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Camping on a flat expanse dotted with scrub vegetation has its good points and its bad ones. The good: no worries about carnivorous dinosaurs ambushing you. The bad: any troublesome beasts you can discern from ridiculously far off have probably already turned their eagle eyes on you. The ugly: no chance of dissuading predators from indulging in their nasty habits.

After breakfast this morning, Brett decided to head over to the river to fill up the water jugs. With no carnivores in sight, she insisted on hoofing it the half mile, rather than driving the Land Rover, to avoid startling whatever skittish creatures might be enjoying a refreshing early-morning drink. If something interesting turns up, she has promised to contact you via walkie-talkie. Truth be told, she scoffed when you first trotted out your dad's old set of walkie-talkies, but they still work fine, and it isn't like you can text each other in the Late Cretaceous. So you dragged them along and insisted that you each keep one with you "just in case."

While Brett is away, you spend your time…