Monday, April 22, 2013

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!

The Genus Stegosaurus Through Time (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 tonight, we are going to be looking at the genus Stegosaurus as a whole, and how our concept of Stegosaurus has changed over time!  Let's dive on in!

Stegosaurus was first discovered by famous paleontologist Othniel Charles Marsh during the Bone Wars (a paleontological competition from Marsh and rival paleontologist Edward Drinker Cope) in the late 1800s, and was first described by him in 1877.  When Stegosaurus was first described by Marsh, he wasn't really sure what it was: he actually thought that it might be a turtle-like creature, as you can see in his illustration from above!  This reconstruction explains why Stegosaurus has its name: covered, shingled, or roofed reptile.  It wasn't until Marsh and his crew found other, more complete specimens of Stegosaurus that he was able to figure out what the animal looked like with a greater degree of accuracy, which you can see in the reconstruction below.

The reconstruction above, while much closer to what we think Stegosaurus looks like today than the first reconstruction, nevertheless has several key differences from today's reconstructions.  One of the main issues that paleontologists face when reconstructing Stegosaurus and its relatives from fossils is that the plates aren't attached to any bones.  The plates are modified osteoderms, used in many different animals to protect themselves from attack (a more extreme example of which can be seen in the close relatives of stegosaurs, the ankylosaurs).  Like the osteoderms in other animals, such as the ankylosaurs, the osteoderms would sort of "float" in the skin, only attaching to the rest of the skeleton by means of softer tissues, softer tissues that don't typically fossilize.  What paleontologists really needed was an articulated specimen of Stegosaurus.

Well, that's exactly what paleontologist Ken Carpenter got in the 1990s!  Using this very complete and articulated specimen, Carpenter and his colleagues were able to solve a number of Stegosaurus mysteries.  For example: the exact placement of the plates.  In Marsh's 1890s reconstruction above, you can see that he had positioned the plates in a single row running down the back.  Later reconstructions by other scientists had been created with a double row of plates, which was proven to be correct by Carpenter's specimen.  It was also shown that the plates alternated down the back, as opposed to the side-by-side reconstructions sometimes seen.

Another mystery that Carpenter's specimen was able to solve is the number and placement of the tail spikes.  As you can see in Marsh's 1890s reconstruction above, he hypothesized that Stegosaurus had four pairs of spikes, and that they pointed upwards at around 10-15 degrees from the vertical.  Carpenter's specimen, coupled with further research, has shown that, to the best of our knowledge, no species of Stegosaurus had that many tail spikes: in fact, from what we know, all species of Stegosaurus had two sets of tail spikes, for a grand total of four.  We also now know that, instead of the spikes being about 10-15 degrees from the vertical, they were almost certainly horizontal to the ground!  This hypothesis is backed up by investigations into the flexibility of Stegosaurus's tail: to successfully bring its tail spikes into play in the 10-15 degree arrangement, Stegosaurus would have had to have a tail much like a scorpion, and all research done up to this point indicates that Stegosaurus had nowhere near that much vertical flexibility in the tail.  However, the horizontal reconstruction makes much more sense, as the tail seems like it would have had a great deal of side-to-side flexibility.

The final main difference between Marsh's 1890s reconstruction and our reconstructions of Stegosaurus today lies in the way it held its tail and its neck.  Due to the Dinosaur Renaissance in the 1960s and 1970s led by John Ostrom and his pupil Robert Bakker, the perception of dinosaurs as lumbering failures changed dramatically to what it is today: not failures of evolution, but instead, a remarkable success that shaped the evolutionary course of the Earth for millions of years.  This change in perception is reflected in how we think dinosaurs moved: we no longer think that they dragged their tails on the ground, barely able to keep their heads from dragging in the mud.  Instead, we view them as much more nimble than we once thought.  And while Stegosaurus may not have been the nimblest of them all, you can clearly see how our ideas of how we think this animal moved around have changed over the years.

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!

