Reply to Ben-Dor and Barkai: A low Zn isotope ratio is not equal to a low Zn content

However, we are afraid that there was a misunderstanding in the interpretation of our data. Ben-Dor and Barkai (2) wrote that "One explanation presented in the [our] paper was that Neandertals may have consumed body parts and animals that were relatively poor in zinc, like the liver or deer." This sentence is not reflecting our conclusions: We discussed Zn isotope ratios (i.e., 66Zn/64Zn ratio expressed as a δ66Zn value) and not Zn concentrations. To explain low δ66Zn values of the Neandertal tooth, we propose that Neandertals ate food items depleted in heavy Zn isotopes (and therefore enriched in light Zn isotopes), but those foods can have variable Zn contents, independent of the Zn isotope composition as such

Carbon, nitrogen, and oxygen stable isotopes in modern tooth enamel: A case study from Gorongosa National Park, central Mozambique

The analyses of the stable isotope ratios of carbon (delta C-13), nitrogen (delta N-15), and oxygen (delta O-18) in animal tissues are powerful tools for reconstructing the feeding behavior of individual animals and characterizing trophic interactions in food webs. Of these biomaterials, tooth enamel is the hardest, most mineralized vertebrate tissue and therefore least likely to be affected by chemical alteration (i.e., its isotopic composition can be preserved over millions of years), making it an important and widely available archive for biologists and paleontologists. Here, we present the first combined measurements of delta C-13, delta N-15, and delta O-18 in enamel from the teeth of modern fauna (herbivores, carnivores, and omnivores) from the well-studied ecosystem of Gorongosa National Park (GNP) in central Mozambique. We use two novel methods to produce high-precision stable isotope enamel data: (i) the "oxidation-denitrification method," which permits the measurement of mineral-bound organic nitrogen in tooth enamel (delta N-15(enamel)), which until now, has not been possible due to enamel's low organic content, and (ii) the "cold trap method," which greatly reduces the sample size required for traditional measurements of inorganic delta C-13(enamel) and delta O-18(enamel) (from >= 0.5 to <= 0.1 mg), permitting analysis of small or valuable teeth and high-resolution serial sampling of enamel. The stable isotope results for GNP fauna reveal important ecological information about the trophic level, dietary niche, and resource consumption. delta N-15(enamel) values clearly differentiate trophic level (i.e., carnivore delta N-15(enamel) values are 4.0 parts per thousand higher, on average, than herbivores), delta C-13(enamel) values distinguish C-3 and/or C-4 biomass consumption, and delta O-18(enamel) values reflect local meteoric water (delta O-18(water)) in the park. Analysis of combined carbon, nitrogen, and oxygen stable isotope data permits geochemical separation of grazers, browsers, omnivores, and carnivores according to their isotopic niche, while mixed-feeding herbivores cannot be clearly distinguished from other dietary groups. These results confirm that combined C, N, and O isotope analyses of a single aliquot of tooth enamel can be used to reconstruct diet and trophic niches. Given its resistance to chemical alteration, the analysis of these three isotopes in tooth enamel has a high potential to open new avenues of research in (paleo)ecology and paleontology.info:eu-repo/semantics/publishedVersio

Carbon, nitrogen, and oxygen stable isotopes in modern tooth enamel: A case study from Gorongosa National Park, central Mozambique

