Little Tiny Teeth — Aaron Elkins

Aaron Elkins is back with more skullduggery for forensic anthropologist Gideon Oliver, the Skeleton Detective. Oliver journeys to the untamed South American rain forest, where his latest find may prove to be his last...

Tagging along on an Amazon riverboat with a group of botanists is Gideon Oliver's idea of a thrill. In fact, if it weren't for the stifling heat and humidity, giant bird-eating spiders, fire ants, hallucinogenic plants, and corrupt military officials, it could well be his dream vacation. Then someone flings a primitive lance from the river's shore, narrowly missing the group leader. And hanging from the lance is a shrunken human head -- the warning of the fierce Chayacuro headhunters...

Hundreds of miles upriver, a deranged passenger kills a botanist, leaps overboard, and flees into the darkness. Why? Long-past, half-forgotten enmities and resentments -- and new ones as well -- might explain it. And when a fresh skeleton turns up in the river, scoured by voracious piranhas, Gideon realizes that in this jungle full of predators, humans may be the deadliest of all...