Would you mind helping me correct the essay ? Thank you very much.
Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.
The reading passage:
Endotherms are animals such as modern birds and mammals that keep their body temperatures constant. For instance, humans are endotherms and maintain an internal temperature of 37°C, no matter whether the environment is warm or cold. Because dinosaurs were reptiles, and modern reptiles are not endotherms, it was long assumed that dinosaurs were not endotherms. However, dinosaurs differ in many ways from modem reptiles, and there is now considerable evidence that dinosaurs were, in fact, endotherms.
One reason for believing that dinosaurs were endotherms is that dinosaur fossils have been discovered in polar regions. Only animals that can maintain a temperature well above that of the surrounding environment could be active in such cold climates.
Leg position and movement
There is a connection between endothermy and the position and movement of the legs. The physiology of endothermy allows sustained physical activity, such as running. But running is efficient only if an animal’s legs are positioned underneath its body, not at the body’s side, as they are for crocodiles and many lizards. The legs of all modern endotherms are underneath the body, and so were the legs of dinosaurs. This strongly suggests that dinosaurs were endotherms.
There is also a connection between endothermy and bone structure. The bones of endotherms usually include structures called Haversian canals. These canals house nerves and blood vessels that allow the living animal to grow quickly, and rapid body growth is in fact a characteristic of endothermy. The presence of Haversian canals in bone is a strong indicator that the animal is an endotherm, and fossilized bones of dinosaurs are usually dense with Haversian canals.
Many scientists have problems with the arguments you read in the passage. They
don’t think those arguments prove that dinosaurs were endotherms.
Take the polar dinosaur argument. When dinosaurs lived, even the polar regions where dinosaur fossils have been found were much warmer than today—warm enough during part of the year for animals that were not endotherms to live. And during the months when the polar regions were cold, the so-called polar dinosaurs could have migrated to warmer areas or hibernated like many modern reptiles do. So the presence of dinosaur fossils in polar regions doesn’t prove the dinosaurs were endotherms.
Well, what about the fact that dinosaurs had their legs placed under their bodies, not out to the side, like a crocodile’s? That doesn’t necessarily mean dinosaurs were high-energy endotherms built for running. There’s another explanation for having legs under the body: this body structure supports more weight. So with legs under their bodies, dinosaurs could grow to a very large size. Being large had advantages for dinosaurs, so we don’t need the idea of endothermy and running to explain why dinosaurs evolved to have their legs under their bodies.
OK, so how about bone structure? Many dinosaur bones do have Haversian canals, that’s true, but dinosaur bones also have growth rings. Growth rings are a thickening of the bone that indicate periods of time when the dinosaurs weren’t rapidly growing. These growth rings are evidence that dinosaurs stopped growing or grew more slowly during cooler periods. This pattern of periodic growth—you know, rapid growth followed by no growth or slow growth and then rapid growth again—is characteristic of animals that are not endotherms. Animals that maintain a constant body temperature year round, as true endotherms do, grow rapidly even when the environment becomes cool.
In the set of the reading and the lecture they both discuss the endotherms like modern birds and mammals which keep their body temperatures constant. On the one hand, the reading argues that dinosaurs differ in many ways from modern reptiles even though it was long assumed that dinosaurs were not endotherms. On the other hand, the lecture opposes by stating that the evidence given by the reading is not proved exactly about the endotherms, especially the dinosaurs.
First of all , the reading states that in polar regions dinosaur fossils have been discovered. In such cold climates, only animals that can maintain a temperature in a good way above that of the surrounding environment could be active there. However, the lecture disagrees by saying that the evironment is warmer than it is today. By stating that polar dinosaurs could not even migrate like other mother reptiles, it has been proved in the different way from the reading.
In addition, the reading goes on to say that between endothermy and the position and movement of the legs, there is a connection. Sustained physical activity is allowed in the physiology of endothermy like running; however, the legs of all modern endotherms are underneath the body, and the legs of dinosaurs were too. In contrast, the lecture emphasizes that the dinosaurs had the high energy which helps them in growing up more efficiently. When the energy was high, it would support more weight for the dinosaurs which made them grow in very large size.
Last but not least, the reading indicates that there is a connection between endothermy and bone structure which includes Haversian canals. These canals allow the living animal to grow quickly and rapid body growth. Paradoxically, the lecture insists that dinosaurs even have haversian canals. They would have something called gruth ring which made the dinosaurs grow more slowly, rapid growth and even stop growing.