Quaternary Sites Research Articles

Herpetofauna diversity from late Holocene wetlands of northeastern Argentina

AbstractThe palaeofauna of the Quaternary is mostly known from the mammals' record, while the herpetofauna is less represented. In the same way, in northeastern Argentina reptile fossils records are scarce, usually represented by preliminary communications. This paper focuses on the study of herpetofauna remains from the Isla El Disparito archaeological site. The faunal materials collected at the site revealed an increase in taxonomic diversity related to the Quaternary herpetofauna in the IED site, with over 50% of the bone remains represented by anurans and at least six recognized squamates taxa. The purpose of this study is to properly identify these new records of herpetofauna remains from northeastern Argentina during the Holocene as well as to provide a dichotomous key of postcranial remains for identifying extant squamates taxa in other Quaternary sites from Argentina. The identified squamate assemblage includes the lizard Ophiodes sp., the snake families Typhlopidae, Dipsadidae, Viperidae and undetermined colubroids, along with anuran bone remains (Anura indet. and ?Hylidae). Additionally, the findings contribute to a better understanding of the herpetological assemblage in Argentina, providing insights into the composition of South American squamates during the Quaternary.

Promoting diversity in geoheritage evaluation: creating an evaluation method for the scientific value of Quaternary sites in arid environments.

A rigorous assessment is an essential part of geoconservation, and choosing an appropriate evaluation method is essential for this process. Globally, an increasing number of sites are being assessed for their geoheritage values, but the most popular methods have been created by researchers with experiences centred in Europe, without considerations of regional differences. To understand whether regional perspectives are required in the evaluation process, this study developed a new method targeting the scientific value of Quaternary geoheritage sites in arid environments, using input from 49 researchers in geosciences and related disciplines with interests in arid landscapes. The results demonstrated the need for a new or modified method, given the different preferences in the weighting system and the necessity to include additional criteria specific to the type of sites targeted by the study. The strong preference to include a new criterion on connections with archaeology/anthropology highlighted the significance of the interdisciplinary scientific values of Quaternary geoheritage sites in arid environments. These findings imply the need for regional diversity or adjustments in geoheritage evaluation. Future research is required to consider such differences for geoheritage values beyond the scientific dimension, such as educational values and touristic values in diverse geographical settings. This article is part of the Theo Murphy meeting issue 'Geodiversity for science and society'.

Antibodies targeting a quaternary site on SARS-CoV-2 spike glycoprotein prevent viral receptor engagement by conformational locking

SARS-CoV-2 continues to evolve, with many variants evading clinically authorized antibodies. To isolate monoclonal antibodies (mAbs) with broadly neutralizing capacities against the virus, we screened serum samples from convalescing COVID-19 patients. We isolated two mAbs, 12-16 and 12-19, which neutralized all SARS-CoV-2 variants tested, including the XBB subvariants, and prevented infection in hamsters challenged with Omicron BA.1 intranasally. Structurally, both antibodies targeted a conserved quaternary epitope located at the interface between the N-terminal domain and subdomain 1, uncovering a site of vulnerability on SARS-CoV-2 spike. These antibodies prevented viral receptor engagement by locking the receptor-binding domain (RBD) of spike in the down conformation, revealing a mechanism of virus neutralization for non-RBD antibodies. Deep mutational scanning showed that SARS-CoV-2 could mutate to escape 12-19, but such mutations are rarely found in circulating viruses. Antibodies 12-16 and 12-19 hold promise as prophylactic agents for immunocompromised persons who do not respond robustly to COVID-19 vaccines.

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.

