Pleistocene Assemblages Research Articles

Beyond Large-Shaped Tools: Technological Innovations and Continuities at the Late Early Pleistocene Assemblage of El Barranc de la Boella (Tarragona, Spain)

The emergence of the mode 2 technocomplex, traditionally characterized by the development of large cutting tools (LCTs) or standardized large-shaped tools, has also implied a range of new technological behaviours. These include enhanced raw material management, more sophisticated knapping strategies, and transport patterns, among other innovations. Unit II of the localities of La Mina, El Forn, and Pit 1 in El Barranc de la Boella (Tarragona, Spain) — dating back to between 0.99–0.78 million years ago — contains the oldest mode 2 assemblages in the European subcontinent and represents an exceptional opportunity to examine the technological features associated with the appearance of LCTs in Europe and to provide clues to shed light to different hypotheses about their appearance. The presence of functionally diverse but environmentally similar localities enables a study of behavioural flexibility and technological variation, marking a critical contribution to understanding early human technological evolution. Our research focuses on the technological behaviours of hominins in unit II of Pit 1, La Mina, and El Forn at Barranc de la Boella, examining five keys technological aspects such as (1) raw material management, (2) core reduction sequences, (3) reduction intensity, (4) large flake production, and (5) the spatiotemporal integrity of reduction sequences. We compare these behaviours with those observed in mode 1 (~ 1.8–0.9 Ma) and early Middle Pleistocene (~ 0.78–0.6 Ma) assemblages across western Europe. Our findings reveal significant advancements and anticipatory behaviours at El Barranc de la Boella, such as the use of procedural templates for core reduction strategies and the production of large-shaped tools governed by principles of gestural economy, and also the existence of different reduction sequences in different raw materials according to specific purposes. The technological behaviours observed at El Barranc de la Boella seem to be more indicative of population dispersals rather than local evolutionary developments from mode 1 technologies. The non-linear evolution of core knapping strategies, along with the variability in large-shaped tool types, suggests multiple waves of hominin dispersals into Europe during this crucial period. We propose that El Barranc de la Boella may represent an early dispersal of the Acheulean from Africa around 1.4 million years ago, potentially connected to assemblages such as ‘Ubeidiya. This study underscores the complexity of lithic technology during this period and contributes significantly to our understanding of the complex emergence and adoption of new technological behaviours in European early mode 2 assemblages, extending beyond the mere appearance of LCTs.

Insufficient Cold Resistance as a Possible Reason for the Absence of Darkling Beetles (Coleoptera, Tenebrionidae) in Pleistocene Sediments of Siberia.

The level of diversity and abundance of darkling beetles (Coleoptera, Tenebrionidae) is the main difference between the late Pleistocene and modern insect faunas of arid regions. In the Pleistocene assemblages they are extremely rare, whereas in the modern ones they predominate. It is assumed that the reason for their rarity in fossil entomological complexes is their lack of cold resistance. The supercooling points (SCP) and low lethal temperatures (LLT) of adults from five species of Altai darkling beetles that overwinter in the soil and larvae from one such species were measured in the laboratory. All beetles supercooled at negative temperatures but could not survive freezing, with the average SCP of the most cold-resistant species between -25.7 and -21.7 °C (Bioramix picipes, Anatolica dashidorzsi, and Penthicus altaicus). However, 50% of the individuals from different species in the experiment died after exposure during two days at temperatures ranging from -22 to -20 °C. The focal species are distributed in parts of Central Asia with an extreme continental climate, and the temperatures measured in the soil of these natural areas turned out to be lower than or close to the limit of cold resistance of the beetles. Overwintering of darkling beetles is therefore only possible in areas with deep snow: in hollows, under bushes, and under large cereals. Darkling beetles with poor cold resistance could not have existed in the colder climate of the late Pleistocene, which explains their absence from fossil fauna.

