Fossil Samples Research Articles

Comparison of different preparation methods for oxygen isotope determination of phosphate in mammal tooth enamel

AbstractWe tested several sample pre-treatment protocols for the study of oxygen isotope ratios in the phosphate phase of mammalian enamel of ten different fossil samples. We investigated the effect of different pre-treatment methods and the duration of the hydrogen fluoride treatment on enamel samples from skeletal phosphate with known δ18O values. The samples had been measured previously, so we could compare the ratios measured in our laboratory with the previous values to choose the best chemical preparation procedure. Four pre-soaking methods and two different time intervals of 2 mol dm−3 hydrogen fluoride treatment were compared during our experiments. In our experimental conditions, the distilled water wash and the 6 h of soaking in hydrogen fluoride gave the closest results to the expected δ-values. The steps of the tested preparation processes were repeated at least three times on each sample, so the reproducibility of the process could be also investigated.

Inaccurate fossil placement does not compromise tip‐dated divergence times

AbstractTime‐scaled phylogenies underpin the interrogation of evolutionary processes across deep timescales, as well as attempts to link these to Earth's history. By inferring the placement of fossils and using their ages as temporal constraints, tip dating under the fossilized birth–death (FBD) process provides a coherent prior on divergence times. At the same time, it also links topological and temporal accuracy, as incorrectly placed fossil terminals should misinform divergence times. This could pose serious issues for obtaining accurate node ages, yet the interaction between topological and temporal error has not been thoroughly explored. We simulate phylogenies and associated morphological datasets using methodologies that incorporate evolution under selection, and are benchmarked against empirical datasets. We find that datasets of 300 characters and realistic levels of missing data generally succeed in inferring the correct placement of fossils on a constrained extant backbone topology, and that true node ages are usually contained within Bayesian posterior distributions. While increased fossil sampling improves the accuracy of inferred ages, topological and temporal errors do not seem to be linked: analyses in which fossils resolve less accurately do not exhibit elevated errors in node age estimates. At the same time, inferred divergence times are biased, probably due to a mismatch between the FBD prior and the shape of our simulated trees. While these results are encouraging, suggesting that even fossils with uncertain affinities can provide useful temporal information, they also emphasize that palaeontological information cannot overturn discrepancies between model priors and the true diversification history.

Late Quaternary communities of shrews, Soricidae, from Ural and Far East Regions of Russia: A protocol for the multifactorial morphospace building

The present paper is a preliminary attempt to develop a protocol for analyzing Late Pleistocene and Holocene paleocommunities of soricids using modern approaches for the morphological data analysis. First, we assessed the abilities of fossil soricid collections from Ural and Far East localities to provide a complex interregional analysis of the phenotype variation. Accordingly, for the first time in the general context, the study provides a species list and chronological position of Ural and Far East shrew fossil samples in terms of inter- and intraregional comparisons to reveal general and specific responses of paleocommunities to climatic fluctuations. Second, under the modern approaches, we prepared 182 three-dimensional models of hemimandibles or isolated m1 and built the morphospace of m1 shape for seven Sorex species from the Upper Pleistocene layer MKl-13 and Middle Holocene layer MKl-7 of Medvezhyi Klyk Cave (South Primorye, Russia). Recent samples from East Siberia (Yakutia) and the northern part of the Far East (Magadanskaya Oblast' and Khabarovsky Kray; “cold” habitats) and South Primorye (“warm” habitats) were included into morphospace to actualize potential responses of the fossil samples to Late Quaternary climate fluctuations. Our analysis revealed: (i) a weak reaction of m1 shape of almost all species to the “cold” and “warm” environmental conditions, except S. daphaenodon Thomas, 1907 and S. caecutiens Laxmann, 1788; (ii) two groups of species, namely “generalized” and “specialized” in m1 shape, in line with the idea of distribution of trophic niches among coexisted shrews; (iii) a diagnostic character for fossil samples of S. unguiculatus Dobson, 1890 and S. isodon Turov, 1924.

