Taphonomic Factors Research Articles

Experimental subaqueous burial of a bird carcass and compaction of plumage

‘Exceptional fossils’ of dinosaurs preserving feathers have radically changed the way we view their paleobiology and the evolution of birds. Understanding how such soft tissues preserve is imperative to accurately interpreting the morphology of fossil feathers. Experimental taphonomy has been integral to such investigations. One such experiment used a printing press to mimic compaction, done subaerially and without sediment burial, and concluded that the leaking of bodily fluid could lead to the clumping of feathers by causing barbs to stick together such that they superficially resemble simpler, less derived, filamentous structures. Here we use a novel, custom-built experimental setup to more accurately mimic subaqueous burial and compaction under low-energy, fine-grain depositional environments applicable to the taphonomic settings most plumage-preserving ‘exceptional fossils’ are found in. We find that when submerged and subsequently buried and compacted, feathers do not clump together and they maintain their original arrangement. Submersion in fluid in and of itself does not lead to clumping of barbs; this would only occur upon pulling feathers out from water into air. Furthermore, sediment encases the feathers, fixing them in place during compaction. Thus, feather clumping that leads to erroneously plesiomorphic morphological interpretations may not be a taphonomic factor of concern when examining fossil feathers. Our current methodology is amenable to further improvements that will continue to more accurately mimic subaqueous burial and compaction, allowing for various hypothesis testing.

Species identification of voles and lemmings from Late Pleistocene deposits in Pin Hole Cave (Creswell Crags, UK) using collagen fingerprinting

Microfaunal remains are commonly used as palaeoenvironmental proxies and have been proposed as a means to identify relative ages of Late Quaternary deposits through biostratigraphy (i.e., utilising ‘Mammal Assemblage Zones’). However, assemblages of faunal remains can include a diverse range of taxa which are often difficult to distinguish using morphological aspects of the surviving bones, particularly when diagnostic features are eroded or missing due to fragmentation. Here we investigate the application of a recently developed method of species identification by collagen fingerprinting to arvicoline rodents (voles and lemmings), the dominant mammalian taxonomic group present at the Late Pleistocene site of Pin Hole Cave, Creswell Crags U.K., which is currently the designated British type locality for the Pin Hole Mammal Assemblage Zone (Oxygen Isotope Stage 3) fauna. We also further explore the potential for studying collagen decay rate via deamidations, and their applicability across the species boundary, in terms of its use for relative ageing of remains. Our results demonstrate the ease with which some taxa can be objectively distinguished to genus (e.g. Microtus from Myodes and Lemmus from Dicrostonyx) and in some cases species (e.g., M. gregalis from M. oeconomus), but that the potential for relative ageing is complicated by a range of taphonomic factors. The results highlight the potential for this new technique in much larger-scale palaeoenvironmental studies investigating temporal changes in vertebrate biodiversity.

Application du SIG pour l’étude de la distribution de divers agents taphonomiques et leurs effets sur les restes fauniques du niveau 3 colluvium d’isernia la pineta : données préliminaires

Prehistoric human occupation at the early Middle Pleistocene, Palaeolithic open-air site of Isernia La Pineta (Molise, Italy) is evidenced by an impressive repertoire of lithic tools and faunal remains recovered from four archaeosurfaces, identified in two sectors of the excavation set area within a complex stratigraphic series. Having been extensively excavated, well-documented and inter-disciplinarily researched for over four decades, these archaeosurfaces were ideal for and subjected to GIS-based spatial studies. In the faunal context, maps were designed and developed to analyse the frequency, density and distribution of osseous remains, different species determined and their representative skeletal parts for archaeosurfaces 3c, 3a and 3S10. Recently, 3 colluvium became prominent for its first human remain discovery, a deciduous incisor (dated to 583- 561 ka by 40Ar/39Ar). Updated archaeozoological and taphonomic analyses of this level’s assemblage revealed the dominance of large ungulates. Systematic and intentional carcass utilisation process for nutrition-rich parts by hominins is supported by evidence of anthropic marks, fractures and notches in certain places. Alterations caused by natural agents included trampling, erosion, exfoliation, evidences of different stages of weathering and deposition of concretions as part of their post-depositional history. This paper, hence, aims to make initial attempts of further spatial queries through 2D maps for 3 colluvium faunal remains in conjunction with additional taphonomy variables like weathering, erosion and exfoliation to see if any patterns regarding their effect, emerge. Results show areas of intermittent dense and sparse concentrations of altered and unaltered remains. It is inferred that fewer remains, less distributed in the central part of the excavated area, probably remained exposed to the impact of these taphonomic factors longer than the higher quantity of remains, more densely distributed in the southern, south western and south eastern part which otherwise experienced quicker burial.

