Meet Pyg!

Meet Pyg, the Triceratops hatchling! Pyg is the blog's new mascot, and will be using her unique blend of entertainment and education to help teach people about her long-lost world. Make sure to follow her on her exploits! I'll be using Pyg to help make our subject matter a little more fun, because, lets face it: dinosaurs are boring. Wow, I'm totally joking, no they're not, they rock! I'm actually with Grace Albers up in Dinosaur National Monument in Utah right now, so you'll probably be seeing some pictures from that trip pretty soon! However, tomorrow we will be talking about the recent Discovery/Megalodon controversy, so make sure to tune in then!

Meet Marshosaurus, Morrison's Mysterious Meat Muncher!

If I were to tell you to picture the environment of the Morrison Formation 150 million years ago (MYA) in the Late Jurassic Period, most of you would probably have no idea what I was talking about.  For some of you, the words “Morrison” and “Late Jurassic” would trigger images of enormous sauropods like Apatosaurus and Diplodocus, with the occasional plated Stegosaurus, and the carnivorous Allosaurus.  For still fewer, images of the ornithopods Camptosaurus and Dryosaurus might appear, the theropods Ceratosaurus and the smaller Ornitholestes, and perhaps another sauropod or two.  Fewer still might picture the theropod Torvosaurus, the ankylosaur Gargoyleosaurus, and the ornithopod Othnielia.  However, very few people indeed would think of the medium sized, 20-foot long theropod Marshosaurus.

Marshosaurus bicentesimus was first named in 1976, and received the second half of its scientific binomial name (bicentesimus) from the fact that it was described during the bicentennial of the United States!  The first part of the name (Marshosaurus) honors the famous paleontologist Othniel Charles Marsh, one of two main participants in the extreme paleontological competition more than 100 years ago!  If you want to learn more about the Bone Wars, be sure to check out a song that I wrote about it below: to the tune of Carrie Underwood's "Two Black Cadillacs!"

Anyways, all silliness aside, I actually got to see what is widely considered to be the most complete Marshosaurus specimen ever discovered about a month back when my friend Sam Lippincott and I got to go on a behind the scenes tour of the Denver Museum of Nature and Science with paleontologist Dr. Ian Miller!  To be honest, even from a paleontologists perspective, the Marshosaurus specimen was definitely not the most exciting thing there, not by a long shot!  Overall, all of the known material attributed to Marshosaurus taken together, there sure isn't much: four fragmentary skeletons, composed of bits and pieces of the spine, skull, and pelvis.

One of two small trays of bones belonging to Marshosaurus that the Denver Museum has on display in the paleo lab for the time being.  Looks like we have some vertebrae and ribs!

One of two small trays of bones belonging to Marshosaurus that the Denver Museum has on display in the paleo lab for the time being.  This box contains the right maxilla of the specimen.  You actually have a right maxilla, too: just tap abut halfway between your nose and your mouth on the right side of your face: that's your right maxilla!

According to a brief article written by paleontologist Dr. Joe Sertich and published in the Denver Museum's magazine, the specimen of Marshosaurus held at the Denver Museum has "large portions of the skull....several vertebrae, bones from the back and neck, and ribs."  Although it doesn't give us a lot to work with, such fragmentary remains are often all that paleontologists have to work with!  It appears to have been enough for some scientists to come to the conclusion that Marshosaurus is a member of the megalosauroids, a distinct group of meat-eating theropod dinosaurs that includes the famous Megalosaurus, the very first dinosaur ever described!  (I would say discovered, but most people suspect that ancient races have been discovering dinosaur bones for hundreds of thousands of years: but more on that later!)  It is thought that Spinosaurus and its relatives are closely related to the megalosauroids as a group.

According to the article, the remains of the Denver Museum's Marshosaurus specimen were discovered at a site in Dinosaur National Monument that, due to a fluke of the law (I would say loophole, but I feel like that's too harsh of a word), allows the Denver Museum to collect fossils and take them back to their collections, as opposed to them going to the collections facility at the visitor's center.  At this particular site, the remains of "at least six other animals made their way back to Denver."  Amongst these remains  includes the small, plant-eating ornithopod Dryosaurus, and the very famous Stegosaurus, as well as a few bits and pieces of a crocodile!

So how likely is it that Marshosaurus will become as famous as Tyrannosaurus and Triceratops?  Not very likely at all!  But it's a cool animal, and I definitely hope we find the remains of more of these guys sometime in the future!

