Plesiosaurs- The Lords of the Ocean

They look like the Loch Ness Monster. We got that out of the way.

In this writer's opinion, plesiosaurs are some of the strangest vertebrate animals to ever live. One the split between reptiles more closely related to lizards and snakes (Lepidosauromorphs) and those more closely related to birds and crocodiles (Archosauromorphs), plesiosaurs fall closer to the lizard side of things. But they don't really look like lizards at all, nor are they terribly closely related to them. Most of the typical plesiosaurs look like someone grafted a snake into the shell of a sea turtle. But there is some degree of variation in body shapes in this group, including ones that looked more like reptilian killer whales than anything else. These creatures were the top reptilian predators of the Mesozoic oceans until giant mosasaurs like Tylosaurus appeared on the scene. Lets dive in (yes that was intended) and learn what we can about the strange, wonderful plesiosaurs.

We know that modern whales came from mammals that went back to living in the ocean (I say "went back to" because all tetrapods come from fish that evolved to live on land), and became highly specialized for living only there. Returns to the ocean are not an unheard of occurrence in vertebrate evolution. In the mammals it happened several times- with the cetaceans (whales/dolphins), the sirenians (manatees/dugongs), and the pinnipeds (seals/sea lions/walrus), as well as to some degree with hippos and Desmostylians. In reptiles, this phenomenon has occurred numerous times. Due to their slower metabolisms, reptiles do very well living in water. The temperature of warm oceans is generally consistent, they can exploit various food sources, and can hold their breaths for long periods of time. This has led numerous groups of reptiles to return to a life in the ocean to exploit open niches present there, an few became so specialized to it as the plesiosaurs. While many aquatic reptiles led a more amphibious lifestyle, returning to land to breed or rest, the more evolved plesiosaurs led their entire lives in the water, much like whales do today. And while reptiles can indeed return to the water relatively easily, plesiosaurs went through a variety of dramatic changes from their ancestral form.

Plesiosaurs, as previously mentioned, have a body much like a sea turtle. They didn't have shells like a turtle exactly, but many other similar features are found in this group. The most obvious similarity is the flippers. It's hard to believe that the turtle-like flippers of a plesiosaur are made up, internally, of the exact same bones found in the limbs of humans. In the front limbs, their upper arm bones are very large, much more so than the lower arm bones, indicating a powerful locomotive ability. Plesiosaurs, in contrast to the ichthyosaurs and mosasaurs, powered their swimming not with their tails (which were rudimentary at best) but with their limbs. Most of the flipper is composed of the "finger" bones, which have become extremely elongated. The digits and wrist make up about half of the length of the limb by themselves. These proportions are similar in the hind limbs. These long, pointed flippers are what was used to paddle through the water. It seems like plesiosaurs were very strong, agile swimmers, and did a lot of moving around. Unlike many other marine reptiles, the trunk region of plesiosaurs was very rigid. The pelvis and chest of these animals were extremely broad and flat, and connected together by a strong network of rib-like bones running across the belly called gastralia. This means that the whole bottom end of plesiosaurs was rigorously sturdy, and gave the animal a barrel-shaped trunk. This may have acted as a bracing device for the body while paddling.

The most obvious and famous aspect of plesiosaurs is their long neck. Actually, not all of these animals had this trait. Scientists split plesiosaurs into two general groups: the long necked plesiousaurids, and the short-necked pliosaurids. We'll talk about the former group first. Anyway, on to that neck. First of all, forget any misconceptions you may have about these animals raising their head out on an s-shaped neck far out of the water, the way a swan does. Plesiosaurs actually seem to have had very little flexibility in their neck, and were just able to break the water's surface with their heads to catch a breath of water. It seems as though wherever the head and neck went, the body would follow. Early paintings of plesiosaurs tend to show its head and neck writhing through the water like a snake to catch fish, but this was also impossible. The plesiosauroids had relatively short, round snouts and smaller, flatter heads than their pliosaur counterparts. Their teeth were many, long, and pointed, suggesting that these animals fed mostly on fish and molluscs. Most scientists view these animals as relatively slow yet powerful swimmers, snatching up unwary fish that swam within range of their necks (which, in animals like Elasmosaurus, could get mind-bogglingly long).  

The other main group is the pliosaurids. In contrast to their long necked, short faced cousins, pliosaurs had short, stocky necks and long pointed snouts. They had similar teeth to the plesiosaurids and the smaller species were likely fish eaters, but the larger ones would likely have gone after bigger prey. And pliosaurs could get very big. Animals such as Liopleurodon, Pliosaurus and Kronosaurus could raged from 30-50 feet long. Unlimited by the constraints of land, these creatures grew massive and would feed on large fish (including sharks) as well as other marine reptiles. Pliosaurs were fast, active hunters and dominated the oceans until the mosasaurs showed up to challenge their reign later.

