During the Mesozoic era, dinosaurs exhibited remarkable biological and geographical diversity, comparable in scale to the variety of modern animal species.
Fossil evidence indicates that dinosaurs inhabited a wide range of environments, from temperate forests to regions that today lie within the Arctic and Antarctic circles.
Although many fossils discovered in polar regions are fragmentary, they nevertheless suggest that dinosaur species in these areas were far more diverse than once assumed.
Several million years ago, the average temperature of the Arctic Circle was significantly warmer than it is today, reaching approximately the mid-teens in degrees Celsius.
Despite this warmth, polar regions still experienced extended periods of daylight and darkness.
Some paleontologists have proposed that certain dinosaur species migrated seasonally, returning to polar regions during warmer months and moving southward during winter, much like modern migratory birds.
Supporting this view, eggshell fragments found in the Arctic indicate that dinosaurs were able to reproduce there, implying a climate suitable for breeding.
While global temperatures had begun to decline before the end of the dinosaur era, many scientists argue that dinosaurs possessed strong cold tolerance, aided by the presence of evergreen vegetation.
Consequently, gradual cooling alone cannot explain their extinction.
Instead, most researchers attribute the mass extinction primarily to a massive asteroid impact that disrupted sunlight, collapsed photosynthesis, and ultimately destroyed the global food chain.
Summary
The passage describes how dinosaurs lived in diverse environments, including warm polar regions, and were capable of surviving cold conditions.
It argues that gradual climate cooling was not the main cause of their extinction, which is instead attributed to a catastrophic asteroid impact that collapsed the global food chain.
摘要
本文指出恐龍曾廣泛分布於多樣環境，包括當時較為溫暖的極地地區，並具備適應寒冷的能力。
文章認為恐龍滅絕並非源於氣候逐漸變冷，而是由一次巨大的隕石撞擊所引發，最終導致全球食物鏈崩潰。