Ceratopsians and Pachycephalosaurs
Around 144 million years ago, began the emergence of the Ornithischian dinosaurs during the cretaceous period and diversified into North America and Asia.
Ornithischians were classified as having a hip structure similar to that of birds, although they are not the descendants of birds. Marginocephalians, meaning "fringed heads" are a group of Ornithischians that have a distinctive skull structure, consisting of a slight shelf or bony frill on the back of the skull, a unique palate, and a short hip structure. These herbivores include two major groups: the Ceratopsians and the Pachcephalosaurians.
These plant-eaters include the Ceratopsians, horned dinosaurs such as the Triceratops, Styrachosaurus, Pentaceratops, and the Protoceratops. Pachycephalosaurians, thick-skulled dinosaurs like such as the Stegoceras and the Pachycephalosaurus. (1)
Ceratopsians and Pachycephalosaurs are closely related in their characteristics. Ceratopsians processed a saddle-shaped boney frill that extended from the skull to the neck and typically had horns over the nose and eyes. The most popular was the triceratops, which could reach over 26 feet and weigh in excess of twelve metric tons. Their frills served as two major functions. It protected the vulnerable neck from being harmed. The second major function that the frill provided was due to the fact that the frill contained a network of blood vessels on its underside, which were used as a means to get rid of excess heat. The Pachycephalosaurs were considered to be bipedal. They were also found to have thick skulls, flattened bodies, and tail that were covered in an array of body rods. Pachycephalosaurs were thought to have been more than fifteen feet long and processed a skull that was surrounded by a rounded dome of solid bone. It was thought that they used their heads in combat or mating contests, but that was disproved fairly recently, which I will discuss later in the paper. Both Ceratopsians and Pachycephalosaurs were “bird-hipped” and both of these suborders contained a backwards pubic bone. Both were Marginocephilia, or “fringed heads”, which is one of three clads under the Orinthiscia order. They were also herbivore dinosaurs that inherited their fringe at the back of the skull from earlier ancestors.(2) Their classi...
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...silophodon, a small, agile bipedal herbivore. The Ceratopsians appeared at beginning of cretaceous period from the family Ornithopoda. Pachycephalosaurs contained a ten inch thick skull, which was actually fairly fragile, and their first line of self defense would be to run away. Ceratopsians, which mean horned face, are large beasts with horns that can defend themselves pretty well. Both were very similar, but contained distinct differences.
Works Cited
1) Carroll, R. L. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York.
2) http://www.trueauthority.com/dinosaurs/about.htm
3) Dr. Robert Riesz, University of Toronto, “Ceratopsia and Ornithopoda” http://www.erin.utoronto.ca/~w3bio356/lectures/ceratopsia_and_ornithopoda.html 4) Enchanted Learning; “Pachycephalosaurus” http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Pachy.shtml
5) American Museum of Natural History
http://www.amnh.org/exhibitions/expeditions/treasure_fossil/Fossils/Specimens/stegosaurus.html
... middle of paper ... ... Larson, R. (1978). The Species of the World.
Dinosaurs are often compared to and resemble modern day reptiles. Scientists will study how these modern day reptiles behave, look, act, and move to draw conclusions on how the dinosaurs would behave, look, act, and move. They also look at the intern make-up of the modern reptiles to predict how the dinosaurs internal make up would be. However, a recent discovery in South Dakota is stirring up some controversy (Hesman). While Mike Hammer was walking around a ranch in South Dakota he stumbled across a “big-eyed” dinosaur that he now refers to as Willo. The thing that caught his eye was the chest cavity of the dinosaur, upon further investigation he found a rock that was preserved in the curve of the dinosaur’s ribs, he was convinced that this rock was once a heart. Hammer then went on to take the dinosaur fossil in for a medical X-ray scan, this X-ray showed evidence that could change how we think about dinosaurs.
Feder and Park present a list of traits that are used by paleoanthropologists to distinguish the appearance of skeletal features and characterize these changes over time. Th...
The coccyx is a triangular-shaped bone located in the axial skeleton at the end of the spine and is inferior to the sacrum. This bone is really a set of small of bones (usually four, but could be three or five) that fuse during development. Since it is shaped like a tail, it is generally referred to as the tailbone. I found it fascinating that genetic research found that the same genes that produce the tails of mice also are responsible for the development of the coccyx. If ever there is a point to be made for evolution, the coccyx is it. I bet we were some awesome-looking creatures in ancient times – moving around, twitching our little tails!
Argentinosaurus is classified as a sauropod. A sauropod is a very large, quadrupedal herbivorous dinosaur. Sauropods had long necks and tails, small heads and massive limbs. It can also be classified as a titanic sauropod. Titanic sauropods ranged from 7 to 110 feet long with small brains. One question you may have is, was the Argentinosaurus herbivorous – feeding on only plants, or carnivorous – feeding on only meat? It was a herbivore. They ate seed ferns, ferns, club mosses, horsetails, and other varieties of various plants.