Quaternary Mammals from Central-Western Argentina in the Stratigraphic Context of Southern South America

This is an updated contribution to the Quaternary geology and paleontology from central-western Argentina, focused on San Luis Province. It is mostly based on unpublished data; only some fossils had previously been briefly mentioned in broader faunal contexts. The fossil-bearing sediments correspond to eolian and alluvial environments of moderate energy, dominated by sands and sandy silts. They overlie high-energy fluvial cycles and underlie edaphic horizons. They have a wide distribution, and several radiocarbon dates allow their regional correlation. Stratigraphic sequences with the precise origin of fossils allow for the improvement of lithostratigraphic and faunal correlations with the Pampean Region (central and east Argentina; La Pampa and Buenos Aires provinces), where Pleistocene assemblages are better known, but also with central-western (Cuyo Region), northwestern, and northeastern Argentina. Faunal remains correspond to large mammals, represented by xenarthrans (Cingulata and Tardigrada), macraucheniids (Litopterna), gomphotheres (Proboscidea), and equids (Perissodactyla), a typical Pleistocene mixture of native (xenarthrans and litopterns) and immigrant mammals.

Palynological characteristics of plant communities in the eastern Arctic during the Early to Middle Calabrian Age

Palynological analysis of Early Pleistocene sediments from Lake El'gygytgyn indicate that climate was warmer than present between c. 1.2860 and 1.6975 Ma (late Gelisian–early Calabrian ages), although variations in the paleovegetation indicate fluctuations between relatively cool and warm conditions. During the coolest intervals, the vegetation on the Anadyr Plateau was a mix of Betula-Salix shrub tundra and Larix forest-tundra. Larix forests, which probably included trees species of Betula and Alnus, characterized the regional vegetation during the warmest times. Slightly cooler interglaciations are indicated by the presence of Larix-forest tundra. Pinus pumila pollen is not consistently present in all interglaciations, indicating that variations in the extent and/or duration of snow cover occurred during these warm intervals. The absence of pollen from this evergreen shrub contrasts with Holocene and Late Pleistocene assemblages, where the taxon is a hallmark of warm conditions. During the Early Pleistocene, Betula pollen indicates the plant's presence during warm and cool intervals, in contrast to Late and Middle Pleistocene spectra where shrub Betula is absent or rare. The pollen data from MIS 55 suggest that it was the coolest of the Pleistocene “super” interglaciations and that the MIS 43 climate was as warm as that of MIS 55. The El'gygytgyn palynological record is a powerful reminder that the distribution of arctic communities can be vastly reduced or eradicated during warm Earth scenarios.

Ecological shifts and hominin adaptations during the Mid-Pleistocene Climate Transition in Northeast Asia as evidenced by isotopic analysis (δ13C, δ18O) of mammalian enamel from Early Paleolithic sites in the Nihewan Basin, China

The Nihewan Basin in North China is one of the most important early archaeological sequences for our understanding of the ecological ranges exploited by hominins and how their adaptive behaviors were shaped by local, regional, and global environmental fluctuations. This study contributes to the topic by conducting stable isotope (δ13C, δ18O) analyses of mammalian tooth enamel from several Early Pleistocene assemblages in the Nihewan Basin dated to ca. 1.2–1.1 Ma, and exploring the links between hominin behavioral adaptations and ecological changes during the Mid-Pleistocene Climate Transition in Northeast Asia mainland. Our isotopic analysis of bulk samples (n = 215) indicates that the Nihewan Basin regional environment underwent significant changes, from landscapes dominated by wet and closed pure C3 vegetation no later than 1.2 Ma, to those dominated by dry and open C3/C4 mixed vegetation during 1.2–1.1 Ma. Additionally, the isotopic analysis of sequential samples (n = 16) suggests seasonal variations. These isotope results interpreted in the context of hominin behavioral traits indicate that hominins exhibited cognitive and technical flexibility in the face of complex and unstable regional ecological settings, suggesting that they adjusted to the environmental fluctuations characteristic of high-latitude arid/semi-arid regions such as the Nihewan Basin over or prior to the Mid-Pleistocene Climate Transition.