Harris Hawk at the Dinosaur Hotel!

A few times now, I have mentioned the fantastic dinosaur-themed renovation that the folks over at the Best Western Denver Southwest.  Complete with life-sized models, museum quality casts lining the hallways, and a pool in the shape of the Western Interior Cretaceous Seaway, this is a hotel that paleo-fans of all ages won't want to miss!  Another awesome thing they do is a weekly raptor show on Saturday's at 5:00 PM.  I don't mean raptor like Velociraptor (which would be both amazing and terrifying at the same time), I mean bird of prey raptors.  But don't be too disappointed: they are still really super cool!  I went for the first time last Saturday, and was blown away by both the birds and the knowledge and passion of the presenter, Anne Price.  I plan on sharing many of these birds with you, and today I am going to share one of my favorites from last week, the Harris hawk!

In this picture, you can see the Harris hawk is not too happy about the great-horned owl being held by another volunteer about ten or fifteen feet in front of it!

There are three different subspecies of the Harris hawk, and this one was native to the Sonoran desert, in the American southwest.  Although sometimes the other sub-species will live in more forested areas, this particular type of Harris hawk prefers a desert life.  

Due to the fact that much of what lives in the desert is spiny, the Harris hawk learns from a very young age how to pick spikes and thorns out of its feet, especially the spines of the saguaro cactus.  This particular cactus is SO huge and so integral to the surrounding ecosystem that it is illegal in Arizona to either harm or destroy a saguaro cactus!

When abbreviated, the scientific name of the Harris hawk, Parabuteo unicintus, spells "P. u."

Unlike many raptors, the Harris hawk is a very social bird, hunting cooperatively in packs often numbering four or five individuals.  These packs, or family groups, will often have one or two of the birds fly down low to flush out prey, and once the prey is on the move, the rest of the pack will swoop in for the kill.

 

Since it is so darn hot in the Sonora Desert,  the adult Harris hawks are forced to shield their nests, with their offspring inside, with their outstretched wings to keep them from cooking alive.  If the "shield-bird" has to move, for whatever reason, an aunt or an uncle or just another member of the pack will instinctively swoop in to take up the shielding duties!  

I feel like since the Harris hawk lives in groups, it would be more tolerant of other birds.  Since they kept the Harris hawk out almost the entire time, even while the other three birds were out, this would make sense.

You can see in the picture above and the picture below that, while the Harris hawk wasn't too bent out of shape because of the presence of the great-horned owl, it wasn't necessarily super excited about it.  I mean, let's face it: if you or I were a hawk in the presence of this incredible owl, I might be a little nervous, too!

Like in most other birds, the Harris hawk is pretty much full-sized when it leaves the nest, since it has to be able to fly, feed, and take care of itself.  When their entire volume is taken into account, the young apparently are often bigger than the adults!  I don't remember exactly why that would be, but most likely due to the fact that the young have just been sittin' around on their heinies, and their parents have been working their heinies off to feed and care for them.

As you can sort of see in the picture below, the innermost toe claw of the Harris hawk, and most (if not all) hawks, is much larger than the other two forward-facing toe claws.  As you can probably see in the picture above, the hallux, or backwards-facing claw, is also much larger than those other two forward-facing claws.  I don't recall if this is a feature seen in other raptors, I'll make sure to ask this Saturday!

I also have a short video that I took there of the Harris hawk.  You can see how it looks, get a good size comparison, and listen to a little bit of the information that Anne has to say about it!

Here is a second video where the Harris hawk is featured, however briefly.  Although it features the red-tailed hawk, at one point the hawk poops on the floor, which unfortunately happens off camera!

Finally, here is another video in which the Harris hawk makes an appearance.  You can see when the camera pans over to the Harris hawk (the cinematography, by the way, is reminiscent of Star Wars or Planet Earth or something like that) that the Harris hawk, like we talked about before, is not terribly happy about the great-horned owls presence so close to it, but it is tolerating it nonetheless.  Despite the fact that it doesn't feature the Harris hawk all that much, it's still a really cool video, and will give you a hint for what's in store for later posts!

Make sure you check out the website for the Raptor Education Foundation by clicking HERE, and checking out the Facebook page for the Best Western Denver Southwest by clicking HERE!  

Mr. Bones Visits the Morrison Natural History Museum!

