Browsing Diet Research Articles

Mesowear analysis of Taubatherium paulacoutoi (Late Oligocene, Tremembé Formation), São Paulo State, Brazil

Despite the benefits of the mesowear analysis method for dietary reconstruction, it has rarely been applied to notoungulates. We here apply traditional mesowear and a mesowear angle approach to an assemblage of the leontiniid Taubatherium paulacoutoi from the Late Oligocene (Deseadan SALMA), Tremembé Formation, Taubaté Basin, Brazil. Using both methods, we find support for a browsing diet hypothesis low in abrasive vegetation, which matches predictions from ecomorphology. However, we found differences between the traditional mesowear signal of Taubatherium, and any modern ungulate species analyzed. We suggest that this supports the use of mesowear angles in notoungulates for dietary reconstruction, given the lack of modern representatives. Keywords: mesowear, Taubatherium, Brazil, Taubaté, Late Oligocene.

Insights into archaeological and modern neotropical biomes: Examining diet and shape variation through white-tailed deer lower third molar

The white-tailed deer (Odocoileus virginianus Zimmermann 1780) holds significant ecological importance across the Americas, both historically and in modern times. This species ranges from southern Canada to Brazil and exhibits polytypic characteristics, adapting well to diverse habitats including temperate, subtropical, semi-arid, rainforest, and savanna environments. In paleontology and archaeology, the comparison of dental characteristics between extant mammal species with known diets is commonly employed to infer the feeding behaviors of their ancient counterparts. This method assumes that extant and fossil species share similar dietary preferences, aiding in the identification of past environmental contexts. Consequently, we employed a multiproxy approach, combining the study of dental wear and 2D geometric morphometrics, to investigate potential relationships between molar shape, diet, and biomes among extant white-tailed deer populations across the Americas. Our analysis included a comparison with archaeological data from Panama. We sampled 274 extant lower second molar specimens for micro- and mesowear analysis, along with 105 lower third molar specimens from natural science museums for 2D geometric morphometric analysis. These were compared with a sample of 65 archaeological specimens from Panama. Our findings revealed distinct variations in the shape of lower m3 molars among extant white-tailed deer populations across different biomes, with notable differences observed in the archaeological samples as well. Micro- and mesowear analyses also indicated biome-related differences, suggesting a general browsing diet for white-tailed deer with nuanced variations across biomes. Mesowear analysis further suggested a dietary spectrum ranging from pure browsers to browser-mixed feeders. These findings offer valuable insights for the interpretation of fossil deer specimens recovered from archaeological sites.

A new specimen of Camelops hesternus (Artiodactyla, Camelidae) from Valsequillo, Puebla, Mexico, with comments about their dietary preferences and the population density of the species

Camelidae is one of the most diverse and successful artiodactyl families, with a long geological history and wide geographical range in North America. Camelops hesternus was the one of last camelids in North America during the Pleistocene (Rancholabrean) and its remains have been found from Alaska south into Mexico. Here, we describe a new specimen of this species based on a complete mandible from the Late Pleistocene sediments of the Cerro Grande de la Mesa Calderón monogenetic volcano in the Valsequillo Basin, Puebla, central Mexico. A mesowear analysis of the dentition indicates wear in the new specimen to be similar to that of the Klipspringer, Oreotragus oreotragus, indicating a browsing diet. The population density of C. hesternus in the Valsequillo Basin was estimated using a differential non-linear equations mathematical model under three scenarios (stress, optimal, and abundance conditions) a indicating the range in its population density of 0.51–1.8 ind/km2, and this species was not abundant in the region. Despite the low population density C. hesternus has been reported in Mexico from 27 Pleistocene localities, with a geographic range from north (29°40′ latitude, Sonora) to south (16°14′ latitude, Chiapas) at an altitude range of 0–200 m asl in Baja California Sur to 2500 m asl in the Trans-Mexican Volcanic Belt.

