A team of researchers have discovered new information about the Tyrannosaurus Rex aging process after determining that a pair of skeletons were adolescent T-rex, not a different species altogether (AFP Photo/WIN MCNAMEE)

一个研究团队在确定了两具恐龙骨架属于幼年霸王龙，而不是新的物种之后，又有了关于霸王龙生长的新发现。

Washington (AFP) - For three decades, paleontologists the world over have been split over a provocative finding: did a dwarf species of Tyrannosaurus rex really once exist?

三十年来，世界各地的古生物学家们对一个令人兴奋的发现产生了分歧:矮暴龙真的曾经存在过吗?

In 1988, paleontologist Robert Bakker and his colleagues at the Cleveland (Ohio) Museum of Natural History reclassified a specimen first discovered in 1942 and displayed at the museum.

1988年，俄亥俄州克利夫兰自然历史博物馆的古生物学家罗伯特·对1942年首次发现并在博物馆展出的一个恐龙标本进行了重新分类。

It was, they said, the first known member of a small new species they baptized as the Nanotyrannus.

巴克和他的同事表示，他们把这一新的物种命名为矮暴龙,而这一标本是该物种的第一个成员。
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Then, in 2001, another team discovered the nearly complete skeleton of a small Tyrannosaurus near the town of Ekalaka in Montana, in the rich and intensively studied fossil formation known as Hell Creek.

而后，在2001年，另一个研究小组在蒙大拿州埃卡拉卡镇附近发现了一具几乎完整的小型霸王龙骨架，这具骨骼化石被称为“地狱溪”。
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They named the creature -- barely bigger than a draft horse -- Jane and soon classified it as a juvenile Tyrannosaurus rex.

他们给这只比驮马大不了多少的动物取名为“简”，不久便把它归为幼年霸王龙。

But a minority of specialists continued to insist that it was part of the newly classified Nanotyrannus species. They pointed to the morphology of its skull and bones, which they said differed from T-rex adults.

但少数专家仍然坚持认为“简”属于新分类的矮暴龙物种。他们指出它的骨头的形态不同于成年霸王龙。

- Answers in the bones -

-答案在骨头里-

In a study published Wednesday in the journal Science Advances, researchers led by Holly Woodward of Oklahoma State University performed a microscopic analysis on samples from the interior of Jane''s tibia and femur bones, as well as from a less complete set of bones from an animal dubbed Petey.

发表在周三的《科学进展》杂志上的一项研究表示，由俄克拉荷马州立大学霍利·伍德沃德带领的研究人员通过显微镜分析了“简”的胫骨和股骨样本，以及一组从一只名叫“皮蒂”的动物取下来的不太完整的骨头。

This technique, known as paleohistology, confirmed that the two were immature individuals -- not adults, the scientists said.

科学家们认为，这项被称为“古组织学”的技术证实了这两组样本属于幼年个体，而不是成年的。

By extension, the study''s authors said, the existence of the Nanotyrannus seems very unlikely.

另外，参与研究的人员表示，矮暴龙似乎不太可能存在。
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"The really cool thing about fossil bones is that a whole bone fossilizes even down to the microscopic size," Woodward told AFP.

伍德沃德对法新社说:“关于骨头化石，真正有趣的是可以从微观角度分析整块骨头。”

"We can infer growth rate, age (and) maturity level."

“我们可以推测出该个体生长速度、年龄和成熟程度。”

The researchers took extremely fine slices from the bone samples -- so thin that light could pass through them -- and then studied them under powerful microscopes.

研究人员从骨头样本中提取极薄的骨头切片——薄到光可以透过它们——然后在性能强大的显微镜下研究这些切片。

The size of the blood vessel openings revealed that the two dinosaurs were still in a phase of rapid growth at the time of death. Had they been adults, this vascularization would have been less prominent.

血管切口的大小表明，这两只恐龙在死亡时仍处于快速生长的阶段。如果它们是成年个体，则这种血管生成的现象就不会那么明显。

- Only a half-dozen specimens -

-仅有半打标本-

The team was also able to count the growth rings in each animal''s bones, much as one can do to determine the age of a tree: 13 years for Jane, and 15 for Petey.

研究小组还能数出每只动物骨头上的“年轮”，就像推测一棵树的年龄一样:“简”是13岁，“皮蒂”是15岁。

The study adds to scientists'' still limited knowledge of the 20-year period between a dinosaur''s hatching and its adulthood.

这项研究拓展了之前科学家们认为的恐龙孵化到成年需要20年的认知。

Jane, who weighed only one ton, died before reaching the phase of exponentially rapid growth that normally would have brought her to an adult weight of just under 10 tons.

"简"的体重仅有一吨，还没有到快速生长的时期就死亡了,如果在正常情况下,"简"成年后的体重应该接近10吨。

"Everyone loves T-rex, but we don''t really know much about how it grew up," Woodward said. "It''s probably the most famous dinosaur in the world, and we mostly just have really large skeletons of it."

伍德沃德表示：“每个人都喜欢霸王龙，但我们根本不知道它是怎么长大的，它也许是世界上最著名的恐龙，而我们大多数人仅仅知道它那巨大的骨架。”

That is partly due to the obsession of collectors and the public with finding and displaying the most enormous T-rex skeletons possible -- unearthed sometimes to the detriment of smaller specimens.

这在一定程度上是由于收藏者和公众痴迷于寻找和展示尽可能巨大的霸王龙骨架——有时这不利于幼年霸王龙骨架的挖掘。

Unfortunately, Woodward said, only five to seven fossils of young T-rex dinosaurs are known to exist in the world, and some of those are in private collections not accessible to researchers.

伍德沃德说：‘不幸的是，目前世界上已知的幼年霸王龙化石只有五到七块，并且其中一些属于私人收藏，研究人员无法对其进行分析。“