Keep your head high: skulls on stakes and cranial trauma in Mesolithic Sweden

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On confluence and contestation in the Orinoco interaction sphere: the engraved rock art of the Atures Rapids

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A quantitative approach for analysing bone modelling patterns from craniofacial surfaces in hominins.

Bone size and shape arise throughout ontogeny as a result of the coordinated activity of osteoblasts and osteoclasts, responsible for bone deposition and resorption, and growth displacements. The modelling processes leave specific microstructural features on the bone surface, which can be used to infer the mechanisms shaping craniofacial traits in extinct and extant species. However, the analysis of bone surfaces from fossils and archaeological samples faces some difficulties related to the bone loss caused by taphonomic factors, and the lack of formal methods for estimating missing information and comparing the patterns of bone modelling among several specimens and samples. The present study provides a new approach for the quantitative analysis of bone formation and resorption patterns obtained from craniofacial surfaces. First, interpolation techniques were used to estimate missing data on high-resolution replicas of the left maxilla in a sample of sub-adult and adult modern humans and sub-adult fossil hominins. The performance of this approach was assessed by simulating variable amounts of missing data. Then, we applied measures of dispersion and central tendency to represent the variation and average pattern of bone modelling within samples. The spatial interpolation resulted in reliable estimations of the type of cell activity (deposition or resorption) in the missing areas, even when large extensions of the bone surface were lost. The quantification of the histological data allowed us to integrate the information of different specimens and depict the areas with higher and lower variation in the bone modelling pattern of the maxilla among specimens. Overall, the main advantages of the quantitative approach used here for generating bone modelling patterns are the high replicability and the possibility of incorporating variation among specimens into the comparisons among samples.

The influence of dissolved oxygen on dinoflagellate cyst distribution across Sluice Pond, a meromictic lake in NE Massachusetts, USA

ABSTRACTAssemblages of dinoflagellate cysts in lakebed sediments across the deep, meromictic basin of Sluice Pond (Lynn, Massachusetts) were compared with measurements of water quality and sediment geochemistry and with testate amoeba and tintinnid assemblages. Lakebed sediments below oxygenated waters (DO >2 mg/L) contain diverse testate amoebae, but sparse Peridinium willei-dominated dinoflagellate cyst assemblages. Sediments collected under hypoxic conditions (DO < 2 mg/L) showed higher preservation of organic carbon and nitrogen, and these deep basin sediments are characterised by diverse dinoflagellate cyst assemblages, but sieved microfossil assemblages are typically dominated by the planktonic Codonella cratera and the pseudo-planktonic Cucurbitella tricuspis. Strong inverse relationships of cysts of Peridinium willei (R2 = 0.81) and Difflugia oblonga tests (R2 = 0.7) with water depth are attributed to variations in bottom water oxygen concentrations. Both ecological and taphonomic factors must be considered when reconstructing palaeoenvironments from microfossil assemblages.

Use of space and site formation processes in a Neolithic lakeside settlement. Pollen and non-pollen palynomorphs spatial analysis in La Draga (Banyoles, NE Iberia)

Several taphonomic factors influence the composition of the palynological record especially in archaeological deposits, where human activities alter the representation of taxa. Spatial analysis by a taphonomic approach to the distribution of pollen and non-pollen palynomorphs (NPP) provides useful information about intra-site spaces and environments in the Early Neolithic lakeside settlement of La Draga (Banyoles, NE Iberia). The spatial correlation of algae, lakeshore and aquatic plants and herbs with an economic value, together with eggs of intestinal parasites and spores of coprophilous fungi, evidence a humid and organic environment beneath a hut, where consumption waste is concentrated. In contrast, high values of arboreal pollen (AP) and spores of fungal indicators of soil erosion show a sub-aerial environment strongly altered by taphonomic processes in outside areas. Finally, the association of the highest values in Cerealia-t and the spatial distribution of grinding stones within Sector D identifies an area of cereal processing, proving the suitability of spatial analysis in archaeopalynology as a powerful tool for reconstructing activity areas within archaeological settlements.

