A few days ago, I sat down and, with several hours of homework to do, watched Ridley Scott's 1979 classic "Alien." It was phenomenal, and I enjoyed it, and went on to watch Predator (great) and Prometheus (not so great). Now, on this excellent but snowy Thursday afternoon, I'm about an hour into "Aliens," knowing that any second now an Alien xenomorph is going to appear out of nowhere and kill something. But that's not why I paused the movie at the 54:44 minute mark. What I've been thinking about is far more pressing: what's the purpose of that enormously distended xenomorph cranium?
If you have no idea what's going on in this picture yet, that means you're probably sane.
Usually with aliens, you can just pass off a big head as an indicator of big brains. Ki-Adi Mundi from Star Wars, for example, has two brains in that big 'ol Cerean cranium of his, and an extra heart to boot. If you rewatch "A New Hope" extra carefully, see if you can't spot Pons Limbic (note the brainy pun) in the Mos Eisley Cantina, the big-brained Siniteen whose head literally resembles a brain. The Guardians of the Universe from the D.C. Comics franchise are often pretty wise, but in light of some recent events, they might not be quite as level headed and emotion spectrumless as we thought (but that's a story for another bright snowy day). The Face of Boe from Doctor Who seems to be pretty smart, given that he's literally just a giant head in a tank and can communicate telepathically. Then there's Zilius Zox, a Red Lantern from the D.C. universe, who also appears to be little more than a giant head. Both Jumba (from Disney's "Lilo and Stitch") and E.T. the Extra-Terrestrial (from E.T. the Extra-Terrestrial) seem to have noggins that are larger than average in proportion to body size, and seem to have above average intelligence to match. Marvin the Martian and Roger from American Dad? Both smart, both big-headed.
A skull of the duck-billed hadrosaurParasaurolophus at the American Museum of Natural History in New York, from my visit last summer with my good friend Zach Evens (who also deserves some credit listing big-brained aliens).
Now what about the aliens, or xenomorphs, from the "Alien" franchise? Although undeniably intelligent to some degree, they aren't what you'd typically think of when the subject of brainy aliens comes up around the dinner table, at least not in terms of processing power. But they definitely have big heads. So what are they used for if not for thinking? We, of course, can turn to the science of dinosaur paleontology to help us with this question. Take a look at the dinosaur skull above. This critter is a hadrosaur, or duck-billed dinosaur, called Parasaurolophus. Scientists believe that it blew air through its special crest to produce a sound very similar to that of a trombone! Many hadrosaurs had wild cranial ornamentation, as did other dinosaurs such as some of the ceratopsians and the pachycephalosaurs, just to name a few. These wacky head-dos almost certainly had a whole lot to do with attracting a mate and sexual selection. Essentially, the bigger your crest is, the more attractive you are. Is it possible a similar sort of thing evolved for the Alien xenomorphs? In "Aliens," we can see that the queen has a different head pattern than do all of the other xenomorphs that we've seen so far, indicating some sort of sexual dimorphism is potentially at work. Interesting. What should you take from this blog post? Probably just that I have way too much time on my hands.
On a brief side note, I realized I've actually talked about the skull of the xenomorphs previously, before I'd even seen the movies. Check out that post, all about otter skulls, by clicking HERE.
Alien vs. predator vs. Parasaurolophus vs. Tyrannosaurus vs. Lego Gilderoy Lockhart vs. Darth Vader vs. Polly Pocket vs. creepy frog candle vs. macaw vs. Apatosaurus vs. medieval archer vs. Boba Fett Pez Dispenser vs. Ambelodon vs. mallard vs. fisherman from an ironic fish cake vs. Jumba vs. Craire Cat Hello Thingy vs. six different types of shark vs. Taz monster truck vs. Aragorn son of Arathorn vs. Liam Payne vs. Marty from "Pirates of the Caribbean" vs. mouse cat toy vs. basilisk lizard vs. Spider-Man vs. penguins with jet packs and missile launchers vs. Themistocles vs. Terri Irwin. And this is why it takes me so long to write a blog post. I think we were all a little surprised about how quickly things escalated. Yeah, I definitely have too much time on my hands.
