A king-sized theropod coprolite


Fossil faeces (coprolites) provide unique trophic perspectives on ancient ecosystems. Yet, although thousands of coprolites have been discovered, specimens that can be unequivocally attributed to carnivorous dinosaurs are almost unknown. A few fossil faeces have been ascribed to herbivorous dinosaurs1,2,3, but it is more difficult to identify coprolites produced by theropods because other carnivorous taxa coexisted with dinosaurs and most faeces are taxonomically ambiguous. Thus sizeable (up to 20 cm long and 10 cm wide) phosphatic coprolites from Belgium4 and India5,6 that have been attributed to dinosaurs might have been produced by contemporaneous crocodylians7 or fish. But there is no ambiguity about the theropod origin of the Cretaceous coprolite we report here. This specimen is more than twice as large as any previously reported carnivore coprolite, and its great size and temporal and geographic context indicate that it was produced by a tyrannosaur, most likely Tyrannosaurus rex. The specimen contains a high proportion (30–50%) of bone fragments, and is rare tangible evidence of theropod diet and digestive processes.

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Figure 1: Large, bone-bearing theropod coprolite with some of the broken pieces that had eroded downslope.
Figure 2: Photomicrograph of a thin section of the theropod coprolite, showing sand- to pebble-sized bone clasts within a microcrystalline phosphatic ground mass.
Figure 3: Photomicrograph of a thin section of the theropod coprolite, showing associated bone fragments that indicate digestive degradation.


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We thank W. Sloboda for the discovery of the coprolite; the Allemand family for permitting access to the land and its fossils; H. N. Bryant, M. J. Jurashius, C. E. Meyer, M. Moreno, R. L. Oscarson, J. F. Parham, D. Pierce, J. Rifkin and B. H. Tiffney for comments and technical assistance; the Royal Saskatchewan Museum, Stanford University, the US Geological Survey, and the University of California at Santa Barbara for technical and administrative assistance; and the late W. V. Sliter for support and encouragement.

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Correspondence to Karen Chin.

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Chin, K., Tokaryk, T., Erickson, G. et al. A king-sized theropod coprolite. Nature 393, 680–682 (1998). https://doi.org/10.1038/31461

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