Holocene vertebrate fauna in Fergana Valley, Kyrgyzstan, based on fossils from the Obishir-5 rock shelter

Central Asia is a region that, owing to its geographical position, has always been at the intersection of cultures. In the Fergana Valley, located in the very heart of Central Asia, the Late Pleistocene–Early Holocene is characterized by the expansion and intensification of human settlements. This cultural event has previously been linked to global climate changes that took place during the Pleistocene–Holocene transition. In order to reconstruct local climatic conditions in the area during this period, it is worth studying the fossil vertebrate faunas from late Quaternary sites in the Fergana Valley. The Obishir-5 rock shelter, dating to the Late Pleistocene–Early Holocene period, discovered in the middle of the 20th century, is a key archeological site in the valley. To date no thorough zooarcheological research has been done on the excavated faunal remains. Here we present the results of the first faunal analysis of the small vertebrates found at this site. We studied the taxonomic composition of remains, which was then used to make paleoenvironmental reconstructions. In total, we identified 13 small mammal species and three bird species. In addition, the assemblage contained one amphibian and two reptile taxa. The faunal composition suggests that during the final Pleistocene and Early Holocene the study area enjoyed a stable climate with vegetation dominated by open biotopes (alpine meadows, steppes, semi-deserts). Its location makes the Fergana Valley an example of a geographically isolated area for a terrestrial fauna which can exist for a long time without being influenced by biotic factors from neighbouring territories.

Comments on ‘Hyaenids, felids and canids as bone accumulators: Does the natural history of extant species support zooarchaeological inferences?’, by Palomares et al. [Quat. Sci. Rev. 284 (2022) 107459

In a recent review paper, Palomares et al. (2022) questioned whether the current behaviour of some carnivorous mammals supports zooarchaeological interpretations of the origin and authorship of certain fossil accumulations in Quaternary sites, concluding that it is questionable. The authors develop classical approach based on actualism to interpret the fossil record but commit some inaccuracies in analogical reasoning, overlook the complexity of taphonomic pathways and the fact that the process of fossil accumulation and assemblage formation is time-dependent. This comment concerns only Lynx pardinus as a taphonomic agent. Based on observations of the fossil record, experimental works in captivity, actualistic work in the wild, and information derived from the current behaviour of the species, I argue that the Iberian lynx should be seriously considered as a relevant taphonomic agent, especially in karstic contexts.

Conserving Quaternary geoheritage in Northern Ireland

Northern Ireland has a rich and varied Quaternary geoheritage. Landforms and sediments from the last glacial phase of the Late Pleistocene are most prevalent, though the record extends from the last interglacial (MIS 5e) to the Holocene. The glacial record in the region continues to play a crucial role in the development of models of the last British-Irish Ice Sheet, with many sites having international significance. It is the role of the Northern Ireland Environment Agency to legally protect and conserve this important Quaternary heritage, and a programme of statutory designation of these sites as Areas of Special Scientific Interest (ASSIs) has been in place for over twenty years. ASSIs are selected from the Pleistocene and Holocene themes of the Earth Science Conservation Review, the process through which geological sites in Northern Ireland are assessed to determine their importance to science, and so to geoconservation. This produced a significant series of reports that have contributed much to the grey and white literature for the Quaternary in the United Kingdom and Ireland. Quaternary geoheritage is recognised in the local planning system and existing and potential UNESCO Global Geoparks further serve to promote and protect this aspect of Northern Ireland's natural heritage. This paper summarises the Quaternary history of Northern Ireland, how ASSIs are selected to reflect this and how they are monitored and managed. It also considers how to ensure continued protection and recognition for Quaternary sites and features in the region.

Structural basis for llama nanobody recognition and neutralization of HIV-1 at the CD4-binding site

Nanobodies can achieve remarkable neutralization of genetically diverse pathogens, including HIV-1. To gain insight into their recognition, we determined crystal structures of four llama nanobodies (J3, A12, C8, and D7), all of which targeted the CD4-binding site, in complex with the HIV-1 envelope (Env) gp120 core, and determined a cryoelectron microscopy (cryo-EM) structure of J3 with the Env trimer. Crystal and cryo-EM structures of J3 complexes revealed this nanobody to mimic binding to the prefusion-closed trimer for the primary site of CD4 recognition as well as a secondary quaternary site. In contrast, crystal structures of A12, C8, and D7 with gp120 revealed epitopes that included portions of the gp120 inner domain, inaccessible on the prefusion-closed trimer. Overall, these structures explain the broad and potent neutralization of J3 and limited neutralization of A12, C8, and D7, which utilized binding modes incompatible with the neutralization-targeted prefusion-closed conformation of Env.