Paleoenvironmental Reconstruction from Faunal Remains: Ecological Basics and Analytical Assumptions

Paleozoologists have long used taxa represented by ancient faunal remains to reconstruct paleoenvironments. Those ancient environments were the selective contexts in which hominin biological and cultural evolution took place. Knowing about those particularistic selective environments and how organisms responded to them is increasingly seen as critically important to identifying both how biota will respond to future (to some degree anthropogenically driven) environmental change, and biological conservation and management applications that will ensure sustainability of ecological resources and services. Reconstructing paleoenvironments requires knowledge of species’ ecological tolerances, geographic ranges, habitats, environments, and niches. It also requires assumptions that extant species had the same ecological tolerances in the past as they do today and that changes in taxonomic composition or abundances reflect environmental change rather than sampling or taphonomic factors. Greater knowledge of ecological processes as well as increased analytical sophistication in paleozoology is providing increasingly rigorous and detailed insights to paleoenvironments.

Preservation of the metaproteome: variability of protein preservation in ancient dental calculus

ABSTRACTProteomic analysis of dental calculus is emerging as a powerful tool for disease and dietary characterisation of archaeological populations. To better understand the variability in protein results from dental calculus, we analysed 21 samples from three Roman-period populations to compare: 1) the quantity of extracted protein; 2) the number of mass spectral queries; and 3) the number of peptide spectral matches and protein identifications. We found little correlation between the quantity of calculus analysed and total protein identifications, as well as no systematic trends between site location and protein preservation. We identified a wide range of individual variability, which may be associated with the mechanisms of calculus formation and/or post-depositional contamination, in addition to taphonomic factors. Our results suggest dental calculus is indeed a stable, long-term reservoir of proteins as previously reported, but further systematic studies are needed to identify mechanisms associated with protein entrapment and survival in dental calculus.

Sea-level changes in the Lopingian (late Permian) of the northwestern Tethys and their effects on the terrestrial palaeoenvironments, biota and fossil preservation

The Lopingian is characterised by an aridisation trend and substantial sea-level changes. Hence, the fossil record of this time interval is strongly affected by ecological and taphonomic factors inherent to these long-term processes. Integrated sedimentological and palaeontological studies in the Bletterbach Gorge (Dolomites, N-Italy) allow discrimination between biological signals and preservational bias, shedding light on the effect of sea-level changes on the preservation potential of terrestrial associations of plant remains and tetrapod footprints. Flora A, composed of more humid elements with larger leaf/shoot fragments, appears close to a sea-level highstand and is interpreted as a (par-)autochthonous assemblage of an intrazonal riparian vegetation. Flora B, dominated by xerophytic elements documented by smaller fragments, corresponds to an allochthonous assemblage of an azonal vegetation preserved in floodplain fines of a progradational fluvial plain associated with a sea-level lowstand. The distribution of vertebrate footprints mirrors that of the plant-bearing horizons and their abundance and morphological diversity strongly increases in correspondence with marine transgressions. This could be related to a more diverse fauna (more complex food-web related to more humid conditions) or more favourable taphonomic conditions. However, the most diversified fauna, recorded during the early phases of the regressive phase, is in our interpretation best explained by the rapid burial of footprints due to the increasing energy. Our study provides an explanation for the change in distribution and preservation of plant and animal fossils in the Bletterbach section and shows how the fossil content of continental successions is deeply influenced by sea-level changes.