As we talked about IN A PREVIOUS POST, dinosaurs are pretty big in Canada. A large number of dinosaur species have been discovered up there, and one of the best places to find dinosaurs is a place near Calgary in Alberta called Dinosaur Provincial Park. As a matter of fact, Dinosaur Provincial Park is a UNESCO World Heritage Site, along with 981 other properties "which the World Heritage Committee considers as having outstanding universal value." Other famous sites include the Great Barrier Reef in Australia; the Galápagos Islands; Stonehenge; the Grand Canyon; and "Memphis and its Necropolis," the site of the Great Pyramids and the Great Sphinx of Giza! Just to name a few. Do you get the idea, though? Dinosaur Provincial Park is kind of a big deal!
But why? What makes a bunch of badlands with some dinosaur bones in them so important to Canada, much less a committee dedicated to protecting such international treasures as the Great Barrier Reef and the Great Pyramids? What makes Dinosaur Provincial Park so GREAT? (Get it? Nevermind, it wasn't that funny anyways.) Here's what the UNESCO website has to say about the park:
The property is unmatched in terms of the number and variety of high quality specimens, over 60 of which represent more than 45 genera and 14 families of dinosaurs, which date back 75-77 million years. The park contains exceptional riparian habitat features as well as "badlands" of outstanding aesthetic value.
The committee also included two main criterion that show why the park is so important:
Criterion (vii): Dinosaur Provincial Park is an outstanding example of major geological processes and fluvial erosion patterns in semi-arid steppes. These "badlands" stretch along 24 kilometers of high quality and virtually undisturbed riparian habitat, presenting a landscape of stark, but exceptional natural beauty.
Criterion (viii): The property is outstanding in the number and variety of high quality specimens representing every known group of Cretaceous dinosaurs. The diversity affords excellent opportunities for paleontology that is both comparative and chronological. Over 300 specimens from the Oldman Formation in the park including more than 150 complete skeletons now reside in more than 30 major museums.
Wow. Well that's a pretty big deal! According to the website, between 1979 and 1991, a grand total of around 23,347 fossils were collected, including an amazing 300 dinosaur skeletons! As mentioned above, the dinosaur skeletons represent every known group of Cretaceous dinosaurs. (I assume that they mean every group that is known to live in North America at the time.) Not only does the sheer amount of fossils allow for a more complete view of an extinct ecosystem, new dinosaurs and other animals have been discovered there, as well as potential behavior that can be inferred from the fossils!
During the Late Cretaceous North America was divided by the Western Interior Seaway, a shallow, continental sea. (To learn more about the seaway, check out a recent post I did on it by clicking HERE). In Dinosaur Provincial Park, you can find the remains of both ocean going animals and land dwellers, as well! The park is, of course, famous for its dinosaurs (as you could probably tell from its name). But many of the marine creatures entombed in the rocks there and in the surrounding area are pretty awesome, as well! For example, Hybodus, an interesting shark!
Before we get to the dinosaurs, let's check out a few other cool creatures found in the park! One of these is a creature we mentioned in a previous post: the post entitled "There Be Dragons," all about the monitor lizards! In the post, I had a picture of a prehistoric monitor lizard named Palaeosaniwa attacking a flock of Ornithomimus. Well, both of these creatures have been found in the park! Below is the picture, created by talented paleo-artist James Field! You can check out his website HERE!
Many animals have been discovered in the park, including turtles, crocodilians, and a ton of plants, but the only other non-dinosaur we are going to look at for now is a small little primitive marsupialmammal called Eodelphis! Eodelphis, whose name means "early opossum," is thought to have weighed a little over a pound which, astonishingly, means that it was one of the largest mammals of its time! It is thought to be related to Didelphodon, another Mesozoic marsupial mammal, who we shall meet in an upcoming post!