The analyses of the stable isotope ratios of carbon (δ13C), nitrogen (δ15N), and oxygen (δ18O) in animal tissues are powerful tools for reconstructing the feeding behavior of individual animals and characterizing trophic interactions in food webs. Of these biomaterials, tooth enamel is the hardest, most mineralized vertebrate tissue and therefore least likely to be affected by chemical alteration (i.e., its isotopic composition can be preserved over millions of years), making it an important and widely available archive for biologists and paleontologists. Here, we present the first combined measurements of δ13C, δ15N, and δ18O in enamel from the teeth of modern fauna (herbivores, carnivores, and omnivores) from the well-studied ecosystem of Gorongosa National Park (GNP) in central Mozambique. We use two novel methods to produce high-precision stable isotope enamel data: (i) the “oxidation-denitrification method,” which permits the measurement of mineral-bound organic nitrogen in tooth enamel (δ15Nenamel), which until now, has not been possible due to enamel’s low organic content, and (ii) the “cold trap method,” which greatly reduces the sample size required for traditional measurements of inorganic δ13Cenamel and δ18Oenamel (from ≥0.5 to ≤0.1 mg), permitting analysis of small or valuable teeth and high-resolution serial sampling of enamel. The stable isotope results for GNP fauna reveal important ecological information about the trophic level, dietary niche, and resource consumption. δ15Nenamel values clearly differentiate trophic level (i.e., carnivore δ15Nenamel values are 4.0‰ higher, on average, than herbivores), δ13Cenamel values distinguish C3 and/or C4 biomass consumption, and δ18Oenamel values reflect local meteoric water (δ18Owater) in the park. Analysis of combined carbon, nitrogen, and oxygen stable isotope data permits geochemical separation of grazers, browsers, omnivores, and carnivores according to their isotopic niche, while mixed-feeding herbivores cannot be clearly distinguished from other dietary groups. These results confirm that combined C, N, and O isotope analyses of a single aliquot of tooth enamel can be used to reconstruct diet and trophic niches. Given its resistance to chemical alteration, the analysis of these three isotopes in tooth enamel has a high potential to open new avenues of research in (paleo)ecology and paleontology

Genomic variation in baboons from central Mozambique unveils complex evolutionary relationships with other Papio species

Background Gorongosa National Park in Mozambique hosts a large population of baboons, numbering over 200 troops. Gorongosa baboons have been tentatively identified as part of Papio ursinus on the basis of previous limited morphological analysis and a handful of mitochondrial DNA sequences. However, a recent morphological and morphometric analysis of Gorongosa baboons pinpointed the occurrence of several traits intermediate between P. ursinus and P. cynocephalus, leaving open the possibility of past and/or ongoing gene flow in the baboon population of Gorongosa National Park. In order to investigate the evolutionary history of baboons in Gorongosa, we generated high and low coverage whole genome sequence data of Gorongosa baboons and compared it to available Papio genomes. Results We confirmed that P. ursinus is the species closest to Gorongosa baboons. However, the Gorongosa baboon genomes share more derived alleles with P. cynocephalus than P. ursinus does, but no recent gene flow between P. ursinus and P. cynocephalus was detected when available Papio genomes were analyzed. Our results, based on the analysis of autosomal, mitochondrial and Y chromosome data, suggest complex, possibly male-biased, gene flow between Gorongosa baboons and P. cynocephalus, hinting to direct or indirect contributions from baboons belonging to the “northern” Papio clade, and signal the presence of population structure within P. ursinus. Conclusions The analysis of genome data generated from baboon samples collected in central Mozambique highlighted a complex set of evolutionary relationships with other baboons. Our results provided new insights in the population dynamics that have shaped baboon diversity.info:eu-repo/semantics/publishedVersio

The first Miocene fossils from coastal woodlands in the southern East African Rift

The Miocene was a key time in the evolution of African ecosystems witnessing the origin of the African apes and the isolation of eastern coastal forests through an expanding arid corridor. Until recently, however, Miocene sites from the southeastern regions of the continent were unknown. Here, we report the first Miocene fossil teeth from the shoulders of the Urema Rift in Gorongosa National Park, Mozambique. We provide the first 1) radiometric ages of the Mazamba Formation, 2) reconstructions of paleovegetation in the region based on pedogenic carbonates and fossil wood, and 3) descriptions of fossil teeth. Gorongosa is unique in the East African Rift in combining marine invertebrates, marine vertebrates, reptiles, terrestrial mammals, and fossil woods in coastal paleoenvironments. The Gorongosa fossil sites offer the first evidence of woodlands and forests on the coastal margins of southeastern Africa during the Miocene, and an exceptional assemblage of fossils including new species

Stable isotope-based paleoenvironmental reconstructions of Neogene terrestrial archives

