Bioerosion in shells from the Early Permian Rio Bonito Formation, Brazil: Taphonomic, paleobiological, and paleoecological implications

• Published in: Palaeogeography, palaeoclimatology, palaeoecology Vol. 505; pp. 256 - 264
• Main Authors: Schmidt-Neto, Hugo, Netto, Renata Guimarães, Villegas-Martín, Jorge
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-09-2018
• Subjects: Composite molds; Early Permian; Ichnology; Shell pavements; Sponge borings; Taphonomy; Ichnology; Shell pavements; Sponge borings; Early Permian; Taphonomy; Composite molds
• ISSN: 0031-0182; 1872-616X
• DOI: 10.1016/j.palaeo.2018.06.003

We report the occurrence of sponge borings in composite molds of heteropectinid shells from Early Permian marine siliciclastic deposits of the Paraná Basin of southern Brazil. Sponge borings are preserved mainly as chambers (Entobia) and channels (Entobia and Clionolithes). Three preservational variations of Entobia are present, morphologically equivalent to the alpha, beta, and gamma ontogenetic stages of clionid sponges. This equivalence suggests that the ontogenetic behavior in clionid sponges remains the same since Early Permian times and points to a conservative evolutionary trend for this group. The pattern of bioerosion and other taphonomic signatures indicate rapid shell burial due to frequent and energetic storm events that might have limited the time available for bioerosion activity. The new findings improve the Paleozoic record of Entobia and Clionolithes and indicate that sponge borings have potential to be preserved in ancient siliciclastic rocks.
•Bioerosion structures attributed to sponge activity occur in Early Permian shell beds.•Preservational variations of Entobia represent sponge ontogenetic stages.•The Paleozoic record of Entobia and Clionolithes is increased in the Paleozoic age.•Fewer bioeroders and quick shell burial constrained bioerosion in the Rio Bonito Formation shelly fauna.