Now for the dinosaurs! I'm going to start with an animal called Centrosaurus. A ceratopsian dinosaur (just like Triceratops), thousands of individuals specimens of Centrosaurus have been discovered in a massive bonebed that extends for hundreds of meters! While paleontologists disagree as to exactly what killed all of these animals, and in such immense numbers, the prevailing theory is that this was a herd of animals that drowned while trying to cross a river. The individuals that make up the herd vary widely in age, which is one of the lines of evidence which supports the herd idea. This is important evidence for paleontologists, as it indicates that these animals lived in groups!
Another dinosaur that is found in the park is the small pachycephalosaur called Stegoceras, who is not to be confused with the similarly named and much more famous Stegosaurus!
Here is another fun dinosaur, called Chirostenotes! This oviraptorosaur was first found in the park, and is definitely quite funky looking!
Dromaeosaurus, a distant cousin of Chirostenotes and a closer relative of the famous Velociraptor, was also first discovered in the park!
Just as Dromaeosaurus has been pushed from the limelight by Velociraptor, so too has Daspletosaurus been pushed by Tyrannosaurus! Daspletosaurus is a tyrannosaur as well, and was first discovered in (surprise surprise) Dinosaur Provincial Park! Two more Dinosaur Provinicial Park natives (and firsts) are Euoplocephalus, one of the tank-like ankylosaurs, and Parasaurolophus, a hadrosaur or duck-billed dinosaur!
I can't WAIT to visit the park one day! In the meantime, HERE is a link to the park's website so you, too can plan your visit!
The horns and frills of Triceratops. The tube-like crest of Parasaurolophus. The two crests of bone on Dilophosaurus. The sail on Spinosaurus. What function do these various bells and whistles that adorned these so-called "Terrible Lizards" serve? For years, most paleontologists assumed that they were for the sole purpose of combat, be it against predators, or the inter-specific variety. But now, more and more paleontologists are looking to birds to answer the question of functionality when it comes to these bony dinosaurian protuberances.
But what, specifically, about birds is it that is helping paleontologists figure out the purpose of these structures? It all boils down to an interesting phenomenon called "sexual selection." Most people are familiar with the term "natural selection." Popularized by Charles Darwin, natural selection essentially states that animals that are unfit to survive and reproduce in a given environment will die, and will be unable to add their genes to the genepool. (Certainly an oversimplified definition, but you get the picture.) Sexual selection, on the other hand, is a mode of natural selection, and introduced by Charles Darwin, as well. Sexual selection states that some individuals in a given population will be more likely to breed than other individuals will because they will stand out above the rest of the population. There are many ways of doing this, and birds are but one example. Horns and antlers are one instance: typically, if an animal has larger horns or antlers, they will be able to not only fend off predators better (i.e. natural selection), but they will be more likely to be able to fend off other males, and be more likely to be picked for the females (i.e. sexual selection). In many animals, form overcomes functionality in this endless quest for a mate, especially on insular (or island) populations. One of my favorite examples of this is the birds of paradise from New Guinea, as you can see in the video below.
That's all well and good, but how does that apply to the dinosaurs that we were talking about above? Well, for years, paleontologists assumed that dinosaurs like Triceratops and its relatives were using their horns and frills to fight off predators. Well, for Triceratops, that makes sense: with forward-facing horns and a two-inch thick frill, fighting off Tyrannosaurus doesn't seem that far out of the realm of possibility. However, upon examination of many of the other relatives of Triceratops (collectively called ceratopsian dinosaurs), you can see that, perhaps, not all of these frills and horns evolved to fight off predators. Below we have just one example. The picture you see is of a skull that below belongs to a ceratopsian dinosaur called Einiosaurus. As you can see, it does not seem anywhere near as well equipped for fighting off predators as Triceratops does. For example, its frill has a pair of massive holes in it. Furthermore, of its three horns, one points downwards, and two point towards the sky at about a forty-five degree angle. Unless Einiosaurus was being attacked by giant woodchuck-like, burrowing dinosaurs, or being dive-bombed by Tyrannosaurs in F-14s (as seen in Calvin and Hobbes!), it is difficult to see how Einiosaurus might have defended itself against its predators using its frill and horns. Another analogy I like to make is this: if you are a knight going into battle, you don't necessarily want to have a pair of giant holes in your shield, and your sword bent and pointing towards the ground.
