A new type of entombment of Peronopsis (Agnostida) in a hyolithid conch

[摘要] An enrolled exoskeleton of the holaspid specimen of a tiny agnostid Peronopsis integra (Beyrich, 1845) entombed inside a conch of the hyolithid ?Buchavalites sp. is described from the middle Cambrian (Drumian) Jince Formation of the Příbram-Jince Basin (Czech Republic). The agnostid is associated with an ichnofossil of the feeding trace classified as Arachnostega-type behaviour. The enrolled attitude of the agnostid exoskeleton suggests that the specimen is a carcass rather than moult. Either the storm disturbance and/or well-protected source of food hypotheses could explain the entombed agnostid. This additional example supports a benthic mode of life in the agnostid P. integra. The studied association of feeding tunnels of an unknown Arachnostega-strategist and Peronopsis preserved inside a hyolithid conch is a case of "frozen" behaviour.

[学科分类] 地质学

[关键词] Agnostid palaeoecology;trilobites;Drumian;Cambrian;Jince Formation;Barrandian area;Příbram-Jince Basin;Czech Republic