The Thagomizer of Stegosaurus (Stegosaurus Week)

This Saturday at the Morrison Natural History Museum in Morrison, Colorado, we will be celebrating Stegosaurus Day, in honor of Colorado's state fossil!  (To learn more, click HERE to be redirected to the Facebook page of the Morrison Natural History Museum!)  So, in honor of Stegosaurus Day, The Natural World is going to have ourselves a little Stegosaurus Week!  Each day, we are going to be looking at a different aspect of Stegosaurus, and today, we are going to be looking at the tail spikes on the tail of Stegosaurus, nicknamed the thagomizer!  What were they used for?  Did they actually use their tail spikes for defense?  And how about that funky name: where did the term "thagomizer" come from?  Well, learn those answers and more in today's post for Stegosaurus Week!

Remember IN THE LAST POST OF STEGOSAURUS WEEK when we mentioned paleontologist Ken Carpenter and his very complete and articulated Stegosaurus skeleton?  Well, in 1993, when Carpenter was presenting his findings, he first used the term "thagomizer" to describe the tail and spikes of Stegosaurus.  Without even knowing its backstory, it seems like a fitting name: but its true origin is even more interesting!  For those of you who have enjoyed Gary Larson's fantastic "The Far Side" comic strip, then you may already know where we are heading with this!  One of my favorite "Far Side" strips is the one above, and, interestingly, it is from this strip that Ken Carpenter got the name "thagomizer!"

Now, one question that has stumped paleontologists for years is, how were the spikes arranged on the thagomizer?  Nowadays, we know that there were two sets of spikes, and they are thought to have been about 180 degrees from each other, forming a horizontal line.  (For a more complete discussion, see the last post in our Stegosaurus Week series, entitled THE GENUS STEGOSAURUS THROUGH TIME.)  But other questions stumped paleontologists, too.  For example: what was the thagomizer used for?  It definitely looks like a very apt defensive weapon, but for a long time, paleontologists had no clues to help them figure out whether defense was actually the answer.

One source of evidence that Stegosaurus and other stegosaurs were using their thagomizers to defend themselves is that many of the spikes have broken tips.  Now, just because a fossil is broken, doesn't necessarily mean that it was broken during the animals life.  Paleontologists can tell whether or not a bone was broken during the life of the animal by looking to see whether the bone shows any signs of healing.  If the fossilized bone shows signs of "remodeling," then the bone broke during the life of the animal, and then started to heal while the animal was still alive.  Following the death of an animal, if somehow a bone becomes broken, it's not going to heal: the animal is already dead!  In a study that examined 51 tail spikes of Stegosaurus, researchers found that about 10% of these spikes had broken tips whose bone had started to grow back.  So clearly, these spikes weren't just for show, and were actually being used for something.

The best evidence that paleontologists have right now that indicates that Stegosaurus was using its thagomizer to defend itself against predators is an Allosaurus tail vertebrae with a hole in it: a hole exactly matching the kind of hole that a thagomizer would have made!  What's very interesting about this fossil is that, while damaged bone in the vicinity of the hole shows signs of healing (indicating that the Allosaurus survived, at least for a little while, following its encounter with Stegosaurus, and that the damage to the vertebrae was not post-mortem), the hole itself doesn't seem to have healed at all.  This has caused some paleontologists to hypothesize that part of the tough outer sheath that would have surrounded the tail spikes in life, probably making them sharper and pointier, of a Stegosaurus became stuck in the tail vertebrae, remaining lodged within the tail vertebrae of that particular Allosaurus, until the animal died!

Another picture that I took at the Denver Museum of Nature and Science of an Allosaurus attacking a Stegosaurus adult and juvenile

Want to learn more about Stegosaurus and it's relatives? Well, check out the Homebase for Stegosaurus Week HERE to partake in more of the festivities!

23-Fact Tuesday: The Polar Bear!

Everyone loves polar bears, so today, for the birthday post of Brooke Harrower, we are going to be taking a 23-Fact Tuesday look at them!  Allons-y!

1.  Despite the fact that the polar bear can be quite a fierce animal, it can also be very playful and gentle.  For proof, click HERE to see a very cute video of polar bears playing with sled dogs!

2.  A group of polar bears is called a celebration.

3.  In an attempt to safely film polar bears up close and personal without disturbing them, one production company resorted to an interesting array of spy cameras.  To see an awesome video of the polar bears playing with the spy cameras, click HERE.

4.  As we saw in the previous video clip, the polar bear is quite the curious animal.  It has to be, to survive in such harsh conditions!  The polar bear is also a lot smarter than many other bears, as can be seen in a comparison of a few different bear brains, below!  Look at how much larger (comparatively) the brain of the polar bear is than that of the American black bear!  Also keep in mind that more wrinkles=a greater surface area=a smarter animal!