The effects of feeding dried browse leaves on rumen ammonia levels, methanogens and protozoa amplification of sheep in the Coastal Savannah of Ghana

Tanniferous browse leaves are reported to inhibit methanogens and protozoa activity in the rumen, thus contributing to a reduction of methane emission. This study evaluated the influence of feeding dried browse leaves to sheep on rumen ammonia concentration, the base pair at which protozoa and methanogens were amplified and double stranded DNA concentration (dsDNA) from rumen fluid and faeces. The eight treatments were urea treated rice straw, Albizzia lebbek (AL), Moringa oleifera (MO), Millettia thonningii (MT), AL + MO, AL + MT, AL + MO + MT and MO + MT. After feeding 32 ram lambs for 3months, one ram lamb on each of the eight experimental diets was randomly selected and slaughtered to obtain rumen fluid. Genomic DNAs were extracted from methanogen and protozoa strains obtained from rumen liquor and from faecal matter of sheep. Rumen ammonia was determined using spectrophotometer. Methanogens and protozoa from rumen fluid and faeces were amplified at 1100 base pair, 200-1100 base pair, 320-1100 base pair and 200-750 base pair respectively. Rumen ammonia concentration, dsDNA from rumen fluid and faeces ranged from 14.51 to 23.01mg/dl, 65 to 900µg/ml and 100 to 950µg/g respectively. The rumen ammonia concentration met the requirements for efficient growth of microbes. The presence of methanogens and protozoa in the rumen fluid and in the faeces indicated that dried browse diets were able to inhibit the growth of both protozoa and methanogens in the rumen by eliminating them, and thus, were excreted in the faeces. Hence, feeding of dried browse leaves can contribute to lower methane emission.

Reticular contraction frequency and ruminal gas dome development in goats do not differ between grass and browse diets.

In investigations of differences between ruminant species feeding on browse or grass, it is often unclear whether observed differences are animal- or forage-specific. Ruminant species have been classified as 'moose-type', with little rumen content stratification, or 'cattle-type' with a distinct rumen contents stratification, including a gas layer. To which extent putative differences in forestomach motility are involved in these patterns is unknown. Using sonography, we investigated the frequency of reticular contractions and the stratification of rumen contents in goats fed exclusively on grass hay (n=6) or dried browse (n=5) directly after feeding, and after another 6 and 12h with no access to feed. The frequency of reticular contractions decreased from immediately after feeding (1.8±0.3min-1 ) to 6h afterwards (1.2±0.2min-1 ) and then remained constant, with no difference between diets. A gas dome became more visible over time, but neither its incidence nor its extent differed between diets. The results are in accord with classifying goats as 'cattle-type' in terms of their digestive physiology, and they add to a growing body of evidence that differences in digestive physiology between ruminant species are more due to species characteristics than different kinds of ingested forages.

Ruminant mesowear reveals consistently browse-dominated diets throughout the early and middle Miocene of eastern Africa

The ecological preferences of ruminant artiodactyls are commonly used to reconstruct the paleoenvironment of Neogene fossil localities throughout Africa. However, comparatively little research has focused on the ecology of ruminant artiodactyls from the Miocene of Africa. Here, we contribute new molar mesowear and hypsodonty data for the ruminant artiodactyls from the early and middle Miocene of Kenya and Uganda. Macroscopic dental characteristics of 608 tragulids, stem pecorans, giraffoids, and bovids dated to between 20 and 13.7 Ma were analyzed. Our hypsodonty results reveal that, whereas tragulids remain brachydont throughout the early and middle Miocene, pecoran ruminants experience an increase in hypsodonty due to the appearance of high-crowned bovids and climacoceratids that migrate into eastern Africa in the middle Miocene. Results from dental mesowear analysis suggest that all tragulids and pecorans were likely browsers, with only one taxon showing mesowear values that overlap with both browsers and mixed feeders in both the upper and lower molars (Canthumeryx sirtensis). None of the taxa analyzed had mesowear scores indicative of a grazing diet. Surprisingly, middle Miocene bovids and climacoceratids, despite possessing gross tooth morphologies adapted to abrasive diets, were largely utilizing a browsing diet. Although the early and middle Miocene habitats of eastern Africa were likely very heterogenous, none of the ruminant artiodactyls present in these habitats is interpreted as having incorporated grasses into their diet in significant quantities.

