From tree to shining sea: taphonomy of the arboreal lizard Geiseltaliellus maarius from Messel, Germany

Abstract

Much has been written about the palaeoenvironment of the middle Eocene fossil Lagerstätte of Messel, Germany, and of the taphonomy of the vertebrates found in it, but taphonomic phenomena among the reptiles in this locality are virtually unstudied. The iguanid Geiseltaliellus maarius is the most common lizard species in Messel. We present taphonomic data for this species and analyse it. Specimens of G. maarius can be divided into three preservation classes, one of which is distinguished purely by decompositional phenomena. Most specimens sank quickly to the bottom of Lake Messel after entering it, but one floated for some time prior to emplacement. In theory, overlying pressure should not preclude the accumulation of gases of decay in submerged carcasses. In one specimen, such gases appear to have built up intracoelomically for many weeks, but did not cause the carcass to rise because of overlying water pressure. Eruption of the gases through the oral and cloacal openings, possibly initiated by a coincident turbidity current, scattered the bones of the skull, the pelvic region, and the proximal part of the tail. G. maarius had evolved a form of intervertebral urotomy (pseudoautotomy), which is indicative of arboreal habits. The waxy substance adipocere, formed after breakdown of fat, has been neglected in discussions of taphonomy, but may constitute an important factor in stabilising carcasses and enabling three-dimensional preservation before diagensis.

Patterns of aquatic decay and disarticulation in juvenile Indo-Pacific crocodiles (Crocodylus porosus), and implications for the taphonomic interpretation of fossil crocodyliform material

“…Articulation of skeletal elements and preservation of soft tissues in Lagerstätten fossils are thought to have resulted from carcasses in good condition decaying in low energy aquatic environments that are anoxic, acidic or hypersaline, all of which limit opportunities for scavenging and destruction of soft tissue (Allison, 1988;Allison and Briggs, 1991;Taylor, 1995;Behrensmeyer et al, 2000). Although rapid or catastrophic burial can form Lagerstätten, other 'stagnation' mechanisms can also result in the formation of Lagerstätten, such as (1) sinking into a soupy substrate (Smith and Wuttke, 2012),…”

Isotope compositions (C, O, Sr, Nd) of vertebrate fossils from the Middle Eocene oil shale of Messel, Germany: Implications for their taphonomy and palaeoenvironment

“…Anoxic bottom water along with a lack of bioturbation and reduced degradation by anaerobic microbes led to the undisturbed deposition of macrofossils of vertebrates at Messel (Schmitz, 1991;Schaal and Ziegler, 1992;von Koenigswald and Storch 1998;Franzen, 2007;Gruber and Micklich, 2007;Mayr, 2009;Joyce et al, 2012;Micklich, 2012;Schwermann et al, 2012;Smith and Wuttke, 2012), plants (Wilde, 1989(Wilde, , 2004Collinson et al, 2012) and invertebrates (Neubert, 1999;Wedmann, 2005), as well as microfossils such as pollen and spores (Thiele-Pfeiffer, 1988;Lenz et al, 2007Lenz et al, , 2011, algae (Goth, 1990;Lenz et al, 2007) and sponge spicules and gemmules (Richter and Wuttke, 1999;Richter and Baszio, 2009). The preservation of the fossils is exceptional with beetles still displaying structural colours (McNamara et al, 2012); feathers featuring preserved arrays of fossilised melanosomes, allowing reconstruction of the original colouration (Vinter et al, 2010); and plant macrofossils preserved as remnants of the original organic material in various stages of compression and degradation (Wilde, 1989;Collinson et al, 2012).…”

Revision of the cranial anatomy and phylogenetic relationships of the Eocene minute boasMesselophis variatusandMesselophis ermannorum(Serpentes, Booidea)

“…The Middle Messel Formation, from which all vertebrate specimens come, was recently dated to approximately 47.4–48.3 Mya, based on the astronomical tuning of pollen abundance profiles and revised 40 Ar/ 39 Ar dating of the phreatomagnatic eruption that produced the Messel crater (Lenz et al ., ). Overall, several processes have served to preserve even the hair, feathers, ‘skin shadows’, wing membranes, stomach, and intestinal contents of some species, and even insect scale colouring, providing evidence for the feeding habits, ecology, and environment of the Eocene flora and fauna (Wuttke, ; Schaal & Ziegler, ; Vinther et al ., ; McNamara et al ., ; Smith & Wuttke, ).…”