Yesterday, Mr. Bones, a local dinosaur enthusiast who's created some amazing looking dinosaur skeleton suits, visited the Morrison Natural History Museum!  The museum was also visited by Greg and Meredith Tally and their children, the fantastic people who are renovating the Best Western Denver Southwest to be a dinosaur-themed hotel!  All of these folks were here to make a brief teaser sort of thing to promote both the dinosaur hotel and the Morrison Museum!  I took a little bit of video, as well as some pictures, so make sure to check them out here!

 Greg Tally is attacked by Mr. Bones!

 Running is useless!

 Just a little too big for the door!

Below, we have a picture of Greg Tally helping out with the cameraman and Mr. Bones!

If you want to see some video of the museum's encounter with Mr. Bones, check out the video below!

Here, we have some shots of Mr. Bones taking a swipe at the museum sign out on the road!

Kids LOVE Mr. Bones!

 One of his other suits, a Utahraptor!  All of the other shots are of him wearing his "Kindergarten Tyrannosaurus rex" suit!

 A size comparison between the two suits.

 Mr. Bones goes in for the kill!

Top Ten Pokémon Inspired By Real Animals

Many of you are probably familiar with the popular video game and TV series "Pokémon."  While I myself never got into it, a few months ago, I did a post about the axolotl, a fascinating little salamander. While I was researching the post (which you can view by clicking HERE), I found that a Pokémon called Wooper was based off of the axolotl.  I thought this was pretty funny, as I thought that no one had ever really heard of the axolotl, much less based a video game character after it!  The more digging I did, the more I realized that this is a fairly common theme: a great many Pokémon are based off of real animals, both living and dead!  So I thought that for the birthday post of my good friend Masaki Kleinkopf, we could look at the Top Ten Pokémon Inspired By Real Animals!

1.  Farfetch'd - Duck

According to my Pokémon sources (AKA the Internet), the Farfetch'd is supposed to live in and around water, just like a real duck!  It's also supposed to taste pretty good: again, like a real duck!

2.  Lanturn - Anglerfish

Probably one of the freakiest animals in the animal kingdom, the deep-sea loving anglerfish bait other fish closer with the so-called "esca" on its head.  The little fish swim closer, attracted to the bioluminescence emanating from the esca, and then the anglerfish snaps them up.  The name of this Pokémon is clearly an homage to this glowing appendage.

3.  Shieldon - Ceratopsian

The ceratopsians are a large group of dinosaurs containing one of the most famous dinosaurs of all time: Triceratops.  Although most sources state that Shieldon is based off of Triceratops, the Pokémon differs in that it has no horns.  This makes a more likely candidate for the origin of Shieldon another, more primitive ceratopsian called Protoceratops.  If you click on the link to a post HERE and scroll down to the second picture, you can see a picture of the skull of Protoceratops.

4.  Sandslash - Pangolin

The Pokémon called Sandslash is clearly based off of a funny, but quite fascinating, animal called the pangolin.  Sandlash features the dermal armor of the pangolin (a fancy way of saying "armor formed from hardened skin, akin to the armadillo"), as well as the massive claws.  The claws, in both the pangolin and, apparently, Sandslash, can be used to attack potential threats, as well as burrowing.  The pangolin uses its claws to burrow into termite mounds, consuming them by the thousands.  Sandslash can also roll into a ball to defend itself from attack, just like the pangolin: however, I don't think that the pangolin can roll away from its attacker while in "ball mode."  For a song about dermal armor that features, amongst many other things, the pangolin, click HERE!

5.  Relicanth - Coelacanth

Relicanth is based off of a very unassuming, but entirely fascinating, fish called the coelacanth.  For many, many years, conventional wisdom had dictated that the coelacanth went extinct at the end of the Cretaceous Period, along with the non-avian dinosaurs, the pterosaurs, and the massive marine reptiles. This assumed extinction was backed up by the fact that no fossils had been discovered, at least none that had been positively attributed to the coelacanth.  It wasn't until 1938, when a live coelacanth was pulled up off the coast of Madagascar, that scientists realized that perhaps the coelacanth wasn't quite as dead as they thought it was.  Since then, other sites along the coast of Africa, as well as in Indonesia, have yielded live coelacanths, giving the prehistoric fish a title it very much deserves: a living fossil.  According to the Pokédex in the game (a sort of encyclopedia that talks all about the different Pokémon), the Relicanth was also recently discovered, and is also labeled as a "living fossil."

