Klug
Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Paläontologisches Institut und Museum » PD Dr. Christian Klug » Klug
Current research project
| Title / Titel | Preservation of primarily organic tissues and soft-tissue attachment structures in molluscs from the German epicontinental Triassic | ||||
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| Abstract (PDF, 14 KB) | |||||
| Summary / Zusammenfassung | In contrast to the expectations of many colleagues, fossils from the Muschelkalk (Ani-sian, Ladinian; Middle Triassic) from the Germanic Basin proved to be extraordinarily well preserved in some respects. In the course of examinations of fossil molluscs from the Germanic Basin, we have discovered bivalves with remains of various organs pre-served in pure apatite as well as the periostracum, the black layer, the black band, and the organic parts of the beaks of cephalopods which are also phosphatised. Addition-ally, a variety of soft-tissue attachment structures are preserved in the cephalopod fos-sils, probably because of the fine-grained, more or less micritic carbonate sediment. Thin apatitic coatings were found on the dorsum in front of and sometimes behind the aperture of 50 specimens of Paraceratites and Ceratites (Ammonoidea) belonging to 14 species and subspecies and in three specimens of Germanonautilus, all from the Mid-dle Triassic of Germany. The proportions, occurrences, position, outline, and preserva-tion in fossil Nautiloidea and Ammonoidea (originally organic matter) of this structure support the hypothesis that it is homologous with the black layer in Recent Nautilus and Allonautilus. It is not yet possible to test whether these cephalopods show homologous styles of the development of these structures or whether the black layer can be identi-fied in a common ancestor. Exceptionally preserved specimens of the genera Myophoria, Neoschizodus and Tri-gonodus (Bivalvia, Palaeoheterodonta, Trigonioida) from carbonate sediments of the Muschelkalk (Anisian, Ladinian) contain phosphatised soft-tissues. This is the oldest re-cord of soft-tissue preservation in bivalves and the first from the German Muschelkalk. The phosphatised remains are here interpreted as relics of the originally chitinous gill supports, the gill axis, the labial palps (?), the adductor muscles, the pedal retractor muscles, the mantle margin including the radial mantle musculature, and the ‘siphons’. According to microprobe analysis, the mineral replacing the soft-tissue is mainly apatite and, more rarely, francolite. Additionally, quartz filled voids within the gill supports and in one sample, it occurs in minute crystals in the phosphatised remain of the adductor muscle of Neoschizodus. Myophoria, Neoschizodus and Trigonodus were soft-bottom dwellers and five of the specimens were discovered in life position. This is indicated by geopetal structures in three specimens. In contrast to many ammonoids, Ceratites, Paraceratites, most Palaeozoic ammonoids, and some Mesozoic ammonoids probably did not have lower mandibles that were suit-able for the closure of the aperture. They probably possessed a dorsally extending mantle (supracephalic mantle fold) and a hood as in Recent Nautilus and Allonautilus which was attached to the black layer. This interpretation is corroborated by a similar morphology of the black layer in an adult specimen of the nautilid Cenoceras from the South German Middle Jurassic and three specimens of Germanonautilus from the South German Middle Triassic (both Nautiloidea). New examinations of numerous steinkerns of the Middle Triassic nautilid Germanonau-tilus from southern Germany revealed new anatomic, ecologic and taphonomic details which are compared with Recent Nautilus. The attachment structures of the cephalic re-tractor muscle and of the dorsal and the posterior mantle (mantle myoadhesive and septal myoadhesive bands, black layer), some with tracking bands (recording the ante-riorward movement of the soft body during ontogeny) were found in several specimens. The shape and proportions of these soft-tissue attachment structures resemble those of Recent Nautilus macromphalus and indicate a similar soft anatomy. Based on their conch geometry, the mode of locomotion of Germanonautilus is reconstructed. Owing to their wide whorl cross section and their high whorl expansion rate, drag of their conchs was high, the aperture was oriented at an oblique angle which made them rather slow horizontal swimmers. |
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| Publications / Publikationen | KLUG, C. & JERJEN, I. (2012): The buccal apparatus with radula of a ceratitic ammonoid from the German Middle Triassic. – In: NEIGE, P. et al. (eds), Cephalopods - Present and Past: Geobios, 45: 57-65, Lyon.KLUG, C., MEYER, E., RICHTER, U. & KORN, D. (2008): Soft-tissue imprints in fossil and Recent cephalopod septa and septum formation. – Lethaia, 41 (4): ca. 20 pp., Oslo.KLUG, C., BRÜHWILER, T., KORN, D., SCHWEIGERT, G., BRAYARD, A. & TILSLEY, J. (2007): Ammonoid shell structures of primary organic composition. – Palaeontology, 50 (6): 1463-1478, London.KLUG, C., URLICHS, M., MONTENARI, M. & SCHULZ, H. (2007): Soft-tissue attachment of Middle Triassic Ceratitida from Germany. – In: Cephalopods – Present and Past. LANDMAN, N. H., DAVIS, R. A., MANGER, W. & MAPES, R. H. (eds), ca. 20 pp.; Springer, New York.Klug, C., Hagdorn, H. & Montenari, M. (2005): Phosphatised soft-tissue in Triassic bi-valves from Germany. Palaeontology, 48 (1): 833-852, London.Klug, C., Korn, D., Richter, U., & Urlichs, M. (2004). The black layer in cephalopods from the German Muschelkalk (Middle Triassic). Palaeontology, 47 (6): 1407-1425, London.Klug, C. (2004). Mature modifications, the black band, the black aperture, the black stripe, and the periostracum in cephalopods from the Upper Muschelkalk (Middle Tri-assic, Germany). Mitteilungen aus dem Geologisch-Paläontologischen Institut der Universität Hamburg, 88: 63-78, Hamburg.Klug, C., & Lehmkuhl, A. (2004). Soft-tissue attachment and taphonomy of the Middle Triassic nautiloid Germanonautilus. Acta Palaeontologica Polonica, 49 (2): 243-258, Warszawa. | ||||
| Keywords / Suchbegriffe | Cephalopoda, Bivalvia, soft-tissue preservation, soft-tissue attachment, evolution, palaeecology, Triassic, Germany | ||||
| Project leadership and contacts / Projektleitung und Kontakte |
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| Funding source(s) / Unterstützt durch |
No project-specific funding |
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| In collaboration with / In Zusammenarbeit mit |
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| Duration of Project / Projektdauer | Jan 2004 to Dec 2014 |