North America didn't exactly "separate" from Eurasia in the way you might think. It's more accurate to say that North America and Eurasia drifted apart over millions of years due to plate tectonics.

Here's a breakdown:

* Around 200 million years ago (mya): North America and Eurasia were part of a single supercontinent called Pangea.

* Around 180 mya: Pangea began to break apart, with the North Atlantic Ocean forming between North America and Eurasia.

* Around 135 mya: North America and Eurasia were well on their way to becoming separate continents.

So, there's not one specific date for when North America "separated" from Eurasia. The process was gradual and took millions of years.