The stable isotope geochemistry of pedogenic and lacustrine carbonate and fossil herbivore tooth enamel is a powerful tool to study the evolution of terrestrial paleoenvironments. This thesis aims to reconstruct Neogene ecosystems in the Karonga Basin in the southern part the East African Rift (EAR) and the Central Anatolian Plateau (CAP). Karonga Basin: Understanding the development of East African savanna biomes is crucial for reconstructing the evolution, migration and dietary behaviors of early hominins. These rift ecosystems range from closed woodland to open grassland savanna and vary widely in fraction of woody cover. Here I present Plio-Pleistocene carbon (δ13C) and oxygen (δ18O) records from pedogenic carbonate and fossil herbivore tooth enamel collected from the Malawi Rift. This is the first southern hemisphere long-term record in the East African Rift. The studied ca. 4.3 Ma to 0.6 Ma deposits of the Chiwondo Beds (Karonga Basin) are home to two hominin fossil finds, a maxillary fragment of Paranthropus boisei and a mandible of Homo rudolfensis, both dated to ca. 2.4 Ma. The study site is situated between the well-known hominin-bearing localities of eastern and southern Africa and hence fills an important geographical gap for early hominin research. The δ13C values of pedogenic carbonate (n = 321) and of enamel from 14 different large-bodied herbivorous mammal taxa (suid, equid, bovid, elephant an hippopotamus; n = 122) permit assessment of the evolutionary history of C3 and C4 biomass, which is closely linked to climate patterns. The reconstruction of C4-grassland development offers insights into the retreat of tree cover and the distribution and seasonality of precipitation. δ18O values reflect hydrological patterns, and we supplement the data of fossil proxy material with analyses of modern meteoric water to evaluate influences of seasonality and evaporation. Consistent δ13C values around -9‰ and δ18O values of ca. 24‰ of the pedogenic carbonate from 14 sections spanning the last 4.3 Ma indicate a relatively mesic and persistent climate with C3-dominated woodland savannas in the Karonga Basin. The data from tooth enamel of suid, elephant, and hippo taxa complement these findings with constantly low δ13C and δ18O values, demonstrating intake of mainly C3 biomass and water from sources which are only very limited affected by evaporation. In contrast, Karonga Basin equid and bovid taxa reflect much more complex dietary patterns, ranging from mixed C3/C4-feeders to strongly C4-influenced diets. Intra-tooth δ18O values also show large variations, indicating water intake from resources that differ in their isotopic composition and therefore experienced different hydrological settings. Overall, the stable isotope data reflect a mostly C3-dominated mesic paleoecosystem, which comprises patches of more open C4-grasslands within the range of migrating mammals. Supplementary analyses of δ18O values of modern meteoric water (precipitation, lake, river and groundwater; n = 111) show a similar magnitude to the fossil herbivore oxygen isotopic values. Expected 18O values of the drinking water calculated from herbivore enamel of animals with a mixed- or C3-diet indicate water intake from barely evaporated sources. Specialized feeders with a high C4-consumtion, however, reflect s|||||||||||||||||||||values of 16O-depleted reservoirs, similar in δ18O |||||||||||| to modern evaporated lakes. The absence of long-term trends towards more positive δ13C and δ18O values in the Karonga Basin contrasts the increasing role of C4-grasslands since ca. 2.5 Ma in the Eastern Rift. Our data hence point to regional differences in climate and vegetation dynamics during the Plio-Pleistocene. Therefore, regions that are home to early hominins such as H. rudolfensis and P. boisei may have had a different environmental history when compared to the Eastern Rift. This suggests that hominin adaptation is not necessarily directly linked to the emergence of open landscapes. Central Anatolian Plateau: The development of relief and climate patterns in the Central Anatolian Plateau is long-standing debate in modern paleoecological studies. This thesis presents long-term δ13C and δ18O records on five lacustrine successions, which are widely distributed across the CAP. Also, new 40Ar/39Ar geochronological data from volcanic ashes are established in addition to existing biostratigraphic and paleomagnetic data. Field relationships combined with stable isotope data of 230 lacustrine carbonates indicate a Late Oligocene environment that was characterized by large, temporally open freshwater lakes in a relatively humid subtropic climate. In the middle Aquitanian, an