The Pros And Cons Of Cold-Blooded Dinosaurs

This researcher proposes that the dinosaurs did not die of heat, in fact she thinks the opposite, that they froze to death instead. Both articles have the same idea about a meteorite hitting the earth yet there is no concrete evidence as to what caused the meteorite to strike and what it did when it got here.

The author states that there is a considerable evidence that dinosaurs were endotherms and provides three resons. In contrast, the professor states that many scientists have problem with the author arguments and she oppses each of the author's reasons.

While the author of the article believes that Brachiosaurus were aquatic animals, the professor disagrees with this statement. The professor points out that in spite of the fact that some species of dinosaur would spend a great deal of time in water, there was no possible that Brachiosaurus were aquatic ones. To strengthen her point, the professor provides sufficient evidence respectively to the points made in the article.

In Stephen Jay Gould’s “Sex, Drugs, Disasters, and the Extinction of Dinosaurs”, Gould investigates three possible theories hypothesizing the reason behind the extinction of dinosaurs. The first theory suggests that dinosaurs became extinct due to a rise in temperature, which caused sperm to die, leading to the sterilization of male dinosaurs. The second hypothesis offer that many dinosaurs consumed bitter plants that contained psychoactive agents which their lives could not detoxify out of their systems. The last speculation about the dinosaur’s extinction is that a large cloud of dust formed in the atmosphere after an asteroid hit Earth’s surface. This dust cloud blocked out the sunlight, causing temperatures to drop and made photosynthesis impossible. Gould uses these three theories to lead to his central claim that science isn’t just about making fascinating claims, but should have a well developed hypothesis.

The reading passage proposes three theories which support the idea that a dinosaur which is called edmontosaurus survived in the winter by migrating to the south, the more hospitable region than the extremely cold in the North Slope. However, the professor in the listening respectively contradicts each theory in the reading passage by using strong evidence as support.

While a theropod “beast-footed” carnivore includes the T. Rex, the ones that likely roamed Wrangel-St.Elias National Park were considerably smaller. The researchers found evidence of a single theropod that was likely a tiny 9 cm long and 7 cm wide due to an impression of the sinusoidal shape. Several ornithopod, medium and large plant-eating dinosaurs, was identified by blunt and rounded digit impressions which are usually 22 cm long and 26 wide. It was the first evidence that dinosaurs roamed this vast region.

All animals were competing for the food sources that remained, but animals with a lower energy requirement were favored for in the conditions. The death of the dinosaurs led to the freeing up of environmental niches that smaller mammals began to fill. Adaptive radiation gave way to numerous mammals, including the Pleisiadapiforms which are believed to be the earliest proto-primates and thrived on a diet of fruit, flowers and insect-pollinators (Silcox, 2014). The evolution and proliferation of angiosperms and the insects that feed off of and pollinated the flowers would become a valuable food source for primates in the later Epochs. According to Hooker (2005), “the warm temperatures worldwide gave rise to thick tropical, sub-tropical, and deciduous forest cover around the globe (the first recognizably modern rainforests,” (as cited by New World Encyclopedia, 2008). “With no large grazing dinosaurs to thin them, Paleocene forests were probably denser than those of the Cretaceous” (New World Encyclopedia, 2008).

Animals differ in their abilities to regulate body temperature (thermoregulation). We sometimes use the terms "cold-blooded" or "warm-blooded." Most reptiles feel cold to the touch, while mammals and birds often feel warm.

The reading and the lecture are both theories of why dinasours were endotherms or cold blooded aninmals. Whereas as the author of the reading states that there is not enough evidence to assume that dinosaurs were endotherms. The lecture casts doubt on the main points made in the reading by providing three reasons.

At first, the reading passage posits that the diet for these dinosaurs proves that they had to migrate to find plants. Conversely, the professor refutes this point by imparting that this ratiocination is invalid on the ground that there was in some period a warm climate in this area. According to the professor, the 24 hours sunshine eventuated in warm weather and extensive daylight would provide a desirable environment

Disease would have been devastating to dinosaurs because they wouldn’t have built up an immune system and they breed very slowly. Bugs would have simply transferred the disease to all the dinosaurs until they were wiped out, but mammals were able to survive simply because the diseases didn’t affect

In this set of material, the reading passage explains that dinosaurs were endotherms because there are three evidences that prove this theory. The lecturer, however, is doubtful about these three evidences that suggest dinosaurs were endotherms.

Because warm blooded animals don’t have to rely on their environment for body temperature, they are able to hunt at any time of the day or in any season, which is a great advantage over cold-blooded animals.  Therefore this “type of intense activity needs a fast metabolism which is much too high for a cold-blooded animal.  Secondly, cold-blooded animals have a hard time living in cold climates and dinosaur fossils have been found in the colder environments” (Eschberger).  However, scientists believe warm blooded animals would have suffered from the heat in warmer climates, where many fossils have been discovered.  Beverly Eschberger discusses how dinosaurs must have been only warm blooded animals due to the factors of, bone structure, and histology, growth rates, predator to prey ratios, speed and agility, rate of evolution, similarities with birds, and insulation.  She also explains the disadvantages of being a warm blooded animal: “a much larger expenditure of energy to maintain elevated metabolism and a commensurate increase in food requirements” (Eschberger).  Just as the conclusion that dinosaurs were truly warm blooded becomes clearer, factors from the cold blooded side switch everything around.  Gigantothermy, rate of food supply, respiratory turbinates and lung structure all cause scientists to believe dinosaurs were in fact cold-blooded.  There have been many attempts to find the real resolution of whether or not dinosaurs were warm or cold

These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaur’s fossils.

They say as mammals continued to evolve, they drove the dinosaurs into extinction (“What Killed the Dinosaurs”). “Not only did mammals likely compete with dinosaurs for resources, many species survived the end-Cretaceous extinction and subsequently came to dominate Earth.” (“What Killed the Dinosaurs?”). This is primarily because the early mammals were a lot smaller than the mammals that exist today. “Some of the world's earliest mammals were the multituberculates, a group of small rodent like animals that first emerged on Earth about 165 million years ago.” (Welsh, Jennifer). Scientists predict that any mass extinction event that caused animals to go extinct affected larger animals than it did the smaller animals, such as mammals ("Dinosaurs Became Extinct 'due to Laying Eggs'"). Mammals remained small for almost 100 million years, while they out competed small and baby dinosaurs for food, shelter and resources until they were extinct. Once the dinosaurs were out of the way mammals were able to evolve and grow large in size like the mammals that exist today today (LiveScience). Fossil evidence sheds some light on this theory as well. Fossils of mammals believed to date back to about eighty five million years ago show that mammals began to change rapidly and grow. “This matches up with other mammal groups, including recently discovered species from the Late Cretaceous (between 100 million and 65 million years ago) showing highly specialized