What we aren't too sure about yet is how exactly plesiosaurs moved their great flippers. Two schools of thought exist- one suggest that plesiosaurs "flew" through the water, flapping their flippers up and down in a figure-eight pattern, somewhat like how a sea turtle or penguin swims. The other theory states that plesiosaurs "rowed" their way through the oceans, the same way a sea lion uses its flippers to row itself along. Both theories have their supporters and detractors, and both certainly have their merit, but neither seems terribly more accurate than the other, as the pectoral and pelvic girdle anatomy has some physical traits that make either theory, in some aspects, seem unlikely. It could very well be that some sort of movement, unseen in modern animals, was utilized by plesiosaurs, but no one is sure what exactly that could be.

The reproductive adaptations of plesiosaurs are no less interesting than the anatomical ones. It's fairly safe to assume that, much like ichthyosaurs, plesiosaurs gave birth to live young in order to get around the problem of being an egg-layer living in the ocean. Scientists first envisioned them as reproducing like sea turtles- crawling out onto beaches and laying their eggs there (there are still a small number of scientists who support this theory). While this may have been feasible for smaller, more primitive plesiosaurs, the much larger ones would have been unable to get into land at all, due to their immense bulk and inability to propel themselves on land. While we only have physical evidence of ichthyosaurs giving birth to live young, it's reasonable to assume that plesiosaurs evolved this trait independently as well. Plesiosaur fossils have been found with single, large, well-developed offspring inside their body cavities, which supports the theory that the young hatched within the mother and emerged shortly after.

The history of the study of plesiosaurs is nearly as interesting as the animals themselves. Discovered and named years before the term Dinosauria was given to a certain group of terrestrial Mesozoic archosaurs, the first plesiosaur fossils were discovered in England. In a time where women were unfortunately excluded from most professional activities in English society, the first plesiosaur bones were unearthed by a Dorset woman named Mary Anning, who discovered not only the first plesiosaur, but the first animal to be identified as an ichthyosaur. Anning, who had great knowledge and talent at anatomy and fossil collecting, made countless other advances and discoveries in the fields of biology and palaeontology, in spite of her low social class and gender. While not allowed to partake fully in the dealings of the scientific community at the time, Anning worked tirelessly at collecting and preparing fossils from the seaside cliffs, which allowed others to advance the knowledge of extinct species. I leave you with the request that, whenever you see a plesiosaur or any other beautiful marine reptile, remember Mary Anning, and all the other incredibly bright women who intrepidly contributed to science in spite of the obstacles laid against them.

Mosasaurs- A Journey Into Prehistoric Seas

One of the unfortunate side-effects of the fame of dinosaurs as a group is that the spotlight often gets taken away from other Mesozoic creatures who were just as impressive. It catches some people off guard to find out that, between the Triassic and Cretaceous, dinosaurs were not the only animals alive at the time. When you consider the diversity of living things in the world today, it's ridiculous to think that, over the span of hundreds of millions of years, only a certain group of Archosaurian vertebrates existed. Even within the Sauropsida (the group that contains all reptiles and birds), there were amazingly diverse and amazingly large creatures roaming the earth at the same time as the dinosaurs. While it is certainly true that dinosaurs were the largest terrestrial animals at the time, the oceans were teeming with all kinds of unrelated marine reptiles. Today, we'll focus on one of them- the mosasaurs.

I'm sure most readers are wondering what the heck a mosasaur is. Well, if I may flog this point a little more, they were not dinosaurs.  Let me explain (this may take  while...)- you can split 'reptiles', birds and mammals into three general groups based on how many holes, called temporal fenestrae, they have in their skulls behind the orbital holes. These holes in the skull allow for attachment of the jaw muscles. Animals with no temporal fenestrae are called anapsids. This group contains many weird extinct creatures, as well as, perhaps, the turtles and tortoises. Animals with one fenestra are called synapsids. These are the mammals and their ancestors. The last group is animals that have two fenestrae, which is what we're concerned with. These are called the diapsids. Now, if you're still with me, you can divide the diapsids into a further two groups. One of them is the archosaurs. These creatures, in their primitive conditions, are united by having a hole in the skull in front of the orbit called the antorbital fenestra. This is the big, triangular hole just before the eyes you often see in many dinosaurs. Archosaurs also have a hole in their lower jaws called the mandibular fenestra. They also tend to have relatively large skulls, round non-overlapping scales, s-shaped necks, and an upright erect posture. As well as a few early primitive animals, the main groups contained within the Archosauria are the crocodiles, pterosaurs, and avian and non-avian dinosaurs. Still with me? Now, going back to the split in the diapsids, the other group that parallels the Archosauria is the Lepidosauria. The lepidosaurs are the tuataras, lizards, and snakes. Lepidosaurs lack many of the skull holes that characterize archosaurs, but they tend to have more kinetic skulls. This means the bones in the skull can move a little to a lot relative to each other. Lepidosaurs also generally have a sprawling posture, which gives them a more primitive, side-to-side form of movement. They also have a sliding joint in the pectoral girdle for locomotion, and keratinous scales, he outer layer of which they shed as they grow. This is the group that the mosasaurs belong to. They bear all the features of the lepidosaurs and are actually classified as a kind of lizard.

tl;dr- mosasaurs aren't dinosaurs because of their skeletons and other things.

