California's La Brea Tar Pits is one of the richest Ice Age fossil localities in the world and offers unmatched potential for reconstructing environmental conditions and ecological relationships in the Late Pleistocene. Plant macrofossils are abundant at the site, but their accurate interpretation requires a better understanding of the processes behind their deposition in hydrocarbon seeps and potential spatial resolution, a topic not yet addressed in asphalt pit related research. In this study we monitor temperature, phenology, and seep activity of two hydrocarbon seeps in southern California over the span of a year. For each seep we surveyed surrounding vegetation within 10 meters and sampled seep surfaces for analysis of trapped plant material. We find hydrocarbon seeps to be highly localized with 77–91% of plant material originating from species found within five meters of the seep. Temperature and time-lapse imagery indicate a greater likelihood of transportation of plant material by wind or animal than by water in these particular seeps. Animal transport through fecal matter or entrapment was the most likely candidate for the species Sambucus mexicana to be transported outside the immediate vicinity of the monitored seeps. Variation in observed viscosity of liquid asphalt correlated with seasonal temperature changes, with higher temperatures coinciding with decreased viscosity and increased seep flow. We find observations of seasonal seep flow connected to a warm season bias of plant material, making phenology an important consideration in the interpretation of plant presence and absence in asphaltic fossil contexts.

Several biological and chemical changes occur during fossilization of organisms. However, the nature and mechanism of fossilization are not yet completely understood. In this study we investigated the changes in chemical composition during fossilization of lanternfish from the lower Miocene Yamami Formation, Chita Peninsula, Japan compared to modern/living lanternfish. This comprised chemical mapping using X-ray microscopic analysis, mineral identification using Raman spectroscopy, and chemical analysis using inductively coupled plasma mass spectrometry and elemental analysis. Carbon and nitrogen were lost significantly during fossilization, whereas slight changes were observed in phosphorus and calcium concentrations, which are major elements of hard tissues. Iron and sulfur concentrations are high in fossil fish compared to modern/living fish due to pyrite formation during fossilization. In agreement with earlier studies, we conclude that in-situ pyrite formation mediated by sulfur-reducing bacteria played an important role in the preservation of soft tissue textures in the Yamami Formation. This includes the preservation in the fossils of delicate organs, such as eyes in the Yamami lanternfish. The oxidation of pyrite is also important for fossil preservation because of the low solubility of iron oxides.

Attenborites janeae is a soft-bodied, enigmatic member of the Ediacara Biota with variable internal and external morphology. This taxon is only found within the Ediacara Member of South Australia at Nilpena Ediacara National Park. It occurs rarely across this site but over 100 specimens occur on a single bedding plane, TB-ARB. Previous research has suggested that fossils of Attenborites represent a taphonomically altered form of the true organism which may have been pelagic. Here we use a combination of morphologic and taphonomic methods to reconstruct the most likely morphology and life habit of Attenborites janeae. Evaluating the characteristics of each fossil and the broader bed population, we find that the variable morphology among Attenborites specimens is a product of biostratinomic collapse and that these fossils represent the deflated form of living organisms that were most likely globose and radially symmetrical. We employ the 3D modeling software Blender to conduct inflation simulations on laser-scanned meshes of each fossil to reconstruct the original morphology. To determine the most likely life habit of Attenborites, we examine the broader sedimentological and preservational context of the taxon. We find a pelagic life habit most parsimonious, consistent with the original hypothesis and the reconstructed morphology, rendering Attenborites the only Ediacara taxon to be supported as pelagic based on both taphonomic and morphological evidence.