Morphotype 2

Morphotype 2

( Fig. 12D)

MATERIAL. — One specimen ( MHNT.PAL.2023.9.56 [ Fig. 12D]) .

DESCRIPTION

The only specimen of this morphotype is subspherical in shape, with a smooth surface. It measures 8.5 mm in diameter and is dark gray to black in color, with a thin whitish layer surrounding it. The specimen contains few small bone fragments and small scales in the form of inclusions, separated from each other. The scales can be attributed to Aeduellidae indet. Based on their rectangular to rhombic shape, their light to absent serrations on their posterior margin, and their ornamentation composed of light growth lines. These scales are identical to those found isolated or articulated on the La Découverte Member described above. The bone fragments observed on the surface cannot be determined due to their fragmentary and altered state.

COMPARISONS

Of the coprolite morphotypes described by Hunt & Lucas (2012), Morphotype 2 described here is close to Morphotype C 1 in its subspherical shape and relatively small size, but differs in age and nature of inclusions (Hunt & Lucas 2012).

The white layer covering MHNT.PAL.2023.9.56 probably represents phosphate deposits resulting from the digestion of organic bone matter (e.g. Mercuzot et al. 2022). The presence of Aeduellidae scales, together with the depositional environment and fauna present in the Bourran Formation, suggests that the producer of Morphotype 2 was a carnivorous aquatic vertebrate. Morphotype 2 could have been produced by a small aquatic vertebrate, perhaps a xenacanth or a carnivorous actinopterygian (e.g. Progyrolepis ).