The researchers also found there were more diverse ancient decapods living within the reefs - where they fed, mated and sought shelter - than in other parts of the ocean.
"One of the main results of this research is that decapod crustaceans are really abundant in reefs in the Cretaceous," Klompmaker wrote in an email. "The presence of corals seemed to promote decapod biodiversity as early as 100 million years ago and may have served as nurseries for speciation."
Last year, Klompmaker reported finding fossils of tiny lobsters huddled together in the seashell of an extinct mollusk known as an ammonoid. The "embracing" lobsters, found in a rock quarry in southern Germany, suggested these fearsome-looking crustaceans were sociable as long ago as 180 million years, when the little crustaceans lived.
"This is the oldest example of gregarious behavior for lobsters in the fossil record - and not just lobsters but the entire group of decapods, which includes lobsters, crabs and shrimp," Klompmaker, who was at Kent State University, said at the time. "What this tells us is that this type of behavior of grouping together may have been very beneficial early on in the evolution of these crustaceans."