Cricetinae in the Quaternary fossil record of the Czech Republic and Slovakia (Rodentia: Cricetidae)

The paper surveys the Quaternary (MN17–Q4) fossil record of Cricetinae in the Czech Republic and Slovakia with particular attention to the current glacial cycle (Q4: Vistulian–Holocene) and immediate history of extant taxa. Vast majority of records were reexamined using standardized techniques of morphometric analysis (in total 625 molars of Cricetus, 805 molars of small hamsters). Cricetus cricetus, recorded in 130 Q4 fossil communities, exhibits almost continuous appearance since the beginning of Vistulian, possibly with considerable range regressions during LGM and middle Holocene. It was recorded also in 27 Early Pleistocene (MN17–Q2) and 6 Middle Pleistocene (Q3) assemblages, with a small-sized form (Cricetus cricetus nanus) in MN17–Q1 stage and a mosaic of Q2–Q3 records exhibiting mostly excessively large size (C. c. runtonensis), similarly as the Vistulian items which are clearly larger than those of the post-LGM and early Holocene age. The appearance of hamster in fossil record shows a mosaic character suggesting temporal spatial and abundance fluctuations: in most sites it absents and in general, it appears as a rather rare sub-recedent element (in Q4 communities with overall dominance of mere 0.55% and this is valid also for its appearance in Early and Middle Pleistocene assemblages). Small hamsters arranged here in the genus Cricetulus (incl. Allocricetus) represent a constant element of the Early and Middle Pleistocene assemblages (43 sites in the Czech Republic and Slovakia). The items of Q4 record (21 communities) clearly differ from the Early to Middle Pleistocene form Cricetulus bursae by a consistently smaller size corresponding to extant species Cricetulus migratorius. The gap is quite distinct conforming even to the possible extinction of C. bursae during the Eemian interglacial followed by early Vistulian expansion of the extant species from its Asiatic range suggested by molecular phylogeography. We examined a question of possible appearance of Phodopus among the Q4 record of small hamsters, yet in our material, we did not succeed to confirm it.

The missing deposits of South Sulawesi: New sources of evidence for the Pleistocene/Holocene archaeological transition

The Indonesian island of Sulawesi, located in the ‘Wallacean’ biogeographical zone at the axis of human migration between the super-continents of Sunda and Sahul, has been linked to many research questions relating to the early movements of humans in the region between the landmasses of Asia and Australia. From an archaeological perspective, South Sulawesi is one of the most intensively investigated parts of Indonesia, although much about the early human story in this region remains unknown. While Pleistocene assemblages are scarce, South Sulawesi contains sites with deposits >50,000 years old, along with rock art of a broadly similar antiquity. Mid-Holocene assemblages reveal a regionally unique technocomplex known as the Toalean. However, knowledge of how these two cultural periods are related has been obscured by a gap in the archaeological record between c.20,000–10,000 years ago. This gap has prevented us from understanding the origins of major developments in stone tool technologies, environmental adaptations, and changes in material culture. Cemented archaeological deposits adhering to cave walls, known as breccias, may prove the solution for researchers interested in these poorly understood time periods. Samples taken from archaeological breccias for radiocarbon dating have shown that the deposits currently missing from the archaeological record can still be found attached to cave walls. These breccias contain archaeological deposits that have been consolidated by calcite precipitation and have remained attached to the walls of caves and rockshelters, while the majority of uncemented deposits were removed from the site by erosion or physical action. The identification of these ‘time capsules’ affirms environmental conditions did not restrict nor prevent occupation or site formation in South Sulawesi during the early Holocene period, and confirms archaeological breccias are a valid source of archaeological data and should be examined to a greater extent in the future. This paper identifies these missing archaeological deposits by dating material from archaeological breccias at the site, Leang Bulu Bettue, in the Maros Regency of South Sulawesi. It suggests that archaeological breccias are a valid and important source of information for consideration in future research.