Okay so, I've exhaustively gone over what mosasaurs are to science. But what exactly are they? I mentioned something about them being lizards, and that's true. However, it's much cooler than that. Picture a modern day Komodo dragon, which is a close relative of our animals of focus. Now, picture a Komodo much, much bigger, living in the Mesozoic oceans, with limbs evolved into flippers and a long, powerful tail for aquatic propulsion. As happens with many different tetrapod groups, the ancestors of mosasaurs were terrestrial animals that returned to the oceans. These creatures ranged from the modestly sized Platecarpus at 14 ft long, to the massive Tylosaurus, which may have reached lengths of around 50 ft. Mosasaurs had elongated, lizard-shaped bodies, with long, streamlined skulls and nostrils places on the top of the snout for easy access to air at the water's surface. Unlike the long, paddle-shaped flippers of plesiosaurs, mosasaurs had short, round flippers adapted for aquatic steering. These flippers were formed by the skin between the digits (yes, mosasaur skeletons still show five fingers on each hand) growing around the digits to form a fleshy flipper. Unlike the long crushing teeth of Tyrannosaurus, mosasaurs had shorter, conical teeth that were slightly curved. This allowed them to grasp slippery, wriggling prey. The jaws of mosasaurs are also pretty neat- there was a kinetic joint in the middle of the lower jaw, on each side, that would have allowed the lower jaws to expand out to the sides, thus increasing the gape of the animal and allowing it to swallow very large prey items. This is basically how modern snakes are able to expand their jaws to swallow big animals. This similarity, among others, has led some palaeontologists to suggest snake are, perhaps, descendants from the mosasaurs.

Being equipped with very long tails leads scientists to presume, as stated earlier, that mosasaurs swam primarily with their tails. This contrasts the other group of large Mesozoic reptiles, the plesiosaurs, that had very short tails and propelled themselves with their long, oar-like flippers. It was assumed for a long time that the way that mosasaurs swam was much like how a modern day snake swims- by wiggling its body from side to side, generating a sort of wave down the whole of its body which propels the animal forward through the water. This is called anguilliform locomotion and is also seen in animals like eels. However, new evidence suggests that some later, more highly derived mosasaurs had a downward-kinked tail, with a fleshy sort of fin sticking out of where the kink in their tail bones occurs. This gave them, essentially, tail flukes that formed a crescent-shaped structure on the end of their tails, much like a shark. And, like a shark, the mosasaurs that had these elaborate tail flukes probably held their bodies quite rigid and propelled themselves by powerful thrusts with their tail fins. This kind of adaptation is also seen in ichthyosaurs, so it could very well have evolved again independently in mosasaurs.

 The way that mosasaurs lived their lives is no less fascinating itself. It seems as though the smaller species fed on mostly fish, while larger mosasaurs could eat fish, sharks, aquatic birds, and other marine reptiles. There's also direct evidence from tooth marks on fossils that mosasaurs would, from time to time, attempt to feed on ammonites, and would even scavenge off the bodies of dinosaurs that had died and drifted out to sea.

One obstacle in their lives they would have had to face was that of giving birth. It's impossible for reptile eggs, with their semi-permiable shells, to be laid in water and survive. The offspring would die. Modern sea turtles get around this problem by hauling themselves onto land (a very difficult process for them) and laying their eggs there. This solution is feasible for the earlier, smaller species of mosasaurs, but for the massive 50 ft Tylosaurus, it would have likely been impossible for such a heavy, bulk animal to get onto land with its small, underdeveloped limbs. Its likely that such a gigantic animal, not being able to support its own weight, would end up crushing itself on land. There is a solution though- fossil specimens of ichthyosaurs have been found in the midst of giving birth to live young. It seems likely that ichthyosaurs, who could also not have gotten themselves onto land, kept their eggs inside their bodies until the young were ready to hatch. The baby ichthyosaurs would then hatch inside their mother and be "born" into the surrounding water. Many scientists now think that mosasaurs adopted this process for giving birth, freeing them from having to leave the water. Now, being descended from land dwelling reptiles (but unrelated to each other), neither ichthyosaurs nor mosasaurs could breathe in water and would have had to come to the surface for air. This poses problems towards giving live birth,  as its a timely affair as any mother will tell you. But nature found a way around this- the ichthyosaur specimen found mid-birth shows the offspring coming out of the mother tail-first. This means that, for the whole time its being born, the young ichthyosaur could still breathe until, at last, its head emerges. It would then, presumably, make a dash to the surface for its first gasp of air. Though we have no direct evidence, it seems likely that mosasaurs used this tail-first live birthing method themselves.

