Paleoecological Interpretations Research Articles

The mountain giant rat of Borneo Sundamys infraluteus (Thomas) and its relations

The genus Sundamys comprises the species Sundamys muelleri, Müller‟s rat, which is widespread in the Sundaic biogeographical subregion, and three other taxa, the mountain giant rats of Borneo S. infraluteus, Java S. maxi and Sumatra S. atchinensis. Nine additional specimens of the Borneo Mountain giant rat are reported, and one field record, adding new locations to the known range of the species in the Crocker Range, notably the vicinity of Gn. Alab, and Gn. Lumaku, Sabah, and at Pa Raye, Kalimantan Utara. Measurements of the specimens, and the first from Gn. Mulu, Sarawak, are tabulated with previously published data. Trapping results indicate that this rat is confined to an altitudinal range, 900 – 2350 m, broadly corresponding with the limits of Lower Montane Forest, especially Oak-Laurel forests, and that it occurs both in pristine habitat and in disturbed forests. The topography of the uplands of northern Borneo provides connections between all locations except Mulu, which is surrounded by lowlands. A review of palaeoecological interpretations indicates that favourable habitat for this rat was more extensive in north-western Borneo in the terminal Pleistocene, but may have been more reduced than at present during warm episodes of the Holocene. Consideration of palaeo-environments in the Sundaic subregion suggests that there may have been no genetic contact between mountain giant rats of Sumatra and Borneo during the Quaternary. Although molecular evidence is lacking, it is reasonable to treat Sundamys infraluteus, S. atchinenesis and Sundamys maxi as distinct species, arising independently by vicariant evolution from a Pliocene ancestry.

Micropaleontological and sedimentological analyses of carbonates rocks in parts of Sokoto Basin, Nigeria: implications for paleoecological interpretation and exploration efforts

This study presents a detailed analysis of the Paleocene and Maastrichtian marine sediments in the Sokoto Basin, Nigeria, using boreholes GSN – BH – 2051 and GSN – BH – 4051, respectively. This study is aimed at integrating sedimentological, micropaleontological and petrographic data in paleoecologic interpretation of depositional environments of the Sokoto Basin. The methods adopted in this research involved the examination of ditch cuttings, carbonate thin sections, and microfossils analyses from the boreholes drilled in Sokoto Basin. The sedimentological data from the borehole showed that the studied stratigraphic unit comprises mainly fine to medium-grained limestone facies, sparitic intraclastic packstone and oolitic-elmicrite wackestone facies. The microfacies obtained from petrography data revealed micro-fossils abundance and diversity associated with the onset of shallow marine transgression which resulted in the deposition of the Dange and Kalambaina Formations, respectively. The assemblages of the larger foraminifera (Opercullnoides bermudezi) and the larger ostracod (Bairdia iIaroensis) in the borehole sections further suggested marginal marine depositional environment for the Kalambaina and Gamba Shale Formations. The paleoecological interpretation suggests varying salinities and dysaerobic conditions during deposition, with implications for understanding basin evolution. The study concludes by highlighting the importance of integrating multiple methods for a detailed understanding of paleoecological and depositional environment of Sokoto sedimentary basin.

Pollen atlas and morphological analysis of the selected types from southeastern Tibet, China

The accuracy of fossil pollen identification is crucial for understanding past plant diversity, vegetation landscape and associated climate change, while dispersed/fossil pollen assignments heavily rely on how robust modern pollen reference is. There is high species richness in southeastern Tibet, China, however, pollen morphological studies in this area are still poorly documented. Here, we present pollen atlas of 57 species (40 genera, 22 families) collected from the Ranwu Lake Basin. Pollen grains were imaged with light microscope (LM, 100X oil-immersion objective lens) and scanning electron microscope (SEM). All pollen types are ordered and presented according to different aperture types and sculpture patterns, facilitating comparison with fossil pollen. Moreover, we selected some representative species mainly based on potential palaeoecological importance, including Sibiraea (Rosaceae), Koenigia cathayana (Polygonaceae), Stellera chamaejasme (Thymelaeaceae), Hordeum vulgare subsp. vulgare and Poa annua (Poaceae), to discuss their pollen identification characteristics for the first time and assess potential applications in Quaternary palaeoecological interpretation. This study enriches modern pollen atlas for Quaternary pollen analysis in the study area and the adjacent regions. Our results provide robust modern reference in pollen-based reconstruction of vegetation history, palaeoclimate and palaeoenvironment, and tracing pollen signal of local human activities as well.