6.  Tirtouga - Archelon

So apparently, some Pokémon can evolve, which is another cool and clever way of adding science into video games without making the video games dumb and boring.  Apparently, the Pokémon Tirtouga isn't necessarily based off of the massive sea turtle Archelon, but Tirtouga actually evolved into another Pokémon called Carracosta that is based off of Archelon.  Tirtouga appears to be based off of either the extant (still living, opposite of extinct) leatherback sea turtle, or perhaps another extinct sea turtle called Protostega.  Either way, all three sea turtles look pretty much the same!

7.  Archen - Archaeopteryx

It's in the name: clearly, the name Archen is based off of the name Archaeopteryx, a fossil bird that is widely considered to be the missing link (at least the first in a long line of links) between dinosaurs and birds.  First discovered in the 1800s, the feathered fossil of Archaeopteryx helped famed naturalist Charles Darwin and his followers to promote his ideas about evolution and natural selection.  According to the Pokédex, Archen is not able to fly, leading people to speculate that Archen is also based partly off of other, non-flying feathered dinosaurs, such as Velociraptor or Deinonychus.

8.  Lileep - Crinoids

Up until last week, I'd never devoted a whole lot of thought to the evolutionary relationships of a fascinating group of creatures called crinoids.  In my mind, if they look like plants, they're probably plants!  Well, I was wrong: the crinoids are actually echinoderms, just like sea urchins and sea stars, and are actually animals!  I also didn't realize that crinoids were still around today: I knew that there were a ton of them in the past, but I didn't realize that some of them had survived to the present day!  Many people believe that Lileep is based off of these strange animals, and it's not too hard to see the resemblance!

9.  Cranidos - Pachycephalosaurus

Of all of the pachycephalosaurs, Pachycephalosaurus seems like the most likely candidate for the inspiration of the strange Pokémon called Cranidos.  The main means of attack of this Pokémon is by head-butting its opponents, a means of combat long attributed to the pachycephalosaurs.  This head-butting is currently under a lot of scrutiny, with some paleontologists saying that yes, of course pachycephalosaurs head-butted each other, in the same fashion that bighorn sheep do today.  On the other hand, some paleontologists say that there is no way these guys could head-butt each other, as their necks would simply snap after a few impacts.  Other paleontologists believe that they did use their heads for head-butting, but not in the way that the previous two groups were hypothesizing: instead of getting a running start and then cracking heads, bighorn sheep style, they would instead just lock heads without the running start, like many types of deer and elk that spar today.  Still others propose that maybe these dinosaurs were smacking each other in the side or in the flank.  Like many facets of paleontology, we may never know what, exactly, they did with their craniums. 

10.  Anorith - Anomalocaris

This is the Pokémon that really inspired me to do a post like this.  Anomalocaris is one of my favorite animals because it is just so weird looking!  Living in the Cambrian Period, about 500 million years ago (MYA), Anomalocaris is definitely one of those animals that does not get a lot of the limelight.  Often found amongst the various and assorted crazies from the Burgess Shale in Canada, Anomalocaris is definitely something that I never expected to be in a video game!  Nevertheless, here it is!

This was the birthday post of Masaki Kleinkopf! Happy birthday, Masaki! If you have a birthday coming up, just email me the date at cuyvaldar123946@gmail.com with the date and your favorite animals, and I will do my best to get a post in! And if you like what you are reading, please feel free to follow us here or via Facebook!

Not Enough Bacteria, Too Many Allergies

If you were to hear someone say "by making our world more sterile, we're actually making ourselves sicker," you might think they were full of it: initially, it sure doesn't sound like it makes any sense. Interestingly, however, it seems as if this may, in fact, be true: our attempts to make our world a cleaner place, we are slowly and steadily weakening our own immune systems!

It all started yesterday as I was working at the Morrison Natural History Museum, watering and destroying the angiosperms from the Jurassic Garden with "extreme prejudice," as angiosperms do not appear to have inhabited Colorado during the Jurassic Period. I started wondering why there was so much dead plant material around the base of the plants in the garden, and, for lack of a better conclusion, decided that it was probably because the bacteria that would normally digest these plants didn't actually live here. (I still don't know whether that is true or not). The topic of bacteria triggered my brain to start thinking about digestive bacteria: I was quite hungry, you see. It had been brought to my attention in the past that, even if humans were somehow able to miraculously clone a dinosaur, we almost certainly couldn't keep them alive. Each animal on the planet has its own, unique set of bacteria that helps it to digest its food. With the extinction of the dinosaurs, it is almost certain that the bacteria that constantly accompanied them in their digest tracts went extinct, as well.

