The Geiseltal biota is a lacustrine-hosted Konservat-Lagerstätte from the Eocene of central Germany. Despite its rich fauna and flora that is represented by at least 50,000 fossil vertebrates, insects and other invertebrates, plants and trace fossils, the taphonomy of the biota is still poorly understood. In particular, the anurans have not been the focus of taphonomic investigation. Here, we analysed the skeletal taphonomy of 168 anurans from Geiseltal and scored each specimen for orientation, completeness and articulation. Most specimens are partial skeletons that were truncated during preparation. This process introduces measurable artefacts into the taphonomic data and should be assessed in future taphonomic studies on fossil vertebrates. The Geiseltal anurans show several recurring taphonomic states, including disarticulation or loss of abdominal bones, loss of one or more limbs, extensive disarticulation and extensive loss of elements across the body. Relatively rare taphonomic states include loss of distal limb elements only, scattered bones and isolated, articulated limbs. These data are the basis of a new taphonomic model for the Geiseltal anurans. Comparative analysis of patterns in completeness and articulation in these specimens and in fossil anurans from other Cenozoic Lagerstätten reveals repeated taphonomic patterns in anuran preservation in lacustrine-hosted settings, such as proximal to distal trends in completeness, preferential loss of small peripheral bones, disarticulation of abdominal bones and reorientation of major body regions and limbs. The taphonomic controls in lacustrine systems are surface water temperature, lake depth, vegetation, exposure to bottom currents, transport mechanisms, extent of scavenging, decay regime, bone size and bone location in the skeleton. In turn, these are ultimately controlled by palaeoclimate, lake physiography and hydrology, and anuran anatomy. A universal approach to quantitative analysis of skeletal taphonomy metrics will allow comparative testing of the relationship between preservation and palaeoenvironment for diverse fossil vertebrates.

Date of data collection: 02/2019–11/2020

Geographic location of data collection: Natural Sciences Collections (ZNS), Halle (Saale), Germany.

SUPPLEMENTARY DATASET 1. Master dataset with skeletal taphonomic data for the Geiseltal anurans. Data are shown for each of 140 specimens used in the study and an additional 28 specimens that were excluded due to poor preservation (precluding confident identification of individual skeletal elements). Specimens lacking a full limb are identified on the basis of the absence of at least one humerus or femur and their respective distal limb elements. Specimens showing isolated limbs only are omitted from this analysis; specimens are also omitted where truncation (i.e. of the torso) prevents confidence of presence/absence of humeri and/or femura. Abbreviations: Ce, ‘Cecilie’ pit; IL, ‘Geiselröhlitz’ site; GMH, Geiseltalmuseum Halle; hyphen (-), unknown; indet., indetermined; Leo, ‘Leonhard’ pit; LMC, lower middle coal; LUC, lower upper coal; MC, middle coal; MUC, middle upper coal; Nw, ‘Neumark-West’ pit; N/A, not applicable; UHM, upper ‘Hauptmittel’ (‘Hauptmittel’: intercalated sandy and silty successions); UMC, upper middle coal; XXXV, most likely Neumark-Süd pit (NsXXXV).

SUPPLEMENTARY DATASET 2. Completeness data. Completeness data for each skeletal element in each specimen. Absence and presence of an element represented by a single bone (e.g. left humerus) are coded ‘0’ and ‘1’, respectively. Completeness categories for multi-bone elements (e.g. left phalanges) are defined in the main text and in the table column header. Abbreviations: Ce, ‘Cecilie’ pit; IL, ‘Geiselröhlitz’ site; GMH, Geiseltalmuseum Halle; hyphen (-), unknown; Leo, ‘Leonhard’ pit; Nw, ‘Neumark-West’ pit; N/A, not applicable (e.g. if the element in question is distal to a truncated element); Trunc#, element truncated, but up to # bones present; xx, not confident; XXXV, most likely Neumark-Süd pit (NsXXXV).

SUPPLEMENTARY DATASET 3. Articulation data. Articulation data for each joint in each specimen. Disarticulation and articulation of a single joint (e.g. left radioulna-humerus) are coded ‘0’ and ‘1’, respectively. Articulation categories for multi-joint elements (e.g. left phalanges) are defined in the main text and in the table column header. Abbreviations: Ce, ‘Cecilie’ pit; IL, ‘Geiselröhlitz’ site; GMH, Geiseltalmuseum Halle; hyphen (-), unknown; Leo, ‘Leonhard’ pit; Nw, ‘Neumark-West’ pit; N/A, not applicable (e.g. if the element in question is distal to a truncated element); Trunc#, element truncated, but up to # bones present; xx, not confident; XXXV, most likely Neumark-Süd pit (NsXXXV).