Sunday, April 21, 2013

Welcome to 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!  This post will serve as the Homebase for the weeks festivities!  Below, we have a schedule of what I hope to have us talk about this week: we'll see whether I end up sticking to it or not!  I am also going to be making a few videos, as well, so be on the lookout for those!
The Posts:

Sunday: Welcome to Stegosaurus Week!
             The Genus Stegosaurus Through Time
Monday: The Thagomizer of Stegosaurus
Tuesday: The Plates of Stegosaurus
Wednesday: Baby Stegos Galore
Thursday: The Morrison Biota
Friday: Stegosaurs of the World
           Part 1: China
           Part 2: England, France, and Portugal
           Part 3: South Africa and Tanzania
           Part 4: Wyoming, Colorado, and Utah
Saturday: Stegosaurus at the Morrison Natural History Museum

The Videos:

How Would Stegosaurus Have Sex? [FOR MATURE AUDIENCES ONLY]
8 Truths about the Stegosaurus

The Songs:

The Stegosaur Song
Bone Wars, Marsh and Cope (to the tune of "Two Black Cadillacs")

Tuesday, April 16, 2013

Animal Questions #1: Jurassic Park Reality, Sea Otter Hand Holding, and the Great Auk Extinction

So I've started a new video series in which I answer questions about animals that you guys have.  I finished Episode 1 today, and if you click on the link below you can watch it, too!


CLICK HERE TO LEARN THE ANSWERS.

I decided I would also write out the questions and answers here, just in case some of you would rather read the questions and answers, instead!  So here they are, in all of their glory and splendor!

1. Could people actually clone dinosaurs and make a real life Jurassic Park?


Ever since the fantastic book Jurassic Park came out in 1990, people started to wonder: could this actually happen? Could we actually bring dinosaurs to life via the miracle of cloning? Following the release of the movie in 1993, the idea was on the mind of even more people. Sadly, (or perhaps fortunately), from what we understand about DNA at this point, we simply cannot clone dinosaurs, not even by using mosquitos trapped in amber. DNA is a very fragile molecule, and does not take all that long to break down. Sure, mammoth mummies frozen in the permafrost in Siberia have successfully yielded DNA. Mammoths, however, only went extinct several thousand years ago. From a geological standpoint, mammoths, you and I lived practically at the same time as each other, when compared to how long ago the dinosaurs roamed the earth. Furthermore, the permafrost has acted as a freezer, helping to preserve the DNA in ideal conditions for scientists to extract it from the mammoth at a later date. So to sum up? To the best of our knowledge, Jurassic Park: not happening. However, Pleistocene or Ice Age Park may not be all that far off!

2. Why do sea otters hold hands while they’re sleeping?


Sea otters often do this to keep themselves from drifting apart from other sea otters. Although adult sea otters generally forage for food by themselves, they will often form large groups, called “rafts,” sometimes numbering as many as 2,000 individuals. When in these rafts, to avoid floating apart from each other, they will sometimes hold hands. They will also sometimes tie themselves to kelp when they are sleeping or feeding to keep from floating away, as well.

3. Why did the great auk go extinct?


For those of you who are unfamiliar with the great auk (Pinguinus impennis), this penguin-like creature (a product of convergent evolution) inhabited the North Atlantic Ocean in the Northern Hemisphere, and became extinct mid-way through the 1800s. The great auk was intensely hunted by humans in European waters for their down feathers, (which were actually used in both pillows and hats), as well as for food. (Not the down feathers, mind you, but the meat of the bird and its eggs). It wasn't until 1553, around the time that the nesting sites of the great auk had been all but eliminated on the European side of the Atlantic, that the great auk first became officially protected. In 1775, people who had broken a law forbidding people from killing the great auk for its feathers were actually beaten publicly! Following the local extinction of the great auk in Greenland in 1815, the sole remaining breeding site of the great auk was a small, volcanic island. Off of the coast of Iceland, the island was dubbed "Geirfuglasker," after the Norse term for "great auk," "Geirfugl." In 1830, however, the great auk population on Geirfuglasker came under siege by two elemental forces that it had no hopes of combating: an underwater volcanic eruption and a subsequent earthquake, which combined to destroy the island, terminating most of the rest of the great auks. That’s not to say that the volcanic eruption and volcano are to blame: humanity definitely takes the bullet for that one.

If you have any questions yourself, ask me here at the blog, email me at cuyvaldar123946@gmail.com, comment below the video, or tweet them at me @TNaturalWorld1. Thanks for watching/reading/whatever you did!

Monday, April 15, 2013

23-Fact Tuesday: Strange Evolution of the Wild Pacific

So the other day, I enjoyed a Discovery/BBC program entitled "Wild Pacific," all about animals and humans in the Pacific.  This episode was entitled "Strange Evolution," and boy, were some of these guys strange!  Let's take a 23-Fact Tuesday look at some of these bizarre creatures!  Allons-y!