5.  Unlike the color of its fur, the skin of the polar bear is actually jet black!

6.  Despite the fact that they are often erroneously pictured together, it is almost entirely impossible for penguins and polar bears to meet naturally in the wild, as no penguins ever really make it past the Equator, with the Galápagos penguin living the furthest north, right on the Equator!  For more information on the subject (as well as some really funny stories) click on the link HERE, to check out a page on the awesome blog March of the Fossil Penguins.

7.  As you can see in the video clip HERE, filming the polar bears for the excellent BBC series Planet Earth could be quite a challenge (see the full post HERE), especially when they come knocking at your door!

8.  The polar bear is the largest extant (still living, opposite of extinct) mammalian carnivore.  The males can grow up to a whopping 1,500 pounds! 

9.  It occurs to me as I eat this delicious cherry popsicle that the polar bear must have some sort of special evolutionary adaptation to prevent brain freeze as it consumes a cold and frozen meal.  Research should be done into this.

10.  Polar bears, after their emergence from their dens following the harsh Arctic winters, have been observed sledding down the hills on which the dens are associated.  Some scientists believe that this action is solely intended to clean the fur, but many others (myself included) believe that it is probably more for fun!  Check out the video HERE.

11.  The polar bear is native to only five countries.  These are Russia, Denmark owned Greenland, Norway owned Svalbard, Alaska, and Canada.

12.  The polar bear is a descendant of the grizzly bear, and was once thought to have diverged from the grizzly possibly only even around 70-100,000 years ago.  Others are more conservative in their estimations, as DNA analysis on one particular fossil specimen indicates that the polar bear diverged from the grizzly bear around 160,000 years ago.  It now seems more likely that the age of divergence of was much earlier in time than even 100,000 years ago, and polar bear fossils dating from earlier than that (round 115,000 years ago) have actually been discovered.

A picture of one of the grizzly bears at the Cheyenne Mountain Zoo doing what the zookeepers call the "Yoga Bear."  This was from the behind the scenes experience that my dad, grandma and grandpa, my friend Masaki and I got to do with Kelley Parker a few months back!  Photo Credit: Masaki Kleinkopf.

Another picture of one of the grizzly bears at the Cheyenne Mountain Zoo doing what the zookeepers call the "Yoga Bear."  This was from the behind the scenes experience that my dad, grandma and grandpa, my friend Masaki and I got to do with Kelley Parker a few months back!  Photo Credit: Masaki Kleinkopf.

13.  The oldest polar bear fossil known to science, the lower jaw of a male, was discovered in 2004.  It's age is thought to be between around 110,000 and 130,000 years old. 

14.  The scientific name for the polar bear, Ursus maritimus is "sumitiram susru" spelled backwards.  This means absolutely nothing and is really not that exciting, unless you are me and think it's funny and clever to spell things backwards and make stupid jokes about it.

15.  Algae, while not threatening to a polar bear in any significant way, can be extremely hard to wash out of the bears fur.  So therefore, in the summer of 2008 when three bears at Higashiyama Zoo and Botanical Gardens in Japan got a bunch of algae stuck in their fur, they were green for the entire summer!  True story!

16.  The polar bear is a fantastic swimmer, aided by its streamlined body and skull as well as its partially webbed feet, and have been spotted swimming strongly in open waters as much as 200 miles from the shore!

17.  The polar bear will consume a wide variety of foods, including everything from seals to walrus, beluga whales to bowhead whale carcasses, birds, and even kelp!

18.  The polar bear is labeled as "Vulnerable" by the IUCN, a position which may deteriorate in years to come with the further melting of the ice caps.

19.  Hybrids of the polar bear and the grizzly bear, sometimes called grolars, have been known to occur both in the wild and in captivity, a further testament to the close genetic relationship between the two bears.

20.  Baby polar bears are possibly some of the cutest animals on the planet, as can be evidenced by the picture below of baby Anori from Germany's Wuppertal Zoo.

21.  Humans are the only animal that hunt polar bears.

22.  So well protected against the cold is the polar bear that they can quickly overheat, even when the temperature is below zero!  In order to combat this, the polar bear will try to avoid running and will rest for many many hours at a time.  Maybe my cat's a polar bear.

23.  Polar bears, like myself when Windows Movie Maker refuses to work, have actually been observed by scientists to throw tantrums when they fail to catch their prey!  The bears have been observed growling disappointedly, kicking piles of snow, and even throwing ice chunks!