Microbially induced calcium carbonate precipitation in fossil consolidation treatments: Preliminary results inducing exogenous Myxococcus xanthus bacteria in a miocene Cheirogaster richardi specimen

This research paper proposes Microbially Induced Calcium Carbonate Precipitation (MICP) as an innovative approach for palaeontological heritage conservation, specifically on deteriorated carbonate fossils. Due to its efficiency in bioconsolidation of carbonate ornamental rocks, Myxococcus xanthus inoculation on carbonate fossils was studied in this research.Treatment was tested on nine fossil samples from decontextualized fragments of Cheirogaster richardi specimens (Can Mata site, Hostalets de Pierola, Catalonia, Spain). The main objective was to evaluate whether treatment with Myxococcus xanthus improved fossil surface cohesion and hardness and mechanical strength without significant physicochemical and aesthetic changes to the surface. Chemical compatibility of the treatment, penetration capacity and absence of noticeable changes in substrate porosity were considered as important issues to be evaluated.Samples were analysed, before and after treatment, by scanning electron microscopy, weight control, spectrophotometry, X-ray diffraction analysis, water absorption analysis, pH and conductivity control, Vickers microindentation and tape test. Results show that hardness increases by a factor of almost two. Cohesion also increases and surface disaggregated particles are bonded together by a calcium carbonate micrometric layer with no noticeable changes in surface roughness. Colour and gloss variations are negligible, and pH, conductivity and weight hardly change. Slight changes in porosity were observed but without total pore clogging.To sum up, results indicate that Myxococcus xanthus biomineralisation is an effective consolidation treatment for carbonate fossils and highly compatible with carbonate substrates. Furthermore, bacterial precipitation of calcium carbonate is a safe and eco-friendly consolidation treatment.

Interrelation of radiocarbon ages from bone fractions in the Brazilian Intertropical Region

AbstractThere is a consensus in the literature that radiocarbon dating performed on bioapatite often produces ages younger than dating performed on collagen. We propose a general regression that could be used to convert the bioapatite radiocarbon ages to the simulated ages on collagen in fossil samples worldwide. This general regression presents several good indices of quality, high correlation (R2 = 0.98), lower values of percent predicted error (%PE = 0.01), and standard error of the estimate (%SEE = 21.83), showing that it is a good tool, as the predicted values are similar to those observed. Using this regression, we converted the radiocarbon ages of bioapatite to the expected age from the collagen fraction made for several taxa from the Brazilian Intertropical Region (BIR) and suggest that these dates could be 1–7 cal ka BP older than previously thought.

Extraction of calcareous dacryoconarid microfossils from limestones and mudrocks by surfactants paired with freeze-thaw processing

Microfossils offer a wealth of paleoenvironmental information, but their extraction from consolidated material, especially ancient rocks, is time-consuming and often lacks systematic methodological development. This study examined the efficacy of repeated freeze-thaw processing paired with different surfactants (anionic, cationic, and detergent) on the extraction of fossils from the order Dacryoconarida, conically shaped calcareous microfossils that occur in diverse marine facies of the Devonian Period. A stepwise technique was developed involving saturation of rocks in either 18 Ω water or 25% NaCl, followed by freezing and then boiling in surfactant (Pinequat, Decon 90, or Calgon in Na2CO3 solution). In comparison with saturation in NaCl solution, saturation in water generally had higher yields of disaggregated material and more intact fossils. All surfactants performed better at extraction compared to boiling in pure water. Across all lithologies examined, Na2CO3-buffered Calgon (sodium hexametaphosphate) disaggregated rock most efficiently, but Na2CO3 solution alone generally had the highest yield of total and intact fossil specimens. Pinequat, a cationic surfactant, yielded more disaggregate for siliclastic samples compared to calcareous samples, but had lower fossil yield. Decon 90, an anionic surfactant, performed better at disaggregating limestones and had higher fossil extraction efficiency than Pinequat across all lithologies. Freeze-thaw processing pairing water saturation and 5% Na2CO3 simmering is an effective treatment for the disaggregation of rocks to extract analytically viable amounts of dacryoconarids from fossiliferous samples. This pairing had greater fossil extraction potential than surfactants at the concentrations tested in this study and is recommended if the elemental composition of the target rocks is unconstrained.

Main anatomical characteristics of the hominin fossil humeri from the Sima de los Huesos Middle Pleistocene site, Sierra de Atapuerca, Burgos, Spain: An update.

Some of the Sima de los Huesos (SH) humeri have been previously studied and described elsewhere. Here we present an updated inventory and a review of the specimens recovered to the present day. The morphological key traits of the adult and subadult specimens are described, discussed, and illustrated. The SH humeri share with Neandertals many traits usually considered to be Neandertal specializations, thus, most of this morphological pattern is not exclusive to them. The variation found within fossil samples stresses the frequential nature of all these traits and in the specific case of the SH humeri, most of the traits considered as phylogenetically relevant are retained by their descendants, the Neandertals. Some traits are plesiomorphic for the entire genus Homo or are present in European hominins since the early Pleistocene. Finally, some other traits display high variability within the SH sample or different hominin samples and are of uncertain phylogenetic value. Altogether, this evidence is consistent with the hypothesis based on the overall cranial and postcranial morphology that the SH hominins are a sister group to the later Neandertals.