The Technological Behaviours of Homo antecessor: Core Management and Reduction Intensity at Gran Dolina-TD6.2 (Atapuerca, Spain)

The ability of early hominins to overcome the constraints imposed by the characteristics of raw materials used for stone tool production is a key topic on the discussion about the evolution of hominin cognitive capabilities and technical behaviours. Thus, technological variability has been the centrepiece on this debate. However, the variability of lithic assemblages cannot be correctly interpreted without understanding site occupational models and function and considering that individual tools represent specific discard moments in a continuous reduction process. In Europe, the earliest technological record is represented by the scarce and scattered Mode 1 technologies, often deriving from occasional occupations or restricted activity areas yielding unrepresentative assemblages. In this paper, we approach the technological behaviours exhibited by Lower Palaeolithic hominins from the subunit TD6.2 of the Gran Dolina site (Atapuerca, Burgos) by including the perspective of reduction intensity studies on the analysis of technological variability. Gran Dolina TD6.2 is a unique and extremely significant archaeological context, as it represents the oldest multi-layered unit of domestic hominin occupations in the Early Pleistocene of Europe. We use the Volumetric Reconstruction Method (VRM) to estimate the original volume of the blanks and quantify the reduction intensity of each core individually to characterise the reduction distribution patterns using Weibull probability distribution functions. Our results suggest differential raw material management in terms of reduction intensity, according to the characteristics of each lithology. This could reflect a solid understanding of raw material qualities and a certain degree of planning. Altogether, the continuity between knapping strategies through reduction denotes constant adaptation to raw material constraints as well as particular knapping conditions, rather than specific compartmentalised mental schemes. In conclusion, Homo antecessor toolmakers would have been situational knappers whose technological behaviour would be highly adaptive. This research constitutes the first reduction approach for the European Early Pleistocene assemblages that will lead to a referential framework for other European Early Pleistocene sites.

Evidence of cave lion (Panthera spelaea) from Pleistocene Northeast China

ABSTRACT The cave lion (Panthera spelaea) was one of the most widespread carnivores in the Pleistocene. The species ranged throughout Eurasia and even into North America as a member of the Mammuthus-Coelodonta fauna. However, the species has not previously been reported from the Mammuthus-Coelodonta fauna from the Pleistocene assemblages of the Songhua River. This study presents evidence of two Panthera spelaea specimens from the Middle and Late Pleistocene Songhua River fossil assemblages (MIS 10–8 and MIS 5–3). A combination of lower population due to vegetation shifts in the region and misidentification of specimens as Panthera tigris may explain why Panthera spelaea has not previously been reported in the region. The Middle Pleistocene specimen displays traits regarded as primitive in European cave lions. The Late Pleistocene specimen displays a mixture of primitive and advanced traits. These traits indicate a morphological transition within the species and also a possible ancestral relationship to Panthera atrox.

A comparative study of the Early Pleistocene carnivore guild from Dmanisi (Georgia)

The carnivore guild of the Early Pleistocene site of Dmanisi is among the most diverse of the Early Pleistocene of the entire Old World. It includes 14 carnivoran taxa: Homotherium latidens, Megantereon whitei, Panthera onca georgica, Acinonyx pardinensis, Lynx issiodorensis; Pachycrocuta brevirostris; Canis (Xenocyon) lycaonoides, Canis borjgali, Vulpes alopecoides; Ursus etruscus; Lutra sp., Martes sp., Meles sp., and Pannonictis sp. The analysis of this rich carnivore guild was carried out under different methodological approaches to compare the assemblage with other chronological coeval European, Asian, and African sites from a paleobiological perspective. To achieve the goal, we used a permutational hierarchical method called boostrapping cluster analysis based on taxonomic absence/presence matrices (at both generic and specific level) and on ecological matrices (considering dietary preferences/hunting strategies of each carnivoran) and carried out Mantels tests assessing magnitude of time, space, ecology, and taxonomy as source of difference between guilds. Our results suggest a close similarity among the Dmanisi carnivore assemblage and other guilds recorded from European late Villafranchian sites such as Pirro Nord, Venta Micena, and Apollonia 1 and, in a lesser extent, to European Epivillafranchian sites as Vallonnet, Untermassfeld, or the Vallparadís Section. Early to Middle Pleistocene Asian carnivore assemblages display several similarities with the Dmanisi guild mainly in the record and diversity of felid and the canid ecomorphotypes. Eastern African sites such as Olduvai and Omo, as well as South African sites, display a lower similarity with the studied sample, basically for the most diverse hyenid taphocoenoses. To sum up, the present study suggests a close similarity between the Dmanisi carnivore guild and other European Late Early Pleistocene assemblages without close parallels with African or Asian assemblages.