The Need for Protecting, Promoting, and Managing a Quaternary Geoheritage Site: Bahluieț Valley at Costești Village (Moldavian Plateau, North-Eastern Romania)

The Bahluieț Valley at Costești village geosite has recently been studied and proposed as a geoheritage site. Previous investigations of the study area were focused on the Costești-Cier archaeological site, which is currently integrated into the National Archaeological Repertoire. In this archaeological site, different levels of populations have been studied (Eneolithic Cucuteni A, Cucuteni AB, and Horodiștea-Erbiceni Culture populations) as well as an earth wall from La Tene (8th‒10th/eleventh century BC) and a 15th‒seventeenth century AD necropolis. In the area of the present-day Costești village, Bahluieț River leaves the Suceava Plateau area (with altitudes of 350‒550 m a.s.l.) and enters the Jijia Hills (with altitudes of 50 to 200 m a.s.l.), flowing between Ulmiș Hill (306 m a.s.l., at north) and Ruginii Hill (326 m a.s.l., at the south). This valley, which is incised more than 100 m below the plateau level, suddenly becomes broader because of massive Late Pleistocene landslides that covered the former Bahluieț river floodplain and are now fossilized by fluvial deposits. During the Holocene, river incision detached paleochannels and fluvial terraces, while the landslides reactivated through retrogressive mechanisms, creating a complex landslide. A cut-off meander island hosts the Costești-Cier archaeological site, which is currently being actively eroded by the river. In the riverbank of this island, a multi-layered stratigraphy can be seen, consisting of landslide and fluvial deposits, palaeosols, and archaeological remains. The layered deposits, the complex landslide, and the fluvial processes have the potential to become one of the most representative Quaternary sites of the Moldavian Plateau and Romania. By using geomorphosite assessment, geomorphological mapping, optically stimulated luminescence dating, and concepts of geoconservation, I show (i) the importance of the geosite due to the presence of the oldest dated fossil landslide in Romania and to the landslide-fluvial-archaeological relations and (ii) the need for protection at local, regional, and national levels considering the active processes that affect the site. I propose a geoconservation strategy for management and promotion of the geoheritage site.

Highly efficient tree search algorithm for irreducible site-occupancy configurations

We present a universal and extremely efficient tree search algorithm for irreducible site-occupancy configurations (implemented in disorder code) that partially avoids the barrier from the combinatorial explosion and allows us to model the compositionally complex materials. The tree search algorithm is developed based on our original algorithm and is leveraging the idea of stopping descending further down the branches of the tree that do not meet the requirements. Meanwhile, the wrongly counted degeneracies of the irreducible site-occupancy configurations, caused by the skipping of some branches of the tree, can be corrected by a degeneracy correction procedure. Using binary face-centered cubic alloys, ternary body-centered cubic alloys, and quaternary simple cubic alloys as examples, we demonstrate that, compared with our original algorithm, the overall efficiency of the tree search algorithm is improved by more than 2 times for binary site occupancy, 70 times for ternary site occupancy, and 50 times for quaternary site occupancy, which is far beyond other similar algorithms. The tree search algorithm developed here can be broadly useful for the modeling of high-entropy alloys and provides support for other methods, such as special quasirandom structures and small set of ordered structures, that require enumerating a set of site-occupancy configurations.

Abstract 11543: Assessing Reporting of Low-Gradient Severe Aortic Stenosis Based on Race and Ethnicity: Observations from a Large Academic Health System

Introduction: Though low-gradient (LG) aortic stenosis (AS) is common and frequently reported as non-severe on transthoracic echocardiogram (TTE) in real world practice, the association of race and ethnicity with LG AS type and reported severity is not well understood. Methods: We identified all adults ≥ 18 years old from 9/2015-11/2019 with AS, aortic valve area < 1.0cm 2 , and mean gradient <40mmHg on TTE within a large academic health system. We determined frequency of LG AS type (classical low-flow LG [CLFLG], paradoxical low-flow LG [PLFLG], and normal-flow LG [NFLG]) by race and ethnicity. We assessed whether race and ethnicity were associated with reporting severe-range AS on TTE using multivariable logistic regression accounting for age, sex, body mass index, mean gradient, aortic valve area, AS type, and quaternary vs. non-quaternary TTE site. Results: Among 2740 adults with LG AS, 92.4% were white, 4.3% were black, and 3.7% were Hispanic. PLFLG AS was the most common LG AS type among white and black patients and the least common among Hispanic patients (Figure). Among those with PLFLG AS, black patients had the highest proportion of TTEs reported as severe-range AS, while Hispanic patients had the lowest; there were no differences in reporting for CLFLG or NFLG AS (Figure). After multivariable adjustment, there were no significant differences in reporting severe-range AS based on black race (adjusted OR 1.63, 95% CI 0.95-2.82) or Hispanic ethnicity (adjusted OR 1.05, 95% 0.39-2.75) compared to white patients. Quaternary site was a strong independent predictor of reporting severe-range AS (adjusted OR 4.97, 95% CI 3.81-6.54). Conclusions: There are race- and ethnicity-based differences in frequency of LG AS type, and in reporting severe AS on TTE for PLFLG AS in particular. Differences in reporting for PLFLG AS are attenuated after accounting for factors such as TTE site. Additional factors influencing reporting of LG AS in real-world practice should be investigated.

Abstract 11588: Variation in Reader-Reported Severity of Paradoxical Low-Flow Low Gradient Aortic Stenosis: Observations from AaLarge Academic Health System

Introduction: Paradoxical low-flow low-gradient (PLFLG) aortic stenosis (AS) is frequently reported as non-severe AS on transthoracic echocardiogram (TTE) in clinical practice. It is uncertain how reader characteristics are associated with reporting of AS severity in patients with PLFLG AS. Methods: We identified all adults ≥ 18 years old from 9/2015-11/2019 with PLFLG AS on TTE within a large academic health system, and included only readers with ≥10 TTEs in this cohort. We determined the proportion of TTEs reported as either severe or moderate-severe and non-severe, and evaluated differences in reporting based on years of experience, volume of PLFLG AS studies interpreted per year, and quaternary vs. non-quaternary care site. We performed unadjusted and adjusted analyses using multivariable logistic regression. Results: Among 1329 patients meeting TTE criteria for PLFLG AS, only 37.3% were reported as severe/moderate-severe AS. Among 53 readers, the median proportion of patients reported as having severe/moderate-severe AS was 31.6% (25 th -75 th percentile 20.0%-50.0%, range 0.0-91.7%). There were differences in reporting between quartiles based on reader years of experience (33.3-40.9% across Q1-Q4 for proportion of patients reported with severe/moderate-severe AS; p = 0.01) but not volume (34.3-43.1% across Q1-Q4; p = 0.10). Quaternary care readers reported severe/moderate-severe AS for a much higher proportion of patients than non-quaternary care readers (64.3% [reader median 55.2%] vs. 30.9% [reader median 27.3%]; p < 0.001) (Figure), and this was the strongest reader-associated predictor of reporting severe-range AS (adjusted OR 7.6, 95% CI 5.1-11.5). Conclusions: Among patients with PLFLG AS, quaternary care TTE readers report severe AS much more commonly than non-quaternary care readers. Greater focus on TTE reporting of PLFLG AS at non-quaternary sites is likely needed to address underreporting of severe AS in this population.

Bird remains from the Middle Paleolithic levels (MIS3) of Llonin Cave (Peñamellera Alta, Asturias, Spain)

Birds are abundant in fossil assemblages of Quaternary sites; they can be used in landscape recon­struction as they are well adapted to the environment. Here we present the analysis of the avian assemblage from the Middle Paleolithic levels of the Llonin Cave, where 558 bird remains have been recovered from levels G-VI and CP-VIII, belonging to at least ten different taxa: Aves indet., Galliformes indet., Lagopus lagopus Linnaeus, 1758, Tetrastes bonasia Linnaeus, 1758, Columba livia/oenas Gmelin, 1789/Linnaeus, 1758, Passeriformes indet., Alaudidae indet., Motacilla sp., Turdus sp., Corvidae indet., Garrulus glandarius Linnaeus, 1758, Pyrrhocorax sp., Pyrrhocorax pyrrhocorax Linnaeus, 1758, Pyrrhocorax graculus Linnaeus, 1766 and Corvus corax Linnaeus, 1758. This assemblage is similar to other assemblages from the Upper Pleistocene of the north of the Iberian Peninsula, and it reflects a mixed landscape, with open areas and woodland. The taphonomic analysis points to a mixed origin of the accumulation, mainly formed by medium-sized corvids dying in the cave, and also raptors accumulating their prey.

Bimolecular Coupling in Olefin Metathesis: Correlating Structure and Decomposition for Leading and Emerging Ruthenium-Carbene Catalysts.

Bimolecular catalyst decomposition is a fundamental, long-standing challenge in olefin metathesis. Emerging ruthenium–cyclic(alkyl)(amino)carbene (CAAC) catalysts, which enable breakthrough advances in productivity and general robustness, are now known to be extraordinarily susceptible to this pathway. The details of the process, however, have hitherto been obscure. The present study provides the first detailed mechanistic insights into the steric and electronic factors that govern bimolecular decomposition. Described is a combined experimental and theoretical study that probes decomposition of the key active species, RuCl2(L)(py)(=CH2) 1 (in which L is the N-heterocyclic carbene (NHC) H2IMes, or a CAAC ligand: the latter vary in the NAr group (NMes, N-2,6-Et2C6H3, or N-2-Me,6-iPrC6H3) and the substituents on the quaternary site flanking the carbene carbon (i.e., CMe2 or CMePh)). The transiently stabilized pyridine adducts 1 were isolated by cryogenic synthesis of the metallacyclobutanes, addition of pyridine, and precipitation. All are shown to decompose via second-order kinetics at −10 °C. The most vulnerable CAAC species, however, decompose more than 1000-fold faster than the H2IMes analogue. Computational studies reveal that the key factor underlying accelerated decomposition of the CAAC derivatives is their stronger trans influence, which weakens the Ru−py bond and increases the transient concentration of the 14-electron methylidene species, RuCl2(L)(=CH2) 2. Fast catalyst initiation, a major design goal in olefin metathesis, thus has the negative consequence of accelerating decomposition. Inhibiting bimolecular decomposition offers major opportunities to transform catalyst productivity and utility, and to realize the outstanding promise of olefin metathesis.

Reassessment of the ‘Abbevillien’ in the perspective of new discoveries from the Lower Palaeolithic and Quaternary sites of Abbeville (Somme, northern France)

ABSTRACTNorth‐West Europe yields few traces of early human occupation, in particular for the Acheulean. In this context, the Somme Valley in northern France offers a route to Britain during various Pleistocene low sea levels, and has provided numerous evidence of Lower Palaeolithic human occupation through fieldwork initiated during the 19th century. These localities are associated with the original definition in the 1930s by the French prehistorian Abbé Henri Breuil of the ‘Abbevillien’ (Abbevillian facies), based on lithic pieces including crudely made bifaces recovered in particular in some famous key localities of Abbeville, Carpentier, Léon and Moulin Quignon quarries. The history of the term and its definition subsequently gave rise to debates concerning the chronocultural framework of Palaeolithic assemblages among the scientific community of prehistorians over time, from Jacques Boucher de Perthes, Gabriel de Mortillet, Geoffroy d'Ault du Mesnil, Victor Commont, Henri Breuil and François Bordes. New investigations at these three localities, all associated with the High Terrace of the Somme system, pushed back the age of the expansion of the Acheulean both in northern France and in Western Europe to c. 670–650 000 years. They imply that early hominins were able to settle in North‐West Europe during both climatic temperate and cold phases. Our work, including new excavations and associated field observations of the three Abbeville localities involved at the onset of the controversy, allows a re‐examination of the Abbevillian and contributes to the discussion of the history of Prehistoric Science and the Earliest ‘Acheuleans’ in North‐West Europe.

The European palaeoecological record of Swedish red-listed beetles

Recent global changes have triggered a biodiversity crisis. However, climate fluctuations have always influenced biodiversity and humans have affected species distributions since prehistoric times. Conservation palaeobiology is a developing field that aims to understand the long-term dynamics of such interactions by studying the geohistorical records in a conservation perspective. Case studies exist for vertebrates and plants, but insects have largely been overlooked so far. Here, we analysed the current red-listed beetle species (Coleoptera) in Sweden and investigated their occurrence and representation in the European Quaternary fossil record. Fossil data currently exist for one third of the Swedish red-listed beetle species. All the red-list conservation classes are represented in the fossil record, which may allow for comparative studies. We found significantly different representations in the fossil records among taxonomic groups and ecological traits, which may depend on the fossil depositional and sampling environments and variation in how difficult species are to identify. Species that are today associated with modern urban environments were mostly found in Quaternary sites with archaeological human settlements, reflecting early human-driven environmental change. Combining modern and fossil insect species data for biodiversity conservation needs to be undertaken with care, and attention paid to biases in both modern and palaeo-data. Nevertheless, this approach opens new opportunities for conservation biology by providing a millennial-scale perspective on biodiversity change, including consideration of the long-term dynamics of species range shifts, species invasions and regional extinctions under changing climates.

Late Quaternary megafaunal extinctions in India: How much do we know?

Understanding global patterns of late Quaternary megafaunal extinction is impeded by geographic variation in data quality and quantity. The magnitude, timing and drivers of megafaunal extinctions remain poorly understood for India, a region with a strong history of palaeontological research. We review available data for all putative extinct Indian megafaunal taxa with direct or indirect reported evidence of potential survival into the global “megafaunal extinction window” (from ∼50,000 years onwards). Assessment of late Quaternary megafaunal species richness is confused by multiple levels of taxonomic uncertainty, including the relationship of named Late Pleistocene taxa to extant taxa, and nomenclatural confusion over correct species names. There is sufficient evidence to recognise up to four genuine global megafaunal species-level extinctions in India during the Late Pleistocene: two proboscideans (Palaeoloxodon namadicus, Stegodon sp.), a hippopotamus (Hexaprotodon sp.), and possibly a horse (Equus namadicus). A fifth extinct megafaunal species, the Indian aurochs Bos [primigenius] namadicus, definitely persisted into the Holocene. Other Indian late Quaternary megafaunal species (Rhinoceros spp., Bubalus palaeindicus, Sus “palaeindicus”, Crocodylus palaeindicus) are likely to be synonyms of extant species. Reconstructing regional extinction dynamics is further impeded by chronological uncertainty; however, attempts to obtain new dates for vertebrate samples from six late Quaternary sites in five regions were unsuccessful. Accurate understanding of the dynamics of megafaunal extinctions in India will require robust taxonomic, chronological and palaeoecological data, and we encourage further investigation of the region’s rich late Quaternary record.

Impact of Chain Length on Release Behavior of Modified Polyethylene Glycol Intercalated-Montmorillonite Nanocomposite.

A new drug delivery nanocomposite system was prepared from sodium montmorillonite (Na+Mt) intercalated with modified polyethylene glycol (PEG). PEGs of different molecular weights (400, 4000, and 8000) were modified with glycidyltrimethylammonium chloride (GTMAC) to provide terminal quaternary ammonium sites capable for attaching with Mt or other materials through ion exchange. The modified PEG-GTMAC derivatives were reacted in excess amount with Na+Mt through ion exchange. The remaining quaternary sites were used for the attachment of sodium diclofenac as a model drug. The structures of the prepared clay-modified PEG-diclofenac systems were characterized using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The release behavior of diclofenac from the different nanocomposites was studied at different pH values. With regard to the PEG chain length, the drug release increased with increasing PEG molecular weight (GCDIII > GCD-III > GCDII > GCDI). The kinetics of the release models was discussed using Korsmeyer-Peppas, Higuchi, and zero- and first-order models. The results of the kinetics study revealed that modified samples with PEG 400 and PEG 4000 (GCD-I and GCDII) exhibited non-Fickian diffusion (anomalous transport) while modified samples with PEG 8000 (GCDIII) exhibited super case-II transport.

Rapid size change associated with intra-island evolutionary radiation in extinct Caribbean \u201cisland-shrews\u201d

BackgroundThe Caribbean offers a unique opportunity to study evolutionary dynamics in insular mammals. However, the recent extinction of most Caribbean non-volant mammals has obstructed evolutionary studies, and poor DNA preservation associated with tropical environments means that very few ancient DNA sequences are available for extinct vertebrates known from the region’s Holocene subfossil record. The endemic Caribbean eulipotyphlan family Nesophontidae (“island-shrews”) became extinct ~ 500 years ago, and the taxonomic validity of many Nesophontes species and their wider evolutionary dynamics remain unclear. Here we use both morphometric and palaeogenomic methods to clarify the status and evolutionary history of Nesophontes species from Hispaniola, the second-largest Caribbean island.ResultsPrincipal component analysis of 65 Nesophontes mandibles from late Quaternary fossil sites across Hispaniola identified three non-overlapping morphometric clusters, providing statistical support for the existence of three size-differentiated Hispaniolan Nesophontes species. We were also able to extract and sequence ancient DNA from a ~ 750-year-old specimen of Nesophontes zamicrus, the smallest non-volant Caribbean mammal, including a whole-mitochondrial genome and partial nuclear genes. Nesophontes paramicrus (39-47 g) and N. zamicrus (~ 10 g) diverged recently during the Middle Pleistocene (mean estimated divergence = 0.699 Ma), comparable to the youngest species splits in Eulipotyphla and other mammal groups. Pairwise genetic distance values for N. paramicrus and N. zamicrus based on mitochondrial and nuclear genes are low, but fall within the range of comparative pairwise data for extant eulipotyphlan species-pairs.ConclusionsOur combined morphometric and palaeogenomic analyses provide evidence for multiple co-occurring species and rapid body size evolution in Hispaniolan Nesophontes, in contrast to patterns of genetic and morphometric differentiation seen in Hispaniola’s extant non-volant land mammals. Different components of Hispaniola’s mammal fauna have therefore exhibited drastically different rates of morphological evolution. Morphological evolution in Nesophontes is also rapid compared to patterns across the Eulipotyphla, and our study provides an important new example of rapid body size change in a small-bodied insular vertebrate lineage. The Caribbean was a hotspot for evolutionary diversification as well as preserving ancient biodiversity, and studying the surviving representatives of its mammal fauna is insufficient to reveal the evolutionary patterns and processes that generated regional diversity.

A mitogenome sequence of an Equus hydruntinus specimen from Late Quaternary site of San Teodoro Cave (Sicily, Italy)

Equus hydruntinus was a small equid that ranged from the Iberian Peninsula to Middle East. In Italy it has been considered present from the Middle Pleistocene to its extinction in the Middle-Late Holocene. E. hydruntinus shares plesiomorphic traits with other known Pleistocene equids. As a consequence, its classification has always been problematic. Genetic analyses on few fossil remains from Iran and Crimea have revealed that E. hydruntinus was more closely related to extant hemiones. To further investigate its systematic position, using target-enrichment capture and next-generation sequencing, we reconstructed a near complete mitogenome of a specimen from San Teodoro Cave from Sicily radiocarbon dated at 23-21 ka cal. BP. Comparisons with extant and extinct equids demonstrate close relationship between this specimen and the Asian wild asses, supporting previous genetic and morphological studies. Furthermore, our findings confirm the occurrence of E. hydruntinus species in Sicily, that presumably might have represented a typical glacial refugium during the LGM.