Hypercementosis in Late Pleistocene Homo sapiens fossils from Klasies River Main Site, South Africa

ObjectiveTo examine early Homo sapiens fossils from the Late Pleistocene site of Klasies River Main Site, South Africa for evidence of hypercementosis. The specimens represent seven adult individuals dated to between 119,000 and 58,000 years ago. These observations are contextualized in relation to the incidences of hypercementosis among recent human populations and fossil human samples and the potential etiologies of hypercementosis. DesignThe fossils were investigated utilizing micro-CT and nano-CT scanning to visualize and measure cementum apposition on permanent incisor, premolar and molar roots. Cementum thickness was measured at mid-root level, and the volume of the cementum sleeve was calculated for the two fossil specimens that display marked hypercementosis. ResultsTwo of the fossils display no evidence of cementum hypertrophy. Three exhibit moderate cementum thickening, barely attaining the quantitative threshold for hypercementosis. Two evince marked hypercementosis. One of the Klasies specimens with marked hypercementosis is judged to be an older individual with periapical abscessing. The second specimen is a younger adult, and seemingly similar in age to other Klasies fossils that exhibit only minimal cementum apposition. However, this second specimen exhibits dento-alveolar ankylosis of the premolar and molars. ConclusionsThese two fossils from Klasies River Main Site provide the earliest manifestation of hypercementosis in Homo sapiens.

The oxygen isotope value of whole wood, α-cellulose, and holocellulose in modern and fossil wood

The oxygen isotope value (δ18O) of α-cellulose extracted from modern and fossil wood has been used widely to reconstruct climate throughout the Quaternary and deep-time. Substantial effort has been made towards developing more efficient and cost-effective methods for obtaining α-cellulose from whole wood, though some research groups advocate for measuring δ18O directly on whole wood due to a constant offset between the δ18O of whole wood and α-cellulose. The utility of alternative substrates to α-cellulose (e.g., whole wood or holocellulose) for paleoclimate reconstruction using fossil wood, however, has not been evaluated. Here we present 48 new δ18O measurements on mummified (subfossil) wood ranging in age from Eocene to Miocene. Whereas the δ18O value of whole wood and α-cellulose is only weakly related in these subfossils, there is a strong linear correlation between the δ18O value of α-cellulose and holocellulose. We augmented this dataset with 1546 new and published oxygen isotope pairs on whole wood, α-cellulose, and holocellulose from modern wood (Quaternary to present) to compare with our pre-Quaternary fossil samples. In contrast to the fossil wood, we found strong correlations between α-cellulose and whole wood and α-cellulose and holocellulose in modern samples. This finding suggests that all three substrates (whole wood, cellulose and holocellulose) derive oxygen isotopes from a common source (i.e., meteoric water) on a global scale, and that processing of α-cellulose may not be required for modern wood in some settings. Because average holocellulose yields in fossil wood were approximately double that of α-cellulose (22.2 ± 12.8% versus 11.6 ± 10.3%), δ18O analysis on holocellulose rather than α-cellulose should produce reliable environmental data while reducing time and sample material required.

The endocast from Dana Aoule North (DAN5/P1): A 1.5 million year-old human braincase from Gona, Afar, Ethiopia.

The nearly complete cranium DAN5/P1 was found at Gona (Afar, Ethiopia), dated to 1.5-1.6Ma, and assigned to the species Homo erectus. Its size is, nonetheless, particularly small for the known range of variation of this taxon, and the cranial capacity has been estimated as 598 cc. In this study, we analyzed a reconstruction of its endocranial cast, to investigate its paleoneurological features. The main anatomical traits of the endocast were described, and its morphology was compared with other fossil and modern human samples. The endocast shows most of the traits associated with less encephalized human taxa, like narrow frontal lobes and a simple meningeal vascular network with posterior parietal branches. The parietal region is relatively tall and rounded, although not especially large. Based on our set of measures, the general endocranial proportions are within the range of fossils included in the species Homo habilis or in the genus Australopithecus. Similarities with the genus Homo include a more posterior position of the frontal lobe relative to the cranial bones, and the general endocranial length and width when size is taken into account. This new specimen extends the known brain size variability of Homo ergaster/erectus, while suggesting that differences in gross brain proportions among early human species, or even between early humans and australopiths, were absent or subtle.

