But some also believe that a gamma ray burst was responsible for the Ordovician extinction around 455 million years ago.

但是也有一些科学家认为伽爆发可能是四十五亿年前奥大灭绝的罪魁祸首。

The Ordovician (440 million years ago) and Devonian (365 million) each wiped out about 80 to 85 percent of species.

奥（44000万年以前）和泥盆（36500万年以前）分别消灭了大约80%——85%的物种。

440 million years ago was the The Ordovician extinction.

4.4亿年前是奥大灭绝。

This is known as the Great Ordovician Biodiversification Event.

这被称为奥物多样性大 事件。

Before the Ordovician, terrestrial life was probably limited to microbes.

在奥之前，陆地命 可能仅限于微物。

470 million years ago, in the Ordovician Period, the first plants began to live on land.

7亿年前，在奥， 第一批植物开始活在陆地上。

And there are extensive black shale deposits in places like China and northern Africa, dating to the late Ordovician.

在中国和北非等地有大量黑色页岩矿床，可追溯到晚奥世。

The very first mass extinction we know of is the Late Ordovician extinction that took place 450 million years ago.

我们所知道的第一次大灭绝是发在 4.5 亿年前的晚奥世大灭绝。

By the time the Cambrian had segued into the Ordovician, cephalopods had entered a golden age.

当寒武进入奥，头足类动物进入了黄金代。

The Ordovician endoceratids cephalopods were the biggest animals of their time, reaching an impressive 6 meters in length.

奥的头足类动物是当最大的动物，身长可达 6 米， 令人印象深刻。

And as the Ordovician progressed, cephalopods began to leave the shallows to explore the open ocean.

随着奥的进展，头足类动物开始离开浅滩探索开阔的海洋。

Plants first began colonizing the land during the  Ordovician period, about 470 million years ago.

大约 4.7 亿年前的奥期，植物首先开始在这片土地上定居。

These spores were dated to 462 million years ago - during that cooling event that took place in the Ordovician Period.

这些孢子可追溯到 4.62 亿年前——在奥发的那次冷却事件期间。

This fish lived in the coastal waters of what's now Bolivia, during the Ordovician Period, some 470 million years ago.

大约 4.7 亿年前的奥期，这种鱼活在现在玻利维亚的沿海水域。

The Ordovician period also saw the advent of more active suspension feeders, like the giant, filter-feeding anomalocarid Aegirocassis.

奥期还出现了更活跃的悬浮式捕食者，例如巨大的滤食性奇虾 Aegirocassis。

Heading into the Ordovician Period, around 485 million years ago, eocrinoids diversified into thousands of forms.

进入大约 4.85 亿年前的奥期，类分泌物多样化为数千种形式。

The fossils they found were about 488 million years old -- which put them in the Ordovician.

他们发现的化石大约有 4.88 亿年的历史——这使它们处于奥。

But his first love is a type of marine creature called trilobites that once teemed in Ordovician seas but haven't existed for a long time except in fossilized form.

但是，他最钟爱的是一种名叫三叶虫的海动物。那种动物一度充满奥的海洋，但早已不复存在，除了以化石的形式。

But, during the Late Ordovician, a second suborder of sea scorpion emerges in the fossil record — the Eurytperina.

但是，在晚奥世期间，化石记录中出现了海蝎的第二个亚目——Eurytperina。

The fossil spores in Argentina weren't just from one kind of plant, but from at least 5 different kinds - a little community of Ordovician plants.

阿根廷的孢子化石不仅来自一种植物，而且来自至少 5 种不同的植物——奥植物的一个小群落。