A groundbreaking study of 2,000 ancient fossils reveals that felids – the cat family – have historically been much better at surviving than the "canid" dog clan, and often at the latter's expense.

    The research finds that cats have played a significant role in making 40 dog species extinct, outcompeting them for scarce food supplies because they are generally more effective hunters.

    The dog family originated in North America about 40 million years ago and reached a maximum diversity around 20 million years later, when there were more than 30 species on the continent. At that point, the cat family arrived from Asia.

    "The arrival of cats to North America had a deadly impact on the diversity of the dog family. We usually expect changes in climate to play the overwhelming role in the evolution of species. Instead, competition among different carnivore species proved to be even more important for the dogs," said the report's lead author, Daniele Silvestro, of the University of Lausanne in Switzerland.

    The influx of cats prompted a period of dramatic decline among the dog clan. This has left North America with just nine species of wild dog today, comprising different variations of wolves and foxes, according to the fossil analysis published in the journal PNAS.

    Millions of years ago, some dog species, such as wolves, were effective killing machines, chasing down their prey at high speed and devouring it. All surviving dog species fall into this "runner" camp.

    But other dog species ambushed their prey in a manner similar to the cat family. However, these dogs weren't as good as the cats at this technique – and all the canid species who used it are now extinct.

    Silvestro explained, "The cats have retractable claws which they only pull out when they catch their prey. This means they don't wear them out and they can keep them sharp. But the dogs can't do this, so they are at a disadvantage to the cats in an ambush situation."

Words to Learn 相关词汇

    大量涌入

    dàliàng yǒngrù

    influx

    a mass arrival or incoming

    伏击

    fújī

    ambush

    a sudden attack made from a concealed position

   从进化角度看猫科比犬科更好

    一项对2000个古代化石进行的开拓性研究揭示了从历史上看，猫科动物家族的生存能力远远强于犬科动物家族，而且猫科动物的生存是以犬科动物的损耗为代价的。

    这项研究发现，猫科动物在40个犬科物种的灭绝过程中发挥了重要作用。由于猫科动物通常是更有效率的捕猎者，在夺取稀少食物的竞争中猫科动物胜过了犬科动物。

    犬科家族起源于约4000万年前的北美洲，在大约2000万年后达到了物种多样性的巅峰，当时在北美洲有超过30个犬类物种。与此同时，猫科动物从亚洲来到此地。

    这项研究报告的第一作者、瑞士洛桑大学的达妮埃尔·西尔韦斯特罗表示：“猫科动物的到来给犬科动物的物种多样性造成致命打击。我们通常设想气候变化在物种进化过程中发挥重要作用。但对于犬科动物来说，不同食肉动物物种间的竞争被证明是更重要的。”

    猫科动物的涌入导致犬科动物数量在一段时间内大幅下降。依据这项发表在美国国家科学院院刊上的化石分析，这造成了如今北美洲仅存九个犬类物种，包括狼和狐狸的不同变种。

    数百万年前，某些犬科物种（比如说狼）是有效的杀戮机器，能以高速追捕猎物并吞食。所有幸存的犬科动物都属于“奔跑系猎手”阵营。

    不过也有其他犬科动物伏击猎物的方式与猫科动物相似。然而，这些犬类动物并不像猫科动物那样擅长这项技能——所有曾使用这项技能的犬科动物都已经灭绝了。

    西尔韦斯特罗解释：“猫科动物只有在抓到猎物时才亮出它们可伸缩的爪子，这意味着它们不会磨损、能够时刻保持锋利，但是犬科动物做不到这一点。因此，同猫科动物相比，它们在伏击方面处于劣势。”