Re-evaluation of alleged bees' nests from the Upper Triassic of Arizona

Abstract

Published records of supposed Triassic bees' nests are based on trace fossils in silicified wood and in sandstone in Upper Triassic strata of the Chinle Group in Petrified Forest National Park, Arizona. A critical, firsthand restudy of these trace fossils indicates that they lack diagnostic features of bees' nests, such as cells with smooth linings and spiral closure caps. Indeed, many of the observations claimed to identify these traces as bees' nests cannot be replicated. Instead, the putative Triassic bees' nests can be classified as: 1. Clavate borings in petrified wood, somewhat similar to Teredolites; these borings preferentially penetrate heart-rot fungus ( Polyporites) and are mostly likely larval chambers of wood-boring beetles. 2. Cylindrical, vertical burrows in sandstone assignable to Skolithos; these are almost certainly arthropod produced. The recognition that the Chinle Group trace fossils are not bees' nests eliminates them as evidence that decouples bee origins from the Cretaceous origin of angiosperms. The Triassic trace fossils in silicified wood are also a new and unique record of likely beetle borings in Triassic wood.