The prehistoric world was teeming with life that came and went long before human beings arrived on this planet. The incredible diversity of weird and fascinating creatures requires much more study to truly understand it, and it's worth remembering that we've still only discovered a fraction of the animals and plants that came before us. So when you think back to the time of the dinosaurs (as cool as they were), remember that they had a plethora of wonderful neighbours that deserve our admiration just as much.

The Truth on the Tyrant- The Facts of Tyrannosaurus Rex

Whenever I ask a child what their favourite dinosaur is, the vast majority of replies are either an enthusiastic "T. rex!!!" or a contemplative "Hmm.... Umm.... T. rex?" Clearly, genuine or not, this dinosaur enjoys perhaps the most popularity of any of the extinct Archosaurs. From the earliest Charles R. Knight paintings to its CGI depictions in modern cinema today, everyone is in love with the tyrant lizard king. Spielberg himself acknowledged that the true star of his film was the Tyrannosaurus. What's surprising, then, is how little the public truly knows its favourite dinosaur. So let's pick on our perceptions of T. rex (and on Jurassic Park, once again) and get to the truth on this tyrant. 

To begin with, everyone knows that Tyrannosaurus was the largest, most ferocious meat-eating dinosaur ever. If there was one dinosaur you did not want to meet in the primeval jungle, it would be Tyrannosaurus. Everyone else comes in second to its size and danger. Well... Not really, actually. I realize I'll be bursting a lot of bubbles here, but Tyrannosaurus was definitely not the biggest carnivorous dinosaur. Now, don't get me wrong, it was one of the biggest, and certainly was the biggest Tyrannosaur (the rex had many earlier, smaller relatives, such as Daspletosaurus and Tarbosaurus). However, bigger Theropods had come and gone by the time T. rex hit the scene. Dinosaurs like Acrocanthosaurus, Gigonotosaurus, and Charcarodontosaurus were all bigger, unrelated Theropods that prowled the Cretaceous before Tyrannosaurus evolved. These creatures certainly would have been impressive in their time, and all of them would have made Tyrannosaurus look a bit shrimpy. However, the dinosaur Spinosaurus towered over all of them, and was likely the biggest meat eating animal to live on land. Spinosaurus was remarkably longer and taller than Tyrannosaurus, and its height was even further exaggerated by its towering neural spines that formed its characteristic sail. Dino nerds may remember that Jurassic Park 3 (for all its many flaws) did acknowledge that Spinosaurus was bigger than Tyrannosaurus (Dr. Grant in fact claims that it "sounds bigger". I'm not sure how one determines that but oh well). The film goes further to drive this point home by showing the Spinosaurus (spoilers) kill the Tyrannosaurus after an epic battle. While, if this match up were to be hypothetically arranged, seems one sided in that Spinosaurus was indeed the larger of the two, Tyrannosaurus fans can take comfort in the fact that T. rex had a much stronger bit. In fact, it had the strongest bite of any known animal, ever. This is aided by T. rex's long, bone-crushing teeth, contrasting the conical, fish grabbing teeth of Spinosaurus. So the outcome, in more ways than one, would be impossible to determine. 

A second misconception involves the seeing abilities of Tyrannosaurus. It's commonly believed that Tyrannosaurus could only see something if it was moving. This is impractical for various reasons, the main one being how an animal who can only see moving objects would be able to avoid trees and rocks and whatnot. But let's assume that it only recognizes prey items by movement. Why on earth would an apex predator who often would have needed to hunt by sight evolve a trait that severely handicapped its ability to find its prey? This makes little evolutionary sense. The truth is that Tyrannosaurus likely had very good eyesight. It had foreword-facing orbits, indicating good binocular vision. It's also reasonable to assume that T. rex had a very good sense of smell, which pokes a hole into the scene in Jurassic Park 1 where the rex is right in front of a very still Dr. Grant and cannot find him. One would assume that, even if T. rex did have terrible eyesight, the sense of smell afforded to most large predators would give away Grants position. 

A third rex myth that's popped up, even in the scientific community, is that Tyrannosaurus was not a hunter but a scavenger, feeding off the bodies of dead dinosaurs like a giant vulture. This theory has gained some popularity, but had largely been discredited by most Theropod experts. There doesn't seem to be much of a reason for a scavenging animal to have such a huge size, an extraordinarily powerful bite, teeth evolved for crushing bone in order to kill large animals, and powerful hind limbs. This contrasts the features of most obligate scavengers. Now, many modern large carnivores will scavenge from relatively freshly killed animals when the opportunity arises, and there's no reason to assume Tyrannosaurus was an exception to this rule. However, its anatomical features suggest that it was an animal that was more than capable of bringing down its own prey. Fossilized bones from various large herbivorous dinosaurs have been found with puncture and lesion marks in them. Many of these marks show signs of healing, indicating that the animal was alive when it received the injury and survived long enough for the injury to heal. This, therefore, shows us that Tyrannosaurus did indeed go after live prey. 

