TPO 第4套 综合写作题目重新选题
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.
Summarize the points made in the lecture, being sure to explain how they support/contradict specific points made in the reading passage.
There is evidence that dinosaurs were endotherms
The discovered fossils demonstrated that dinosaurs could maintain their temperature in cold climate
Because their legs were positioned underneath the body, dinosaurs could sustain running as modern endotherms
The bones structure, Harverisan canals, of dinosaurs indicated that they could grow as quickly as endotherms
Point 1: Warmer than today; migrated to warmer areas or hibernated
Point 2: Not for running; support more weight, large size, advantages
Point 3: Growth rings; periodic growth, rapid followed by no or slow, then rapid; rapidly, even, cool