Calcareous nannofossil biostratigraphy, bioevents, and palaeoecological interpretation of the lower-middle Miocene outcrops in west central Sinai (Egypt)

The Burdigalian/Langhian (B/L) boundary has not yet been designated as a Global Stratotype Section and Point (GSSP), despite various proposed zonal schemes. In the Gulf of Suez region of Egypt, the Burdigalian-Langhian successions are notable for hosting significant hydrocarbon reservoirs within a tectonic rift setting. Therefore, biostatigraphy plays a crucial role in exploration endeavors in this area. The nannofossil biostratigraphy is investigated in two sections, Wadi Baba and Wadi Gharandel, of the lower-middle Miocene from west-central Sinai. Three biozones, NN3 (Sphenolithus belemnos) Zone, NN4 (Helicosphaera ampliaperta) Zone, and NN5 (Sphenolithus heteromorphus) Zone, are identified from the studied interval. The NN4 Zone could be divided into MNN4a/b and MNN4c. Important biovents are discussed, such as the S. heteromorphus paracme interval and the first occurrence and evolution of the Discoaster exilis and Discoaster variabilis groups. Based on the cluster analysis, the recorded taxa can be subdivided into four groups that reflect their palaeoclimatic preferences. The paleoecological interpretation of the studied Rudies Formation indicates prevailing cool and eutrophic nutrient conditions based on the dominance of taxa such as Coccolithus pelagicus, Reticulofenestra minuta, and Cyclicargolithus floridanus. The nannofossil taxa responses to sea level curve are interpreted. Fluctuations in taxa abundance and diversity indicate a slight rise in the sea level at the base of the Burdigalian followed by sudden drop in the sea level at the middle Burdigalian. High sea-level conditions prevailed again until the B/L boundary. During the Langhian period, many small-scale fluctuations in sea-level curve are detected.

Investigating Holocene relative sea-level changes and coastal dynamics in the mid-Tyrrhenian coast, Italy: An interdisciplinary study

Understanding millennial changes in relative sea level (RSL) and coastal responses in stable regions is crucial for deciphering the intricate relationship between natural dynamics and human adaptation. This interdisciplinary study explores the interplay between mid-to-Late Holocene sea-level fluctuations and tectonic along the mid-Tyrrhenian coast.The study area, located between the Fondi and Garigliano coastal plains, held great significance in ancient times. In particular, the strategic role of Formia, a monitoring point for the Tyrrhenian Sea, made this city one of the most important commercial hub during Roman occupation, leading to a significant urbanization of the coastal stretch testified by well-preserved remains nowadays scattered along the submerged or semi-submerged coastal sectors.This study reconstructs the mid-to-Late Holocene morpho-evolution and RSL changes in the study area by creating a geodatabase made of 52 sea-level markers (SLMs) derived from direct geoarchaeological measurements, stratigraphic and palaeoecological interpretations of new borehole data, and previously published stratigraphic data. Specifically, the radiocarbon dating of three peat samples provided new data ranging between 7.62 ± 47 and 1.00 ± 51 ka BP on the sea level history in the area. Based on our dataset, between 9.0 and 8.0 ka BP, the sea level rose from −19 m to −6.5 m at a rate of about 15.6 mm/y, slowing to 0.8 mm/y afterwards, stabilizing at its current position. Results suggest that during the 1st century BC, local sea level was no higher than −0.55 ± 0.29 m.The collected RSL data support the hypothesis of tectonic stability of this sector during the last 2.0 ka, testified by the position of the SLMs in accordance with the glacio-hydro-isostatic adjustment (GIA) models and supported by the determination of average vertical ground movement rates of −0.017 ± 0.23 mm/y.Finally, in terms of coastal changes the overlay between new data from geoarchaeological surveys, reinterpretation of previously-published stratigraphic data, and geomorphological analysis allowed us to deduce a general coastal progradation trend in the historical time for both low-lying and rocky sectors, due to natural and anthropogenic forcing factors.