This, obviously, ruins a lot of people's ideas as to what Tyrannosaurus would have looked like and how it would have behaved. If this is somewhat disappointing, it's important to remember that our view of this dinosaur has changed dramatically over the years since it was first described in the early 1900's. Sadly reality doesn't always concede to how we would like things to be, but at the same time each newly confirmed theory brings us closer to the ultimate truth about how things were and are. 

Prehistoric Imports: Where Canada's Large Mammals Came From (And Where Some Have Gone)

Canada has an impressive collection of large native mammals that everyone should feel proud about. We can boast five species of deer- the white tail, mule, elk (Wapiti), caribou, and moose. Though much reduced in range, two of Alberta's national parks are home to enormous populations of American bison. Our carnivores are no less impressive. Grizzly bears roam our western mountains, polar bears frequent the Arctic region, and black bears are found all across the country. Dogs like wolves, coyotes and foxes too make their home throughout the land, and cougars, bobcats and lynx make up our elusive wild cat population. We also have very recognizable smaller mammals, such as our emblem, the beaver, as well as small carnivores like weasels, minks, and badgers. These species all give off a distinctly Canadian feeling to those who are from here. It's interesting to learn, then, that most of the species listed here have very close relatives that are found throughout northern Eurasia. Some of these species themselves even occupy ranges that spread across the northern latitudes of both landmasses. Where does some of this overlap come from? Why can you go to Eastern Europe and run into beavers and moose? There's an answer to this: faunal interchange.

If you went back in time to the period where huge glaciation events ended up in most of North America being covered by vast sheets of ice (colloquially dubbed the "Ice Age"), you would find that the Bering Straight, the expanse of water separating the eastern tip of Russia from the western tip of Alaska, is gone. Due to the effects of glaciation, the sea levels have dramatically receded. In place of a frigid cold sea, there would be a great bridge of land joining Asia ands North America, known as Beringia. This land bridge facilitated the movement of both plants (the Boreal Forest, covering most of northern Europe, Asia and North America, has a fairly uniform set of plant species) and animals between Eurasia and North America. What species went where is a subject of interest.

Most people are surprised to learn that both camels and horses first evolved in North America. It's fairly common knowledge that all of our domestic horses here were brought over from Europe by Europeans, and small bands of wild horses still roam their native habitats on the plains of Mongolia. It's also pretty hard to picture a camel running around on the North American prairies. But they were here. When the land bridge connected them to Asia, wild horses made the trek over to the 'Old World'. Why? Possibly food. More territory perhaps. Niches for a medium-sized, galloping, grazing animal were open in Asia at the time. Either way, horses made it to Asia and spread further into Europe and Africa too, eventually going extinct in their ancestral homeland of North America. It wasn't until the Spanish brought them back during early colonization that horses once again got to see the land they (unknown to them) originated in. As for camels- the modern Dromedary and Bactrian camels, which inhabit the Middle-East and central Asia respectively, owe their ancestry to camels that followed horses on the journey from North America to Asia. Meanwhile, their relatives, the guanaco and vicuna (as well as their domestic descendants- the llama and alpaca), come from North American camels that went south into South America when the Panamanian land bridge formed.

So what did the Americas get in return for camels and horses? Well... Beavers, bears, bison, big cats, caribou, elk, foxes, humans, mammoths, mastodons, moose, wolverines, and weasels. To name a few. Yes, the ancestors of these animals which proceeded to diversify throughout North America had their start in Eurasia. These creatures traversed back and forth across Beringia and, when the land bridge vanished beneath the sea, they were trapped on both sides. The grey wolf, as well, followed a similar path from it's original home in North America, spreading widely throughout Europe and Asia. However, the level of similarity between mammals living on one side of the Pacific versus the other has some variation to it.

While beavers in the genus Castor occupy both continents, a different species is present on each landmass (canadensis in North America, fiber in Eurasia). The brown bear Ursus arctos is present on both sides, but each continent has a different collection of subspecies. The genus Bison originated in Eurasia. Although different species spread around that landmass, the only surviving one is the wisent (Bison bonasus). Upon arrival in North America, several other bison species evolved and eventually gave rise to the American bison (Bison bison) that exists to this day. Cats, such as cheetahs, lions and the famous Smilodon ranged across NA but are now extinct (however, the jaguar, a close relative of lions, tigers, and leopards manages to make a living from Mexico southwards). Moose and the relatives of todays American elk (also known as Wapiti) are present on both continents but arose in Europe. Red foxes naturally range throughout most of the Northern hemisphere and it's probable that they too came across on the land bridge (although some have argues that they were brought over by Europeans during early colonization events).

