Paleoecology and taphonomy of spatangoid echinoid-produced burrows (Scolicia) in slope and basin floor deposits from the Eocene of Cuba

The morphological variability in the preservation of the trace fossil Scolicia is mainly taphonomic and results from different factors. However, only a few papers have discussed this issue using a taphonomical approach. In addition, although Scolicia is commonly present in deep-sea and shelf ichnoassemblages, its record in slope deposits is scarce. Herein, variations in the preservation of Scolicia are discussed in slope and basin floor contexts from the Eocene Capdevila Formation, western Cuba. The studied specimens come from two outcrops located in the Artemisa and Pinar del Rķo
regions. The burrows were assigned to Scolicia prisca, Scolicia isp. var. vertebralis, and Scolicia isp. var. laminites. The observed variations in the diagnostic features of Scolicia reflect the wide variation expected in burrows made by spatangoid echinoids. Furthermore, we demonstrated that S. vertebralis could be a preservational variant of S. prisca and that S. prisca could be produced as furrows by extant echinoids, and not necessarily represent eroded burrows. In the Artemisa section, Scolicia is associated with basin floor deposits in bathyal context and form part of the Nereites ichnofacies. In
the Pinar de Rķo section, Scolicia occur in shallower slope deposits and is included in the impoverished Cruziana ichnofacies. Their presence in slope deposits could be due to different factors, such as the predominance of sandy substrates, high sedimentation rate, and good oxygenation, which also led to an absence of trace fossils of the Zoophycos ichnofacies, which is typical of slope settings.