Evaluating the impact of water flotation and the state of the wood in archaeological wood charcoal remains: Implications for the reconstruction of past vegetation and identification of firewood gathering strategies at Tell Qarassa North (south Syria)

The development of water flotation during the second half of the 20th century constituted a milestone in archaeobotany, since it allowed the systematic recovery of plant macroremains by processing large amounts of sediment for the first time. However, little attention has been paid to the fact that in certain cases, hyper-fragmentation or complete destruction of charred plant macroremains occurs as soon as they come into contact with water. At the early Pre-Pottery Neolithic B site of Tell Qarassa North (south Syria) the destruction of wood charcoal remains was documented during the flotation process. The aim of this work is to evaluate the assemblage and to determine the factors that conditioned the preservation or disintegration of wood charcoal remains. In particular, attention is paid to the distribution of the alterations (e.g. vitrification, decayed wood) by taxa, and the proportions with which they are present before and after flotation. To test some of the patterns observed in the archaeological material a small-scale experiment on modern wood charcoal remains is carried out. The results enable a critic reconstruction of the type of vegetation and firewood gathering strategies at Tell Qarassa North. This work has, overall, important implications for the understanding of the taphonomic factors that affect wood charcoal assemblages.

Investigation of biodegradation in three different sediment cores from a shellmound (sambaqui) of Brazil, using Ascaris lumbricoides eggs as a model

For more than 30years, paleoparasitologists attempted to recover parasite remains from burial sediments and archaeological layers in Brazilian shellmounds. These sites are located along the shoreline of the country especially at the South and Southeastern regions, and for that reason they are exposed to frequent rainfall. Most of the shellmounds were built in coastal plains, associated with waterbodies, under the influence of high tides and/or inundation. Biodegradation is a factor that affects parasite preservation, especially in open archaeological sites. However, this hypothesis has never been tested in sediments from shellmounds. This study aimed to experimentally evaluate the biodegradation of Ascaris lumbricoides eggs and DNA from three intact cores collected from a shellmound. The cores and control sediments were collected from archaeological profiles composed of different materials. Each core received about 1,000,000 recent eggs, and water was poured over twice a week during 45days, simulating the main climate condition of the environment. The water was collected at the end of each core to observe the egg movement through the archaeological layers of the cores. Soil was sampled in different levels: 31 soil samples from the cores and 12 control samples were analyzed by the spontaneous sedimentation technique and 23 soil samples from the cores and all the control samples were analyzed for the DNA of the parasite. Parasitological evidence was only found in the superficial layers and very few eggs were recovered. Bioactivity caused destruction of most of the eggs and DNA. This research also supports the previous hypothesis that taphonomic factors probably are responsible for fewer findings of A. lumbricoides eggs in South American archaeological sites, especially in open environment sites.

Food residues as indicators of processed plants in hunter-gatherers’ pottery from La Pampa (Argentina)

This paper presents the results of archaeobotanical studies of plant microremains adhered to the surfaces of charred cooking-pot residues, corresponding to a context of hunter-gatherer societies in semiarid environments (Western Pampa, Argentina). Microparticles (starch granules, phytoliths, micro-charcoal, ochre-coloured organic matter and fungal remains) were identified, and the taphonomic factors that affected the plant microremains were described. Results indicate the use of ceramic containers for processing wild plants (Poaceae and Prosopis sp.), cultivated plants (Zea mays L.) and other ingredients. This study suggests the importance of plants in the diet of Pampean hunter-gatherers and the effective use of ceramic containers for processing and preparation of these resources.

Earth's oldest jellyfish strandings: a unique taphonomic window or just another day at the beach?