Some of the most well known animals to make it to North America were the hairy elephants- the mammoths and mastodons. Fossils of these creatures have been found from Europe to Siberia, down through Alaska and Canada and further south into the United States. As the vegetation and climate of both continents homogenized, cold-adapted elephants made the trip east across the land bridge, where they survived up until the last 10,000 years, leaving a few remarkably preserved bodies frozen into the ice of the north. It's interesting to note that, up until a certain point in time, some native people of northern Russia and Canada were trading in mammoth ivory, and believed the beasts were still alive out there somewhere. While untrue, it's a tantalizing thought.

Brontosaurus Blues

Name off some of the first dinosaur names you ever learned as a child. Triceratops. Tyrannosaurus. Stegosaurus. Brontosaurus? Yea, of course, everyone knows Brontosaurus. The definitive Sauropod, the one everyone thinks of when people talk about the "long neck" dinosaurs. You see its big round body, long neck and tail and tiny, periscope-like head in countless books and movies and paintings of prehistoric life. Indeed, if there was ever a dinosaur's dinosaur, it would have to be Brontosaurus. 

So what if I told you there was never such thing as Brontosaurus? 

Well, not technically anyway. The animal who's fossils we found and subsequently named "Brontosaurus" certainly existed. But here comes my dark raincloud to hover over the parade dedicated to our love for this dinosaur. To understand why Brontosaurus is no longer used by scientists today, we first have to look at some rules. 

There's a strict set of them guiding how exactly we're allowed to name species. Not their common names mind you. Those aren't always reliable and are subject to variation, as some animals are known by different common names in different areas (for example- the cougar, as it's called in Canada, is also known as the mountain lion in the USA and the puma in South America). It's the species scientific names that have rules attached to them. These names are binomial and are the same everywhere, no matter what. Going back to the cougar, although its common name varies between people, to science it's always known as Puma concolor. That way, there's no question about what species you're talking about. As a side note, as far as dinosaurs go, we don't really have common names for them, so all dinosaurs are known by the genus part of their scientific names. That's the first word in their binomial scientific name. For example, in Tyrannosaurus rex (one of the few dinosaurs often referred to by its full name), the "Tyrannosaurus" part is the animal's genus, while the "rex" part is its species. 

So what does all that have to do with Brontosaurus? Well, back in the late 19th century, there was a very prominent palaeontologist names Othneil Charles Marsh, who discovered a huge Sauropod dinosaur, and named it "Apatosaurus". For those who have never heard of it, Apatosaurus looked a lot like what you think of Brontosaurus looking like. Exactly like it, in fact. Shortly after this discovery, Marsh dug up more, similar fossils from a site close by and, in his zealous attempt to name more dinosaurs than his arch-rival Edward Drinker Cope, he named the animal that these new bones belonged to "Brontosaurus". Everybody immediately thought Brontosaurus was pretty awesome, with artists such as the legendary Charles R. Knight doing several famous paintings of the creature. From a very early point, Brontosaurus became engrained into popular culture along side such celebrities and Triceratops and T. rex.

Then, years later, a scientist named Elmer Riggs made an startling discovery: he was closely examining and comparing the fossils of both Apatosaurus and Brontosaurs. Riggs noticed that the two animals were so similar that they actually should belong in the same genus together (this type of event all too commonly creeps up in palaeontology). Now that it had been decided that the two animals were similar enough to be grouped under the same genus, the question arises- do we call them both Apatosaurus or Brontosaurus? Well, the codes of zoological nomenclature have an answer to this: if two specimens of an animal, once thought to represent two distinct types, are found to be the same thing, the name that was first given to describing the the animal is the name that is kept. Marsh coined the name Apatosaurus in 1877, and Brontosaurus in 1879. So, since Apatosaurus was the first name used to describe the animal, everything that we used to call Brontosaurus now should be called Apatosaurus. That's why there was, in a sense, no such thing as Brontosaurus. 

Obviously the name Brontosaurus is dying a very slow death. While scientific institutions consistently refer to the animal in question as Apatosaurus, it seems like many people are having a lot of trouble breaking the Brontosaurus habit. So should the people who love Brontosaurus so dearly just grit their collective teeth, accept Apatosaurus and throw Brontosaurus reluctantly away? Well, yes and no. It still is technically correct to us Apatosaurus and only Apatosaurus when you're dealing, scientifically, with this dinosaur. The naming system is designed to avoid confusion (although this isn't always the result), so switching between the two names isn't a logically sound solution. We all should learn to love Apatosaurus. However, this doesn't mean the Brontosaurus has to go away completely. I'm acquainted with a few people in the field of palaeontology who make a habit of colloquially referring to the Sauropods in general as the "Brontosaurs" (Brontosaurus does mean "thunder lizard", so it's a pretty fitting name for the group). At the end of the day, when all the politics of naming organisms has got you down and confused, it's worth taking a moment to reflect on the fact that these creatures certainly never knew, nor cared, what names we would later give them.  

