Geotimes, September 1995, reprinted with permission.
Paleontologists have long believed that flowering plants co-evolved with bees and wasps in the early Cretaceous, and that radiation and the diversification of flowering plants helped to trigger bee, wasp, and insect evolution. But doctoral student Stephen Hasiotis, of the University of Colorado in Boulder and a researcher at the U.S. Geological Survey, found nests and groups of cocoons of bees and wasps have been buzzing around Earth 140-155 million years longer than previously believed. These insects, it seems, predate the known appearance of flowering plants by at least 110 million years.
This new evidence suggests that the evolution and diversification of angiosperms took advantage of the long-established behavior of bees and wasps," Hasiotis told colleagues at a regional meeting of the Rocky Mountain Section of the Geological Society of America, May 18 and 19, 1995 in Bozeman, Mont. The fossil evidence includes more than 100 bee-like nests found in petrified trees within an ancient log field dating to about 220 million years ago. The bee nests consist of a series of flask-shaped, smooth-walled enclosures, or cells, strung together in lines or connected in symmetrical, three-dimensional clumps. In paleosols, Hasiotis and colleagues, Russ Dubiel of the USGS and Tim Demko of Colorado State University, also found the fossilized remains of several underground bee nests and clusters of spindle-shaped cocoons that closely resemble cocoons of modern wasps.
The physical structure of the nests indicates that bees and wasps exhibited a complex social pattern involving cooperative behaviour between the nest-establishing female (queen) and her successive generations of offspring much earlier than previously thought. Fossilized nests reveal a construction similar to modern nests and cocoons. No bee or wasp body parts were found in the Chinle Formation nests; but for the insects to be able to construct and maneuver around the individual cells, they had to possess the same flexible and jointed head, thorax and abdomen with strong legs, and the ability to fold wings behind and flat against the back as their modern descendants. "If it looked like a bee and made a nest like a bee, it was probably a bee, " says Hasiotis.
Before the advent of flowering plants, bees probably collected pollen, resin, and sap from plants and coniferous trees. To compete with these gymnosperms, primitive angiosperms probably took advantage of bee and wasp behaviour by developing various colors of flowers as a pollination strategy, suggest Hasiotis. "Over time, most of the insect activity probably shifted to the flowering plants," he added. "I think we are seeing a 'leap-frogging effect,' in which evolutionary changes in one group were taken advantage of by the other group through time."
In 1993, Hasiotis and Dubiel reported the discovery of fossilized termite nests in Arizona dating back 200 million years, more evidence that insects developed complex social behavior at least 100 million years earlier than previously believed, and much earlier than angiosperms appeared.