A revisit to the Early Pliocene site of Abla (Guadix-Baza Basin, southern Spain)

The Guadix-Baza Basin (southern Spain) displays one of the best continental records from the Late Miocene to the Middle Pleistocene in western Europe, with many localities of fossil small mammals in a quite complete and continuous stratigraphic sequence. The Late Miocene continentalization of the Guadix-Baza Basin was firstly mentioned in the 1980s based on the presumed presence of Hipparion gromovae granatensis at the site of Abla (Almería province). Subsequent discoveries of late Turolian deposits confirmed the Late Miocene continentalization of the basin. The interest in the Abla site led to a second sampling campaign to look for microvertebrate fossils, which proved successful. In this paper, a complete taxonomic study of the novel microvertebrate fauna from Abla is presented, providing updated information on the age of the locality. Representatives of the vertebrate families Cyprinidae, Alytidae, Anguidae, Soricidae, Cricetidae, and Muridae have been identified. The presence of Stephanomys specimens exceeding the size of latest Miocene-earliest Pliocene species allows us to correlate the Abla site with the Early Pliocene (Ruscinian), a younger age than initially stated. A qualitative paleoecological interpretation based on the herpetofauna suggests the dominance of open environments with presence of permanent water bodies during the deposition of the Abla site, under warmer and more humid climate conditions than today in the Guadix-Baza Basin. A revision of the Hipparion remains from this locality showed that the sample is closer to Hipparion fissurae than to the initially assigned species.

Lower Campanian calcareous nannofossils: Morphometry and palaeoenvironmental implications of the Aspidolithus group (Rhenodanubian Flysch Zone, Austria)

Our calcareous nannofossil study focused on eleven samples from the lower Campanian (UC14a–UC14b) of the Loibichl section, located in the Rhenodanubian Flysch Zone of the Austrian Alps. Relative counts of calcareous nannofossil assemblages were followed by a morphometrical analysis on 1021 specimens belonging to the Aspidolithus genus (Aspidolithus enormis and Aspidolithus parcus). For this analysis, a light microscope was utilized to improve our understanding of the taxonomic concepts of this group during a phase of rapid morphological evolution. The analysis included the maximum length (L), the width of the outer rim versus the small diameter of the central area (b/a), and the number of perforations in the central area. The CaCO3 content and bulk carbonate stable isotope ratios of δ13C and δ18O were analysed to facilitate stratigraphic and palaeoecological interpretations. Additionally, this study was to determine whether variations in nannofossil morphometrics were driven by changing palaeoenvironmental conditions. This study identified five morphotypes: A. enormis subsp. 1, A. enormis subsp. 2, A. parcus expansus, A. parcus parcus, and A. parcus constrictus. The morphometric analysis substantiated the differentiation between “small” morphotypes (L < 8.5 μm; A. enormis) and the “large” A. parcus group (L > 8.5 μm). However, the results did not show any significant patterns that would justify a natural separation of the “subspecies” within the A. enormis and A. parcus group. Our statistical analysis suggests that these morphometric changes may be related to various palaeoenvironmental proxies. Further high-resolution morphometric analysis is required to verify the impact of contrasting environmental factors on Aspidolithus-size variation.