This line of thought made me think about the passing of bacteria from the parents to their offspring. How is it done? I assumed that they weren't born with it, but I wasn't sure. I ended up thinking that perhaps, in animals that regurgitate food into the mouths of their young (like penguins), perhaps this was how the bacteria was passed. With perfect timing, out came Matt Mossbrucker, the director and curator at the Morrison Museum. I asked him whether it was, indeed, regurgitation that passed the bacteria on, and he said yes: partially. You know how many animals (such as your dog and cat at home) will eat poop? That's at least part of the reason: they're trying to get bacteria from the poop to help them digest their food!

After thinking about it for a few seconds, I realized that humans (most of us, anyways) neither regurgitate our food for our young 'uns, nor do we eat each others poop. So I asked Matt whether humans get this bacteria through breast milk: turns out, we don't. So how do we get the bacteria?

According to recent research, humans aren't getting enough bacteria to digest their food. Much of this research seems to indicate that perhaps this is the reason why so many humans have digestive issues, allergies, and the like. Matt also said that, just like I said in the introduction, "by making our world more sterile, we're actually making ourselves sicker." Still sound paradoxical? Well, ultimately, humans are trying so dang hard to sterilize their world with hand sanitizer, bleach, alcohol, and soap, that we aren't being exposed to as many pathogens. While in some cases this is a good thing, in other cases, our immune systems, just like the six-pack of someone who doesn't exercise, slowly weaken.  And, of course, a weak immune system is good for no one!

So is the moral of the story to stop washing your hands?  No, of course not.  It's to go out there and eat poop.  See you later, everyone!

Alphabet Animals: The Letter Q (Extinct)

In our last post, we looked at some extant, or still living (as opposed to extinct) animals whose name begins with the letter "Q."  Today, we are going to look at a few more of these animals, but this time we are going to be looking at some of those extinct animals!  Let's go, team!

1.  Quetzalcoatlus - One of the largest flying animals of all time, Quetzalcoatlus is not a dinosaur like it is often thought to be.  Instead, Quetzalcoatlus is a memeber of a distinct group of archosaurs (a large groups of reptiles that includes crocodilians and dinosaurs) called the pterosaurs.  Quetzalcoatlus lived in the Late Cretaceous Period of North America, between around 68-65 MYA.

2.  Qantassaurus - A small Australian ornithopod, Qantassaurus was named by paleontologist-couple Patricia Vickers-Rich and Tom Rich after the Australian airline Qantas.  Qantassaurus lived about 115 MYA, when Australia was still a little south of the Antarctic Circle!

3.  Qiaowanlong - A sauropod dinosaur from Yujinzi Basin of Gansu, China, Qiaowanlong was first discovered in 2007, and lived about 100 MYA in the Early Cretaceous Period.

4.  Quagga - An extinct subspecies of the plains zebra, the quagga was once found in the Karoo of South Africa, and was the first extinct creature to have its DNA studied by scientists.  The quagga was actually hunted to extinction by humans: the last wild one is thought to have been shot in the late 1870s, while the last specimen ever known to have existed died on August 12, 1883 at a zoo in Amsterdam in the Netherlands.

5. Qingxiusaurus - Described in 2008, Qingxiusaurus is yet another sauropod dinosaur whose name begins with a "Q."  Like Qiaowanlong, Qingxiusaurus was also found in China.  Qingxiusaurus lived much later than Qiaowanlong, however, in the Late Cretaceous Period.

6.  Qiupalong - An ornithomimosaur, or ostrich dinosaur, Qiupalong lived during the Late Cretaceous Period of China, and is the first ornithomimosaur that is definitively known from outside the Gobi Desert in Asia.

7.  Quaesitosaurus - With a name meaning "extraordinary lizard," Quaesitosaurus lived between around 85 and 70 MYA in Mongolia.  It was first discovered in 1983, and its skull was likened to that of a horse.

8.  Quilmesaurus - Native to Argentina during the Late Cretaceous Period, not a lot is known about Quilmesaurus.  It is estimated to have been between around 16 - 20 feet long.

9.  Qinlingosaurus - Yet another Late Cretaceous Asian sauropod, Qinlingosaurus was named after the Qinling Mountains of China in 1996.  