So how does this all tie in to Stegosaurus? Well, a same sort of discussion has centered around Stegosaurus for many years. Were the plates used for defense? Or were they used for something else? First let's address the idea of defense. IN THE PREVIOUS POST, we discussed the thagomizer, the group of tail spikes, on the rear end of Stegosaurus. These tail spikes were almost certainly used to fend off enemies, and seemed to have done a very good job, too. So, if you think about it, if you were to cover a stegosaur in these spikes, it would be almost impervious to attack, right? Well, what's interesting is that, early in stegosaur evolution, many of these animals actually did have a lot more spikes than Stegosaurus did. As a matter of fact, the plates of Stegosaurus are nothing more than heavily modified spikes! Below, we have a few more primitive stegosaurs, all of whom demonstrate the fact that, prior to Stegosaurus, many of the plates were actually spikes!
So if the spikes were better than plates were at defending an animal against predators (which is the only logical conclusion that I think people can draw from the data at hand), then why did some of the stegosaurs change? For many years, paleontologists thought that they had a pair of answers to this interesting dilemma. The first was the idea that perhaps Stegosaurus used its plates as a thermoregulaton device. If the animal was too cold, then it could turn its body so that its plates faced the sun, maximizing its surface area that was facing the sun, and enabling it to warm up quicker. The reverse would have also worked: when it became to hot, Stegosaurus could turn perpendicular to the sun, minimizing the surface area that was absorbing the sun. Another theory was that Stegosaurus could flush blood to the plates, turning them a brighter color. This could have either frightened off enemies, or instead it could have been used to attract a mate.
These two ideas seem fairly good in theory: however, much like the skull of Einiosaurus, there are a few massive holes in this logic. If Stegosaurus used its plates as a thermoregulatory device, why do close relatives of Stegosaurus have very different plate shapes, or sometimes fewer plates altogether? If there was one design that these animals used to warm up or cool down, one would imagine they would all converge on the same design. But they didn't, which casts some serious doubt on the whole thermoregulatory idea.
There are two theories that seem to hold the most water today. The first one has the same general idea that the "flushing the plates full of blood" idea has: make yourself more noticeable, as these plates were very impressive looking structures. And, since they alternated down the back (SEE THE FIRST STEGOSAURUS WEEK POST HERE), then a side-on look of Stegosaurus would have been a very impressive sight, indeed! Other stegosaurs of the opposite sex would undoubtedly think so, and these plates probably served a large role in attracting a mate! Predators might have thought that the side-on view was impressive, too, and this might have caused them to think twice about attacking Stegosaurus. It also might have caused other members of the same species to back down, too, in cases where inter-specific combat might have otherwise come into play. As Matt Mossbrucker, the director and curator at the Morrison Natural History Museum likes to say, "think a skinny kid in a puffy coat."
Finally, the plates might have helped stegosaurs to differentiate from one another. This is a tactic often used in animals today (again, the birds of paradise and many other birds: see the last paragraph of our post on the cichlids of the Great African Rift Lakes HERE), and is thought to have been a tactic used by many extinct animals, as well. For example, the various horns and frills of the ceratopsian dinosaurs (like Triceratops and Einiosaurus that we were talking about before) are now thought by many paleontologists to have been used to tell each individual species apart, and its possible that that is what the stegosaurs were doing, too.
Want to learn more about Stegosaurus? Well, check out the Homebase for Stegosaurus WeekHERE to partake in more of the festivities!
Just a few days ago, we had our first ever guest blog post by David Church. Mr. Church did his top ten favorite dinosaurs, which got me thinking about what my favorite dinosaurs were, and inspired me to do this post! So here is my top ten favorite dinosaur list!