1.  The dingiso, a bear-faced, dog-sized tree kangaroo native to the rainforests of New Guinea, only became known to science in 1994, showing that there are still many, many fascinating natural phenomenon that have yet to be discovered by humans!

2.  Prior to the arrival of humans on Hawaii, it has been estimated that only one new species of animal or plant washed up on the shores every 35,000 years!

3.  With few terrestrial predators on the islands of New Zealand, the Fiordland crested penguin has moved from nesting along the shore to nesting within forests, moving along freshwater streams to reach their nests!

4.   The young of the Fiordland crested penguin are, of course, born in the forests.  They don't actually see the ocean (although the nests are usually close enough to hear and smell it) until they are about three months old, at which time they embark on their very first fishing trip: alone!

5.  On the island of Santa Catalina in the South Pacific, local fisherman fish in a simply fascinating fashion: they actually use spider webs from the golden orb spider that are reportedly as strong as kevlar to capture fish whose mouths are too narrow for conventional fishhooks!  Click on the link HERE to watch a short and fascinating video about this!

6.  Prior to human colonization of New Zealand, the only mammals that made it to its shores were bats and marine mammals.

7.  With so few terrestrial predators, one bat, the short-tailed bat, actually spends much of its time on the ground, foraging through the leaf litter, searching for the flightless weta, a relative of the locust.  In order to prevent damage to their delicate wing membranes, the short-tailed bat has developed special sheaths on its wings.  Interestingly, this terrestrial foraging behavior is probably very similar to how the bat's mouse-like ancestors behaved.

8.  The flightless kakapo is the world's largest parrot, and has developed sensitive whiskers on its face in order to help it navigate its way through the dark.  It's nocturnal behavior, as well as its size I would assume, has earned it the nickname "the owl parrot."

9.  The favorite food of the kakapo are the tiny seeds of the rimu tree and, since the bird is flightless, it has developed strong claws to help it climb up into the trees to reach the seeds.  Interestingly, the kakapo only breeds when the trees produce a "bumper crop," which is only about once every four years or so.

10.  Due to this odd cycle of breeding of the kakapo, the bird reproduces less often than almost any other bird.  By contrast, however, it lives longer than most others, sometimes up to 60 years!

11.  During breeding season, the male kakapo makes a "booming" sound to attract a female.  The male booms nonstop each night for 8 hours a night for up to three nights, resulting in thousands of booms.  The wind can carry the booms for up to three miles!  The female, of course, only responds to the males booms if the rimu seeds are plentiful.  Click HERE to check out some footage of the kakapo booming.

12.  LAST KAKAPO FACT, I PROMISE!!  The kakapo was almost hunted to extinction by humans for food and feathers, but they are making a human-assisted comeback now, climbing from only 51 individuals in 1995 to 91 individuals today!  (Possibly more, as I believe the television program is a year or two old or so.)

13.  The Australian brushtail possum was imported by colonists for fur to New Zealand over two centuries ago.  With no natural predators, however, it has spread like a plague, stripping trees of their vegetation.  About 70 million of them are estimated to inhabit the forests now.  That's like 350,000 a year, not including the ones that died.  Holy.  Cow.

14.  Introduced species can cause terrible problems to insular (island) ecosystems.  One of the most extreme examples is thought to be Easter Island, where it has been hypothesized that rats were what did in the colony.

15. For nearly 100 million years, the tuatara and its ancestors have remained almost entirely the same.  During the time of the dinosaurs, the tuatara's ancestors were very numerous, but following their extinction 65.5 MYA, they just couldn't compete, and were slowly extirpated across the globe.  Except in New Zealand, where they still reside today!  Incredibly, the tuatara sometimes can go an entire hour with only one breath!

16.  60 MYA, what is now the island of New Caledonia broke off from Australia, and is now 800 miles from the mainland.  This has allowed its native fauna to evolve in new and fantastic ways: such as the flightless, chicken-sized kagu, the only extant member of an ancient lineage.  HERE we have a fantastic video of this ridiculous bird!

17.  The monkey-tailed skink is the largest skink in the world, and is native to the Solomon Islands, an archipelago of nearly 1,000 tropical islands).  The monkey-tailed skink grows to around 3 ft. in length and weighs around 2 lbs., which is about 1,000 times heavier than the world's smallest skink.