Nautilid beaks: unsuspected disparity and palaeoecological interpretation

Nautilid beaks: unsuspected disparity and palaeoecological interpretation

Simulating taphonomic processes on teeth: The impact of sediment pressure and thermal alteration on dental microwear

Dietary reconstructions based on dental microwear methodologies may be limited due to the various taphonomic processes that affect the formation of archaeological deposits. These limitations are primarily affected by two issues: 1) taphonomic alterations occurring over dental microwear patterns which mimic dietary signals and can lead to confusion in quantifying these signals, and 2) the exclusion of teeth due to structural damage caused by taphonomic processes, resulting in a reduction of the sample size. Thus, it is necessary to understand how taphonomic processes impact teeth to avoid biases in dietary reconstructions and improve the validity of their interpretations. Under these considerations, we conducted two experiments: one involving the simulation of sediment pressure, and the other focusing on thermal alterations. A hydraulic press and a muffle furnace were used for these purposes. The results of the experiments allowed us to characterise the alterations produced by abrasion caused by sediment pressure, enabling differentiation from dietary signals (scratches, pits, and gouges) and excluding them from dental microwear analyses. However, the thermal alteration experiment showed that this process does not produce significant effects, and even carbonized teeth retain dental microwear, making them appropriate for dietary reconstructions. Additionally, a comparison of archaeological teeth from level IIIb of Teixoneres Cave (Moià, Barcelona) was conducted, confirming the inferences drawn from the experimental results. This research highlights the importance of conducting such studies to better understand the impact of taphonomic processes on dental microwear, which is crucial for accurate dietary and palaeoecological interpretations.

High-resolution UAV maps of the Gobi Desert provide new insights into the Upper Cretaceous of Mongolia

The Gobi Desert of southern Mongolia is home to an incredibly rich record of dinosaurs and other vertebrate fossils from the latest Cretaceous Period. Together, more than a dozen sites in several basins have produced one of the richest palaeofaunas known from this interval anywhere in the world. Most of this diversity has been recovered from the fluvial deposits of the Nemegt Formation. Despite historic and ongoing research in southern Mongolia, accurate maps and geological data for the main fossil sites are still lacking, limiting our ability to investigate how local palaeoecological dynamics influenced Nemegt taxa, their geographic distribution, and their evolutionary patterns. One of these sites, Guriliin Tsav, has produced more than a hundred significant fossil specimens to date, but still remains one of the lesser known Nemegt localities. In part this is because many expeditions have instead focused on the nearby Bügiin Tsav, one of the largest and richest localities for the Nemegt Formation. To address this gap, a project was initiated in 2018 to produce a high-resolution topographic map of Guriliin Tsav using Unmanned Aerial Vehicles (UAV), and consequently, to plot the geographic and stratigraphic distributions of palaeontological resources on this map. In so doing, we also collected stratigraphic and taphonomic data from the area, allowing for the first detailed palaeoecological interpretation of Guriliin Tsav and a comparison with other localities of southern Mongolia. Here we present the results of this project, and also discuss new topographic and stratigraphic data from Bügiin Tsav. This sheds new light into the temporal and geographic distribution of vertebrate taxa in the latest Cretaceous of Mongolia.

A late Oligocene molluscan fauna and Oligocene coastal outcrops from Vilsund, NW Denmark