Happy birthday Brooke, hope you enjoy!  And remember, if you have a birthday coming up, just email me the date at cuyvaldar123946@gmail.com with the date and your favorite animal, and I will do my best to get a post in!

The Thagomizer of Stegosaurus

Stegosaurus is a very famous dinosaurs, one of the most famous, along with Triceratops and Tyrannosaurus.  All three of these dinosaurs have been found in Colorado; in fact, the first Triceratops bones were actually found in Denver, and Stegosaurus is the state dinosaur of Colorado!  Stegosaurus has also been found in Wyoming and Utah, in the Morrison Formation, as well as in Portugal.  The row of plates along its back make it very interesting looking, as do the spikes on the end of its tail, nicknamed a "thagomizer."  Holes in the vertebrae of a potential predator of Stegosaurus, Allosaurus, fit exactly with the size of one of the spikes on the tail of the Stegosaurus, showing that there was almost certainly a predator-prey relationship between the two, as was previously suspected.  Studies have shown that the tail end of Kentrosaurus, a close relative of Stegosaurus, also with a thagomizer on its tail, could have been brought around to the side of the dinosaur, potentially swatting at enemies trying to attack the Stegosaur from the side.

Finally, discoveries of articulated Stegosaurus skeletons show that the spikes were actually horizontal from the ground, as opposed to held at an angle, as you can see in the outdated and incorrect picture below.

It's an interesting word, though, isn't it: "thagomizer."  It certainly doesn't sound like a very sciency name; in fact, when I first heard it, I immediately thought it sounded like something out of one of my favorite comic strips, Calvin and Hobbes, by Bill Watterson.  Well, if you thought that as well, then you were actually surprisingly close to the mark, as the term did in fact come from a comic strip, another one of my favorites: The Far Side.

The term wasn't used scientifically until the year 1993, at the annual meeting of the Society of Vertebrate Paleontology, by the one-time Curator of Paleontology at the Denver Museum of Nature and Science Ken Carpenter.  The name has been used multiple times since then, in different mediums; books and television shows (including another personal favorite, BBC's Planet Dinosaur), as well as places such as the Smithsonian Institution and Dinosaur National Monument.  Although an informal name, it is popular, and has amusing origins.

Gary Larson created a great number of hilarious The Far Side cartoons covering all sorts of topics.  However, it seems like a large number of them featured animals, or were in some way nature related.  You will undoubtedly see a great many of them in this blog as time goes on, but here are a few other amusing dinosaur ones.

Masiakasaurus knopfleri, and Other Interestingly Named Creatures

A few months ago, while reading Dr. Scott Sampson's book Dinosaur Odyssey (you probably know him as the guy from Dinosaur Train), he has a very brief section of his book where he talks about some interesting scientific names of sometimes not that interesting of creatures.  He presents nine of them, and here I present them to you, as well.

1.  Masiakasaurus knopfleri
This dinosaur, from Late Cretaceous Madagascar, was named by Scott Sampson and his colleagues, means the "vicious lizard of Knopfler," meaning Mark Knopfler, a famous musician.

 2.  Milesdavis zlichovianus
This trilobite was named after the famous jazz musician Miles Davis.

3.  Mozartella beethoveni
This wasp was named after two famous classical musicians, Wolfgang Amadeus Mozart and Ludwig van Beethoven.

4.  Dicrotenipes thanatogratus
This one is probably less obvious to most of you out there, but in Greek, thanatos means "dead" (think Thanos, the villain for the next "Avengers" movie from Marvel: he loves and worships death), and in Latin, gratus means "grateful."  This midge was named after the famous band, Grateful Dead.

5.  Montypythonoides riversleighensis
This extinct Australian snake was named after the Monty Python franchise, but unfortunately, the name is now outdated; its correct scientific name now is Morelia riversleighensis.

6.  Strigiphilus garylarsoni
Named after the famed cartoonist Gary Larson of The Far Side fame (watch for at least one post featuring him next week).  Besides having this owl louse named after him, also has had a beetle and a butterfly named in his honor. Regarding the owl louse, he said “I considered this an extreme honor. Besides, I knew no one was going to write and ask to name a new species of swan after me. You have to grab these opportunities when they come along.”

7.   Ninjemys oweni
"Owen's Ninja Turtle" is named after the famous group, the Teenage Mutant Ninja Turtles, and was found in Pleistocene-aged rocks in Queensland, Australia.

8.  Gozillus

http://www.csmonitor.com/Science/2012/0425/Mysterious-Godzillus-fossil-find-stumps-scientists

9.  Darthvaderum greensladeae
One of my personal favorites, this mite was named after the famous Darth Vader, from Star Wars.