Dinosaurs are fascinating, but half-truths and myths about them are common.（恐龙令人着迷，但关于它们的半真半假之谈和谣传也十分普遍。） For years, scientists thought dinosaurs were just giant reptiles.（多年来，科学家曾一度认为恐龙不过是体型巨大的爬行动物。） Some dinosaurs were huge. But many were about the size of modern-day birds or dogs.（有些恐龙确实庞大无比，但许多恐龙的体型其实仅相当于当今的鸟类或犬类。） Were dinosaurs warm- or cold-blooded? Paleontologists are still not sure.（恐龙究竟是温血动物还是冷血动物？古生物学家至今尚无定论。） But they now believe a few dinosaurs were intelligent.（但他们现在确信，有少数恐龙是颇具智慧的。） Some smaller ones—like the two-meter Troodon—had fairly large brains.（一些体型较小的恐龙——比如两米长的伤齿龙（Troodon）——拥有相当发达的大脑。）

While some scientists think Tyrannosaurus rex was a powerful predator, others think the opposite is true.（尽管一些科学家认为霸王龙（T. rex）是凶悍的顶级掠食者，但另一些人却持相反观点。） For example, in the movies, T. rex is often a fast-moving giant.（例如在电影中，霸王龙往往被塑造成敏捷飞奔的庞然大物。） In reality, though, this dinosaur could not run fast.（然而在现实中，这种恐龙根本跑不快。） It was too large to move very quickly, so it probably moved about as fast as an elephant.（它的体躯过于沉重，无法快速移动，奔跑速度大概仅仅和大象相当。） T. rex also had very small arms and probably wasn’t a powerful hunter.（此外，霸王龙的前肢非常短小，很可能并不是一个强悍的捕猎手。） It may have been a scavenger instead, eating dead animals.（相反，它可能主要是一种食腐动物，靠捡食现成的动物尸体为生。）

Some reptiles, known as pterosaurs, were able to fly.（一些被称为翼龙的古爬行动物具备飞行能力。） But—even though they looked like them—these were not dinosaurs.（然而——尽管它们看起来很像恐龙——它们在分类学上并不是恐龙。） Pterosaurs such as Tupuxuara could probably fly up to 16,000 kilometers nonstop.（像古神翼龙（Tupuxuara）这样的翼龙，或许能够连续不间断飞行长达16,000公里。） Scientists believe pterosaurs were actually very heavy.（科学家认为翼龙实际上体态沉重。） So they probably could not take off from the ground like birds.（因此，它们大概无法像鸟类那样直接从地面原地起飞。） Instead, they first had to drop or throw themselves from trees in order to fly—much like bats.（相反，它们必须先从高树或悬崖上俯冲突跃而下才能滑翔起飞——这与蝙蝠的起飞机制十分相似。）

Dinosaurs completely disappeared about 66 million years ago.（恐龙在大约6600万年前彻底销声匿迹。） Scientists think they died out because of a global climate change: The Earth’s temperature became too cold for them to survive.（科学家认为它们灭绝是由于全球气候剧变：地球温度骤降，变得严寒难耐，导致它们无法生存。） Now you can only see dinosaurs in museums.（如今，你只能在博物馆里瞻仰恐龙的化石。） However, scientists believe that modern-day birds are, in fact, dinosaurs’ descendants.（然而科学家证实，现代鸟类实际上就是恐龙的直系后裔。） If this is true, then dinosaurs’ relatives are still walking—and flying—among us!（如果确凿无疑，那么恐龙的近亲后代至今依然在我们的身边漫步与翱翔！）