If you're enjoying this podcast, we would love to tell you about Common Descent.

Common Descent is a podcast about paleontology, evolution, and the history of life on Earth,

hosted by two paleontologists with an unending enthusiasm for the wonders of the world.

Each episode cover science news, followed by a deep dive into a main topic requested by the audience.

Recent episodes of feature topics like eels, hibernation, and fungi.

In addition to the main series, Common Descent also features side projects that explore science and pop culture,

where the host examined the science and movies or speculate on the hypothetical evolution of fictional monsters.

Listen to Common Descent on Spotify, Apple, or wherever you get your podcasts.

Late in the Jurassic period, Western North America is a land of giants.

It's home to towering beasts like the long-necked diplodocus and armored creatures like the

spiked-tailed stegosaurus.

And we know this, thanks, in no small part, to the Morrison Formation.

In our time, this rock sequence is a fossil hunter's paradise,

stretching from Montana and South Dakota all the way down to New Mexico and Arizona.

Altogether, it covers over 1.2 million square kilometers.

The scope of this formation is huge, both in terms of space and time.

The oldest Morrison deposits date back almost 157 million years, and the youngest are around 149 million years old.

So the formation as a whole represents about 7 million years' worth of geologic time.

And needless to say, a lot can happen in 7 million years.

The landscape surrounding you could be any one of a diverse, ever-changing array of Jurassic habitats. At certain times, there are dense conifer forests along the banks of rivers.

At others, there are drier plains that kind of resemble the great savannahs we know today, only with ferns instead of grasses.

As you take your first tentative steps out into this ancient world, it feels both alien and familiar.

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