Christophe Lécuyer

Claude Bernard University Lyon 1 | UCBL · Laboratoire de géologie de Lyon, terre, planètes et environnement

The secondary adaptation of Cetacea to a fully marine lifestyle raises the question of their ability to maintain their water balance in a hyperosmotic environment. Cetacea have access to four potential sources of water: surrounding salt oceanic water, dietary free water, metabolic water and inhaled water vapor to a lesser degree. Here, we measured...

The assessment of the potential blurring effect of diagenetic processes represents the greatest challenge for geochemists whose purpose is to reconstruct environmental parameters based on isotopic proxies. Numerous studies performed on phosphatic remains from terrestrial and marine sedimentary deposits have shown post-depositional isotopic modifica...

Introduction After decades of debate on the origin of turtles, it is now widely accepted that they are diapsid reptiles originating in the Permian from a terrestrial ancestor. It seems that the initial development of the structures that will later form the unique turtle bony shell took place as a response to a fossorial lifestyle. However, the earl...

The palaeoecology of the Xenacanthiformes (Chondrichthyes) is still a matter of discussion. Historically considered as freshwater organisms, hypotheses of euryhaline ecology including migratory behaviour were recently proposed based on the histology of their dorsal spines. However, recent studies still argued for a full freshwater ecology based on...

Sebecids constitute a family of notosuchian crocodylomorphs of probable terrestrial habits. They are notable for having survived the Cretaceous-Paleogene mass extinction and are known until the Miocene in South America. However, ecological traits that favoured their resilience in continental ecosystems remain unknown. Here, using a multi-isotopic a...

Located in the French Southern Alps, the Cerveyrette area is a watershed of about 100 km2 including a torrent and a high-altitude swampy plain dominated by a nival regime. The apparent cyclicity of very small magnitude in the δ18O (− 14.4 ± 0.6 ‰) of the river waters is interpreted to partly reflect seasonal variations in the isotopic compositions...

Dinosaur eggshell fragments attributed to the oofamilies Spheroolithidae and Prismatoolithidae and recovered from the latest Cretaceous Kakanaut Formation of North-eastern Russia (Chukotka) constitute one of the northernmost records of dinosaur reproductive behaviors. The high palaeolatitude of the locality (~75° N), as well as the cool near-polar...

Most of our knowledge of past seawater temperature history is based on δ18O values of calcium carbonate fossil shells. However, the determination of past temperatures using this proxy requires the knowledge of past seawater δ18O values, which is generally poorly constrained. Other paleothermometers using carbonate archives, such as Mg/Ca ratios and...

Excess nutrients from agricultural and urban development have created a cascade of ecological crises around the globe. Nutrient pollution has triggered eutrophication in most freshwater and coastal ecosystems, contributing to a loss in biodiversity, harm to human health, and trillions in economic damage every year. Much of the research conducted on...

Deep-sea hydrothermal vent communities, revealing patterns of niche partitioning, live in a limited area characterised by sharp physico-chemical gradients. In this study, we investigated carbon, sulfur, nitrogen stable isotopes as well as arsenic (As) speciations and concentrations for two snails (Alviniconcha sp. and Ifremeria nautilei) and a crus...

La dernière période interglaciaire (Last Interglacial, LIG, ou Stade Isotopique Marin 5.5, SIM 5.5), comprise entre ≈129 et ≈116 milliers d'années avant aujourd'hui (ci-dessous ka), est peu documentée, en particulier en domaine continental en raison de la rareté des dépôts attribuables à cette période qui correspond à l'Eemien dans la chronostratig...

The Last Interglacial (LIG or Marine Isotopic Substage 5.5, MIS5.5), which is comprised between ≈129 and ≈116 thousand years Before Present (hereafter ky BP), is poorly documented, especially in continental areas, owing to the scarcity of deposits attributable to this period, which corresponds to the Eemian in the chronostratigraphy of northwestern...

Most of our knowledge of past ocean temperature history is based on the δ18O measurements of calcium carbonate fossil shells. However, the determination of past temperature using this proxy requires the knowledge of past ocean δ18O, which is generally poorly constrained. Other carbonate-based paleothermometers, such as Mg / Ca ratios, and clumped i...

Stable hydrogen isotope measurement of body tissues faces analytical and interpretative challenges such as hydrogen exchange with atmosphere or competitive influence of drinking water and food intake. Samples from the Gallic site of Thézy-Glimont, France, have already been investigated isotopically for climate reconstruction and diet investigation...

Ribemont‐sur‐Ancre, France, is the biggest excavated human skeletal assemblage of Northern Gaul. It is interpreted as a post‐battle deposit constructed to celebrate war. However, the chronology of the site, its organization and the origin of the buried warriors are still poorly understood. These problems are studied by a multi‐proxy approach, based...