Birds- An Origin Simplified

When I talk to people about dinosaurs, more often than not, two things will eventually come up. The first, as always, is Jurassic Park. Do I like it (yes), how realistic is it (not terribly), and could we ever do something like that (probably not in the foreseeable future). And, aside from Tyrannosaurus, the one animal that always gets brought up in the wake of this movie is Velociraptor.

Everyone thinks it was awesome, even if we can now look back at it's depiction in the film and acknowledge the flaws present- despite close relatives coming from the region, Velociraptor was not found in the western United States (it's a Mongolian genus). It was not as big as depicted in the film. As Dr. Grant puts it, Velociraptor was between 5 and 6 feet high and 9 feet long. In reality, Velociraptor was roughly the size of a small turkey and likely not much more dangerous to something the size of a human (it's cousin Deinonychus, however, does bear a similar design to what is shown in the film and is also found in the USA). Another thing that science has proven and we've been getting good at warming up to is the fact that Velociraptor, and most likely all of its relatives, had feathers. This is a trait I see more and more in popular depictions of these animals. However, I've also found that the average person without a degree in palaeontology often struggles to put the pieces together and fully grasp the evolutionary implications we draw from the fact that the 'raptors' had feathers. Does that mean they could fly? Did birds really come from dinosaurs? Modern birds aren't dinosaurs, though... Right? These are questions I hear often. Let's clear up this messy subject.

What you must first understand is that the historical perception of scientists and the public as a whole really affects on how we think about birds and dinosaurs today. So I hope you'll be able to suffer me a jaunt down history lane. The group Dinosauria was first coined by Sir Richard Owen, the legendary English anatomist in 1842. Back in those days, only three types of what would later be called dinosaurs were known: Megalosaurus, Iguanadon and Hylaeosaurus. Not too much was known about these creatures aside from the fact that they had similar hip and limb structures, and so Owen united them based on that. It was obvious that these creatures were 'reptiles' (I use the term loosely), and since the general conception of reptiles back then was of creatures that were dull, ugly and sluggish, early palaeontologists depicted these first dinosaurs as such. Soon the world became dinosaur crazy and many different species were being discovered throughout Europe, the opening North American frontier, and other such places. This led us to gain a more three-dimensional view of dinosaurs as perhaps not as lazy and lizard-like as we'd assumed. While the Bone Wars raged across the American West, a very special fossil was unearthed in Germany.

 It was the skeleton of a small, carnivorous Theropod from the late Jurassic. If that had been all that was preserved, we would have called it a Theropod dinosaur and left it at that. However, surrounding the body, limbs, and tail was a coat of fossilized feathers. Feathers identical in structure to that of a modern bird. Now, in those days, the origin of birds was a pretty big mystery. The early supporters of Darwin's evolutionary theory were busy putting together how organisms were related, but no one had yet found anything to really put the birds alongside. Scientists like Edward D. Cope noticed similarities between the skeletons of Theropod dinosaurs and modern birds (the shape of the bones and structures, especially in the limbs, the upright posture of the body, the way the head was supported, the presence of hollow bones... the list goes on), but this wasn't enough to convince everyone. Not until this little feathered dinosaur emerged from Germany, which was named Archaeopteryx. Thomas H. Huxley, the other legendary English anatomist and die-hard supporter of Darwin, looked at Archaeopteryx and saw that it was certainly a dinosaur- it had a long bony tail (as opposed to the short stump present in birds), a mouth full of teeth (all modern birds have toothless beaks), and three dinosaurian fingers (in birds, one finger has been lost and the other two have fused into one). However, it's birdlike features balanced out its dinosaurian features- it's feathers were well suited for some degree of flight and its fingers were much more slender and elongated than what was seen in other dinosaurs at that time. Huxley saw this as evidence that birds had evolved from dinosaurs, and that Archaeopteryx was and early along the continuum between the two. We might even call it the first bird.

Huxley's idea, however, was largely ignored by the scientific community, who still saw dinosaurs, for the most part, as slow, scaly behemoths who lived and died, leaving no descendants. Then, in the 1970's, discoveries were made, and perceptions began to change. John Ostrom discovered our old friend Deinonychus, and noted the slender, gracile, upright (one might say bird-like) structure of the skeleton, which implied an active and fast lifestyle for the animal. Around the same time, Robert Bakker published The Dinosaur Heresies, in which he argued that many, if not most, dinosaurs were not the stupid, cold-blooded, lizard-like creatures we thought they were. Instead they were active, fast, and highly successful in their time (some may have even been warm-blooded, just like mammals and -gasp- birds). Based on his analysis of Deinonychus, Ostrom reawakened Huxley's theory that birds had evolved from dinosaurs. He argued that the two groups were so closely related that we really should start thinking of birds as living dinosaurs in their own right. His evidence was convincing, and scientists started to listen.

