Archive for the ‘essays’ Category

imageConjecture. Speculation. Educated guesses. These words describe the plague (and also the fun) that befalls the science of vertebrate paleontology, the study of extinct life forms that possessed backbones. To me, and to many other children trapped inside the bodies of grown men and women, the most exciting and marvelous of these extinct groups is the Dinosauria. Watching films such as Jurassic world and documentaries such as Walking with dinosaurs, you would think that scientists knew a great deal about these giants that walked the earth(and still fly the earth in the form of birds) much longer than modern man has. But paleontologists have really only scratched the surface. The fact is, all we know about the extinct forms within the dinosaur class is what their bones tell us, and those bones can’t tell us what they sounded like, how they were colored(usually) or how intelligent they were as animals(the encephalation quotient – brain size to body size ratio – is a joke to me. Lots of animals show surprising intelligence with a low EQ, such as green anoles and monitor lizards). Furthermore, a lot of what scientists theorize about dinosaurs is in a state of constant change. Megalosaurus was once thought to walk on four legs. T. Rex was originally depicted with a dragging tail. Velociraptor wasn’t thought to have feathers. Oviraptor was thought to be an egg eater, when in fact the eggs discovered under it’s skeleton were proven to be it’s own offspring and not it’s meal. These are only a few theories and speculations that have changed over the years. And with new skeletons discovered practically weekly, the theories are sure to parallel evolution itself in terms of growth and change. One theory has pretty much stayed constant however: the idea of dinosaurs living and moving together in massive herds that outnumber the African buffalo and other animals. This theory in particular interests me, and it is the topic of this article. But which species were social and which were not? Just the herbivores like the sauropods? Or carnivores like the tyrannosaurs? Or could ALL dinosaurs have been social animals? Let’s review the evidence(admittedly mostly circumstantial and ambiguous, as usual with dinosaurs). When dinosaurs were first seriously studied in the 19th century, the original consensus put forth by Sir RichardOwen of fast moving, successful creatures was the common opinion regarding these majestic creatures. But, like the spikes on a business graph, this theory was dropped in the early 20th century in favor of the portrayal of dinosaurs as slow, dim witted, lethargic beasts that either sat all day under trees and in lakes like breathing carcasses, or nasty, putrid, vile monsters whose brains only permitted the function of instinct for killing prey. Of course, this spike on the graph dropped off too and was replaced by the original view when scientists like Bob Bakker and John Ostrom ushered in the Dinosaur Renaissance and proved that dinosaurs were not only warm blooded and quick, but were also attentive and possibly intelligent parents(John Horner’s Maiasaura discovery was a wonderful example of this). Dinosaurs like the sauropods and hadrosaurs were being discovered brooding their eggs like theirs modern day feathery descendants. Even some carnivores like Oviraptor and the troodonts were found nesting like attentive parents. For the herding animals, such as Maiasaura(name means “good mother lizard”), it seemed obvious that the babies were cared for by the mother and then remained in the herd as part of the family as they grew. Others, like the sauropods, were theorized to abandon their eggs like sea turtles. But that too is just a theory, unlike the obvious nesting and parenting behavior in Maiasaura. Dinosaurs were quickly catching the public’s eye as very complex animals akin to modern birds and mammals. One of the most important finds and also one of the earliest in the dinosaur renaissance was Deinonychus(the raptors of Jurassic World and Park are actually deinonychus. The name Velociraptor was based on a taxonomical error that placed deinonychus under the genus Velociraptor, which actually was much smaller and lived in Mongolia). This creature was a key factor to the dinosaur renaissance’s depiction of dinosaurs as active, endothermic creatures. Strong jaws with nasty teeth, meat hook claws on it’s hands and feet, long legs for sprinting, and a compact but powerfully built body made this dinosaur one of the most rapacious to ever live. Since it’s original discovery, other excavations have shown that they preyed upon tenontosaurus, a rather large ornithopod compared to the raptors themselves. The first, discovered in the Yale Quarry in the Cloverly of Montana, contained four adult raptors and one juvenile (which to me suggests family groups, but we will get to that later) clustered around one tenontosaurus, their apparent kill. The second discovery was in the Antlers Formation of Oklahoma, with six partial tenontosaurs and one partial raptor. These finds, coupled with the small size and build of deinonychus(reminiscent of wild wolves or hyenas), suggest pack hunting behavior, for one deinonychus certainly wasn’t strong enough to take down a multi ton herbivore on it’s own. For a long time, pack hunting among the raptors and even a social and predatory hierarchy(though if it existed, the structure cannot be known) was accepted as