In 1767, while in London, Franklin was sent fossilized specimens of mastodon bones and teeth by George Groghan, an Indian agent and land speculator. They came from the shores of the Ohio River in Kentucky, below Fort Duquesne. Franklin sent one of the teeth to a French colleague, saying that some English naturalists believe the teeth are those of carnivores. "But," he continued, "it appears to me that Animals capable of carrying such large and heavy Tusks, must themselves be large Creatures, too bulky to have the Activity necessary for pursuing and taking Prey;...and that those Knobs might be as useful to grind the small Branches of Trees, as to chaw Flesh." His fascination with the bones and teeth led Franklin, in other correspondence, to speculate about climatic change and continental drift.
Mentioned in Franklin's correspondence, and found in the area of his Philadelphia home