THE EFFECTS OF FEED ON THE INTAKE, DIGESTIBILITY AND GROWTH RATE OF WEST AFRICAN DWARF GOATS FED GLIRICIDIA sepium AND LEUCAENA LEUCOCOEPHALA

The study evaluated the effects of level of feed offer on dry matter intake (DMI) , digestibility, the parts of plants selected and on the growth rate of West African dwarf (WAD) goats without resulting in toxicity. Seven different levels of feed offer ranging from 40g/kg0.75/day to 130Wkg0.75/day in increments of 15g/kg0.75) were fed to two groups of goats. The first group was fed 100% Gliricidia while the while the second was fed 50% Gliricidia and 50% Leucaena diet (50/50). The level of feed offer had significant effect on the DIM and digestible DMI (DDMI) of the goat (P < 0.01). The Leucaena intake in a 50/50 diet was always higher than the Gliricidia intake except at 55g1kg0.75 offer level. The level of feed offer had significant effects on the parts of plants selected (P < 0.01.) and on the growth rate. The leaf intake was statistically higher than the stem intake (P < 0.01). All the goats on 40g/kg0.75 and 55g/kg0.75 on a 100% Gliricidia diet lost weight while only those on 40g/kg0.75 lost weight on a 50/50 diet. There was no significant difference in the growth rate of goats on feed offer levels of 70g to 130g/kg0.75 (P > 0.05). The study indicate that goats performance was higher on a mixed browse diet than on Gliricidia alone. Goats performed best at 100g/kg0.75 offer level.

Diets of Pleistocene insular dwarf deer revealed by dental microwear texture analysis

Microwear is defined as the microscopic scars left during mastication on the surfaces of teeth. Because microwear reflects the physical properties of the food eaten by animal, it has been used for reconstruction of the diets of extinct animals. We investigated the dental microwear of the extinct insular dwarf deer Cervus astylodon using materials excavated from Late Pleistocene archaeological sites on Okinawa Island (the Hananda-Gama Cave site and the Yamashita-cho Cave I site). We applied three-dimensional surface texture analysis to quantitatively evaluate microwear features. We analyzed 293 individual sika deer (Cervus nippon) from 15 populations in Japan with quantitative dietary data clarified by rumen contents or feces analyses, constructing one of the most comprehensive microwear databases of extant ruminants. We found that deer with a higher consumption of graminoids showed rougher tooth surfaces than those browsing on trees owing to the high content of abrasive silica in graminoid leaves. Using a regression equation relating surface roughness parameters and the percentage of graminoids in the diet, we estimated that C. astylodon from the Hananda-Gama Cave might have consumed a diet consisting of approximately 44% graminoids, whereas we estimate a predominantly graminoid-based diet (ca. 78%) for deer from the Yamashita-cho Cave. Therefore, contrary to the findings of mesowear and stable carbon isotope analysis, which indicated a browsing diet, we propose that C. astylodon were mixed feeders or possibly grazers. These findings provided an important implication of their peculiar evolution on islands.

