If you have small children, there's a quiz they can take to become Jr rangers. Plan on additional time as they have to study the history inside to be able to do this. Definitely bring lunch, drinks, etc. It's a bit like a campsite, so what you would need for a day camping. It's remote, nearest gas or market is 30 minutes drive. I would make a day of it. It's about an hour from Fort Robinson so you might consider spending time there as well. It's a beautiful place. But bring boots and look out for snakes.
If you're only going to do the displays that are inside, one or two hours. If you're going to do the hike you'll need half a day.
Half a day if you plan on hiking
A few hours.
1-2 hours for most people, up to 5 hours if you plan on going on most trails
30 minutes inside checking out the fossils and about 2 hours walking the trails. Great place to bring lunch and eat under a tree.
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