increase in lake δ18O values reflects more arid settings and an overall increasing dominance of closed saline lakes. This time was probably characterized by frequent climatic fluctuations, recording the influence of seasonality, topography and the waxing and waning of aridity.Die stabile Kohlenstoff- (δ13C) und Sauerstoff- (δ18O) Isotopengeochemie von pedogenen und limnischen Karbonaten und fossilem Zahnschmelz von Pflanzenfressern ist ein aussagekräftiges Werkzeug, um die Evolution von terrestrischen Paläolandschaften zu erforschen. Ziel dieser Dissertation ist die Rekonstruktion neogenen Ökosysteme, zum einen die des Karonga Beckens im Großen Afrikanischen Grabenbruch (EAR), zum anderen die des Zentralanatolischen Plateaus (CAP) in der Türkei. Karonga Becken: Die Entwicklung ostafrikanischer Savannen hat einen starken Einfluss auf die Evolution, Migration und Ernährung früher Hominini. Diese Ökosysteme reichen von geschlossenen Baumsavannen bis hin zu offenen Graslandschaften und variieren im Anteil der Bewaldung, was eine enorme Ressourcenvielfalt für die zugehörige Fauna zur Folge hat. Diese Doktorarbeit repräsentiert die erste paläoökologische Studie anhand von Langzeitarchiven in dem sich auf der Südhalbkugel befindlichen Teil des EAR. Die untersuchten Chiwondo und Chitimwe Sedimente (ca. 4.3 bis 0.6 Ma) beinhalten neben pedogenen Karbonaten auch Fossilien einer diversen Fauna, welche von Großsäugern dominiert wird und unter anderem Fossilien von frühen Hominini (Homo rudolfensis und Paranthropus boisei) umfasst. Die Hominini Fossilen sind jeweils auf ca. 2.4 Ma datiert, dies ist die bisher früheste nachgewiesene Koexistenz beider Gattungen. Anhand von δ13C Werten der Bodenkarbonate und fossiler Zahnproben kann die evolutionäre Geschichte von C3- und C4-Pflanzen, welche stark mit klimatischen Veränderungen im EAR verbunden ist, untersucht werden. δ18O Analysen geben vor allem Einblicke in die hydrologische Entwicklung eines Gebietes. Niedrige, kaum fluktuierende δ13C Werte von ca. -9‰ und δ18O Werte von ca. 24‰ der Plio-Pleistozänen pedogenen Karbonate deuten auf eine ständig bewaldete Savanne hin, die von C3-Pflanzen dominiert wird und in einer relativ feuchten Region existiert. Ebenfalls relativ niedrige Isotopendaten des Zahnschmelzes von Suiden, Elefanten und Flusspferden unterstützen diese Interpretation. Isotopenanalysen von Equiden und Boviden aus dem Karonga Becken deuten allerdings auf ein weitaus komplexeres Nahrungsangebot hin. Während einige Individuen eine gemischte C3- und C4-Ernährung hatten, gab es auch reine (C4-)Grasfresser. Das Trinkwasser dieser Tiere war meistens wesentlich stärker von Evaporation beeinflusst als das der C3-Konsumenten. Zusammenfassend reflektieren die Isotopendaten zu Zeiten des Plio-Pleistozäns eine Savanne im Karonga Becken, welche großflächig über 60% bewaldet war und nur in trockeneren Gebieten offene Bereiche mit Graslandschaften aufwies. Die Abwesenheit von einem langfristigen Trend zu positiveren δ13C und δ18O Werten im Karonga Becken steht im Gegensatz zu der gut dokumentierten zunehmenden Rolle von C4-Gassavannen im östlichen Teil des Großen Afrikanischen Grabenbruchs. Daher deuten unsere Ergebnisse auf regional unterschiedliche Klima- und Vegetationsmuster im Norden und Süden der Intertropischen Konvergenzzone im Plio-Pleistozän hin. Schlussfolgernd waren Landschaften in denen frühe Hominini (H. rudolfensis und P. boisei) lebten unterschiedlich in Bezug auf Vegetation, Klima und Ressourcen, was die Evolution unserer Vorfahren nicht zwingend mit der flächendeckenden Ausbreitung von offenen Graslandschaften koppelt. Zentralanatolisches Plateau: Die Entwicklung des Reliefs und Klimas im Zentralanatolischen Plateau steht seit langem ebenfalls im Fokus von paläoökologischen Studien. Hier präsentieren wir Sauerstoff- und Kohlenstoffisotopendaten von fünf Oligo-Miozänen lakustrischen Abfolgen die weiträumig über das CAP verteilt sind. Außerdem ergänzen wir existierende biostratigraphische und paläomagnetische Daten mit neuen geochronologischen 40Ar/39Ar Datierungen vulkanischer Aschen für eine zeitliche Einordnung der untersuchten sedimentären Becken. Geländebeobachtungen und stabile Isotopenwerte von 230 Seesedimenten deuten auf ein von großen exorheischen Frischwasserseen dominiertes Ökosystem im feuchten Klima des späten Oligozäns hin. Im mittleren Aquitanium steigen die δ18O Werte an und reflektieren ein zunehmend arides Klima und eine wachsende Dominanz von endorheischen, teilweise salzhaltigen Seen. Diese Zeit war vermutlich von wechselnden klimatischen Bedingungen beherrscht, was einen steigenden Einfluss von Saisonalität, Topographie und dem Ab- und Zunehmen von Trockenheit zeigt