First occurrence of musk ox Ovibos moschatus in the Late Pleistocene (MIS 3) record from NW Iberia: Paleobiogeographic and paleoenvironmental implications

A remarkable musk ox (Ovibos moschatus) assemblage was recovered at Cowshead Cave (Picos de Europa Mountains, NW Spain). This find is of special paleobiogeographic relevance since it involves the first occurrence of this species in NW Iberia and extends the boundary of its Eurasian distribution range to the SW.Fossils correspond to at least two individuals: one young male about 20 months old, which includes an extraordinarily well-preserved skull, and one subadult of about 38–44 months. The bone deposit, dated to 34.9 ± 0.4 cal ka BP (MIS 3), accumulated in a karst cave that acted as a natural trap, agreeing with the geomorphology and the good preservation of the remains.Considering that musk ox skulls of young individuals are extremely rare in the Pleistocene record, the detailed comparative study of the skull here presented provides new and relevant information. The skull from Cowshead is larger than modern specimens of similar individual age from Greenland; additionally, some remarkable morphological peculiarities in skull and teeth were identified.One metacarpal of the subadult individual was compared to recent and Pleistocene specimens and was among the largest in the entire sample. Significant differences in morphology and size between fossil and recent metacarpals were detected.Teeth microwear analysis suggests a browsing diet based on twigs and leaves at the time of death, which is consistent with a winter diet.The cold and arid environment inferred from the presence of musk ox is consistent with the paleontological record, since cold-adapted mammals occurred at other contemporary assemblages from NW Iberia.

Dental wear analyses of Middle Pleistocene site of Lunel-Viel (Hérault, France): Did Equus and Bos live in a wetland?

This study presents comparison of dental meso and micro-wear analyses on Middle Pleistocene equids and bovids from Lunel-Viel I (Hérault, France) with their extant counterpart from Camargue. Previous paleoenvironnemental observations hypothesize a great proximity between the Camargue wetland and Lunel-Viel environment. Teeth wear analyses provides an innovative approach to describe eco-ethological parameters, such as diet and biotope.Camarque's horses and cattle diets are similar and characterized by a mixed feeding. Lunel-Viel I's Equus had a grass-dominated mixed feeding diet while Bos had a browsing diet. The differences in the feeding habits and resource partitioning between the two taxa in the two locations suggest two different biotopes. While the extant sample still need to be completed, preliminary observations indicate that it is very unlikely bovids and equids from Lunel-Viel inhabited a biotope like nowadays Camague.This study highlights the contributions of a combined comparative approach and adds new data to analyse the paleodietary patterns of extinct ungulates.

Invasive species, not environmental changes, restrict the population and geographical range of the quokka (Setonix brachyurus)

AbstractEuropean arrival into Australia had large‐scale impacts on the local flora and fauna. Most notably, Europeans brought with them numerous non‐native species, including the European red fox (Vulpes vulpes), European rabbit (Oryctolagus cuniculus), and the goat (Capra hircus) among many others. The introduction of these species had significant consequences on native Australian mammals, causing some small‐ to medium‐sized herbivores to become geographically restricted to primarily islands. Here, we examined the dietary ecology of the quokka (Setonix brachyurus), a native marsupial herbivore with a restricted geographic range in Western Australia before and after European arrival. Fossils from south‐western Australia and modern specimens were examined via dental microwear texture analysis and stable isotope analysis to assess whether the diet of the quokka had changed dramatically over time. Collectively, we help clarify whether there were any ecological reasons as to why this marsupial became geographically restricted, aside from the presence of invasive predators on mainland Australia. The quokka maintains a browsing diet from the Pleistocene to the present on the mainland, but modern island populations eat drier and tougher foods when living on islands lacking invasive mammals. There is also an apparent shift in the feeding environment of the quokkas on mainland Australia, from more open forests/shrublands in the Pleistocene to denser and wetter forests. Multi‐proxy data collectively indicate that the restricted range of the quokka today is most likely a result of predation from non‐native taxa and/or other human influences—not because of a lack of suitable habitat.

