A new study has found that a dinosaur's size was not necessarily linked to how quickly it grew.
一项新研究发现，恐龙的体型与其生长速度没有必然联系。
 
The research results come from studying a group of dinosaurs called theropods. Some theropods, like the meat-eating Tyrannosaurus rex, could grow to about the size of a bus. Others were much smaller, including some that grew to about the size of a cat.
研究结果来自于对一群被称为兽脚类恐龙的研究。一些兽脚类动物，例如食肉的霸王龙，可以长到大约一辆公共汽车的大小。其他的要小得多，包括一些长到猫那么大的。
 
Scientists have long believed that theropods generally followed a set pattern for growth. It was thought that dinosaurs that grew the fastest also got bigger than other theropods. And the ones that grew slower were believed to grow up to be smaller.
长期以来，科学家们一直认为兽脚类动物通常遵循既定的生长模式。人们认为，生长最快的恐龙也比其他兽脚类恐龙更大。那些长得慢的被认为会长得更小。
 
But the new study – which recently appeared in the publication Science – raises questions about that theory.
但最近发表在《科学》杂志上的这项新研究对这一理论提出了质疑。
 
The researchers examined rings called "cortical growth marks" in different theropod species. The marks appeared inside the dinosaurs' bones each year. They are similar to rings inside a tree that can be counted to tell how old the tree is. Widely spaced rings suggest a faster growth rate, while closely spaced rings suggest slower growth.
研究人员检查了不同兽脚类动物物种中称为“皮质生长标记”的环。这些标记每年都会出现在恐龙的骨骼中。它们类似于树内的年轮，可以通过数数来判断这棵树的年龄。间隔较宽的环表明生长速度较快，而间隔较近的环表明生长速度较慢。
 
The scientists found no common pattern linked to body size. Some huge theropods grew quickly and stopped growing, while some grew slower over a longer period of time to reach the same size. Some small theropods grew quickly and others grew slowly.
科学家们没有发现与体型相关的共同模式。一些巨大的兽脚亚目动物生长迅速并停止生长，而一些在更长的时间内生长缓慢以达到相同的大小。一些小型兽脚类动物长得很快，而另一些则长得很慢。
 
Mike D'Emic is a professor of biology at Adelphi University in New York City. He was the lead writer of the study. D'Emic told Reuters news agency the latest research "overturns" past thinking about the growth of theropods.
Mike D'Emic 是纽约市阿德尔菲大学的生物学教授。他是这项研究的主要作者。D'Emic告诉路透社，最新的研究“推翻”了过去关于兽脚类动物生长的想法。
 
He added that the study suggests other groups should also be studied to see if the research results hold up with other animals.
他补充说，这项研究表明还应该研究其他群体，看看研究结果是否适用于其他动物。
 
"It's equally likely that an animal evolved larger body size by growing at the same rate for longer, rather than just growing faster," D'Emic said. "It is surprising and important to know that animals are just as likely to evolve to gigantic sizes at slow rates."
“动物同样有可能通过以相同的速度生长更长时间而不是仅仅生长得更快而进化出更大的体型，”D'Emic 说。“知道动物同样有可能以缓慢的速度进化成巨大的体型是令人惊讶和重要的。”
 
The study found that Tyrannosaurus rex – which could grow to 12 meters long – was an example of a big and fast-growing theropod. Acrocanthosaurus – which is a bit smaller than T. rex – was an example of a big but slow-growing theropod.
研究发现，霸王龙——可以长到 12 米长——是大型且快速生长的兽脚类动物的一个例子。比霸王龙稍小的高棘龙是大型但生长缓慢的兽脚类动物的一个例子。
 
The researchers said the 2-meter-long Coelophysis was a fast-growing, smaller theropod. Xixianykus, one of the tiniest dinosaurs at 50 centimeters long, was a small and slow-growing theropod.
研究人员表示，这种 2 米长的腔骨龙是一种生长迅速、体型较小的兽脚类动物。Xixianykus 是最小的恐龙之一，只有 50 厘米长，是一种体型小且生长缓慢的兽脚亚目恐龙。
 
The study found that Spinosaurus – a 15-meter theropod that spent time on land and in the water – grew much more slowly than Tyrannosaurus. And it found that Mapusaurus, which reached about 11.5 meters, grew even faster than Tyrannosaurus.
研究发现，棘龙——一种 15 米长的兽脚亚目恐龙，在陆地和水中都呆过一段时间——生长速度比霸王龙慢得多。并且发现达到11.5米左右的马普龙，其生长速度甚至比霸王龙还要快。
 
Patrick O'Connor is an evolutionary biologist and was a co-writer of the study. He told Reuters that the study should open the door to new research about how growth rates are connected to the size of many different animal groups.
帕特里克·奥康纳 (Patrick O'Connor) 是一位进化生物学家，也是该研究的合著者。他告诉路透社，这项研究应该为关于增长率如何与许多不同动物群体的大小相关的新研究打开大门。