AbstractDiscoidal macrofossils reported herein from the lower Cambrian Zabriskie Quartzite (Great Basin, western United States) record the oldest Phanerozoic medusozoan body fossils, as well as the oldest medusozoan stranding event on record. Moreover, these fossils provide evidence of a significant shift in the taphonomic mode characteristic of preservation of nonmineralized taxa in coarse-grained siliciclastic successions near the onset of the Phanerozoic. Taphonomic and sedimentological evidence recorded by these and younger examples of stranded Cambrian medusae is consistent in suggesting that several of the requirements for preservation of these fossils were holdovers from the Ediacaran Period, including the presence of microbial mats and a lack of carcass disturbance by scavenging and/or bioturbating taxa. To shed further light upon the taphonomic factors necessary for the preservation of Cambrian medusae, we compared the biostratinomy and sedimentology of Cambrian medusa strandings to those of Ediacara Biota assemblages from lithologically similar successions. We find key secular disparities in the taphonomic histories of these two types of fossil assemblage. Inconsistencies between the preservational styles characteristic of fossil assemblages preserved in sandstone lithofacies on each side of the Precambrian–Cambrian boundary are explained by a considerable change in the preferred depositional setting in which these macrofossil assemblages are preserved. Thus, rather than documenting a single taphonomic continuum through the Precambrian–Cambrian transition, the Zabriskie and younger medusozoan body fossil assemblages record the advent of an entirely new, yet still very rarely exploited, taphonomic window exclusive to the Cambrian Period.

Dead shell assemblages faithfully record living molluscan assemblages at One Tree Reef

Reef-associated sediments accumulate over time recording the history of biological communities. The agreement between live and dead assemblages has been extensively studied, because discrepancies between the two can reveal taphonomic bias, anthropogenic impact, and/or a decrease in temporal resolution of dead assemblages to centennial scales (i.e., time averaging). Given the potential of sedimentary assemblages to provide temporal perspectives on the history of modern communities, assessments of live-dead agreement in reef mollusk assemblage composition are necessary and timely for understanding rapid environmental change. One Tree Reef (OTR) (southern Great Barrier Reef, Australia) has had very little direct anthropogenic influence over the past four decades, making it a good system for focusing on taphonomic patterns. Live (n=1335) and dead (n=6919) molluscan assemblages were collected from three shallow (6m) carbonate soft-sediment lagoons. Diversity and evenness metrics indicated no significant difference between the live and dead assemblages, and dead assemblage rank order abundance explains 82% of that of the live assemblage. Differences in composition were largely due to sample size, the low probability of sampling rare species and to a lesser degree differences in skeletal durability. Taphonomic factors were responsible for less than 20% of the differences in species composition between live and dead shell assemblages. The live molluscan assemblage sampled was similar to the live assemblage sampled 30years ago. Given that time averaging is approximately 19years in the OTR lagoon, we conclude that the composition of the living assemblage has remained largely unchanged for the last 30years. These findings indicate that dead assemblages preserved in shallow, fully carbonate environments primarily reflect the composition of the original source communities, making them useful to identify recent changes in coral reef areas where anthropogenic impacts are present.

The faunal remains from Bundu Farm and Pniel 6: Examining the problematic Middle Stone Age archaeological record within the southern African interior

Open-air and interior sites are not prominently featured among models of Middle Stone Age (MSA) subsistence behavior in southern Africa. Thus, the current view of MSA subsistence reflects adaptations interpreted predominantly from coastal rockshelter locations. An attempt to address this gap is presented here with the analysis of the faunal assemblages from Bundu Farm and Pniel 6, two early MSA open-air sites located well within the interior of southern Africa in the Northern Cape, South Africa. Zooarchaeological and taphonomic signatures of the Bundu Farm assemblage suggest some primary access to animal carcasses, while the same measures imply secondary scavenging by early MSA hominins at Pniel 6. A number of other open-air interior sites include similarly ambiguous evidence for the role of hunting and/or scavenging in hominin subsistence during the MSA. Due to the lack of archaeological surveys directed at finding open-air sites and several taphonomic factors that disproportionately obscure indications of hominin behavior in open-air settings, the archaeological records between open-air interior sites and coastal rockshelter sites are fundamentally incomparable. From an ecological perspective, MSA subsistence was a product of behavioral adaptations to environmental factors and resource availability, the influences of which were likely different between interior and coastal ecosystems. Much like historical hunter-gathers of the region, MSA hominins inhabiting the more marginal environments within the southern African interior may have relied more heavily on gathered plant foods rather than hunting for subsistence.