The bears from Dmanisi and the first dispersal of early Homo out of Africa

We report on the taxonomy and paleodiet of the bear population that inhabited the emblematic palaeoanthropological Early Pleistocene (1.8 Ma) site of Dmanisi (Georgia), based on a dual approach combining morphometrics and microwear of upper and lower teeth. Given that the teeth of Ursus etruscus Cuvier, 1823 from Dmanisi show considerable size variability, their systematic position has been debated. However, a comparative study of the coefficients of variation for tooth size measurements in several modern bear species shows that the variability in tooth size of the ursid population from Dmanisi could result from sexual dimorphism. The analysis of tooth microwear indicates that these bears inhabited a mixed environment of open plain with forest patches, where they had a browsing diet with a substantial contribution of meat and/or fish. Comparative tooth morphometric analyses of modern ursids and fossil U. etruscus indicate that this extinct species had an omnivorous behavior similar to that of extant brown bears. The ecological interactions of the Dmanisi bears with other members of the large mammals community, including the first hominins that dispersed out of Africa, are discussed in the light of this new evidence.

Digesta passage in nondomestic ruminants: Separation mechanisms in ‘moose-type’ and ‘cattle-type’ species, and seemingly atypical browsers

Ruminants have been classified as having a ‘moose-type’ or ‘cattle-type’ digestive physiology. ‘Cattle-type’ ruminants have a clear difference in the mean retention time (MRT) of fluid vs. small particles in the reticulorumen (RR), with a high ‘selectivity factor’ (SF = MRTparticle/ MRTfluid, >1.80), and are typically grazers and intermediate feeders. ‘Moose-type’ ruminants have lower SF (<1.80), possibly because of defensive salivary proteins that constrain amounts of (high-viscosity) saliva, and are typically restricted to browsing. To further contribute to testing this physiology-diet correlation, we performed 55 individual passage measurements in 4/6 species that have/have not been investigated previously, respectively. Co-EDTA was used as a solute (fluid) and Cr-mordanted hay particles (<2 mm) as particle markers. Results are related to the percentage of grass in the natural diet taken from the literature. Moose (Alces alces, n = 4 on 4 to 5 diets each and n = 2 on a single diet, 5% grass, SF 1.46 ± 0.22) and giraffe (Giraffa camelopardalis, n = 3 on 3 to 5 diets each, 1%, 1.42 ± 0.23) as classical ‘moose-type’, and cattle (Bos taurus, n = 2, 70%, 2.04) as classical ‘cattle-type’ ruminants yielded results similar to those previously published, as did waterbuck (Kobus ellipsiprymnus, n = 5, 84%, 2.46 ± 0.49), corroborating that the SF represents, to a large extent, a species-specific characteristic. Results in oryx (Oryx leucoryx, n = 1, 75%, 2.60) and sitatunga (Tragelaphus spekii, n = 4, 68%, 1.81 ± 0.21) correspond to the concept of ‘cattle-type’ ruminants being grazers or intermediate feeders. However, European bison (Bison bonasus, n = 1, 10%, 2.74), nyala (T. angasii, n = 6, 20%, 1.95 ± 0.25), bongo (T. eurycerus, n = 3, 13%, 2.39 ± 0.54) and gerenuk (Litocranius walleri, n = 1, 0%, 2.25) appear as ‘cattle-type’ ruminants, yet have a browse-dominated diet. While the results do not challenge the view that a ‘moose-type’ digestive physiology is an adaptation to browse diets, they indicate that it may not be the only adaptation that enables ruminants to use browse. Apparently, a ‘cattle-type’ digestive physiology with a high SF does not necessarily preclude a browsing diet niche. High-SF browsers might have the benefit of an increased harvest of RR microbiota and grit removal prior to rumination; how they defend themselves against secondary plant compounds in browse remains to be investigated.

