Ichnology of Late Cretaceous echinoids from the Maastrichtian type area (The Netherlands, Belgium) 2. A pentagonal attachment scar on Echinocorys gr. conoidea (Goldfuss)

Introduction Tests of large-sized Late Cretaceous holasteroid echinoid genera, such as Echinocorys Leske and Hemipneustes L. Agassiz, uncommonly preserve growth reactions to invasive interactions with settling, cementing and boring invertebrates, and lesions caused by vertebrates, that occurred during the life of the echinoid (for example, Donovan and Jagt, 2002; Donovan et al., 2008). There may be subtle evidence that infestations manifested themselves in vivo. The corollary of this is that infestations not associated with test modifications are interpreted as having occurred, most probably, post mortem, but prior to final burial of the echinoid test. The naked test of a dead echinoid on a soft chalk bottom may have provided a hard substrate and would thus have facilitated those benthic invertebrates that were obligate encrusters or borers, such as certain groups of bivalve and brachiopod, and most bryozoans, but would have been of limited or no interest to predatory vertebrates. There is ample evidence that species of these superficially burrowing holasteroid echinoids, both dead and alive, hosted a wide range of infesting organisms (for example, Joysey, 1959; Voigt and Soule, 1973; Donovan and Jagt, 2005; Jagt et al., 2007; Neumann and Wisshak, 2006; Wisshak and Neumann, 2006). Herein, we describe an unusual attachment trace on a test of Echinocorys, one of the commonest and most widely distributed echinoid genera in the Upper Cretaceous of Europe. The specimen is deposited in the collections of the Natuurhistorisch Museum Maastricht, The Netherlands (NHMM). NL-2300 RA Leiden, The Netherlands + Natuurhistorisch Museum Maastricht (SCZ), de Bosquetplein 6-7, NL-6211 KJ Maastricht, The Netherlands # Molenberg 4, NL-6191 KM Beek, The Netherlands The tests of large holasteroid echinoids provided hard substrates that could become infested, both before and after death, by a range of invertebrates during the Late Cretaceous. A specimen of Echinocorys gr. conoidea (Goldfuss) from the (late Maastrichtian) upper Lixhe 1 Member, Gulpen Formation, of the Lixhe area, Belgium, preserves an elongate pentagonal scar. This trace fossil is non-penetrative and is probably the result of shallow embedment of an unmineralized, sessile invertebrate (a sea anemone?) on the test of the live echinoid. The elongation in an adapical-abapical direction may reflect the normal morphology of the producing species or was perhaps a plastic response to environment. Abstract Bulletin of the Mizunami Fossil Museum, no. 36 (2010), p. 51–53, 2 figs. © 200, Mizunami Fossil Museum Fig. 1. Outline map of the study area (redrawn and simplified after Jagt, 1999, fig. 1; Donovan and Jagt, 2004, fig. 1), showing political boundaries (dashed lines), rivers and canals (solid lines), the city of Maastricht and the Lixhe area. The inset map of The Netherlands, Belgium and Germany shows the approximate position of the main map (box).