Fossil Squamates of Pedernales Province, Dominican Republic: Novel Record of Human-Induced Extinction and Extirpation

Hispaniola (Haiti & Dominican Republic (D.R.)), is the second largest island in the Caribbean and is a hotspot of squamate diversity (~184 species), yet little is known about their fossil record and how it relates to the present. Past studies on mammalian communities suggest that many rodent species go extinct after human arrival (~7,000 y.B.P.), most significantly after European colonization (~530 y.B.P.) corresponding to a rapid loss of 70-98% of original forest. Pedernales Province in the D.R., has much of its original forest cover, yet fossil squamates from this region have not been documented. Our study of Holocene dry cave fossil sites and a new archeological site located in Pedernales allows for evaluation of extinction in squamates in an area where deforestation is not a primary concern. Using dentigerous elements, several genera of squamates (Ameiva, Anolis, Celestus, Cyclura, Leiocephalus, and Geckos) were identified. We recorded their abundance at each depth, and found Anolis, Celestus, and Geckos to be the most common fossils. From this collection we discovered two new species of Celestus, a new species of Gecko, and revised the taxonomy of Leiocephalus. One of the newly identified large Celestus species, originally only known from fossils, was later discovered in a separate cave as a living specimen. These results suggest that deforestation is not the only driver of extinction in the D.R., and that even in well preserved areas, extinction of small taxa is happening. Additionally, some cryptic taxa may be unrecognized. The arrival of domesticated animals and associated pests (mice, rats, etc.), likely had a dramatic influence on these extinctions, as well as direct human predation, first reported here. Further radiocarbon and geochemical sampling of these herpetofaunal fossils will help assess why these species went extinct, and such trends can inform modern conservation efforts as to which taxa are most at risk.

Expanding the Fossil Record of Soldier Fly Larvae—An Important Component of the Cretaceous Amber Forest

Larvae of soldier flies and their closest relatives (Diptera: Stratiomyomorpha) are important decomposers of organic material, including wood, that take part in carbon cycling. They also play a certain role in the modern-day animal and human food industry, representing economic value. Larvae of Stratiomyomorpha are considered to be rather rare in the fossil record. Indeed, only very few larvae have been reported so far. Here, we demonstrate that larvae of Stratiomyomorpha are in fact abundant in the Cretaceous, at least in Myanmar amber (about 100 million years old), based on more than 100 amber pieces containing larvae. The specimens could be differentiated into three morphotypes, two already described in a previous work, and a new one. For one morphotype, three larval stages could be distinguished by analysing the dimensions of the head capsules. A quantitative analysis of body shapes indicates a lower morphological diversity of the fossil sample in comparison to the extant fauna, but suggests that they might have had a different ecology in the past. It appears that the data set is not yet saturated, i.e., that more fossil larvae of this group, including different morphologies, are expected to be found.

SAMPLE PREPARATION METHODS USED AT THE AUSTRALIAN NATIONAL UNIVERSITY RADIOCARBON FACILITY

ABSTRACTThe Single Stage AMS radiocarbon facility at the Australian National University has operated for the past 14 years. This paper presents the pretreatment methods used for the major sample types dated and reflects on whether quality assurance protocols can adequately detect altered materials. The majority of fossil samples dated by the facility are from tropical and arid environments where diagenesis of both organic samples and carbonates is often severe. A large proportion of the samples submitted cannot be dated, and screening and quality assurance methods are crucial. Based on analysis of 250 measurements on bone collagen, quality assurance indicators for bone are revised. From May 2021, the laboratory has accepted dates on collagen where yield >0.5%, %C is in the range of 39.7–46.9, and the C:N ratio is between 3.00 and 3.30.

Climate obstruction and Facebook advertising: how a sample of climate obstruction organizations use social media to disseminate discourses of delay

In this article, we present the results of a content analysis of a sample of fossil fuel corporations, industry associations, and advocacy groups’ ads using Facebook ad services during the election year from January 2020 to January 2021. Creating a messaging typology, we analyzed 30,100 ads on Facebook and found that different organizations used these messages to reinforce pre-existing beliefs on the importance of fossil fuels. In doing so, these organizations can use Facebook to reassert their interests in the public voice and support standards of behavior that rely on fossil fuels, protecting their industries. Additionally, we found differences between the types of messaging and ads targeted to particular users by age, gender, and state. These ads represent the evolving misinformation playbook from climate obstruction organizations that require further attention and consideration, particularly via social media platforms that may have limited or unclear regulations.