Heavier rumen–reticulum organs in white-tailed deer (Odocoileus virginianus) is consistent with dietary bulk not quality

The organs that make up the gastrointestinal tract have high energy demands. Therefore, when these organs vary in mass, they should impact metabolic requirements. Mass of the rumen–reticulum organs, the organs that comprise the largest part of the gastrointestinal tract of ruminants, might vary from bulk or nutrient availability of the diet. We examined differences in mass of the rumen–reticulum organs in white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from two sites in Texas, USA, with different diet types. Specifically, at one site deer were fed a pelleted ration and at the other site deer consumed a natural browse diet. Accounting for body mass, deer consuming the browse diet had rumen–reticulum organ masses that were about 1.7 times heavier than deer consuming the pelleted diet. Deer consuming the browse diet also had lower diet quality, as indexed by crude protein concentration, than deer consuming the pelleted diet. The digesta loads of deer, however, were similar for the two types of diet. Our study findings are consistent with increased mass of rumen–reticulum organs from greater bulk, not diet quality. Understanding variation in rumen–reticulum organ mass has implications for understanding energy conservation in white-tailed deer.

Dietary response of early Pleistocene ungulate communities to the climate oscillations of the Gelasian/Calabrian transition in Central Italy

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.

Dietary traits of the late Early Pleistocene Bison menneri (Bovidae, Mammalia) from its type site Untermassfeld (Central Germany) and the problem of Pleistocene ‘wood bison’

Over the course of the Early and early Middle Pleistocene, a climatic cooling trend led to the partial opening up of landscapes in the western Palaearctic. This led to a gradual replacement of browsers by grazers, whilst some herbivore species shifted their diet towards including more grass. Wear patterns of herbivore cheek teeth can inform our understanding of the timing and extent of this change and indicate levels of dietary plasticity. One of the indicator species of the faunal turnover is the first large-sized form of bison in the Palaearctic, Bison menneri. The dental mesowear of the palaeopopulation from the species' late Early Pleistocene type site of Untermassfeld in Central Germany and the Late Pleistocene B. priscus from Taubach, both from habitat mosaics of forested habitats and more open landscapes, have a mixed feeder profile similar to that of North American wood bison, which has a distinct preference for open habitats but occasionally consumes a high amount of browse as a fall-back food. In contrast, the grazer mesowear signature of early Middle Pleistocene B. schoetensacki voigtstedtensis from Voigtstedt indicates these animals likely did not regularly feed in the densely forested area around the site. The mesowear of B. schoetensacki from Süssenborn, in a more open environment, is similar to that of extant European bison. Both Pleistocene and extant bison are grazers to mixed feeders with relatively high tolerance of a suboptimal browsing diet. None of these species can be regarded as true ‘wood bison’.

Regional variation in the browsing diet of Pleistocene Mammut americanum (Mammalia, Proboscidea) as recorded by dental microwear textures

Analyses into the feeding ecology of Mammut americanum have reconstructed this extinct proboscidean as a forest-dwelling browser that thrived across North America during the Pleistocene. However, the level of variability in mastodon diet that may have existed across its spatio-temporal range remains unresolved. We address this deficiency through comparison of dental microwear textures in a large sample (N=65) of M. americanum teeth from six geographic and chronologically distinct locations from the Late Pleistocene of North America. Mastodon microwear textures correspond to a woody browsing diet, congruent with results from other dietary proxies. However, microwear textures reveal that southern populations from Florida (associated with a cypress swamp habitat) had a slightly softer, tougher browsing diet compared to northern populations (associated with boreal forest and open-pine parkland habitats) in the Late Pleistocene. In addition, there was no significant difference in microwear variables associated with food hardness or toughness in mastodons from two temporally distinct populations from Missouri, despite a significant environmental shift from open-pine parkland to boreal forest through time. Our findings elucidate M. americanum as a species with some plasticity in its browsing strategy across its range, with regional populations capable of having different diets yet able to maintain their ecological niche in the face of local environmental shifts in the Late Pleistocene. This has implications for the future testing of environmentally-induced extinction hypotheses during the latest Pleistocene and also illustrates the importance of measuring population-level dietary variation to better understand total feeding ecology in an extinct species.

