The skeletal taphonomy of anurans from the Eocene Geiseltal Konservat‐Lagerstätte, Germany: insights into the controls on fossil anuran preservation

Abstract

The Geiseltal biota is an Eocene lacustrine Konservat-Lagerst€ atte in central Germany. Despite its rich fauna and flora (over 50 000 fossil vertebrates, insects and other invertebrates, plants and trace fossils) the taphonomy of the biota, and of the anurans in particular, is poorly understood. We analysed the skeletal taphonomy of 168 anurans, scoring each specimen for orientation, completeness and articulation. Most are partial skeletons, truncated during preparation. This process introduces measurable artefacts into the taphonomic data, which requires further study. We identified 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 states include: loss of distal limb elements only, scattered bones, and isolated, articulated limbs. These data inform a new taphonomic model for the Geiseltal anurans. Comparative analysis of patterns in completeness and articulation in these specimens and anurans from other Cenozoic Lagerst€ atten reveals repeated patterns in 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. Taphonomic controls in lacustrine systems are surface water temperature, lake depth, vegetation, exposure to bottom currents, transport mechanisms, scavenging, decay regime, bone size and location in the skeleton; all ultimately controlled by palaeoclimate, lake physiography and hydrology, and anuran anatomy. A universal approach to quantitative analysis of skeletal taphonomy metrics will enable comparative testing of the relationship between preservation and palaeoenvironment for diverse fossil vertebrates.

Decoding the drivers of deep‐time wetland biodiversity: insights from an early Permian tropical lake ecosystem

“…Martinez‐Delclòs & Martinell 1993; Falk et al . 2022). In addition, some elements of the former biocoenosis could have escaped preservation, while biotas from surrounding terrestrial and aquatic environments entered the limnic setting (see Briggs et al .…”

A cretaceous frog with eggs from northwestern China provides fossil evidence for sexual maturity preceding skeletal maturity in anurans

“…The most likely cause of death for the female represented by JQ-HX-QW-02 is drowning or exhaustion in relation to mating, constituting the first Mesozoic case of death linked to mating behaviour (figure 6). This latter cause of death has also been considered to be a major cause of death in some Cenozoic anurans [79,81–85].

Figure 6Reconstructed Early Cretaceous living environment of the Gansubatrachus qilianensis .

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Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers

“…Instead, refloating may have been prevented by low temperatures and/or deep waters. At low temperatures, low rates of decay and thus of gas production (plus ongoing escape of gases via various orifices) can inhibit the accumulation of sufficient gases for carcasses to become buoyant 79 , 80 ; experimental work has demonstrated that, below about 16 °C, fish carcasses can remain on the water bottom for weeks to months without floating 80 . In deep waters, high hydrostatic pressure compresses decay gases and results in their dissolution, thereby suppressing flotation of the carcasses 79 , 80 .…”

“…At low temperatures, low rates of decay and thus of gas production (plus ongoing escape of gases via various orifices) can inhibit the accumulation of sufficient gases for carcasses to become buoyant 79 , 80 ; experimental work has demonstrated that, below about 16 °C, fish carcasses can remain on the water bottom for weeks to months without floating 80 . In deep waters, high hydrostatic pressure compresses decay gases and results in their dissolution, thereby suppressing flotation of the carcasses 79 , 80 . Consistent with this cold, deep water scenario, previous palaeoclimatic reconstruction for the Jehol Biota indicates cold local conditions with a mean air temperature of 10 ± 4 °C 81 ; further, although the exact water depths are unknown, the Jehol lakes had steep margins and sufficiently high depth-to-fetch ratios to develop stratification 46 , 82 .…”