Ordovician

They have changed little in appearance since the Ordovician period, 450 million years ago.

They are late Ordovician in age (roughly 450 million years old).

The age of the impact event is estimated to be about 450 million years (Ordovician).

Therefore an Ordovician age of the arkose is most likely.

How could a modern artifact be stuck in Ordovician rock?

Their fossil record extends back to the Ordovician period (460 million years ago).

The early Ordovician surge in marine diversity also began around this time.

This also marks the end of the Ordovician period.

This order dates back to the lower Ordovician period.

Lingula is known to have existed since the early Ordovician period.

The earth's climate 450 million years ago (the Ordovician period) is one of the big unknowns.

Similar conditions and wildlife remained in place during the early part of the ensuing Ordovician period.

However, this is due to the Ordovician rocks being more accessible to collectors than the older ones.

The most common animal in the Ordovician fossil record seems to have been brachiopods.

Dichograptus species are very widespread in the early Ordovician rocks.

As time passed there was a possible lowering of local temperatures in the succeeding Ordovician period.

The conglomerate is estimated to be Ordovician in age.

The answer is that the concretion itself is not Ordovician.

The earliest fossil of fungi appears about 460 million years ago in the Ordovician period.

Recent research show that ancient moss could explain why the Ordovician ice ages occurred.

Meet the biggest predators the planet had yet seen - Ordovician orthocones.

Ordovician trilobites left behind remains in northern and southwestern Illinois.

This makes it easier to place many more species in time relative to the beginning of the Ordovician Period.

This trend would continue into the Ordovician period.

The lake is located on paleozoic limestone of the Ordovician period.