Stegosaurus at the Morrison Natural History Museum (Stegosaurus Week)

So as you probably know (at least if you've been following us here for Stegosaurus Week), the whole point of the special week was to celebrate Stegosaurus Day at the Morrison Natural History Museum in Morrison, Colorado!  But what Stegosaurus-related exhibits does the Morrison Natural History Museum even have?  Well.  I am so glad you asked.  Let's dive on in!  

The first Stegosaurus-related thing that you will see is just a small exhibit, whose size is not a good representation of its importance.  The four groups of bones that you see here are part of the holotype specimen of Stegosaurus!  It was with these bones, as well as the rest of the specimen (part of which is at the Morrison Museum, the rest in the collections at Yale in Connecticut)  that paleontologist Othniel Charles Marsh first named and described the genus Stegosaurus in 1877, during the famous (or rather, infamous) Bone Wars.  Below, we have a picture with the four different groups of bones highlighted in red. 

The first bone that we see below is part of one of the plates of Stegosaurus!  The entire specimen actually extends back several inches, but the fossil part of the specimen is only on the very top layer.

Next, we have part of the femur of Stegosaurus!

Here we have two different types of vertebrae of Stegosaurus, lumbar and caudal (back and tail) vertebrae.

The next picture is an illustration by paleoartist Fabio Pastori of what this animal would have looked like.  Meet Stegosaurus armatus, one of four species of Stegosaurus that are currently considered to be valid!

Next, we have some more VERY interesting Stegosaurus fossils, as well as a cute little baby Stegosaurus model!  This little guy below is about a foot long, and is a life-size representation of the animal that would have made that footprint.  Besides being the very first baby Stegosaurus footprint discovered anywhere in the world, this footprint is especially interesting because it shows that the baby Stegosaurus was walking on its back legs, without its front legs touching the ground!

Here we have another Stegosaurus footprint: or rather, a trio of footprints!  The main footprint on this slab of Jurassic-aged rock contains what is largely considered to be the best adult Stegosaurus hind foot track in the world!

This footprint-containing slab is of particular importance to the paleontological community for another reason other than preservation quality: not only does the slab contain a very well preserved hindfoot track of an adult Stegosaurus, it also contains a forefoot track, probably from the same individual, as well as a partially crushed juvenile Stegosaurus track.  This partially crushed juvenile Stegosaurus track is of particular importance, as it seems to be pretty strong evidence that the adult and the juvenile were traveling together! 

Next, we have a cast of a skull of Stegosaurus, next to a cast of the foot of the animal, as well as a reconstruction of the foot itself! 

Next, we have a VERY interesting block of fossil-containing rock!

It all started when the block was brought into the museum because of the dinosaur bones, like the rib bone you can see below from an unidentified dinosaur....

....and these bones, on the back of the block.  It wasn't until the block was brought inside the museum that researchers noticed something that they hadn't been able to see outside: some tiny dinosaur footprints!

Here are two of the footprints, below.  The one on the left, about the size of the palm of my hand, is thought to belong to a mid-sized ornithopod, likely a hypsilophodont or a heterodontosaur, we don't really know.  The much smaller one on the right (which isn't much larger than a house cats) is even harder to identify, and could belong to a wide variety of dinosaurs.

  

Here is another picture by Fabio Pastori, depicting the small ornithopod that might have made the tracks.

The other tracks on the slab are by and large considered to be much more interesting.  What you are looking at below are some more baby Stegosaurus footprints!  Remember the baby Stegosaurus footprint that we discussed below, and remember the model of the animal that was thought to have made it?  The model is about the size of the animal that is thought to have made the little tracks on the left in the picture below!  What's particularly interesting about these footprints, however, is that they show the footprints of at least two individual Stegosaurus, each probably just a few months old, superimposed on each other!  This seems like pretty good evidence that these guys were also moving in groups, just like the other slab of Stegosaurus footprints shows us with older individuals!  The smaller footprint on the right (again, around the size of a domestic cat's footprint) is from a much smaller individual, probably just a hatchling!  It is also possible that this hatchling was moving with the other juveniles, as well!  

This is a model of the hatchling Stegosaurus that made the footprint on the right in the three pictures that we have above.

Finally, we have a size comparison of footprints of Stegosaurus at different ages!  The bottom one is from an infant Stegosaurus, maybe an inch and a half or so in diameter.  The top one is from an adult, larger than your average dinner plate!

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!