Trace fossils of possible parasites inside the gut contents of a hadrosaurid dinosaur, Upper Cretaceous Judith River Formation, Montana

AbstractTiny sinuous trace fossils have been found within probable gut contents of an exceptionally preserved specimen of a hadrosaurid dinosaur,Brachylophosaurus canadensis, from the Judith River Formation of Montana. Approximately 280 examples of the trace fossils were observed in 19 samples of gut region material. The tubular structures typically are about 0.3 mm across. Many have thin calcareous linings or layers, and some exhibit fine surficial striae. At least two dozen of these trace fossils share walls with adjacent tubular traces, and this association can extend for several millimeters. While the trace fossils share some characteristics with fine rhizoliths, these features are most consistent with tiny burrows, or possibly body impressions, of worms (vermiform organisms) of uncertain biologic affinity. Such trace fossils have not been reported previously, and herein described asParvitubulites striatusn. gen. n. sp. Either autochthonous (parasites) or allochthonous (scavengers) worms may have created the trace fossils, but taphonomic factors suggest that autochthonous burrowers are more likely. Several lines of evidence, such as constant diameters and matching directional changes, suggest that the paired trace fossils were made by two individuals moving at the same time, which implies sustained intraspecific contact.Parvitubulites striatusprovides a rare record of interactions between terrestrial, meiofaunal-sized, soft-bodied invertebrates and a dinosaur carcass. The evidence that the worms may have parasitized a living hadrosaur and subsequently left traces of intraspecific behavior between individual worms adds unique information to our understanding of Mesozoic trophic interactions.

Why so many dipnoans? A multidisciplinary approach on the Lower Cretaceous lungfish record from Tunisia

The Lower Cretaceous record of vertebrates from Africa is problematic as the majority of fossil localities lack adequate stratigraphic and paleoecological data when compared with coeval Laurasian deposits. Thereby, our comprehension of paleocommunities and paleobiogeographic patterns may be affected by the lack of multidisciplinary approach. Among taxonomically and paleoecological significant clades, lungfishes (Sarcopterygii, Dipnoi) are commonly found in the Cretaceous fresh water, brackish and marginal-marine deposits of Gondwana, although identifiable elements are limited to isolated tooth plates. We provide the first taxonomic identification of dipnoans from the Ain el Guettar Formation of southern Tunisia (Oum ed Diab member, Albian). Identification of tooth plates based on morphological parameters and phylogenetic analyses indicates the co-occurrence in a discrete stratigraphic unit of at least five lineages referable to Equinoxiodus, Neoceratodus, Asiatoceratodus and/or Ferganoceratodus, Ceratodus, and Lavocatodus. This unusually high diversity is unparalleled in the fossil record and is also challenged by an actualistic comparison with extant taxa. We suggest that a series of taphonomic factors significantly inflated observed lungfish diversity in the estuarine and marginal-marine deposits of the Oum ed Diab member. Therefore, we recognize the fossil fauna as representative of a larger, inland paleo-hydrographic system. This study confirms the paleoecological scenario resulted from the analyses on terrestrial reptiles from the Oum ed Diab member.

Taphonomic considerations for the analysis of parasites in archaeological materials

Archaeoparasitological analyses of human remains can present interpretative challenges arising from diverse preservation environments. Three archaeoparasitological studies are used to demonstrate the impacts of five major types of taphonomic factors on parasite egg preservation. In the first case, an analysis of a historic Lithuanian mummy revealed infections with Trichuris trichiura and Ascaris lumbricoides and illustrates taphonomic issues unique to mummies. The second case involved the analysis of coprolites collected from medieval burials in Nivelles, Belgium. One burial demonstrated a high concentration of T. trichiura eggs (approximately 1,577,679 total eggs) and A. lumbricoides eggs (approximately 202,350 total eggs). Preservation was affected mostly by water percolation with differential preservation of eggs based on morphological characteristics. The third case is based on material from embalming jars of the Medici family. No parasite eggs were recovered; however, an abundance of mites and dipteran puparia were encountered, suggesting that arthropods may play a larger role in parasite egg preservation than previously supposed. Differential parasite egg preservation is discussed in light of variances in five major types of taphonomic factors: abiotic, contextual, anthropogenic, organismal, and ecological. Accounting for these factors is a vital component in the interpretation of archaeoparasitological data and should be included in future archaeoparasitological reports.