteroids. So whenever you find lots of iridium in Earth’s crust, you can justifiably assume an asteroid put it there.

The most likely scenario is that a large asteroid, about 10 km in diameter, smashed into Earth, flinging dust and debris high into Earth’s atmosphere. Enough to block out the sun worldwide for several years. This global dust cloud would have included plenty of material from the asteroid itself, which would have been partially vaporized by the heat of the impact.

A major problem with the original 1980 paper was that, at the time, no known impact crater of the appropriate age was sufficiently large. But of course, that was back in 1980. The crater has since been found in the Yucatan Peninsula, and now just about everybody knows the story of the K-T Event (even if they don’t know it’s called that).

P.S.: The K-T Event is not to be confused with the Katie Event. You know, that time your BFF Katie had waaaaay too much to drink and threw a temper tantrum of apocalyptic proportions.

Addendum: While there does seem to be general, widespread consensus that the K-T asteroid impact either caused the extinction of the dinosaurs or contributed significantly to their demise, there is not universal agreement. As Planetary Defense Commander notes in the comments, there are other possibilities worth considering.