Abstract: A rich late Oligocene molluscan fauna from a coastal cliff at Vilsund on the island of Mors, Jylland, Denmark, was studied. A summary of the upper Palaeogene sedimentary sequence in NW Jylland is given and lithostratigraphical and biostratigraphical correlations are suggested. The molluscan fauna contains 120 species, and the nonmolluscs are briefly mentioned. The new species Mitromorpha (Mitrolumna) danica n. sp. and Cerithiopsis vilsundensis n. sp. are established. Mitromorpha (Mitrolumna) danica n. sp. is the first representative of the gastropod genus Mitromorpha Carpenter, 1865 and subgenus Mitrolumna Bucquoy, Dautzenberg &amp; Dollfus, 1883 from the Cenozoic of Denmark. Eubela (s. lat.) zetes (Kautsky, 1925) represents the oldest record of the genus Eubela Dall, 1889. Andersondrillia Schnetler &amp; Beyer, 1990 is considered to be a junior synonym of Benthomangelia Thiele, 1925. The bivalve genus Cubiostrea Sacco, 1897 is recorded from the upper Oligocene of the North Sea Basin for the first time. In the systematical part, several species are treated, including 16 species which have not been recorded previously from the Danish upper Oligocene; a synopsis of the representatives of the genus Streptodictyon Tembrock, 1961 in the Danish Oligocene is also given. Aphanitoma ingerae Schnetler &amp; Palm, 2008 is transferred to the genus Mitromorpha, subgenus Mitrolumna. The fauna is compared with other Danish and German late Oligocene faunas and palaeoecological interpretations are suggested. As many of the mollusc species have not previously been illustrated from the Dan– ish upper Oligocene, the fauna is extensively illustrated. Dinocyst assemblages have been studied to help date the investigated successions. The assemblages indicate that the glauconitic clay from Vilsund should be assigned to the provisionally named stratigraphical Unit X in Śliwińskaet al. (2012) or the lowermost Brejning Formation. Unit X was previously only known from the interval 61.5–67.5 m in the Harre-1 borehole. Schnetler &amp; Beyer (1990) assigned the glauconitic clay in the coastal cliff at Mogenstrup to the Brejning Formation, but dinocyst studies herein indicate that these strata should be assigned either to Unit X, most likely the upper part, or the lowermost Brejning Formation (see Appendix). This interpretation is supported by the foraminifers and the pectinid species Palliolum hausmanni (Goldfuss, 1835). The occurrence of other nearby outcrops of differing Oligocene ages is demonstrated. The outcrops are described and dated by means of dinocysts and foraminifers and include a section showing a depositional contact between the lowermost Rupelian Viborg Formation and Chattian Branden Clay. The age of the Mogenstrup section is also demonstrated by means of dinocysts.

Thanetian-Ypresian Alveolines from the Western Desert and the Nile Valley, Egypt

Five alveolinid species were identified from the Naqb Formation of Bahariya Oasis; Glomalveolina telementensis (Paleocene), Alveolina ankarensis (early Ypresian), Alveolina decipiens (early Ypresian), Alveolina recondita (early Ypresian), Alveolina cf. vredenburgi (early Ypresian). They are indicative of the SBZ7-8 Zone. The studied section is mainly composed of multiple Alveolina horizons. An index marker worth mentioning is Alveolina decipiens which is also recorded from the El Nusf Formation of the Farafra Oasis; this allows for correlation between the two sections. Alveolina decipiens of the El Nusf Formation is associated with Nummulites solitarius and Nummulites frassi and indicates that this horizon belongs to SBZ7-8. One species was recorded from the Minia Formation, Nile Valley; Alveolina ruetimeyeri (late Ypresian), SBZ12. Its occurrence in highly carbonate sediments allowed for paleoecologic interpretations.

A palynological atlas of the Cerrado-Caatinga ecotone in northeastern Brazil

Describing the diversity of Brazilian plant species, as well as the wide variety in the associated pollen grains, is crucial to understanding their evolution and ensuring effective conservation. The accurate identification of pollen is key to successful pollen studies and the consistent paleoecological interpretation of past vegetation changes. Pollen analysts usually identify plant taxa from reference collections built from herbaria material. In Brazil, pollen atlases primarily focus on three main vegetation domains, namely, the Amazon Forest, the Atlantic Forest, and the Cerrado, while information about Caatinga pollen taxa is dispersed across multiple studies; this significantly impedes efforts to further develop palynological research. To address this gap, we built a palynological atlas for the state of Piauí which is covered by the biomes Caatinga and Cerrado along with their transitional zones. These domains encompass various vegetation types, including dense shrubland, grassland, palm swamp formation, riverine forest, seasonal deciduous and semi-deciduous forests, as well as valley-side marshes. We collected flower buds from the Herbarium Prisco Bezerra (EAC) at the Federal University of Ceará and extracted the pollen grains for the pollen reference slides. The atlas comprises 398 species from 99 families, with the most represented families being Asteraceae, Bignoniaceae, Euphorbiaceae, Fabaceae, Lamiaceae, Malvaceae, Malpighiaceae, and Rubiaceae. Each taxa is presented with a description of the pollen grain, a photo showing polar and equatorial views, and ecological information as life form (liana/scandent/vine, herb, subshrub, shrub or tree), substrate, and vegetation type to support further studies.

African bovid tribe classification using transfer learning and computer vision.