Assorted Allosaurus bones from our visit to the Cleveland-Lloyd Dinosaur Quarry
8. Spinosaurus
Spinosaurus is an enormous carnivorous dinosaur that we have talked about on multiple occasions, both in our "Biggest Carnivorous Dinosaur" trilogy of posts awhile back, but also in Mr. Church's Top Ten list. Spinosaurus, despite the fact that it is easily the largest known carnivorous dinosaur, with an estimated length of almost sixty feet, did not eat meat like the other enormous dinosaurs: instead, Spinosaurus was a piscivore, or a fish eater. This giant creature lived in Africa during the Cretaceous Period.
7. Parasaurolophus
Parasaurolophus is another one of those dinosaurs that overlaps from Mr. Church's list to my own. Parasaurolophus is certainly an interesting creature! A member of the hadrosaurs, or duck-billed dinosaurs, Parasaurolophus, as Mr. Church discussed, is the only dinosaur I know of where paleontologists know with a high degree of accuracy what they sounded like. The large crest on the back of the head of Parasaurolophus is full of hollow tubing, similar in shape and structure to the trombone, as well as similar in sound, too. Unfortunately, I could not find a sound file or video of the call, so if anyone has access to a scientifically reconstructed call, let me know!
Today, almost all paleontologists believe in one of two scenarios that brought upon the downfall of the dinosaurs; the Silver Bullet Hypothesis, and the Blitzkrieg Hypothesis. Proponents of the Silver Bullet Hypothesis consider the asteroid that hit Mexico 65.5 MYA to be the cause of the dinosaurs extinction, while fans of the Blitzkrieg Hypothesis believe that the asteroid worked in concert with other factors, like a number of extraordinarily large volcanic impacts and receding sea levels. Although both of these hypotheses hold great weight, and stand up well to investigation, I find myself more in the Silver Bullet camp. (If you are unsure, check out this video: http://www.youtube.com/watch?v=5gqq2rgOmi8 . It's a bit long, but you can skip parts of it and still get the gist. I was simply blown away after watching it, and landed smack-dab in the center of the Silver Bullet camp.)
However, this post is not to talk about the merits of the generally accepted dinosaur-death hypotheses; just like the post regarding the oddly named animals (http://thenaturalworld1.blogspot.com/2012/07/masiakasaurus-knopfleri-and-other.html), Scott Sampson's book Dinosaur Odyssey had another especially interesting tale, a tale about the many different hypotheses (over one hundred in all!) about how the dinosaurs died from over the years. Here are some of the more interesting ones, quoted from Scott Sampson's book:
1. Disease
2. Slipped Vertebral Discs: Because dinosaurs were so big
3. Loss of Interest in Sex
4. Poisonous Plants 1: The consumption of these plants led to a deadly diarrhea amongst the dinosaurs
5. Poisonous Plants 2: The consumption of these plants led to a deadly constipation amongst the dinosaurs
6. Fungal Invasions
7. Climatic Change 1: Global Warming
8. Climatic Change 2: Global Cooling
9. Cosmic Radiation From a Supernova
10. Egg-Eating Mammals
11. Sunspots
12. Nasty Aliens
13. Not Enough Room on Noah's Ark
14. The Racial Senility Hypothesis: Dinosaurs, as a group, were young and restless when they first appeared in the Late Triassic Period. During the Early Jurassic, the dinosaurs experienced "adolescence," as they expanded "in both form and diversity." When they reached the Late Jurassic and Early Cretaceous, the dinosaurs had "reached their evolutionary peak;" they were middle-aged, and had nowhere to go but down. Thus, in the Late Cretaceous Period, when the dinosaurs like Triceratops, Parasaurolophus, and Pachycephalosaurus grew interesting crests, frills and the like, these were "the result of hormones gone wild and certainly symbolic of a group on its way out."
Obviously, some of these solutions are more interesting than others, but all of them are, at this point in the study of dinosaurs, outdated. But who knows: perhaps, someday soon, someone will discover proof that it was aliens, and not an asteroid, that ultimately did-in the dinos.
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