Dietary versatility of Early Pleistocene hominins

SIGNIFICANCE: Clumped and stable isotope data of paleosol carbonate and fossil tooth enamel inform about paleoenvironments of Early Pleistocene hominins. Data on woodland- vs. grassland-dominated ecosystems, soil temperatures, aridity, and the diet of Homo rudolfensis and Paranthropus boisei ca. 2.4 Ma show that they were adapted to C3 resources in wooded savanna environments in relatively cool and wet climates in the Malawi Rift. In contrast, time-equivalent Paranthropus living in open and drier settings in the northern East African Rift relied on C4 plants, a trend that became enhanced after 2 Ma, while southern African Paranthropus persistently relied mainly on C3 resources. In its early evolutionary history, Homo already showed a high versatility, suggesting that Pleistocene Homo and Paranthropus were already dietary generalists.New geochemical data from the Malawi Rift (Chiwondo Beds, Karonga Basin) fill a major spatial gap in our knowledge of hominin adaptations on a continental scale. Oxygen (δ18O), carbon (δ13C), and clumped (Δ47) isotope data on paleosols, hominins, and selected fauna elucidate an unexpected diversity in the Pleistocene hominin diet in the various habitats of the East African Rift System (EARS). Food sources of early Homo and Paranthropus thriving in relatively cool and wet wooded savanna ecosystems along the western shore of paleolake Malawi contained a large fraction of C3 plant material. Complementary water consumption reconstructions suggest that ca. 2.4 Ma, early Homo (Homo rudolfensis) and Paranthropus (Paranthropus boisei) remained rather stationary near freshwater sources along the lake margins. Time-equivalent Paranthropus aethiopicus from the Eastern Rift further north in the EARS consumed a higher fraction of C4 resources, an adaptation that grew more pronounced with increasing openness of the savanna setting after 2 Ma, while Homo maintained a high versatility. However, southern African Paranthropus robustus had, similar to the Malawi Rift individuals, C3-dominated feeding strategies throughout the Early Pleistocene. Collectively, the stable isotope and faunal data presented here document that early Homo and Paranthropus were dietary opportunists and able to cope with a wide range of paleohabitats, which clearly demonstrates their high behavioral flexibility in the African Early Pleistocene

