The study of faunal change through time in the fossil record requires a careful assessment of the potential biases introduced by the filtering of death assemblages by depositional environments and other agents of accumulation such as predators. The investigation of taphonomy of the mammalian remains from the Arikareean-aged Cabbage Patch beds of western Montana reported here used both sedimentological evidence and characteristics of the preservation of the fossil specimens to test two hypotheses regarding their preservation pattern: (1) the pattern of faunal change through the section is not a product of differences in the preservation of fossils and (2) the taphonomic characteristics of fossil specimens are linked to the environments in which they were preserved. The interpretation of the sedimentological data, combined with the analyses of the taphonomic filtering of mammalian fossils, suggests that the attritional accumulation of fossils in floodplain settings was the result of predator activity, attrition, and local reworking by fluvial processes. The fossils from these deposits experienced little transport. Moreover, despite complexities in the dataset, select specimen characteristics, including size, shape, and surface modifications, can be linked to the depositional environments determined from sedimentological data. The fossils recovered from a high energy deposit of the lower Cabbage Patch are significantly different from those found in low energy deposits. These low depositional energy fossil assemblages appear to be sufficiently taphonomically similar to be used in faunal analyses despite a change in postmortem filtering through the section.

In 2015, a group of small predominantly tridactyl tracks was discovered in the lower Shawan Member of the Lufeng Formation during an expedition to the Dalishu area, Lufeng County, Yunnan Province, China. The tracks are attributable to Anomoepus, and although mostly tridactyl, they include a few examples with characteristic tetradactyl morphology. Although considered a characteristic index ichnotaxon of a footprint-based Lower Jurassic biochron, Anomoepus has often been overlooked in assemblages dominated by theropod tracks. This is one of the earliest Anomoepus records from the Jurassic of China, and the fifth report of Anomoepus from China at all. To date, four reports represent sites inferred to be Lower or Middle Jurassic in age, with one dated as Upper Jurassic. It is an important component of Early Jurassic ichnofaunas because it points to the presence of ornithischian trackmakers, which are often rare or missing in the local skeletal faunas (Lufengosaurus faunas).

Collecting and analyzing semi-quantitative ichnological parameters such as size-diversity index and bioturbation intensity, can increase the resolution of paleoenvironmental analyses. Specialized software, PyCHNO, was designed to ease, improve, and standardize current ichnological data collection techniques. With PyCHNO, ichnological data derived from burrow diameter measurements, trace fossil identification (ichnogenus level), and bioturbation index are collected at a user-defined scale, and size-diversity index is calculated from these measurements. Data collected in PyCHNO, including size-diversity index, maximum burrow diameter, trace fossil diversity, trace fossil taxon abundance, and bioturbation index is easily exported as text files or plotted as PDF logs.

In this paper we examine quantitative ichnological data of silty-mudstone beds from inclined heterolithic stratification (IHS) in order to understand the spatial and temporal controls affecting bioturbation in IHS. Data collected for this study include bed-scale averaged bioturbation intensity, size-diversity index, and ichnogenera abundances. These data were used to assign each bed into one of 10 clusters using K-Means clustering. The clusters were ranked according to interpreted intensity of cumulative depositional ecologic stress. Time-series, where each silty-mudstone bed represents a time-step with a corresponding ecologic stress value, were constructed from the interpreted ecologic stress cluster analysis results. To identify and interpret spatial and temporal variation in the ichnological time-series, two time-series analysis methods were employed: dynamic time-warping and continuous wavelet transforms. Dynamic time-warping is used as a descriptor of the spatial similarity between ecologic stresses, and continuous wavelet transforms are used to interpret cyclical patterns in the ichnological time-series. Spatially, the variability and cyclicity observed in the ecologic stress time-series can be linked to estuary scale stresses and more localized stresses (i.e., bar-form scale depositional stress). This is reflected by the relatively similar periodicities observed in the ecologic stress time-series. Temporally, cyclical ecologic stress patterns occur somewhat predictably in periods of approximately four, or multiples of four, which are consistent with El Nino cyclicity.

Complex ant nests from the lower Paleogene Maíz Gordo Formation of Salta (northwestern Argentina), included in the new ichnospecies Krausichnus sisi (Krausichnidae), are composed of columns of up to 1 m high and 160 flat, stacked chambers which are connected by vertical, straight, and parallel shafts. Columns are interconnected by lateral extensions of chambers, which are recognizable by their dark linings. Columns of densely packed flat chambers are similar to extant nests of Monomorium (Myrmicinae), which are postulated as the potential producers. Independent entrances and strong enlargements of columns by addition of chambers suggest that these functioned as individual, yet interconnected, nests. Such systems are compatible with polydomy, which is defined as the arrangement of an ant colony in at least two spatially separated nests. Krausichnus sisi traces polydomy in ants to the early Paleogene of South America in warm and semiarid fluvial valleys with calcareous sandy soils and dry woodland vegetation. These nests provide the oldest record of this behavior in ants and are a rare case for study of the underground architecture of polydomous nests.

Time-averaging has evolved from an unrecognized variable in paleoecological analyses to a key concept in understanding the dynamics of sedimentary systems and the formation of fossil deposits. Here we used radiocarbon-calibrated amino acid racemization ages from 173 Fulvia tenuicostata shells collected from Sydney Harbour (NSW, Australia) to quantify time-averaging in surficial and excavated death assemblages. A novel approach to estimating the total age-estimate variability of a collection of specimens is presented that integrates the age-estimation error associated with the AAR calibration model and the effect of time-averaging variability on the age distribution. Fulvia collected from a single 1.6-m deep excavation were used to quantify changes in time-averaging with burial depth. Fulvia collected from surficial death assemblages at six sites were used to quantify spatial variation in time-averaging. The median shell age increased from ∼ 150 yr to ∼ 4230 yr and time-averaging from ∼ 40 yr to ∼ 960 yr with increased burial depth. While four sites contained surface shell assemblages with median ages of ∼ 150 yr and time-averaging of ∼ 40 yr, two sites had death assemblages with older median ages and time-averaging > 1900 yr. A decline in the abundance of Fulvia in the post-colonial period is likely responsible for the rarity of very young shells in the surface death assemblages, while local factors such as dredging and other human activities are likely responsible for the total age-estimate variability in the two highly time-averaged surface collections. These analyses provide a geochronological context for assessing ecological changes in the harbor's benthic communities since colonization and offer an important perspective on the formation of Holocene fossil deposits.