The argument that birds are dinosaurs received even more merit when, in the following decades, small Theropod fossils began turning up from China that bore what were obviously feathers. Scientists also noted the presence of a furcula (aka wishbone) in Theropod dinosaurs, something also seen only in birds. The evidence was now pretty well undeniable. Palaeontologists now assert that we now must think of birds as highly adapted dinosaurs that evolved the ability to fly and survived the Cretaceous extinction. As Dr. Grant says in Jurassic Park, bet you'll never look at birds the same way again.

But hang on a minute! Let's go back to the raptors. How do we know that they had feathers? We haven't found Velociraptors or Deinonychus with preserved feathers! True, but, look at it this way- let's say your grandfather has brown skin. So does your father. Let's also say you have a child, and they too  have brown skin. It would make a lot of sense if you yourself had brown skin too. Now apply that logic into a more broad evolutionary view. If the older relatives of a species have a certain trait (such as feathers) and the younger relatives of said species also have that trait, it would make sense for the species in question to have that trait too. Let's look at Velociraptor. One of the most significant feathered dinosaurs we've found so far is a creature called Microraptor. Microraptor was an older relative of Velociraptor and Deinonychus and all the other 'raptors'. It also just so happens to have a good coat feathers. Logic dictates then, that if more primitive raptors such as Microraptor had feathers, and their more evolved cousins the birds had them too, then dinosaurs like Velociraptor almost certainly had a good coat of feathers. From this we've been able to infer that other types of dinosaurs that were closely related to the raptors (the technical term is Dromaeosaurids, and they're considered to be the 'sister-group' to the birds), such as the Ornithomimids, Oviraptorids, and even the fearsome Tyrannosaurs had feathers too.

Alright, you're likely asking yourself, dinosaurs had feathers. So could they all fly? I mean, why else have feathers if not to fly with them? Do we consider all feathered dinosaurs to be birds? Let me answer these in order: we figure that at least some feathered non-avian dinosaurs could glide, such as Microraptor. Not sustained powered flight, mind you. Just glide. Dinosaurs likely evolved feathers at first not for flying but for another purpose- insulation.

The difference between cold-blooded and warm-blooded animals is that cold-blooded ones get their heat from the outside environment (their blood isn't actually cold). They get all the heat they need from the sun, and are able to tolerate wider ranges of temperatures. As a result, they generally have slower metabolisms. That's why creatures like lizards are so sluggish. Warm-blooded animals, such as mammals and birds, generate their own heat from inside their bodies. In order to do this, they have to have much faster metabolisms, and are generally more active than cold-blooded animals. Now, in order to keep their body temperature at a constant level, most warm-blooded creatures living in environments that aren't always very warm need some way to keep the heat from escaping their bodies. They need insulation. Mammals got around that by evolving hair which effectively traps heat inside and keeps the cold out. Theropod dinosaurs, being warm-blooded, found a similar solution by evolving modified scales that became more and more filamentous and hair-like. These modified scales became effective as an insulatory device. After a long time, some of these dinosaurs began to use these modified scale for not just keeping warm but also getting airborne. This is how and why feathers first appeared. This principle is still seen in modern emus, who instead use their feathers for keeping cool air in and warm air out in the hot Australian outback.

Now, where do we draw the line between things that are dinosaurs but not birds and things that are both dinosaurs and birds? Well, most scientists use Archaeopteryx as a sort of benchmark. Archaeopteryx is more bird-like than the next closest things to birds, the Dromaeosaurids. Therefore, if we consider Archaeopteryx to be the earliest bird, everything more bird-like than it gets labelled as a bird, while everything less bird-like is just a dinosaur. This, however, doesn't mean that all modern birds evolved from Archaeopteryx. It simply means that Archaeopteryx is an early offshoot from the common ancestor that gave rise to it and all modern birds, and who probably looked a lot like Archaeopteryx, who would also share an earlier common ancestor with the Dromaeosaurids. The more fossils we find and the more ideas we set forth, the clearer a picture we will get.

It's often hard to look at chickadees, robins, and sparrows, feeding at a backyard feeder while chirping to each other and flitting around the yard, and see them as in with a group that also contains the ferocious Tyrannosaurus rex. This peaceful, domestic scene is far removed from savage Mesozoic many millions of years ago. But science is filled with surprising revelations that often boggle the mind. You never know what you'll dig up.