The taphonomy of anurans from the Eocene Geiseltal Konservat-Lagerstätte

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dc.check.date2026-05-31
dc.contributor.advisorMcNamara, Maria
dc.contributor.advisorexternalWings, Oliver
dc.contributor.authorFalk, Danielen
dc.contributor.funderIrish Research Council for Science, Engineering and Technologyen
dc.date.accessioned2025-02-05T16:28:11Z
dc.date.available2025-02-05T16:28:11Z
dc.date.issued2024
dc.date.submitted2024
dc.description.abstractThe Eocene Geiseltal fossil site is represented by ca. 50,000 fossil specimens that were recovered from open-cast lignite mines in central Germany in the early to mid-20th century. The fossils were excavated primarily from organic-rich sediments of lacustrine and fluvial deposits and are curated in the Geiseltal Collection of the Natural Sciences Collections of the Martin Luther University Halle-Wittenberg in Halle (Saale). The fossil collection includes vertebrates, invertebrates, plants and trace fossils. Despite its rich fauna and flora, the taphonomy of the biota is poorly understood. This is because the primary fossil collections, studied extensively in the early 20th century, were not accessible for study using modern techniques. The Geiseltal biota is famous for reports of three dimensionally preserved soft tissues; the subcellular anatomical details described for various soft tissues in different vertebrate groups and in the anurans in particular, represent a fidelity of preservation that is among the highest known for any Konservat-Lagerstätte. Intriguingly, the proposed mode of preservation, direct replication in silica, is not known in other fossils, but has not been verified using modern approaches. This thesis addresses these issues using quantitative taphonomic approaches, microbeam techniques (scanning electron microscopy, micro-Fourier transform infrared spectroscopy, micro-Raman spectroscopy, X-ray diffraction and synchrotron rapid scanning-X-ray fluorescence) and statistical analysis to elucidate the taphonomy of the Geiseltal anurans (i.e., frogs and toads). Critical assessment of trends in the articulation and completeness of the fossil anurans reveals a hierarchy of taphonomic controls, whereby preservation is controlled at the specimen level by the size and location of bones, by the three-dimensional configuration of joints, by the impact of predators and scavengers, by the duration of pre-depositional transport and the impact of bottom currents on the lake floor. The studied Geiseltal anurans lack most of the soft tissues reported originally; there is no evidence for preservation in silica. Instead, the only soft tissue features present are melanosome films and the anuran-specific mid-dermal Eberth-Katschenko (E-K) layer, preserved as sulfurised organic remains and as a phosphatised replacement, respectively. Multivariate analysis of geometry data of melanosomes preserved in anurans from Geiseltal, other fossil biotas and extant anurans reveals that the evolution of melanosomes in the skin is decoupled from that of melanosomes in the eyes and internal tissues. This most likely reflects disparate physiological constraints on melanosome function since the Middle Eocene. In summary, comparison of the taphonomy of the Geiseltal anurans with fossils from other lacustrine Konservat-Lagerstätten reveals that the skeletal and soft tissue features of the Geiseltal anurans are not unique. The mode of preservation of the Geiseltal anurans also applies to anurans from other lacustrine Konservat-Lagerstätten, revealing high-level controls on the preservation of anurans in the fossil record. The major controls on skeletal taphonomy are the broad palaeoclimatic setting, which controls lake water temperature, lake physiography, which controls the lake depth and lake size and anatomy, which control the size and location, respectively, of bones. These results potentially apply to other vertebrate groups. The major controls on the preservation of anuran soft tissues are the availability of phosphate ions and reduced sulfur species, the development of microenvironments during decay and the tissue chemistry. This thesis highlights the power of combining quantitative, analytical and comparative approaches to assess the skeletal and soft tissue taphonomy of fossil vertebrates in order to develop models for the preservation of fossil vertebrates in lacustrine environments. This thesis also demonstrates that comparative analysis of melanosome data from fossil and extant specimens in a single vertebrate group can inform on the evolution of melanin in that group. Finally, scientific investigation of fossil collections using modern analytical techniques is essential to critically re-evaluate both historical fossil interpretations and established scientific paradigms.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationFalk, D. 2024. The taphonomy of anurans from the Eocene Geiseltal Konservat-Lagerstätte. PhD Thesis, University College Cork.
dc.identifier.endpage379
dc.identifier.urihttps://hdl.handle.net/10468/16976
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectIrish Research Council for Science, Engineering and Technology (Grant no. GOIPG/2018/3354)
dc.rights© 2024, Daniel Falk.
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subjectFossil amphibian
dc.subjectFossil preservation
dc.subjectSkeletal taphonomy
dc.subjectGeiseltal
dc.subjectKonservat-Lagerstätte
dc.subjectEocene
dc.subjectFrog
dc.subjectToad
dc.subjectAnura
dc.subjectMelanosome
dc.subjectSoft-tissue preservation
dc.subjectSulfurisation
dc.subjectPhosphatisation
dc.subjectMuseum collections
dc.subjectLagerstätte
dc.subjectSilicification
dc.subjectTaphonomy
dc.subjectQuantitative analysis
dc.titleThe taphonomy of anurans from the Eocene Geiseltal Konservat-Lagerstätteen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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