18.  The monkey-tailed skink is an oddity amongst skinks.  Not only is it the largest skink in the world (as we mentioned above), it is also the only skink in the world to have a prehensile tail, which it uses to grasp branches while climbing in trees, assisted by its thick, sharp claws.   This is also an oddity, as most skins are terrestrial (meaning they live on the ground), as opposed to arboreal (which means that they live in the trees).  Furthermore, most skinks are insectivores, while the monkey-tailed skink is mostly vegetarian, consuming the leaves in the trees.

19.  The New Zealand kea, named for its call and native to the southern Alps, is considered to be one of the most intelligent and playful birds in the world.  As a matter of fact, some keas will damage cars out of curiosity!

20.  Up to thirty non-native species arrive on Hawaii every year due to humans, such as the Jackson's chameleon, native to east Africa, which was imported in the 1970s to Hawaii as an exotic pet.

21.  Another biological organism introduced by humans to Hawaii was sugarcane.  Like most places that humans visited, however, they also accidentally introduced rats.  And the rats ate the sugarcane.  Well, the humans who were trying to make a profit off of the sugarcane didn't like that, not one bit.  So, in the hopes of extirpating the rat population, the humans introduced the Indian mongoose.  However, what the humans failed to take into account was the fact that the Indian mongoose is diurnal, or lives during the day....while the rats are nocturnal, and move around at night.  So instead of eating the rats, the Indian mongoose eats the native birds.  Hawaii: 0.  Human Stupidity: A whole lot more than it should be.

22.  The ancestors of the I'iwi, a long billed honeycreeper endemic to Hawaii, were blown to Hawaii about 4 MYA, and looked very different from what they looked like today.  It is thought that they looked something like the Palila, a short billed finch that uses its tough beak to tear open tough seed pods.

23.  The last fact isn't from the program.  It's from "The Song of the Dodo" by David Quammen, one of my favorite books of all time.  It's a quote: "Islands are where species go to die."  He means that islands can be very dangerous places for animals to live.  But now with all the messes humans have introduced, that effect has been exasperated.  Just something to think about.

Wednesday, April 10, 2013

My Hearing's Alright (to the tune of "Feelin' Alright")

The most recent song: presenting "My Hearing's Alright," to the tune of "Feelin' Alright" by Joe Cocker.  Pretty sure that this is the only song ever to work the primitive bat Onychonycteris in!  Below is the link to the song:




Here are the lyrics to the song:


Seems I've got to have the best hearing
Cuz under a few feet of snow I hear lemmings
My hearing's just as good as a dolphin
Random clicks and whistles or so it seems
To them its sounds as loud as a scream
But they're using echolocation to help them see

My hearing's alright, (uh oh)
My hearing's quite good myself (uh oh) (x2)

There's no use in, tryin' to go and hide
Above your heads I'm way up high
Using echolocation while I'm above to help myself while flyin'
Suddenly under an attack, bugs just don't know why
Eating mosquitoes and their allies
Other bats drink blood I can't deny

My hearing's alright, (uh oh)
My hearing's quite good myself (uh oh) (x2)

52.5 million years from today
A bat named Onychonycteris lived, that's hard to say
Researchers say that this bat could fly but not echolocate
So these bats probably flew during the day
'Til something came along to take their place
The birds had come at last: to the night they chased

My hearing's alright, (uh oh)
My hearing's quite good myself (uh oh) (x2)





Are you diggin' the songs?  Well, then check out our playlist below!


Cowbird (to the tune of"I Know, You Know," the theme song from "Psych")

So song number ten, "Cowbird," goes to the tune of "I Know, You Know," the theme song from the very popular television "Psych."  It also probably requires a little explanation: the cowbird is a type of bird which lays its eggs in the nests of other birds, when the parents aren't paying attention.  The surrogate mother then has to raise her own children, as well as the other birds.  However, the cowbird doesn't let the other baby birds survive for long, and will push the eggs, as well as the other chicks, out of the nest.  So now that you have a little background, now you can enjoy "Cowbird!"  Below is the link to the song:




Here are the lyrics to the song:

In between the pines there's a lot of obscurity
I'm not inclined to resign to maternity
If it's too tight, then it's so long
I'll push out all your eggs so that they fall to the lawn
Oprah Winfrey I would appall

I know, you know that this just couldn't be true
I know, you know that I'm much bigger than you
Embrace the deception, my appetite with no end
Might send my surrogate mother go flying around the bend





Are you diggin' the songs?  Well, then check out our playlist below!


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