Dental eruption sequence and hypsodonty index of a Pleistocene macraucheniid from the Brazilian Intertropical Region

AbstractLitopterna is represented in the Pleistocene of the Brazilian Intertropical Region by a monospecific genus of Macraucheniidae, Xenorhinotherium. Although most of the knowledge about this family is derived from the dentition, some dental features still remain unknown. This study describes the eruption sequence of permanent dentition and classifies the hypsodonty status of X. bahiense. The specimens studied are from Toca dos Ossos, a limestone cave located in Bahia State. We perform qualitative macroscopic analysis to describe the eruption dental sequence. Additionally, we perform quantitative analysis to determine the hypsodonty index. The dental eruption sequence of the juvenile specimen is M1, M2, I1, I2, M3, I3, P1, P2, P3, and P4. In addition, the analysis of tooth wear in adult specimens provides similar results. The hypsodonty index assigns a mesodont tooth crown for X. bahiense. The dental eruption sequence is most similar to a rapid-growth extant mammal. Moreover, our results do not support afrotherian-like delayed dental eruption to Litopterna. The hypsodonty index can be related to data on vegetation of the Brazilian Intertropical Region and the shape of the premaxilla of X. bahiense, both of which suggest a browsing diet for this macraucheniid.

Dietary and palaeoenvironmental inferences in Neolicaphrium recens Frenguelli, 1921 (Litopterna, Proterotheriidae) using carbon and oxygen stable isotopes (Late Pleistocene; Uruguay)

The Proterotheriidae (Early Palaeocene-Late Pleistocene) were small to medium sized cursorial native South American ungulates (Order Litopterna), having had its diversity peak in the Miocene. During the Pleistocene, the proterotheriid diversity decreased to a single species, Neolicaphrium recens Frenguelli (1921), and few specimens are available from a relatively narrow area at medium latitudes of South America. The first study using stable isotopes (δ13C and δ18O) as proxies is provided here, in order to known dietary preferences and testing previous environmental inferences. The analysed specimens belong to outcrops with OSL ages of 40–30 ka (Late Pleistocene, Sopas Formation of northern Uruguay). The δ13C results of both specimens suggest that at this latitude and tempo, N. recens had browser-feeding preferences, mostly a C3 diet of open canopy forest in an environment of semi-open woodland or forested savannahs and that C4 vegetation would have had a small fraction in their diet. δ18O data suggests a diet composed mostly by fruits, follow by floor plants, with few indication of a folivore diet. The specialized forest browsing diet does not significantly vary based on its site of origin, since both specimens remain in the same isotopic range.

Supplemental nutrients increase the consumption of chemically defended shrubs by free-ranging herbivores

Large herbivores are purported to continue consuming toxin-containing forages as long as their capacity to neutralize, detoxify and excrete dietary toxins is not exceeded. This capacity depends on the availability of liver enzymes, energy and amino acid precursors. While this may explain increased intake of toxin-rich forages by herbivores supplemented with nutrients, a different effect may emerge in rangelands dominated by forages that are rich in condensed tannins which are not as degradable and readily absorbable as toxins. In a field experiment, we investigated the effects of supplementing animals with a high-energy source (yellow maize grain) and a high-protein source (soybean meal) on browse intake, foraging behaviour and diet composition of goats in a semi-arid savanna. In line with our prediction, nutrient supplementation increased the percentage time spent by goats on browsing and subsequently enhanced browse intake. Supplemented goats consumed more condensed tannins than goats that were not supplemented. Goats from supplemented groups tended to compose different diets from goats that received no supplement. Supplementation may have modified animals’ requirements for nutrients in ways that influenced feeding behaviour. We contend that supplements likely replaced the nutrients that are routinely bound and rendered indigestible by condensed tannins and thus increased the intake of tannin-rich forages through delaying a negative post-ingestive feedback (aversion) from dietary tannins. In conclusion, we showed that nutrient supplementation can be used to increase defoliation of tannin-rich shrubs by mixed feeders which suggests a potential for browsers and mixed-feeders to serve as biological bush control agents. Furthermore, these results have serious implication for herbivores and the environment.