Dietary versatility of Early Pleistocene hominins

SIGNIFICANCE: Clumped and stable isotope data of paleosol carbonate and fossil tooth enamel inform about paleoenvironments of Early Pleistocene hominins. Data on woodland- vs. grassland-dominated ecosystems, soil temperatures, aridity, and the diet of Homo rudolfensis and Paranthropus boisei ca. 2.4 Ma show that they were adapted to C3 resources in wooded savanna environments in relatively cool and wet climates in the Malawi Rift. In contrast, time-equivalent Paranthropus living in open and drier settings in the northern East African Rift relied on C4 plants, a trend that became enhanced after 2 Ma, while southern African Paranthropus persistently relied mainly on C3 resources. In its early evolutionary history, Homo already showed a high versatility, suggesting that Pleistocene Homo and Paranthropus were already dietary generalists.New geochemical data from the Malawi Rift (Chiwondo Beds, Karonga Basin) fill a major spatial gap in our knowledge of hominin adaptations on a continental scale. Oxygen (δ18O), carbon (δ13C), and clumped (Δ47) isotope data on paleosols, hominins, and selected fauna elucidate an unexpected diversity in the Pleistocene hominin diet in the various habitats of the East African Rift System (EARS). Food sources of early Homo and Paranthropus thriving in relatively cool and wet wooded savanna ecosystems along the western shore of paleolake Malawi contained a large fraction of C3 plant material. Complementary water consumption reconstructions suggest that ca. 2.4 Ma, early Homo (Homo rudolfensis) and Paranthropus (Paranthropus boisei) remained rather stationary near freshwater sources along the lake margins. Time-equivalent Paranthropus aethiopicus from the Eastern Rift further north in the EARS consumed a higher fraction of C4 resources, an adaptation that grew more pronounced with increasing openness of the savanna setting after 2 Ma, while Homo maintained a high versatility. However, southern African Paranthropus robustus had, similar to the Malawi Rift individuals, C3-dominated feeding strategies throughout the Early Pleistocene. Collectively, the stable isotope and faunal data presented here document that early Homo and Paranthropus were dietary opportunists and able to cope with a wide range of paleohabitats, which clearly demonstrates their high behavioral flexibility in the African Early Pleistocene

Slight pressure imbalances can affect accuracy and precision of dual inlet-based clumped isotope analysis

<p>It is well known that a subtle nonlinearity can occur during clumped isotope analysis of CO₂ that – if remaining unaddressed – limits accuracy. The nonlinearity is induced by a negative background on the <i>m</i>/<i>z</i> 47 ion Faraday cup, whose magnitude is correlated with the intensity of the <i>m</i>/<i>z</i> 44 ion beam. The origin of the negative background remains unclear, but is possibly due to secondary electrons. Usually, CO₂ gases of distinct bulk isotopic compositions are equilibrated at 1000 °C and measured along with the samples in order to be able to correct for this effect. Alternatively, measured <i>m</i>/<i>z</i> 47 beam intensities can be corrected for the contribution of secondary electrons after monitoring how the negative background on <i>m</i>/<i>z</i> 47 evolves with the intensity of the <i>m</i>/<i>z</i> 44 ion beam. The latter correction procedure seems to work well if the <i>m</i>/<i>z</i> 44 cup exhibits a wider slit width than the <i>m</i>/<i>z</i> 47 cup. Here we show that the negative <i>m</i>/<i>z</i> 47 background affects precision of dual inlet-based clumped isotope measurements of CO₂ unless raw <i>m</i>/<i>z</i> 47 intensities are directly corrected for the contribution of secondary electrons. Moreover, inaccurate results can be obtained even if the heated gas approach is used to correct for the observed nonlinearity. The impact of the negative background on accuracy and precision arises from small imbalances in <i>m</i>/<i>z</i> 44 ion beam intensities between reference and sample CO₂ measurements. It becomes the more significant the larger the relative contribution of secondary electrons to the <i>m</i>/<i>z</i> 47 signal is and the higher the flux rate of CO₂ into the ion source is set. These problems can be overcome by correcting the measured <i>m</i>/<i>z</i> 47 ion beam intensities of sample and reference gas for the contributions deriving from secondary electrons after scaling these contributions to the intensities of the corresponding <i>m</i>/<i>z</i> 49 ion beams. Accuracy and precision of this correction are demonstrated by clumped isotope analysis of three internal carbonate standards. The proposed correction scheme can be easily applied if the slit width of the <i>m</i>/<i>z</i> 49 Faraday cup is bigger than that of the <i>m</i>/<i>z</i> 47 cup.</p