84.5 – 80 million years ago
When Jane Goodall reported in 1960 that chimpanzees at her field site in Gombe, Tanzania, were making tools, she made headlines. The discovery toppled a supposed pillar of human uniqueness, enshrined in the catchphrase “Man the Toolmaker.” Louis Leakey, upon getting the news from a telegram sent by Goodall, wrote “Now we must redefine tool, redefine Man, or accept chimpanzees as humans.”
We’ve grown more blasé since then, and the gradually accumulating evidence for dinosaur tool use has attracted a lot less attention. The evidence is similar to what we find for early human ancestors, Homo habilis and earlier. It takes the form of manuports, stones that have been transported a long way out of their geological context. Although the inference was resisted at first, it now looks almost certain that they were picked up and carried, probably by dinosaurs who used them as hammers to smash bones (or, less plausibly, to attract mates). Most suspected manuports weigh just a few pounds (a kilogram or two), and the most likely tool users in this case are the various raptors. A small fraction of manuports are much larger – up to fifty pounds (over twenty kilograms) – and may have been carried by larger dinosaurs like Tyrannosaurus rex. T. rex was clearly a carnivore, but people have long wondered how she got her meat, whether by hunting or scavenging. The latest finds raise the possibility that she was a specialized predator, dropping rocks from above to smash armored prey like tortoises and ankylosaurs.
Tool use is sometimes taken as evidence of sophisticated cognition. With dinosaurs, however, we may be seeing something different, the evolution of complex tool-using instincts over many tens of millions of years, no more indicative of high intelligence than honeybee dances or spider webs. If there is a parallel with human evolution it is not that dinosaurs were especially smart, but that the process of evolution, given as a starting point a pair of forelimbs not being used for locomotion, is likely to find (or exapt) some new function for them.
The suggested evolutionary scenario for instinctive tool use in dinosaurs is supported by findings regarding another group of organisms, still abundant today: ethologists discovered decades ago that complex tool using abilities without a high level of intelligence are present among some varieties of gull. More recently, these gull abilities have turned out to be widespread.
Logarithmic History 