The bias types and drivers of the Furongian Biodiversity Gap

The Furongian Biodiversity Gap (FBG), which is well known as the biodiversity minimum between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE), has recently been the subject of much research seeking to identify the onset of the GOBE. Whether the FBG is a real evolutionary trend or a bias gap due to insufficient sampling has been controversial. In this study, a systematic investigation of the relationships between fossil sampling intensity, spatial extent, and biodiversity during the Cambrian and Ordovician, using data from the Paleobiology Database (PBDB) is carried out to gain a better understanding of this lowstand in biodiversity. Special focus is placed on the types of bias and the internal and external bias drivers affecting the FBG. The results show that external factors such as a low degree of research interest, socioeconomic influence, and unevenness of research intensity have led to limited fossil sampling and research, which have interacted with internal factors (biological and geological preservation) and led to biases in understanding the FBG. The bias types of the FBG are multi-dimensional. Temporally, there are fewer fossil collections from the Furongian. Geographically, the lack of fossil data at middle and high latitudes results in a low geographical extent and unevenness of the spatial distribution of Furongian fossils. Taxonomically, trilobites and conodonts, which are of high biological importance, are the main studied fossil groups from the Furongian. Lithologically, widely distributed shales deposited in the Furongian and their biotas are not sufficiently studied. Moreover, the above analysis of the FBG based on the PBDB is inherently affected by database bias. The FBG is interpreted as a collection failure which requires more fossil data and methodological innovation for a better and comprehensive interpretation.

Ancient deep ocean as a harbor of biotic innovation revealed by Carboniferous ophiuroid microfossils

Fossil-informed molecular phylogenies have emerged as the most powerful tool for correlating biotic evolution and Earth history. The accuracy of these trees, however, depends on the completeness of fossil sampling. For most organismal clades, the available fossil record is insufficiently sampled. This is especially true for groups with a multi-element skeleton, such as echinoderms and vertebrates, where sampling efforts focus largely on rare finds of intact skeletons. For these groups, inconspicuous but informative skeletal fragments are commonly neglected. This sampling bias excludes the numerous paleoenvironments in which preservation of intact skeletons is extremely unlikely, in particular deep-water settings. We describe new finds of brittle-star, or ophiuroid, fossils retrieved from sieving residues of sediments deposited during the Atokan (Upper Carboniferous) on the deep shelf to upper slope of the Ardmore Basin in present-day southern Oklahoma, USA. Although preserved as disarticulated, microscopic ossicles, the pristine preservation of the skeletal microstructure allows for precise identification of the remains. Comparative anatomical and phylogenetic analyses confirm the presence of basal representatives of the extant ophiuroid orders Ophioscolecida and Amphilepidida. Our finds provide the first unambiguous fossil evidence that the early crown-group diversification of the Ophiuroidea was well under way long before the end-Permian mass extinction, and that a significant part of this diversification took place in deep-water settings, as previously predicted by molecular evidence.

Ancient deep ocean as a harbor of biotic innovation revealed by Carboniferous ophiuroid microfossils

Abstract Fossil-informed molecular phylogenies have emerged as the most powerful tool for correlating biotic evolution and Earth history. The accuracy of these trees, however, depends on the completeness of fossil sampling. For most organismal clades, the available fossil record is insufficiently sampled. This is especially true for groups with a multi-element skeleton, such as echinoderms and vertebrates, where sampling efforts focus largely on rare finds of intact skeletons. For these groups, inconspicuous but informative skeletal fragments are commonly neglected. This sampling bias excludes the numerous paleoenvironments in which preservation of intact skeletons is extremely unlikely, in particular deep-water settings. We describe new finds of brittle-star, or ophiuroid, fossils retrieved from sieving residues of sediments deposited during the Atokan (Upper Carboniferous) on the deep shelf to upper slope of the Ardmore Basin in present-day southern Oklahoma, USA. Although preserved as disarticulated, microscopic ossicles, the pristine preservation of the skeletal microstructure allows for precise identification of the remains. Comparative anatomical and phylogenetic analyses confirm the presence of basal representatives of the extant ophiuroid orders Ophioscolecida and Amphilepidida. Our finds provide the first unambiguous fossil evidence that the early crown-group diversification of the Ophiuroidea was well under way long before the end-Permian mass extinction, and that a significant part of this diversification took place in deep-water settings, as previously predicted by molecular evidence.

