Did you know?
Fossilised droppings, called coprolites, can reveal what prehistoric animals ate.
From Mary Anning’s discoveries at Lyme Regis to unexpected dinosaur meals, fossilised droppings offer unusually intimate evidence of prehistoric life.
2 min read
A meal preserved
A skeleton preserves an animal’s anatomy; a coprolite may preserve something rather more intimate: the remains of its meals. These fossilised faeces are trace fossils, recording an animal’s activity rather than its body. Within them, bone fragments, fish scales, seeds, leaves, pollen and bark can survive as evidence of consumption.
Under a microscope, recognisable plant structures may remain visible despite partial digestion. Shape, size and geological setting provide further clues: spiral coprolites, for instance, can point towards fishes with spiral intestines. Such details help narrow the possibilities, but rarely amount to an unequivocal identification of the animal responsible.
Anning’s eye for evidence
At Lyme Regis in Dorset, Mary Anning recognised the significance of objects locally called bezoar stones as early as 1824. They contained fish scales and bones and occurred within the abdomens of ichthyosaurs: marine reptiles, not dinosaurs. Their unpromising appearance concealed valuable evidence of ancient feeding.
Anning supplied specimens and observations to William Buckland, who acknowledged her contributions in print. Her place in this history matters: despite her expertise, she was ineligible to join the Geological Society, an institution to whose science she contributed.
Buckland discussed fossil faeces at the Geological Society of London in February 1829 and proposed the name coprolite that May. His fuller account appeared in 1835. The scientific announcement and the published treatment belong to different dates, a small but worthwhile distinction.
An unexpected course
Coprolites can also unsettle comfortable assumptions about diet. A study published in 2017 examined specimens from Utah’s Kaiparowits Formation containing decayed conifer wood and fragmented crustacean shells. The evidence indicated that large, predominantly plant-eating dinosaurs also consumed animals: a less exclusive menu than the label herbivore might suggest.
The precise dinosaur and crustacean identities remained uncertain. Nor does evidence of consumption establish a complete or year-round diet. That is both the attraction and the discipline of coprolite research: it brings an ancient meal remarkably close, without supplying the diner’s entire biography.