Objective analytical identification methods are still a minority in the praxis of paleobiological sciences. Subjective interpretation of fossils and their modifications remains a nonreplicable expert endeavor. Identification of African bovids is a crucial element in the reconstruction of paleo-landscapes, ungulate paleoecology, and, eventually, hominin adaptation and ecosystemic reconstruction. Recent analytical efforts drawing on Fourier functional analysis and discrimination methods applied to occlusal surfaces of teeth have provided a highly accurate framework to correctly classify African bovid tribes and taxa. Artificial intelligence tools, like computer vision, have also shown their potential to be objectively more accurate in the identification of taphonomic agency than human experts. For this reason, here we implement some of the most successful computer vision methods, using transfer learning and ensemble analysis, to classify bidimensional images of African bovid teeth and show that 92% of the large testing set of images of African bovid tribes analyzed could be correctly classified. This brings an objective tool to paleoecological interpretation, where bovid identification and paleoecological interpretation can be more confidently carried out.

Mandibular anatomy of the paracryptodire Glyptops ornatus supports active hunting behavior in a Jurassic turtle.

The mandible of turtles is rich in osteological characters that are relevant for systematic purposes. Shape variation additionally reflects upon various feeding strategies and are thus informative for the palaeoecological interpretation of extinct species based on fossils. The mandibular anatomy of non-baenid paracryptodires has so far been undescribed. Based on digital segmentation of a computed tomography scan, I herein describe the mandible of the pleurosternid paracryptodire Glyptops ornatus. This taxon has a slender and gracile jaw, with weakly developed muscle attachment sites for adductor muscles (i.e., adductor fossa, coronoid process, and retroarticular process) and strongly reduced triturating ridges. These features are typical for suction-feeding aquatic hunters, thereby contrasting with the robust, durophagous-adapted mandibles of many baenid or compsemydid paracryptodires. In addition, the mandible of G. ornatus is characterized by the presence of a large splenial with a dorsal splenial-dentary contact, the presence of a splenial foramen, and the strong reduction of the foramen dentofaciale majus and the absence of a posterior intermandibular foramen.

The marine fossils and paleoecological significance of the Southern edge of South Sumatra Basin in Linggapura Lampung, Indonesia

The South Sumatra Basin is identified as a Paleogene-Neogene sedimentary basin with Mesozoic basements. It is located in the eastern Barisan Mountains, covering Jambi, South Sumatra, and Linggapura (Lampung), Indonesia. Linggapura represents the southernmost part of the South Sumatra Basin. The basin consists of two well-known rock formations, namely the Talangakar and Baturaja Formations. In this study, we investigated these formations through fossil records and paleoecological interpretations. Our investigation was based on measured stratigraphy and fossil observations along the Way Penandingan River in Linggapura, Lampung. We discovered that the bottom of this area consists of Cretaceous granitoid, which forms a nonconformity with the sedimentary rocks in this area. The Talangakar Formation in this region comprises quartzy-grained sandstone and conglomerates containing fossilized remains of terrestrial plants/vegetation. These plant fossils have undergone coalification, with some being silicified. The Batujara Formation in Linggapura is dominated by bioclasts, primarily consisting of Miocene shoreface-lagoonal larger benthic foraminifera, along with other marine and ichnofossils. Based on our findings, we suggest that the paleoecological condition of this area is associated with shoreline transgression during the Oligo-Miocene period. The hotter Miocene climate contributed to a rise in sea levels, resulting in shoreline transgression. Gradually, the area transformed from a terrestrial environment to a highly bioproductive marine environment, at least from the Late Oligocene to the Early Miocene. This study represents an important milestone in better understanding the paleoenvironmental conditions at the edge of the South Sumatra Basin throughout its geological history.