My partner and I researched the amazing dinosaur called the velociraptor. Velociraptors are a dinosaur that has many similar features as a common turkey. For example, this dinosaurs had feathers, but not covered completely like a turkey. They are about 2 and a half feet tall with hollow bones. Like most birds, they have a wishbone and talon feet. They also had quill knobs. They couldn’t fly because they were too small, but they used them to hunt. They had long thin tall to help them balance when they were running. Their strong legs helped the run up to 40 miles per hour! Velociraptors were known as one of the top ten most dangerous dinosaurs in their time (the late cretaceous period) because of their sharp claws and sharp curved teeth. These dinosaurs were great hunters, their claw would puncture the flesh of their prey but not rip through it, yet their teeth would. Their teeth and claws helped
Many people once believed that pterosaurs were weak flyers, or at least the larger ones were. The idea was that they used their large wings to glide instead of flap like flying creatures. This is now known to be false. Pterosaurs were also thought to be dinosaurs with similar anatomical features. Studies have shown now though that since the pterosaurs were not flappers but active flyers, their hearts were similar to those of mammals with four chambers, needed for an active way of life, unlike reptiles. In the past century, pterosaurs fossils have been known to be found with fur, which leads scientists to believe that pterosaurs needed insulation to keep in heat which indicated pterosaurs were active like mammals and warm blooded. 1
...ll. This group still remained successful during the Jurassic period and had a wide geopraphic distribution. Other reptiles evolved to not only live on land, but to fly. The earliest known birds appeared during this period; Archaeoteryx being the first to be considered the intermediate between the birds and predatory dinosaurs. It is debated on whether this ancient bird could actually fly or merely glid from tree to tree. Carnosaurus, meaning “meat-eating” is another group of dinosaurs that ruled during the Jurassic. With such large herbivorous prey animals, the correlation of these large predators make sense of why they were so common. An Allosaurus was one of the most common Carnosaurs in North America. Upon finding numerous intact skeletons in fossil beds, it has been reported that the Allosaurus was superficially similar to the later evolving Tyrannosaurus rex.
A group of scientists from North Carolina and Oregon used medical technology to search an iron-stained concretion inside the specimen’s chest. With the assistance of imaging equipment and software, they were able to reconstruct 3-dimensional structures through the interior of the concretion. The images reveal a heart that was more like that of a bird or a mammal than those of reptiles, significantly adding to evidence suggesting that at least some dinosaurs had high metabolic rates. In addition, the heart appears to have been four chambered with a single aorta, which is most commonly found in mammals or birds.
Bindon, Jim 2004 Fossil Hominids. ANT 270 Notes. http://www.as.ua.edu/ant/bindon/ant270/lectures/ hominids1.pdf Delson, Eric 1981
The Triceratops were very interesting dinosaurs. They were very smart and strategic. They moved in herds and used mating calls. They were very complex. They had an interesting body shape that gave them an advantage towards their predators. They were known for their horns and parrot-like beaks. They were herbivores that lived in North America. Triceratopses were very interesting.
1. Stanford, Craig. Allen, John S. Anton, Susan C. Exploring Biological Anthropology second edition. Pearson Education, Inc. 2008. Pages 238-420.
The fossil record of horses extends back to an odd-toed ungulate mammal belonging to the taxonomic family Equidae, a dog-like ancestor 55 to 42 million years ago in the genus Hyracotherium in North America. Hyracotherium had a primitively little face , four-toed forefeet, three-toed hind feet, an arched back, small brain, and higher hindquarters than forehand. Later genus has increased in body size, brain complexity, the size of cheek teeth, lengthening of the face, and reduction of toe number. However, even though horses got larger over time but these trends are not seen in all of the horse lines. Genus such as Hipparion existed from 23 to 2 million years ago, showed gains in size, But some later genus such as Archeohippus, and Calippus got smaller again (Boundless, 2016),(Encyclopedia of Life,2015), (equineworld.co.uk, 2014), (Molen, M.
Norell, Mark, Lowell Dingus, and Eugene S. Gaffney. "Why Did Nonavian Dinosaurs Become Extinct?" Discovering Dinosaurs: Evolution, Extinction, and the Lessons of Prehistory. Berkeley: U of California, 1995. N. pag. Print.
Reptiles are vertebrate, or backboned animals constituting the class Reptilia and are characterized by a combination of features, none of which alone could separate all reptiles from all other animals.The characteristics of reptiles are numerous, therefore can not be explained in great detail in this report. In no special order, the characteristics of reptiles are: cold-bloodedness; the presence of lungs; direct development, without larval forms as in amphibians; a dry skin with scales but not feathers or hair; an amniote egg; internal fertilization; a three or four-chambered heart; two aortic arches (blood vessels) carrying blood from the heart to the body, unlike mammals and birds that only have one; a metanephric kidney; twelve pairs of cranial nerves; and skeletal features such as limbs with usually five clawed fingers or toes, at least two spinal bones associated with the pelvis, a single ball-and-socket connection at the head-neck joint instead of two, as in advanced amphibians and mammals, and an incomplete or complete partition along the roof of the mouth, separating the food and air passageways so that breathing can continue while food is being chewed. These and other traditional defining characteristics of reptiles have been subjected to considerable modification in recent times. The extinct flying reptiles, called pterosaurs or pterodactyls, are now thought to have been warm-blooded and covered with hair. Also, the dinosaurs are also now considered by many authorities to have been warm-blooded. The earliest known bird, archaeopteryx, is now regarded by many to have been a small dinosaur, despite its covering of feathers The extinct ancestors of the mammals, the therapsids, or mammallike reptiles, are also believed to have been warm-blooded and haired.