fact. Recently however, some scientists have suggested that deinonychus and other dromaeosaurs(all raptors) only gathered together around large dead animals to partake In a random, orderless feeding frenzy akin to Komodo dragons and crocodiles. Though the evidence for pack behavior is admittedly ambiguous, I disagree with the feeding frenzy theory. Dinosaurs are birds. They are the same thing. And raptors were among the closest in form and presumably behavior to the birds we have today. And what do birds do? Usually they travel in flocks(though I admit there are a few solitary species). Other dinosaurs, specifically herbivores like sauropods and hadrosaurine ornithopods, have pretty much been proven to live together and raise their young(perhaps so for sauropods, perhaps not, but the hadrosaurs were definitely present parents) in massive herds. Since all dinosaurs, including birds, evolved from a common ancestor, and since one of the earliest dinosaurs, coelophysis, have been found together in groups numbering well over a hundred, is it too bold to hazard a guess that ALL dinosaurs(or at least most) lived in herds/packs/families ALL of the time? Sure, scientists can say the coelophysis find was just like the raptor finds and that the animals were only together randomly searching for water or food before they died, but then why did the dinosaurs flourish after the Triassic period? During the Triassic, dinosaurs were the underdogs, just like our ancestors were the underdogs during the end of the Mesosoic Era. They were much smaller than all the animals around them, and they were far from the top of the food chain. But perhaps family hierarchy from coelophysis down millions of years to the Cretaceous raptors is the reason the Dinosauria flourished as the most successful animals to ever exist(face it:after insects and plants, no other form of life has been able to hold a candle to the success of the terrible lizards, not even man himself). Furthermore, if we use the efficiency required in evolution(survival of the fittest) as a frame of reference, raptors and other small meat eaters had bodies that would be most efficient for cooperative hunting(and even everyday living) behavior. In the words of world renown Dino-hunter Robert Bakker, “the life of dinosaurian hunters was hard. Most skeletons we excavate have clear marks of old wounds. To survive and raise their young, the predators needed more than sharp teeth and strong claws. They needed social bonds.” Further support for dinosaur social structure are footprints found in the Shandong province of China. The tracks are of another dromaeosaurid(raptor) dinosaur species, Dromaeopodus shandongensis, with six separate individuals walking together in the same direction at the same time. Pack hunters? Family groups? I believe so. What could be more terrifying than a troop of raptors poised to attack? Nothing, except a pack of perhaps even more efficient and much larger predators: the tyrant dinosaurs. With eyes facing forward for excellent binocular vision, long, powerful legs built for short sprints, a weight of seven tons, and the strongest jaws and teeth of any predator in earth’s history, Tyrannosaurs Rex and it’s relatives were the apex of dinosaur predators. One would be terrifying enough, but what about ten? It just might have been possible, as demonstrated by a recent find. Richard McCrea from the Peace Region Paleontology Research Center In British Columbia led a team that discovered a similar trackway to the Chinese dromaeosaurs, except that these were made by tyrannosaurs, three of them to be precise. Moving in the same direction, imprinted at the same time. Social, much? However, if all dinosaurs, including tyrannosaurids and raptors, lived together in groups, the predators were not above attacking and cannibalizing each other during “family squabbles” similar to modern day lions. There are many tyrannosaur skeletons with healed bite marks matching those of other tyrannosaurs. Velociraptor, the Mongolian cousin of Deinonychus(remember when you see Jurassic World that those raptors are actually Deinonychus, though the true velociraptors were probably just as fearsome, albeit smaller) also presumably attacked each other. One skeleton shows bite marks on the skull from another raptor, although I think that this unfortunate individual did not actually survive the fight. To quote Bakker again, “Top predators are the most quarrelsome, cannibalistic category in the ecosystem. It’s impossible that these tyrannosaurs would clump together in a common cause unless they were sharing genes.” So some wounds on these animals may have been from family squabbles, and more serious and even fatal ones may have been caused by members from another pack(this is perhaps too fantastic, but just imagine a bloody war between two groups of tyrannosaurs or two groups of raptors over territory or food. Part of me wants to be there, and part of me doesnt. The sane part.). In conclusion, I personally imagine that almost all of the dinosaur genera lived together in families and were never, if rarely, solitary. But of course, this is just a theory, held by many real paleontologists(and I hope they do not read this article, for this amateur Dino thinker would be laughed at), and theories will always be subject to change. Comments left for discussion will be greatly appreciated. Keep on thinking! -Shane

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