Palynological investigation of an Upper Triassic sequence in Nanjing area, eastern China, with paleoecological implications

The end-Triassic is characterized by a significant biotic crisis in both marine and terrestrial realms. However, terrestrial records in eastern Tethys are relatively limited, especially in eastern China. The Fanjiatang Formation represents the Upper Triassic sequence in southern Jiangsu and Anhui provinces of eastern China, yielding a rich plant and bivalve fossil record. The present study provides the first detailed palynological investigation for the Upper Triassic of Nanjing area, eastern China. Six of twenty processed palynological samples are productive, and more than 70 terrestrial spore and pollen fossil taxa were identified. A palynological assemblage, namely, the Concavisporites–Dictyophyllidites–Kyrtomisporis–Classopollis Assemblage was established, characterized by abundant fern spores, mainly including Concavisporites, Dictyophyllidites and Kyrtomisporis, and much less abundant gymnosperm pollen grains (important taxa include Alisporites, Chasmatosporites, and Classopollis), indicating a Late Triassic Norian–Rhaetian age. In conjunction with previously reported macro-plant data, the palynofloral analysis reveals a vegetation dominated by ferns, with diverse cycadophytes, less abundant lycophytes, bryophytes, equisetales, ginkgophytes and seed ferns, and a few conifers. Paleovegetation and semiquantitative palynological analysis permit a paleoecological interpretation, suggesting a lowland groundcover-dominated vegetation under (sub)tropical warm and humid climate in Nanjing area during this time interval. More detailed palynological and macro-plant data through the whole Upper Triassic in this region are necessary in the future to better reveal the Late Triassic paleoecological settings and variations on land prior to the end-Triassic mass extinction in eastern Tethys.

What can be gained from studying coprolite taphonomy: the case of Villanueva-1 (Palencia, Spain)

ABSTRACT Coprolites are relatively common trace fossils in Quaternary sites and are used to obtain a variety of information that goes from environment reconstruction to dating sites or recovering DNA among others. However, little attention is given to taphonomic processes undergone by the coprolites that might compromise their validity as sources of information. In this paper, we present the study of the Middle Pleistocene coprolites of Villanueva-1 from a taphonomic point of view and discuss the results of the analyses performed and how the taphonomic alterations identified have an effect on palaeoecological interpretations based on these fossils. Modifications prior to burial may be determined by direct observation of shape, colour, fractures and inclusions. Some diagenetic alterations can also be inferred from colour differences, but mostly require destructive analyses in order to identify the degree of chemical and structural changes that might interfere with content preservation, such as pollen, DNA, or organic carbon for dating purposes.

Oldest evidence of abundant C 4 grasses and habitat heterogeneity in eastern Africa

The assembly of Africa's iconic C4 grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C4 grasses are thought to have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C4 biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C4 grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C4 grass-dominated habitats in Africa-and globally-by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution.

The interaction between large mammals and Acheulean tools during the Middle Pleistocene in the Manzanares valley (Madrid, Spain): new evidence for Santa Elena and Oxígeno sites

The fluvial deposits of the Manzanares and Jarama rivers present one of the largest concentrations of lithic and faunal remains of Pleistocene sites in Europe. In the Manzanares River close to the confluence of the Jarama River, the stepped terrace system disappears and gives way to the Complex Terrace of Butarque (CTB), where the sites of Santa Elena and Oxígeno are located. Different numerical dates obtained from the visible CTB’s bottom suggest that it was deposited during the MIS 6 or even MIS 7. This paper provides the first taphonomic and palaeoecological interpretation of both collections. A total of 445 fossil elements have been recorded in Oxígeno. The most represented are cranial fragments of Elephas sp. About Santa Elena, 130 fossil elements have been recorded. The best represented are fragments of Bos/Bison sp. horns and Elephas sp. tusks. The taphonomic processes identified at both sites bring to light a complex taphonomic history. The incidence of processes related to fluvial transport is higher in Oxígeno than in Santa Elena. Besides, dismemberment cut marks have been identified exclusively on the humerus of Bos primigenius in Santa Elena. Several tooth marks from carnivores have been recorded: small pits and scores at Oxígeno as well as pits and furrowing on Bos primigenius and Megaloceros sp. bones from Santa Elena. The faunal association depict an open landscape of wet meadows with herbaceous vegetation adjacent to riparian wood habitats associated with the Manzanares alluvial plain, where hominids and predators competed to some unknown extent.