@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Filter feeding in Late Jurassic pterosaurs supported by coprolite contents

Citation: Qvarnström M, Elgh E, Owocki K, Ahlberg PE, Niedźwiedzki G. 2019. Filter feeding in Late Jurassic pterosaurs supported by coprolite contents. PeerJ 7:e7375 https://doi.org/10.7717/peerj.7375

(A) Map showing the location of the Wierzbica Quarry in Poland. (B) The location of the Wierzbica Quarry in a simplified geological map of the northern margin of the Holy Cross Mountains (based on Czarnocki, 1938; Urban & Gagol, 2008). (C) Detailed geological section of the tidal flat record with a consecutive succession of facies associations (1–5). The horizons with pterosaur tracks and coprolites are located at the bottom of facies association 4 (upper horizon with tracks) and within facies association 2 (lower horizon with tracks), (modified from Pieńkowski & Niedźwiedzki, 2005). (D) Details of the bottom of track layer 1 with record of pterosaur tracks (m–manus; p–pes) and coprolites (cop). (E) The studied coprolite specimens (MUZ PGI 1663.II.15a-c). (F, G) SEM images of coprolite matrix showing more or less irregular spheres and voids after bacterial activity. (H) EDS spectrum showing the geochemical composition of the coprolite matrix.

Feeding apparatus of Ctenochasma elegans and Phoenicopterus chilensis.
Schematic drawing of (A) the jaws and teeth of Ctenochasma elegans (redrawn from Bennett, 2007) and (B) the beak of the recent Chilean Flamingo (redrawn from Mascitti & Kravetz, 2002).

Diets of pterosaurs have mainly been inferred from indirect evidence such as comparative anatomy, associations of co-occurring fossils, and functional morphology. Gut contents are rare, and until now there is only a single coprolite (fossil dropping), with unidentified inclusions, known. Here we describe three coprolites collected from a palaeosurface with numerous pterosaur tracks found in early Kimmeridgian (Hypselocyclum Zone) intertidal deposits of the Wierzbica Quarry, Poland. The specimens’ morphology and association to the tracks suggest a pterosaur producer. Synchrotron scans reveal numerous small inclusions, with foraminifera making up the majority of the identifiable ones. Other small remains include shells/carapaces (of bivalves, ostracods, and other crustaceans/arthropods) and bristles (some possibly of polychaete worms). The high density of the small shelly inclusions suggest that they were not accidently ingested, but constituted an important food source for the pterosaur(s), perhaps together with unpreserved soft-bodied animals. The combined evidence from the tracks and coprolites suggest a filter-feeding ctenochasmatid as the most likely tracemaker. If true, this significantly expands the bromalite record for this pterosaur group, which was previously only known from gastroliths. Moreover, this study also provides the first direct evidence of filter feeding in Jurassic pterosaurs and shows that they had a similar diet to the recent Chilean flamingo (Phoenicopterus chilensis).

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev