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The Guadix-Baza Basin (GBB) in Andalucía, Spain, comprises palaeontological and archaeological sites dating from the Early Pliocene to the Middle Pleistocene, including some of the earliest sites with evidence for the presence of early humans (Homo sp.) in Europe. Thus, the history of climate and environments in this basin contributes significantly to our understanding of the conditions under which early humans spread into Europe during the Early Pleistocene. Here we present estimates of precipitation and primary productivity in the GBB from the Pliocene to the Middle Pleistocene based on dental ecometrics in fossil communities of large herbivorous mammals, and perform an ecometrics-based distribution modelling to analyse the environmental conditions of Early and Middle Pleistocene human sites in Europe. Our results show that Early Pleistocene humans generally occupied on average relatively diverse habitats with ecotones, such as woodlands and savannas, but avoided very open and harsh (cool or dry) environments. During the Middle Pleistocene in Europe, humans occupied a comparatively much broader range of environments than during the Early Pleistocene, but were on average more concentrated in environments where the dental ecometric of mammals indicate wooded palaeoenvironments. In the earliest human occupation sites of the GBB, Barranco Leon and Fuente Nueva 3, the mean annual precipitation and net primary production estimates indicate climatic conditions close to modern Mediterranean sclerophyllous woodland environments, but with slightly higher primary productivity,indicating some similarity with East African woodlands. On the other hand, the environments did not resemble African grassland savannas. The browse-dominated diets of ungulates from Barranco Leon and Fuente Nueva 3 further suggest palaeoenvironments where grasses were a minor component of the vegetation. In the slightly older site of Venta Micena that has no evidence for the presence of hominins, dental ecometric estimates indicate climate and environments similar to Mediterranean “forest steppe” environments existing in the surroundings of Baza today. Grasses were prevalent in the diet of some taxa, especially equids, in Venta Micena, but most of the species show browse-dominated diets even there.

Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil data, rigorous attempts to identify this phenomenon in the fossil record are largely uncommon. Here I focus on direct evidence of the diet (through tooth-wear patterns) and ecologically-relevant traits of one of the most renowned fossil vertebrates-the Miocene ruminant Hoplitomeryx from the island of Gargano-to deepen our understanding of the most likely causal forces under which adaptive radiations emerge on islands. Results show how accelerated accumulation of species and early-bursts of ecological diversification occur after invading an island, and provide insights on the interplay between diet and demographic (population-density), ecological (competition/food requirements) and abiotic (climate-instability) factors, identified as drivers of adaptive diversification. A pronounced event of overpopulation and a phase of aridity determined most of the rate and magnitude of radiation, and pushed species to expand diets from soft-leafy foods to tougher-harder items. Unexpectedly, results show that herbivorous mammals are restricted to browsing habits on small-islands, even if bursts of ecological diversification and dietary divergence occur. This study deepens our understanding of the mechanisms promoting adaptive radiations, and forces us to reevaluate the role of diet in the origins and evolution of islands mammals.

Background The two main primate groups recorded throughout the European Miocene, hominoids and pliopithecoids, seldom co-occur. Due to both their rarity and insufficiently understood palaeoecology, it is currently unclear whether the infrequent co-occurrence of these groups is due to sampling bias or reflects different ecological preferences. Here we rely on the densely sampled primate-bearing sequence of Abocador de Can Mata (ACM) in Spain to test whether turnovers in primate assemblages are correlated with palaeoenvironmental changes. We reconstruct dietary evolution through time (ca. 12.6–11.4 Ma), and hence climate and habitat, using tooth-wear patterns and carbon and oxygen isotope compositions of enamel of the ubiquitous musk-deer Micromeryx. Results Our results reveal that primate species composition is strongly correlated with distinct environmental phases. Large-bodied hominoids (dryopithecines) are recorded in humid, densely-forested environments on the lowermost portion of the ACM sequence. In contrast, pliopithecoids inhabited less humid, patchy ecosystems, being replaced by dryopithecines and the small-bodied Pliobates toward the top of the series in gallery forests embedded in mosaic environments. Conclusions These results support the view that pliopithecoid primates preferred less humid habitats than hominoids, and reveal that differences in behavioural ecology were the main factor underpinning their rare co-occurrence during the European Miocene. Our findings further support that ACM hominoids, like Miocene apes as a whole, inhabited more seasonal environments than extant apes. Finally, this study highlights the importance of high-resolution, local investigations to complement larger-scale analyses and illustrates that continuous and densely sampled fossiliferous sequences are essential for deciphering the complex interplay between biotic and abiotic factors that shaped past diversity.

Climatic oscillations at the Gelasian/Calabrian transition modified terrestrial palaeoenvironmental settings in the European region. A gradual drop in global temperatures beginning about 2.7 Ma led to drier conditions and to a reduction in, and subsequent disappearance of, sub-tropical vegetation in the central Mediterranean area by ca 1.2 Ma. Large ungulates are sensitive to vegetation changes and faced with harsher environmental settings may shift their feeding strategies to exploit available food resources in different ecosystems. In fossil assemblages such dietary adaptations are reflected by tooth morphology (a phylogenetic signal) and tooth wear degree (a direct signal of the species' diet). In this paper, we investigate how large herbivores responded to palaeoenvironmental changes that occurred at the passage between the Gelasian and Calabrian ages in the Italian Peninsula, analysing the dental wear patterns and hypsodonty of the early Pleistocene fossil ungulates assemblage of Olivola (Aulla, Central Italy). We found that while ungulate feeding behaviours during the Gelasian spanned from browsers to grazers, in the locality of Olivola this group of herbivores display a narrower range of diet types with many taxa adopting a mixed feeding behaviour. Cervids in particular, whose fossils are often associated only with wooded environments, as a response to the reduction of covered sub-tropical vegetation, shifted from a strict browsing diet in mostly closed habitats to a more abrasive one taking advantage of the spread of open landscapes. We also provide new data on the feeding behaviour of the rare fossil caprines, Procamptoceras and Gallogoral meneghinii, suggesting a grass-rich mixed diet for the former and a certain degree of dietary plasticity for the latter. Our research thus contributes to the better understanding of how ungulates adapted in the past to exploit different resource types during pivotal climatic changes and how environments changed in Central Italy on the onset of colder and more arid conditions.

Resource competition and niche partitioning among the exceptionally high number of sympatric ungulates of the Early Pleistocene site of Coste San Giacomo (Central Italy) is here examined through the study of their dietary proclivities and body size. The main aim of this study is to investigate the niche differentiation mechanisms that let the fossil ungulates coexist in the same region. We also provide information about the complementarity of two different methodologies that observe diet variation at a different time scales (inner and outer mesowear) in the study of dental wear patterns of fossil ungulates. Results from analyses of dental wear degree and body masses predictions show that a wide range of feeding behaviours were adopted by the taxonomical groups (i.e., cervids, bovids and equids) in order to avoid competition. Among larger ungulates diet ranges from strict browsing (Eucladoceros sp., Gazellospira torticornis), to mixed feeding (Gallogoral meneghinii, Leptobos sp.) to pure grazing (Equus stenonis), whereas smaller taxa are more selective feeders (Axis cf. lyra, Croizetoceros cf. ramosus) with only one exception (Gazella borbonica). When taxa with the same feeding behaviour occurred in the same habitat, competition was minimised by differences in body size.

Mastication of dietary items with different mechanical properties leaves distinctive microscopic marks on the surface of tooth enamel. The inspection of such marks (dental microwear analysis) is informative about the dietary habitus in fossil as well as in modern species. Dental microwear analysis relies on the morphology, abundance, direction, and distribution of these microscopic marks. We present a new freely available software implementation, MicroWeaR, that, compared to traditional dental microwear tools, allows more rapid, observer error free, and inexpensive quantification and classification of all the microscopic marks (also including for the first time different subtypes of scars). Classification parameters and graphical rendering of the output are fully settable by the user. MicroWeaR includes functions to (a) sample the marks, (b) classify features into categories as pits or scratches and then into their respective subcategories (large pits, coarse scratches, etc.), (c) generate an output table with summary information, and (d) obtain a visual surface-map where marks are highlighted. We provide a tutorial to reproduce the steps required to perform microwear analysis and to test tool functionalities. Then, we present two case studies to illustrate how MicroWeaR works. The first regards a Miocene great ape obtained from through environmental scanning electron microscope, and other a Pleistocene cervid acquired by a stereomicroscope. © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

The Middle Pleistocene site of Fontana Ranuccio (Anagni Basin, Central Italy) has yielded nearly 25,000 remains belonging to large and small vertebrates, including four isolated teeth of Homo sp., and a rich lithic assemblage containing bone tools. Here we provide new dental wear analyses of the ungulate community to improve the palaeoenvironmental reconstruction for the site. Analyses indicate a mostly browsing diet for the cervids and a grazing diet for the perissodactyls Stephanorhinus sp. and Equus cf. E. mosbachensis, suggesting a range of habitats that spanned from forests to open grasslands. A discrepancy between mesowear and microwear results is observed in the case of the bovid, Bos primigenius; this can be tentatively explained as resulting from a temporal switch towards a sub-optimal diet, possibly reflecting the effects of marked seasonality. Findings shed new light on the structure of the 400 kyr ecosystems that existed during the early occupation of Homo in Europe.

Quaternary glacial/interglacial alternations, influenced by orbital obliquity cycles with a 41-ka long periodicity, started in the northern hemisphere around 2.6 Ma ago. Such alternations affected the terrestrial ecosystems, especially those of the Mediterranean region, with changes in the floristic communities and the dispersal and radiation of a number of large mammal open dwellers. Analyses of tooth wear patterns of ungulates from the Early Pleistocene site of Coste San Giacomo allow for a more objective reconstruction on the paleoenvironments and the climate in the Italian Peninsula during this epoch. Our results show that this area was composed by a mosaic of biomes, in particular by steppe and woodlands/wetlands. Evidence of such heterogeneity is provided by the wide spectrum of feeding behaviours found among the numerous ungulate herbivores here recorded, with cervids (Axis cf. lyra, Croizetoceros cf. ramosus and Eucladoceros sp.) exhibiting browser diets, most of the bovids (Gazella borbonica and Leptobos sp. and Gallogoral meneghinii) being intermediate feeders and the equid Equus stenonis showing a strict grazer behaviour. These results provide new insights for a timing of changing ecosystems in Southern Europe and reveal the environmental legacy of this global climatic shift, which is essential for understanding the early occupation of Homo in Europe. Thus, our data provide new evidence that such an environmental heterogeneity and a wide spectrum of available food resources could have been the main factors favouring the settlement of early species of Homo in this area.

Despite its long history of scientific study, the causes underlying the extinction of the insular hominoid Oreopithecus bambolii are still a matter of ongoing debate. While some authors consider intense tectonism and invading species the cause of its extinction ca. 6.7 Ma, others propose climatic change as the main contributing factor. We rely on long-term patterns of tooth wear and hypsodonty of the Baccinello and Fiume Santo herbivore-faunas to reconstruct changes in habitat prior to, during and after the extinction. While a mosaic of habitats was represented in Baccinello V1 (as shown by a record of browsers, mixed feeders and species engaged in grazing), more closed forests (higher proportion of browsers, shortage of mixed feeders and lack of grazers) characterised Baccinello V2. Finally, there was a partial loss of canopy cover and development of open-patches and low-abrasive grasses in Baccinello V3 (as denoted by new records of taxa involved in grazing)—although still dominated by a forested habitat (since browse was a component in all diets). Our results provide evidence for two perceptible shifts in climate, one between 8.1 and 7.1 Ma and other ca. 6.7 Ma, though this latter was not drastic enough to lead to intensive forest loss, substantially alter the local vegetation or affect Oreopithecus lifestyle—especially if considering the growing evidence of its versatile diet. Although the disappearance of Oreopithecus is complex, our data reject the hypothesis of environmental change as the main factor in the extinction of Oreopithecus and Maremma fauna. When our results are analysed together with other evidence, faunal interaction and predation by invading species from mainland Europe seems to be the most parsimonious explanation for this extinction event. This contrasts with European hominoid extinctions that were associated with major climatic shifts that led to environmental uniformity and restriction of the preferred habitats of Miocene apes.

The mammalian fossil record of Spain is long and taxonomically well resolved, offering the most complete record of faunal change for the Neogene of Europe. We evaluated changes in diversification, composition, trophic structure, and size structure of large mammals over the middle and late Miocene with methods applied to this record for the first time, including ordination of fossil localities to improve temporal resolution and estimation of confidence intervals on taxa temporal ranges. By contrast, analysis within the traditional Mammal Neogene (MN) biochronology obscures important aspects of diversification. We used inferred temporal ranges of species and evaluated per capita rates of origination, extinction, diversification, and turnover over 0.5-Myr time intervals.Three periods of significant faunal change occurred between 12.0 and 5.5 Ma: (1) From 12.0 to 10.5 Ma, elevated origination rates led to an increase in diversity without significant change in ecological structure. Immigrants and geographic-range shifts of species to lower latitudes during an interval of global cooling contributed to these faunal changes. (2) From 9.5 to 7.5 Ma, high extinction rates followed by high origination rates coincided with significant changes in taxonomic composition and ecological structure. These changes represent the Vallesian Crisis, with replacement of a fauna of forest affinities (with frugivores and browsers) by a fauna of open woodlands (with grazers and mixed feeders). (3) From 6.5 to 5.5 Ma, high extinction rates reduced diversity without substantial changes in ecological structure, and large mammal faunas became highly endemic across the northern Mediterranean region. This interval includes the Messinian Salinity Crisis, the desiccation of the Mediterranean basin. Extinction may have been caused by geographic isolation and aridification, with evolution of endemic lineages giving rise to new species in the early Pliocene. These distinct macroevolutionary patterns of faunal change correspond to different geographic scales of inferred climatic and tectonic drivers.

Pliopithecinae and Crouzeliinae (Primates: Pliopithecidae) are distinguished dentally by the sharper crests, more compressed cusps, larger foveae, and narrower molars of the latter. Traditionally, such differences were qualitatively related to increased folivory in crouzeliines. This was subsequently disproved by microwear and shearing crest analyses, indicating that all pliopithecids were soft-fruit eaters, except for the more folivorous crouzeliine Barberapithecus. This seems however at odds with the occlusal morphology of the latter, intermediate between those of Pliopithecus and the more derived crouzeliine Anapithecus. To further assess dietary evolution in this group, we report results of dental microwear for two Iberian pliopithecids: Pliopithecus canmatensis, from several Abocador de Can Mata localities (11.8–11.7 Ma, MN8), and Barberapithecus huerzeleri from Castell de Barbera (ca. 11.2–10.5 Ma, MN8, or MN9). Contrary to previously published results, our analyses suggest that all pliopithecids, including Barberapithecus, had a frugivorous diet with a significant sclerocarpic component—apparently more marked in some pliopithecines (such as P. canmatensis) than in the crouzeliine Anapithecus. If our interpretation is correct, it would mean that, within the framework of a frugivorous diet with some hard-object feeding, crouzeliine dental evolution would have been driven by selection pressures towards increased soft-fruit consumption instead of folivory. Dental differences between pliopithecids and hominoids with a significant sclerocarpic component (i.e., orangutans) might be related to phylogenetic constraints, different food-processing methods and/or fracture toughness of hard foods consumed. Although additional research would be required, results suggest that dietary niche partitioning played a significant role in the radiation of European pliopithecids. Am J Phys Anthropol 151:573–582, 2013. © 2013 Wiley Periodicals, Inc.

Mammals of numerous lineages have evolved high‐crowned (hypsodont) teeth particularly during the last 20 million years. This major phenotypic change is one of the most widely studied evolutionary phenomena in a broad range of disciplines, though the mechanisms underlying its transformation remain unresolved. Here, we present the first Finite Element Analysis (FEA) to investigate the alternative hypothesis that there is a biomechanical link between increased hypsodonty and a more effective mastication in deer. Our FE experiments compared patterns of stress and strain within and between different fossil and living species under different loading conditions, and found that more hypsodont teeth are suited for restricting stresses to those areas where chewing loading occurs. This mechanical improvement is consequence of specific and pronounced variations in tooth geometry and morphology of the occlusal surface that are strongly related to crown growth in the vertical plane. We demonstrate that hypsodonty enables selenodont‐teeth to adopt a mechanically improved design that increases the pressure whilst shearing foods. As ruminants are physiologically limited by both the quantity of food consumed and the time spent in the mastication and digestion, hypsodonty is highly advantageous when feeding on mechanically resistant, tough and fibrous foods. Consequently, it allows grass‐eaters to spend less time chewing, thereby increasing the volume of food ingested and/or providing more time for digestion. This study provides a promising line of evidences in support of biomechanical effectiveness, in addition to or instead of increased wear resistance, as a factor in explaining the evolutionary origins of the hypsodont phenotype., his study was funded by the Spanish Ministerio de Economía y Competitividad (projects CGL2010‐216723, CGL2010‐19116 and CGL2011‐25754, and JCI‐2011‐11697 to D.D.M.), the Research Group BSCH‐UCM910607 and the government of Aragón (E05).

Dietary behaviour and competition for resources are investigated for the small-sized ruminants Andegameryx Ginsburg, 1971 and Procervulus Gaudry, 1877 representatives of two largely distinct states of diversification of pecorans. Results obtained from dental microwear and mesowear methodologies are concordant with a mixed feeder strategy for the taxa from the Early Miocene environments of the Iberian Chain (Central Spain). Further, the Spanish taxa investigated had less abrasive diets than their relatives from others similarly aged localities in Europe. This fact raises an important evolutionary uncertainty concerning the traditional characterization of first pecorans as specialized browsers. Instead, data strongly corroborate the recently proposed notion that some Pecora ruminant lineages were able to consume a mixture of browse and grass, and that were originally facultative mixed feeders. However, there is a large degree of variation of their dental wear features. Species were not dependent on...

A combined approach of dental microwear and mesowear was used to characterize the dietary adaptations of Middle Miocene ruminants from central Spain. Using their diets as environmental proxies allows us to reconstruct the environmental and climatic conditions that prevailed in this area during the epoch in which the dispersal of hominoids and pliopithecoids took place in Iberia (Late Aragonian; zones MN6–MN7/8). Constructed feeding of cervids and bovids suggests that, in general, species inhabited dry and seasonal landscapes. However, more browsing and less intermediate signatures are found in MN7/8 compared to MN6. Further, there were less grass-dominated mixed feeders in MN7/8. Dental data (higher densities of pits, lower densities of scratches and lower mesowear scores) strongly suggest the presence of a considerable humid episode and a change in the vegetation in the transition from MN6 to MN7/8, thus suggesting a higher similarity to the areas in which primates occurred than previously expected (Valles–Penedes Basin). Some of the studied localities, such as Toril 3A, point to a mosaic of biomes that provided a range of opportunities for species that depended primarily on browsing. When competition and resource partitioning among ruminants found in Spain is reconstructed, results support the hypothesis that ecologically similar species maintained sympatry by exhibiting a generalistic (mixed) dietary behaviour, and one explanation could be that diets shifted seasonally. Thus, if significant seasonal habits were exhibited, species ate many of the same plant species, but often did so at different times of the year. Instead, if dietary specialization (browsing) was displayed, as occurred in the more humid and with denser tree cover environments such as Toril 3A, taxa may have exploited different plant species of browse material (fruits/seeds versus leaves).

The oldest known Cervidae lineage, Procervulus , is a useful example for understanding the adaptations of mammalian clades to climatic and environmental changes. It appeared in the Lower Miocene (MN3), persisted through the Miocene Climatic Optimum, and became extinct at the onset of the Mid-Miocene general cooling. A combined approach of dental microwear and mesowear is undertaken to reconstruct its feeding behaviour to learn whether and how it responded to new environmental circumstances. None of the Early and Middle Miocene fossil taxa in the Calatayud–Daroca and Rubielos de Mora basins (NE Spain) had a wholly browser or grazer lifestyle, but rather dietary strategies equaling those of extant mixed feeders. However, members of Procervulus were sensitive to changes in the structure of ecosystems and vegetation that occurred during the Middle Miocene, and responded to these by substantially increasing the intake of grasses and abrasives. Despite this, it did not apparently display the sufficiently high trophic flexibility to bring about a change in its feeding style. Two possible, probably interrelated, causes can be pointed out; constraints imposed by both its small body size and its brachydont cheek teeth. If such a change in the feeding style was crucial for its survival, Procervulus disappeared as a consequence of an insufficient response to environmental changes because it may have been unable to compensate for the low nutritional content and abrasiveness of the new food items over a prolonged period. As the last Procervulus and the first bovids in the basin have similar dental wear signals, competition could be another possible explanation for its disappearance. Middle Miocene Procervulus could have been at a clear disadvantage after the advent of Tethytragus , whose teeth present morphologies that suggest better adaptation to grass-eating. Since diets tend to reflect habitats, the wear signals and assignments obtained from the Ramblian and earliest Aragonian cervids are indicative of humid climates and mixed environments, where closed areas were well developed and browse vegetation was abundant. In contrast, data from late Early and Middle Aragonian cervids and bovids reflect dry-seasonal and more open scenarios, with a higher diversity of grasses and abrasives.

Received 19 May 2015, Accepted 15 October 2015, Available online 23 October 2015, Most of the Pleistocene species of Equus from Mexico have been considered to be grazers and highly specialized on the basis of their craniodental features, and therefore analogous to their modern relatives from an ecological point of view. Here we rely on dental wear analyses of three different species of Rancholabrean Equus that exhibit differences in limb proportions and body mass and occurred in two different habitats in order to test whether species exhibited more heterogeneous dietary capabilities compared to modern horses. Overall, and although our analyses show grazer lifestyles, there is a significant degree of dietary variability among taxa according to the site, apparently as a response to differences in climate and environmental conditions, with intermediate feeding preferences on the basis of the last items consumed during the last days prior to death in some cases. Accordingly, fossil Equus might have been more sensitive to different environments and diverse in terms of dietary preferences, thus incorporating a higher proportion of browse vegetation if necessary, than their modern relatives. These results highlight the dietary plasticity of certain fossil species, and evidence the caution that should be paid when reconstructing the ecology of fossil species using their modern relatives as analogs., This work was funded by the Mexican Consejo Nacional de Ciencia y Tecnología CONACYT (ref. 132620 and grant to AHM-L) and the Spanish Ministerio de Economia y Competitividad (JCI-2011-11697 to DDM).

Key innovations are newly acquired structures that permit the performance of a new function and open new adaptive zones, and are, therefore, of paramount significance for understanding the history of the Ruminan tia, particularly its diversification through the Miocene. Here we review and discuss what is known about these evolutionary novelties, with special emphasis on the appearance and evolution of cranial appendages and highcrowned (or hypsodont) teeth. Cranial appendages probably favored the diversification of pecorans by being structures strongly related to sexual selection, whereas the acquisition of hypsodont teeth could have expanded potential dietary breadth and allowed species to extend diets into the grazing range without eliminating browsing as a potential diet. When analyzed in conjunction with patterns of faunal diversity and in the context of climatic changes, it seems that the overall view that ruminant cranial appendages and hypsodonty may have started responding to increased patterns of seasonality and the opening-up of ecosystems is roughly valid. Instead, they occurred through several distinct pulses and varied widely among continents. This review is, to our knowledge, the first to highlight that the evolution of these innovations has been far from constant and uniform through time. Furthermore, we identify that both a first attempt to increase hypsodonty starting in the early Mio cene and a first evolution of antlers and pronghorns were interrupted as a consequence of wide climatic fluctua tions in the early–middle Miocene transition.

Here, we test whether the increase in tooth height in insular endemics results from the expansion of the dietary niche under resource limitation, as widely considered, or whether it represents an investment in dental durability in response to the selection for extended longevity under low levels of extrinsic mortality. We tested these hypotheses in the extremely hypsodont fossil bovid Myotragus balearicus from the Balearic Islands, an ideal model to study the evolutionary trends on islands. Dental abrasion was significantly lower in the insular bovid than in highly hypsodont continental artiodactyls, suggesting that feeding habits are not the sole driving force behind increased crown height. However, the estimated longevity for M. balearicus based on dental durability was two times that predicted from body mass. Survivorship curves confirm that an extraordinarily large number of individuals approached the longevity of the species. Our results, hence, provide evidence that hypsodonty in insular endemics is the outcome of selection for increased durability of the permanent dentition in association with an extended lifespan. In the context of insularity, our results lend additional support to the disposable soma theory of ageing confirming the dependency of somatic maintenance and repair on lifespan, and its control by resource availability and extrinsic mortality.

Integration between phylogenetic systematics and paleontological data has proved to be an effective method for identifying periods that lack fossil evidence in the evolutionary history of clades. In this study we aim to analyze whether there is any correlation between various ecomorphological variables and the duration of these underrepresented portions of lineages, which we call ghost lineages for simplicity, in ruminants. Analyses within phylogenetic (Generalized Estimating Equations) and non-phylogenetic (ANOVAs and Pearson correlations) frameworks were performed on the whole phylogeny of this suborder of Cetartiodactyla (Mammalia). This is the first time ghost lineages are focused in this way. To test the robustness of our data, we compared the magnitude of ghost lineages among different continents and among phylogenies pruned at different ages (4, 8, 12, 16, and 20 Ma). Differences in mean ghost lineage were not significantly related to either geographic or temporal factors. Our results indicate that the proportion of the known fossil record in ruminants appears to be influenced by the preservation potential of the bone remains in different environments. Furthermore, large geographical ranges of species increase the likelihood of preservation., The authors also thank the Unit of Information Resources for Research (URICI-CSIC) for the co-financing of this publication in Open Access.

In a recent paper, Eronen et al. (2010; hereafter EEFJ) observe differences in occlusal morphology, tooth crown height, and mesowear pattern between populations of the Miocene tridactyl equid Anchitherium from Spain and Germany, proposing that Spanish Anchitherium underwent adaptive evolution to local or regional arid conditions. However, these authors do not take into account the actual diversity of Iberian representatives of Anchitherium, or the fact that the Spanish fossils cover a wider temporal and geographical range than those from Germany. For these reasons, we suggest that their subsequent statistical work should be reconsidered.

Global climate shifts and ecological flexibility are two major factors that may affect rates of speciation and extinction across clades. Here, we connect past climate to changes in diet and diversification dynamics of ruminant mammals. Using novel versions of Multi-State Speciation and Extinction models, we explore the most likely scenarios for evolutionary transitions among diets in this clade and ask whether ruminant lineages with different feeding styles (browsing, grazing and mixed feeding) underwent differential rates of diversification concomitant with global temperature change. The best model of trait change had transitions from browsers to grazers via mixed feeding, with appreciable rates of transition to and from grazing and mixed feeding. Diversification rates in mixed-feeder and grazer lineages tracked the palaeotemperature curve, exhibiting higher rates during the Miocene thermal maxima. The origination of facultative mixed diet and grazing states may have triggered two adaptive radiations—one during the Oligocene–Miocene transition and the other during Middle-to-Late Miocene. Our estimate of mixed diets for basal lineages of both bovids and cervids is congruent with fossil evidence, while the reconstruction of browser ancestors for some impoverished clades—Giraffidae and Tragulidae—is not. Our results offer model-based neontological support to previous palaeontological findings and fossil-based hypothesis highlighting the importance of dietary innovations—especially mixed feeding—in the success of ruminants during the Neogene.

13 pages, 6 figures, 4 tables., [Background] Specialised leaf-eating is almost universally regarded as the ancestral state of all ruminants, yet little evidence can be cited in support of this assumption, apart from the fact that all early ruminants had low crowned cheek teeth. Instead, recent years have seen the emergence evidence contradicting the conventional view that low tooth crowns always indicate leaf-eating and high tooth crowns grass-eating., [Results] Here we report the results of two independent palaeodietary reconstructions for one of the earliest deer, Procervulus ginsburgi from the Early Miocene of Spain, suggesting that despite having lower tooth crowns than any living ruminant, this species included a significant proportion of grass in its diet., [Conclusion] The phylogenetic distribution of feeding styles strongly supports that leaf-grass mixed feeding was the original feeding style of deer, and that later dietary specialization on leaves or grass occurred independently in several lineages. Evidence for other ruminant clades suggests that facultative mixed feeding may in fact have been the primitive dietary state of the Ruminantia, which would have been morphologically expressed only under specific environmental factors., Excavations were funded and supported by the Cultural Heritage Department of the government of Aragón. This research was supported by the Spanish Ministerio de Educación y Ciencia (CGL 2004-00400, CGL2005-03900/BTE and grant AP2003-0468) and by the government of Aragón (E05).