Use of meat resources in the Early Pleistocene assemblages from Fuente Nueva 3 (Orce, Granada, Spain)

Over the last few decades, several types of evidence such as presence of hominin remains, lithic assemblages, and bones with anthropogenic surface modifications have demonstrated that early human communities inhabited the European subcontinent prior to the Jaramillo Subchron (1.07–0.98 Ma). While most studies have focused primarily on early European lithic technologies and raw material management, relatively little is known about food procurement strategies. While there is some evidence showing access to meat and other animal-based food resources, their mode of acquisition and associated butchery processes are still poorly understood. This paper presents a taphonomic and zooarchaeological analysis of the Fuente Nueva-3 (FN3) (Guadix-Baza, Spain) faunal assemblage, providing a more in-depth understanding of early hominin subsistence strategies in Europe. The present results show that hominins had access to the meat and marrow of a wide range of animal taxa, including elephants, hippopotami, and small- and medium-sized animals. At the same time, evidence of carnivore activity at the site suggests that these communities likely faced some degree of competition from large predators when acquiring and processing carcasses.

The skeleton of Congruus kitcheneri, a semiarboreal kangaroo from the Pleistocene of southern Australia.

The macropodine kangaroo, Wallabia kitcheneri, was first described in 1989 from a Pleistocene deposit within Mammoth Cave, southwestern Australia, on the basis of a few partial dentaries and maxilla fragments. Here, we recognize W. kitcheneri within the Pleistocene assemblages of the Thylacoleo Caves, south-central Australia, where it is represented by several cranial specimens and two near-complete skeletons, a probable male and female. We reallocate this species to the hitherto monotypic genus Congruus. Congruus kitcheneri differs from all other macropodid species by having a highly unusual pocket within the wall of the nasal cavity. It is distinguished from C. congruus by having a longer, narrower rostrum, a taller occiput and a deeper jugal. Congruus is closest to Protemnodon in overall cranial morphology but is smaller and less robust. In most postcranial attributes, Congruus also resembles Protemnodon, including general limb robustness and the atypical ratio of 14 thoracic to five lumbar vertebrae. It is distinguished by the high mobility of its glenohumeral joints, the development of muscle attachment sites for strong adduction and mobility of the forelimb, and large, robust manual and pedal digits with strongly recurved distal phalanges. These adaptations resemble those of tree-kangaroos more than ground-dwelling macropodines. We interpret this to imply that C. kitcheneri was semiarboreal, with a propensity to climb and move slowly through trees. This is the first evidence for the secondary adoption of a climbing habit within crown macropodines.

Analysis of Late Pleistocene megafauna and puparia from the Lent dredging site, province of Gelderland (the Netherlands)

Abstract More than 900 vertebrate bones, ranging from Late Pleistocene to Holocene in age, have been identified in a collection that was recovered by a single dredging operation for the construction of artificial lakes near Lent (Nijmegen, province of Gelderland, the Netherlands). The Late Pleistocene assemblage comprises mainly Weichselian glacial fauna such as mammoths, reindeer and bison. Some Eemian fauna is represented as well, e.g. straight-tusked elephant. The abundance of certain species over others suggests that preservation bias had a considerable impact on this assemblage, while its time-averaged nature resulted in overrepresentation of certain species. A case study is here conducted on a fragmentary skull of a subadult woolly mammoth bull with embedded blowfly puparia. Some of these puparia are fully developed, indicating prolonged exposure of the mammoth carcass.

