Coprolites

A large amount of coprolites (fossilized faeces) have been found in Iharkút during the excavations. These fossils could be very informative about the animals feeding habits and their environment.

The size of these remains ranges from 4-5 millimetre to more than 10 centimetre. They are usually brown (light brown or dun) with fine-grained texture. The surface of the coprolites is mostly smooth without signs of transportation or desiccation cracks, it is plausible that most of these coprolites were produced by aquatic vertebrates. The fine-grained matrix contains small holes, digested plant and animal residues, which are visible in thin sections and on CT-scans. The coprolites contain cuticle remains and coalified seeds. Among the animal residues bone fragments, fish scales and teeth, and mollusc shell fragments are frequent. Some coprolites contain pollen grains and diatoms.

Not only the bone- but also the plant-bearing coprolites are phosphatic with mineral apatite in their matrix. The high phosphatic content and the apatite are derived from the animal nutriment. It is not possible to ascertain the real producer of the coprolites, but the animal residues are evidence of predation. According to these remains, the Lepisosteiformes and Pycnodontiformes fish were prey in the ancient ecosystem. Based on the digestive status of the scales and teeth from the coprolites, Pannoniasaurus or adult Lepisosteiformes fish could be their predators. Coprolites with mollusc shells may derived from Pycnodontiformes fish or Iharkutosuchus (based on the tooth morphology of these animals). The plant remains in the phosphatic coprolites may imply an omnivore producer (perhaps Iharkutosuchus) or were caused by accidental swallowing.

Rapid burial and the mineral content of the animal nutriment (calcium, phosphorus: in the form of apatite) may caused the good preservation of the excrement.

Figure 1. Coiled coprolites
Figure 1. Coiled coprolites
Figure 2. Coiled cylindrical coprolites
Figure 2. Coiled cylindrical coprolites
Figure 3. Coprolite with bone remain
Figure 3. Coprolite with bone remain
Figure 4. Cylindrical coprolites
Figure 4. Cylindrical coprolites
Figure 5. Rounded coprolites
Figure 5. Rounded coprolites
Figure 6. Spirally coiled coprolite
Figure 6. Spirally coiled coprolite

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