Virtual Fossils for Widening Geoeducation Approaches: A Case Study Based on the Cretaceous Sites of Figueira da Foz (Portugal) and Tamajón (Spain)

Accessible palaeontological sites conform highly adequate out-of-school environments for meaningful learning experiences regarding formal and non-formal teaching of geosciences. With a perspective of international cooperation, two correlative Cenomanian–Turonian (Upper Cretaceous) outcrops from the Iberian Peninsula have been chosen as the focus of this project—the sections of Figueira da Foz (Portugal) and Tamajón (Spain)—along with the Palaeontological and Archaeological Interpretation Centre of Tamajón (CIPAT). Virtualization of fossil samples and sites has been undertaken by means of phase-shift scanning, photogrammetry, and small object scanning by structured light and laser triangulation, resulting in three-dimensional virtual models of the main fossil tracks and invertebrate fossil samples. These virtual fossils have allowed the development of transdisciplinary didactic activities for different educational levels and the general public, which have been presented as file cards where the age of participants, objectives, multiple intelligences, European Union key competences, needed resources, development, and further observations are specified. This work aims to contribute to improving the design and development of didactic sequences for out-of-school education at these sites, organizing effective transdisciplinary teaching tools, and developing awareness, values, and responsibility towards geoheritage.

Pollen-based quantitative paleoclimatic record spanning the Mid-Brunhes Event in the Nihewan Basin, north China

The Middle Pleistocene is an important period of global climatic and environmental evolution during the Quaternary. We conducted pollen analyses of 144 fossil samples and combined 1436 modern surface samples to characterize the processes of vegetation succession and climate change in the Nihewan Basin during the Middle Pleistocene, especially the Mid-Brunhes Event. The results showed that the pollen assemblages during 0.8–0.3 Ma were dominated by herbaceous pollen (> 60%), indicating that the vegetation in the study area was mainly forest steppe. The quantitative climatic reconstruction indicates that annual average temperature (Tann) was generally >6 °C, and annual average precipitation (Pann) was generally >490 mm. The warm climatic conditions persisted for a long interval, and the interval of cold conditions was shorter. Compared with the warm period, during the interval of cold climate Tann decreased by ∼4 °C, and Pann decreased by ∼130 mm. The interval of 0.478–0.424 Ma, Picea dominated the pollen assemblages (> 80%), Tann was generally <2 °C, and Pann was generally <400 mm, which may be a manifestation of the Mid-Brunhes event in the Nihewan Basin, which is corresponded with MIS 12. During this period, Northern Hemisphere insolation and the atmospheric CO2 concentration were low, the Eurasian ice sheet expanded, the winter monsoon strengthened, and the regional climate was cold and dry. The intervals of 0.742–0.478 Ma and 0.424–0.266 Ma were two pronounced warm periods in the Nihewan Basin, which correspond well with MIS 13 and MIS 11, respectively. MIS 13 was the warmest and wettest period during the studied interval, and it may have been related to the unusually strong summer monsoon caused by the climatic asymmetry between the Northern and Southern Hemispheres.

New insights into the origin of buckwheat cultivation in southwestern China from pollen data.

Buckwheat is an important crop which originated in China and spread widely across Eurasia. However, exactly where in China domestication took place remains controversial. Archaeological and palynological records suggest a longer cultivation history of buckwheat in northern China than in southwestern China, but this conflicts with phylogenetic evidence implicating southwestern China as the centre of origin and diversity of buckwheat. We investigate alternative methodologies for inferring the occurrence of buckwheat cultivation and suggest that relative abundance could provide a reliable measure for distinguishing between wild and cultivated buckwheat in both present-day and fossil samples. Approximately 12 800-yr palaeoecological record shows that Fagopyrum pollen occurred only infrequently before the early Holocene. As southwestern China entered the early agricultural period, c. 8000-7000 yr ago, a slight increase in abundance of Fagopyrum pollen was observed. Approximately 4000 yr ago, concurrent with the Pu minority beginning to develop dry-land agriculture, the abundance of Fagopyrum pollen increased significantly, suggesting the cultivation of this crop. Fagopyrum pollen rose to a maximum value c. 1270 yr ago, suggesting an intensification of agricultural activity. These findings fill a gap in the Fagopyrum pollen record in southwestern China and provide new indications that early cultivation may have occurred in this region.