评论
打印
The non-avian dinosaurs — the giants of the Mesozoic — reached sizes no land mammal has ever dreamed of.
中生代的巨型非鸟类恐龙，其体型之大是陆地哺乳动物做梦也想不到的。
There were massive meat-eaters, not to mention those long-necked herbivores.
那里有大量的食肉动物，更不用说那些长脖子的食草动物了。
But today's dinosaurs — that is, birds — are a lot smaller.
但是现在的恐龙——也就是鸟类——要小很多。
I mean, the bee hummingbird is basically bee-sized, and it lays eggs the size of coffee beans.
我是说，蜂鸟基本上和蜜蜂一样大小，它产卵的大小和咖啡豆差不多。
So... did there used to be there tiny, non-avian dinos, too?
所以以前也有小型的非鸟类恐龙吗？
Well, there's somewhat of an ongoing debate in paleontology circles as to whether there were lots of tiny dinosaur species,
在古生物学界，关于是否存在许多微小的恐龙物种
or whether non-avian dinosaur lineages were just… bigger overall.
或者非鸟类恐龙谱系是否只是整体上更大，一直存在争论
But either way, we're pretty sure that there were at least some mini-dinosaurs scurrying about in the Mesozoic
但无论如何，我们很确定至少有一些小型恐龙存在于中生代，
because we've found their footprints.
因为我们发现了它们的足迹。
The meter-long Microraptor was the smallest known dinosaur at the time of its discovery in 1999.
米长小盗龙是已知最小的恐龙，被发现了于1999年。
Since then, we've found other, smaller fossils — like a specimen of Anchiornis whose body mass was estimated to be a mere 110 grams.
自那时起，我们还发现了其他更小的化石——比如一种近鸟龙，据估计体重只有110克。
It probably wasn't fully grown, though. And that's probably as small as we'll ever find — at least, in terms of fossilised bones.
不过，它可能还没有完全长大。这可能是我们所能找到的最小的——至少，就骨骼化石而言。
See, one of the reasons we don't see a lot of small dinosaurs —
我们没有看到太多小型恐龙的原因之一——
whether they're juveniles of larger animals or adults from small species — is that there are biases in the fossil record.
无论是大型动物的幼体还是小型动物的成年体——是因为化石记录中存在偏见。
For a skeleton or body to fossilize, it has to be buried quickly in sediment, and not destroyed or ripped apart by scavengers in the process.
要使骨骼或身体成为化石，它必须迅速地埋藏在沉积物中，并且在这个过程中不被食腐动物破坏或撕裂。
And small bodies are generally more fragile, so they're less likely to survive being buried.
体型小通常就更脆弱，所以它们被埋起来的可能性更小。
Plus, small fossils are… small. They're not as obvious as, say, a T. rex femur sticking out of a cliffside.
另外，小化石也很小。它们不像从悬崖边上伸出的霸王龙股骨那么明显。
And that may be why the smallest dinosaurs we have evidence for are ones we haven't found at all.
这可能就是为什么我们有证据证明的最小的恐龙是我们根本没有发现的。
Instead, they come from incredibly well-preserved footprints in South Korea.
相反，它们来自保存极为完好的韩国足迹。
Technically, these are ichnotaxa: the name paleontologists give to these trace fossils.
严格地说，这些是ichnotaxa：古生物学家给这些痕迹化石起的名字。
Because you can't technically name a dinosaur you haven't got, and you also can't connect tracks to existing fossils with perfect certainty.
因为从技术上来说，你不能给没有发现的恐龙命名，你也不能完全肯定地把足迹和现存的化石联系起来。
So, they name the footprints. And one of them, Minisauripus, has been found in abundance.
所以他们给足迹命名。其中的一种，小龙足迹，已经被大量发现。
In a 2019 paper, scientists published tracks so detailed that they preserved perfect impressions of skin, complete with tiny, half-millimeter scales.
在2019年的一篇论文中，科学家们公布了很详细的足迹，它们保留了完美的皮肤印痕，包括微小的半毫米尺度。
That was enough detail to be sure they weren't made by actual birds or their ancestors.
这些细节足以确保它们不是由真正的鸟类或它们的祖先留下的。
And nearly all of the Minisauripus tracks are less than three centimeters long.
几乎所有的小龙足迹都不到3厘米长。
While scientists are understandably reluctant to guess the size of something based on footprints alone,
虽然科学家们不愿仅根据脚印来猜测物体的大小，这是可以理解的，
the team estimated the track-maker to be about 28 centimeters long and weigh only a few dozen grams, so, similar to a blackbird.
但团队估计足迹制造者约28厘米长，仅几十克重，和乌鸫差不多。
You might think these were just baby Velociraptors or something — except the tracks are all about the same size.
你可能认为这些只不过是小型迅猛龙或者别的什么——除了足迹都是一样大的。
If they'd been made by juveniles, you'd expect a bunch of different sizes. So it seems likely these track-makers were fully grown.
如果它们是幼龙，那么你会看到一堆不同的大小。因此，这些足迹制造者似乎是完全成熟的。
The same team has also published evidence for an even smaller dino — one that made tracks just a centimeter long.
该团队还公布了一种更小恐龙的证据——这种恐龙的足迹只有一厘米长。
They dubbed these tracks Dromaeosauriformipes rarus, and they may have been made by a Velociraptor-like dino that,
他们将这些足迹命名为Dromaeosauriformipes rarus，这些足迹可能是由一种类迅猛龙的恐龙留下的，
when fully grown, was small enough to hold in your hands.
这种恐龙在完全长大后，小到可以拿在手里。
But, the team couldn't totally eliminate the possibility that the tracks were made by hatchlings or juveniles
但研究团队不能完全排除这种可能性，即这些痕迹是由幼体留下的，
rather than adults from a tiny species. They say we'd need a skeleton to be certain. And there's no guarantee we'll ever get one.
而不是由一个小物种的成年体留下的。他们表示自己需要一具骨架才能确定。也不知道能不能有。
One thing's for sure, though: These footprints tell us that there were tiny dinosaurs living alongside the massive ones we know so well.
但有一件事是肯定的：这些足迹告诉我们，在我们熟知的大型恐龙旁边生活着小型恐龙。
And the more of them we find, the more we'll learn about the ecosystems of the past.
我们发现的越多，我们对过去生态系统的了解就越多。
Thanks for watching this episode of SciShow, which is produced by Complexly.
感谢收看本期节目，本期节目由Complexly制作。
If you enjoyed learning about these teeny little dinos, I have a feeling you'll enjoy one of our other channels: PBS Eons.
如果你喜欢了解这些微小的恐龙，我觉得你会喜欢我们的另一个频道：PBS Eons。
PBS Eons explores the history of life on Earth, from the very first organisms in the Archaean
PBS Eons探索了地球上生命的历史，从最早的太古生物
to the other human species that walked alongside us.
到其他与我们同行的人类物种。
It's basically your chance to time travel — without running afoul of any paradoxes.
这给了大家时光旅行的机会——没有任何矛盾的冲突。
If that sounds like your jam, you can head on over to YouTube.com/Eons.
如果这是你的菜，你可以前往YouTube.com/Eons进行观看。