Technological adaptations of early humans at the Lower Pleistocene Nihewan Basin, North China: the case of the bipolar technique

The Nihewan Basin in North China has proved to be a key area for the study of human evolution outside of Africa due to its continuous record of hominin occupation since the Early Pleistocene. Lower Paleolithic lithic assemblages at Nihewan are attributed to the East Asian Mode 1 techno-complex, which is often defined by the widespread use of freehand knapping techniques. However, our ongoing investigation of several early Pleistocene archaeological sites at Nihewan has revealed a higher prevalence of bipolar stone artifacts than previously considered, which may have been underestimated in the past due to the disparity of analytical techniques applied to Early Stone Age assemblages and the poor quality of the Nihewan Basin raw materials. This has constrained the identification of bipolar attributes and their differentiation from freehand knapping products. This study aims to investigate technological and economical differences between the two techniques based on experimental results of chert from the Nihewan Basin, creating a referential framework for the study of bipolar artifacts that we apply, to the Early Pleistocene assemblages of Xiaochangliang and Cenjiawan. Our results not only highlight morphological and technological differences between bipolar and freehand products but also demonstrate that both techniques share significant similarities in terms of dimensions and productivity. Overall, our results help to contextualize the technological flexibility of East Asian Mode 1 assemblages in the Nihewan Basin, where early hominins employed alternative flaking techniques, often in the same assemblage, to overcome constrains imposed by the poor quality of most of the raw materials available.

Frugivore-fruit size relationships between palms and mammals reveal past and future defaunation impacts

Mammalian frugivores are critical seed dispersers, but many are under threat of extinction. Futhermore, the impact of past and future defaunation on plant assemblages has yet to be quantified at the global scale. Here, we integrate palm and mammalian frugivore trait and occurrence data and reveal a global positive relationship between fruit size and frugivore body size. Global variation in fruit size is better explained by present-day frugivore assemblages than by Late Pleistocene assemblages, suggesting ecological and evolutionary reorganization after end-Pleistocene extinctions, except in the Neotropics, where some large-fruited palm species may have outlived their main seed dispersers by thousands of years. Our simulations of frugivore extinction over the next 100 years suggest that the impact of defaunation will be highest in the Old World tropics, and an up to 4% assemblage-level decrease in fruit size would be required to maintain the global body size–fruit size relationship. Overall, our results suggest that while some palm species may be able to keep pace with future defaunation through evolutionary changes in fruit size, large-fruited species may be especially vulnerable to continued defaunation.

Extinction of North AmericanCuvieronius(Mammalia: Proboscidea: Gomphotheriidae) driven by dietary resource competition with sympatric mammoths and mastodons

AbstractThe gomphotheres were a diverse and widespread group of proboscideans occupying Eurasia, North America, and South America throughout the Neogene. Their decline was temporally and spatially heterogeneous, and the gomphotheres ultimately became extinct during the late Pleistocene; however, the genusCuvieroniusis rarely represented in late Pleistocene assemblages in North America. Two alternative hypotheses have been invoked to explain this phenomenon: (1) competitive exclusion by sympatric mammoths and mastodons or (2) ecologic displacement due to an environmental transition from closed forests to open grasslands. To test whether competition for resources contributed to the demise of North AmericanCuvieronius, we present herein a large collection of stable isotope and dental microwear data from populations occupying their Pleistocene refugium in the Atlantic Coastal Plain. Results suggest thatCuvieroniusconsumed a wide range of resources with variable textural and photosynthetic properties and was not specialized on either grasses or browse. Further, we document evidence for the consumption of similar foods between contemporaneous gomphotheres, mammoths, and mastodons. The generalist feeding strategy of the gomphotheres likely facilitated their high Miocene abundance and diversity. However, this “jack of all trades and master of none” feeding strategy may have proved challenging following the arrival of mammoths and likely contributed to the extirpation ofCuvieroniusin North America.

