Newly sequenced DNA from bones found in the Yukon and Wyoming reveals that despite its slender body, Miracinonyx trumani is more closely related to a different modern-day feline.
在育空州和怀俄明州发现的骨骼中，新测序的 DNA 显示，尽管 Miracinonyx trumani 体型较为纤细，但它与另一种现代猫科动物更为亲近。
Many scientists have long suspectedthere was something fishy about Miracinonyx trumani, the extinct so-called “American cheetah.”
许多科学家长期以来一直怀疑，已经灭绝的“美国猎豹”——Miracinonyx trumani 身上肯定有一些不寻常之处。
It was first identified in the 1970s as a close relative to the cheetahs found in Asia and Africa today because of its slender build, elongated forelimbs, and enlarged nasal cavities. Those features likely allowed it to run fast, though probably not as fast as modern cheetahs. A genetic analysis in 2005already suggested it was not a cheetah, as did some anatomical differences.
这种动物在 20 世纪 70 年代被首次发现，被认为是与如今在亚洲和非洲发现的猎豹有亲缘关系的物种。它拥有修长的身体结构、延长的前肢以及较大的鼻腔空间。这些特征使其能够快速奔跑，不过其速度可能不如现代猎豹。2005 年的一项基因分析表明，这种动物并非猎豹，因为存在一些解剖学上的差异。
Now, a new study examining four fossils of the extinct cat from the Yukon and Wyoming has reached a similar, definitive conclusion: the American cheetah was no cheetah.
现在，一项针对来自育空州和怀俄明州的四种已灭绝猫科动物化石的研究也得出了类似的结论：这些美洲猎豹其实并不属于猎豹类动物。
“Trying to understand the evolution, the behavior, the ecology of a species from the shape of their physical remains is a really, really hard task,”says Molly Cassatt-Johnstone, a graduate student at the Paleogenomics Lab at the University of California, Santa Cruz, and lead author of the study. By sequencing the species’ DNA and analyzing the chemical composition of its remains, the new study makes a giant leap ahead.
“试图通过化石的形态来理解一个物种的进化、行为以及生态特征，是一项非常困难的任务，”加州大学圣克鲁兹分校古基因组学实验室的研究生莫莉·卡萨特-约翰斯通说。这项研究的首要作者指出，通过对该物种的 DNA 进行测序，并分析其化石的化学成分，这项新的研究取得了巨大的进展。
(Cheetah mummies found in Arabian caves provide rare genome from a lost population)
在阿拉伯的洞穴中发现的猎豹木乃伊，为我们提供了关于一个已灭绝种群的珍贵基因组信息。
When the researchers used the DNA to construct a feline family tree, the four “American cheetahs” didn’t end up anywhere near African or Asiatic cheetahs. As cheetah-like as their fossilized remains may have looked, their DNA places them closer to the branch of the American puma, also known as the cougar or mountain lion. It also shows that the two are sister species that shared a common ancestor until about 2.6 million years ago.
当研究人员利用 DNA 构建猫科动物的家族树时，这四种“美洲猎豹”的归属并不接近非洲或亚洲的猎豹。尽管它们的化石遗骸看起来很像是猎豹，但 DNA 分析表明，它们实际上更接近于美洲美洲狮，也就是人们常说的山狮。此外，研究还表明，这两种动物是姐妹物种，在大约 260 万年前之前拥有共同的祖先。
That timing coincides with a period of rapid cooling on the continent, during which grasslands expanded rapidly. The cheetah-like features that gave M. trumani its pet name may have helped it survive on these plains by outrunning its prey and the larger predators it would have been wise to avoid. The Yukon bones, which were about 30,000 years old, show this North American feline lived as far north as the Arctic.
这一时间恰好与大陆快速冷却的时期相吻合，而在这段时间里，草原地区的面积迅速扩大。让 M. trumani 获得“猎豹式特征”的这些特征，可能帮助它能够在这些平原上生存下来——因为它能够跑赢猎物，同时也能避开那些体型更大的捕食者。来自育空地区的化石化石距今约 30,000 年，这表明这种北美洲猫科动物曾经生活在北极地区，甚至更北的地方。
“This study is the first published record of Miracinonyx in Canada,” says National Geographic Explorer Julie Meachen, a functional morphologist and paleoecologist at Des Moines University in Iowa and a coauthor of the study. She led the 2014 expedition that found several specimens in Wyoming’s Natural Trap Cave. “It shows this extinct species could survive in various habitats and was eating very different things in different places.”
“这项研究是首次有记录表明米拉辛诺龙存在于加拿大，”《国家地理》探险家朱莉·梅钦说道。她是一位功能形态学家和古生态学家，任职于爱荷华州德莫因大学，也是这项研究的共同作者之一。她领导了 2014 年的考察队，在怀俄明州的天然陷阱洞穴发现了几只米拉辛诺龙标本。“这表明这种已灭绝的物种能够适应各种栖息地，并且在不同地方的食物种类也各不相同。”
The team published their findings Friday in the journal Current Biology.
该团队于周五在《当代生物学》杂志上发表了他们的研究成果。
“The major conclusion that Miracinonyx and pumas were sister species seems plausible,” says Stephen O’Brien, a molecular biologist who produced an earlier construction of the felid family tree but was not involved in the recent work. He adds that it is common for genetic evidence from fossils to result in such revisions. “We are regularly correcting evolutionary conclusions that were based on anatomical interpretations.”
“米拉西诺尼克斯和美洲狮是姐妹物种这一结论似乎是有道理的，”分子生物学家斯蒂芬·奥布莱恩说道。他之前曾对猫科动物的进化树进行过研究，但并未参与这项最新的研究。他补充说，从化石中提取的遗传证据常常会导致这样的修正。“我们经常需要修正那些基于解剖学解释而得出的进化结论。”