Lower Pliocene gastropod assemblages from northwestern France: Palaeoceanographic and palaeobiogeographic implications

Upper Miocene to Pleistocene assemblages of northwestern France are commonly grouped as Redonian faunas. Although earlier authors recognized their diverse and heterochronic character, Redonian assemblages continued to be monographed as if they were homogeneous, hindering understanding. Here we critically review the lower Pliocene (Zanclean) Assemblage III gastropod faunas of the Nantes region (241 species within 145 genera) and consider their palaeoenvironmental and palaeobiogeographic implications. They occur in the wider context of a post-Miocene decrease in faunal diversity along the Atlantic seaboard of Europe. This decline has been linked to the loss of thermophilic faunal elements due to a cooling in Mean Monthly Sea Surface Temperature (MMSST). Based on Assemblage III gastropods, MMSSTs in the Ligerian Gulf of northwestern France were characterized by subtropical temperatures in Zanclean times (not cooler than approximately 16 °C in February to 22 °C in August and September, compared to present day values of 9.5 °C to 18.5 °C for this latitude). At generic level, the Assemblage III fauna lies at the northern limit of the subtropical French-Iberian molluscan province, which also included the Pliocene faunas of the Mondego Basin of Portugal. However, at species level, it is unlike other Redonian or French-Iberian assemblages of Pliocene age and justifies the creation of a distinct Ligerian molluscan subprovince. The origin and evolution of the assemblage were strongly dependent on the geography of northwestern France during the Pliocene; once the Ligerian Gulf vanished, so did the subprovince.

Трасологические исследования комплексов позднего плейстоцена и раннего голоцена Северо-Восточной Азии. История и современное состояние

Трасологические исследования комплексов позднего плейстоцена и раннего голоцена Северо-Восточной Азии. История и современное состояние

Reconstructing the mass and thermal ecology of North American Pleistocene tortoises

AbstractResearchers often interpret the presence of tortoises in Pleistocene assemblages as evidence of an interglacial age, based on an assumption that these fossils indicate thermic climates, as modern giant tortoises require. Since the Paleocene, tortoises have been common components of terrestrial fossil assemblages and have repeatedly evolved species of giant size. Whereas extant giant tortoises are found only on islands off the coasts of South America and Africa, at least two species persisted in North America until the terminal Pleistocene. These tortoises,Hesperotestudo crassiscutataandGopherus“hexagonatus,” both of which reached carapace lengths of >1 m, were distributed across the southern United States. This study provides new metrics to derive quantitative weight estimates from measurements of the tortoise shell. The linear measurements of 69 anatomical features of the shells of 108 live tortoises indicate that the regression between straight carapace length and weight is most significant, with a maximumr2> 0.99. This regression is useful for tortoises that weigh between 1.8 and 339 kg. This mass estimate, coupled with a heat dissipation rate derived from thermoregulation modeling, provides estimates of how long tortoises can maintain a viable body temperature at low ambient temperatures. Depending on size, a tortoise can survive a maximum of 2.3 to 33 hours of freezing temperatures, which corresponds to a mean annual temperature ≥22°C and a mean winter low temperature ≥7.5°C. This analysis infers warmer temperatures at Pleistocene sites with fossil tortoise occurrences than previous qualitative estimates.

Molluskan Grazing Traces (Ichnogenus Radulichnus Voigt, 1977) on a Pleistocene Bivalve from Southern Brazil, With the Proposal of a New Ichnospecies

The ichnogenus Radulichnus Voigt, 1977 is recorded for the first time from a bivalve, Anomalocardia brasiliana (Gmelin, 1791), in a late Pleistocene molluskan assemblage from the southern Brazilian coastal plain. Grazing traces comprise short (<1 mm), parallel furrows, arranged in rows on the inner (concave) shell surface and mostly concentrated in its central area. Radulichnus accommodates scratches on hard substrates produced by the radula of grazing gastropod or polyplacophorans. Our literature survey on fossil and extant traces, as well as studies on the grazing mechanism in living mollusks, document at least two distinct morphotypes that are related to differences in the feeding modes of the producers. We propose to distinguish a second ichnospecies of Radulichnus, in addition to the type, R. inopinatus Voigt, 1977 (produced by gastropods), which is named R. transversus isp. nov., and attributed to polyplacophorans. Grazing traces on the shell of A. brasiliana match the morphotype produced by polyplacophorans mollusks, and are indicative of its complex taphonomic history in comparison with other shells in this assemblage.