The vertebrate fossil record documents a plethora of transitions between aquatic and terrestrial environments but their causes are still debated. Quantifying the salinity of living environments is therefore crucial for precising the sequence of ecological transitions. Here, we measured lithium stable isotope composition of mineralized tissues (δ7Li...

The northeastern region of Iberia constitutes a natural pass-area for arriving populations into the peninsula and becomes a key area to understand Neanderthal resilience to changing environmental conditions experienced during Marine Isotope Stage 3 (MIS 3; 60–30 ka). Short-term but repeated occupations by Neanderthal groups occurred in Teixoneres C...

Strategies used by marine vertebrates to regulate their body temperature can result in local variations, and the knowledge of these regional heterothermies is crucial for better understanding the thermophysiologies of extant and extinct organisms. In order to investigate regional heterothermies in vertebrates, we analysed the oxygen isotope composi...

Tiupampa fauna (Santa Lucia Formation, Bolivia, Lower Paleocene) is of particular interest because representatives of the sebecids (Zulmasuchus querejazus (Buffetaut & Marshall 1992)), this family of altirostral notosuchians to which an exclusively terrestrial ecology is attributed (Pol et al., 2012), are found there. Through the multi-isotopic geo...

The Alps Mountains play a major role in the water cycle at a regional scale in Europe. This mountain range acts as the ‘water tower’ of Europe by storing large volumes of ice and snow, and by regulating the runoff of the rivers constituting freshwater reservoirs of paramount importance for the biodiversity and human activity. Located in the French...

The Gauls, who occupied most of Western Europe during the Second Iron Age (500 BCE–50 BCE), exploited their environ- ment through farming and trading of local resources. The study of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes of 8 humans and 12 animals from the Gallic site of Thézy-Glimont, Picardie, France, provides an insig...

Periods of high atmospheric CO2 levels during the Cretaceous–early Paleogene (∼ 140 to 34 Myr ago) were marked by very high polar temperatures and reduced latitudinal gradients relative to the Holocene. These features represent a challenge for most climate models, implying either higher-than-predicted climate sensitivity to atmospheric CO2 or syste...

Strategies used by marine vertebrates to regulate their body temperature can result in local variations, and the knowledge of these regional heterothermies is crucial for better understanding the thermophysiologies of extant and extinct organisms. In order to investigate regional heterothermy in vertebrates, we analysed the oxygen isotope compositi...

Here we report on the oxygen isotope compositions of four proposed apatite reference materials (chlorapatite MGMH#133648 and fluorapatite specimens MGMH#128441A, MZ-TH, and ES-MM). The samples were initially screened for 18O/16O homogeneity using secondary ion mass spectrometry (SIMS) followed by δ18O determinations in six gas source isotope ratio...

Past environments of the Earth's surface may be deciphered and modelled using stable isotopes along with mineralogical, sedimentological, biological, palaeontological, chemical and climatological methodologies. This volume is devoted to studies investigating the distribution of stable isotopes in precipitation and groundwaters and their interaction...

The volume is devoted to Earth Surface environmental reconstructions and environmental changes, which may be deciphered and modeled using stable isotopes along with mineralogical/chemical, sedimentological, palaeontological/biological and climatological methodologies. The book is divided into two sections, both of them using stable isotopes analysi...

The evolution of thermometabolism in pseudosuchians (Late Triassic to the present) remains a partly unsolved issue: extant taxa (crocodilians) are ectothermic, but the clade was inferred ancestrally endothermic. Here we inferred the thermometabolic regime of two neosuchian groups, Goniopholididae (Early Jurassic to Late Cretaceous) and Dyrosauridae...

This volume is devoted to Earth surface environmental reconstructions and environmental changes that may be deciphered and modelled using stable isotopes along with mineralogical/chemical, sedimentological, palaeontological/biological and climatological methodologies. The book is divided into two sections, both using stable isotopes (δD, δ ¹⁸ O, δ...

Stable isotopes of hydrogen, carbon and oxygen are used to investigate numerous physical and chemical processes in the water and inorganic carbon cycles. Measuring and comparing natural isotopic variations requires reliable primary reference materials and consistent data treatment. However, these reference materials have changed over time, while ad...

Periods of high atmospheric CO2 levels during the Cretaceous-Early Paleogene (~140 to 33 My ago) were marked by very high polar temperatures and reduced latitudinal gradients relative to the Holocene. These features represent a challenge for most climate models, implying either higher-than-predicted climate sensitivity to atmospheric CO2, or system...

The hard and soft tissue remains of a pre-Hispanic population of the Gran Canaria Island at six different archaeological localities were studied using 14C dating and stable isotope compositions. Radiocarbon dating indicates island occupation ranging from the beginning of the 7th to the mid-14th century. We analyzed the oxygen isotope compositions o...

The evolution of Earth's atmosphere is of extreme importance to the lithosphere, hydrosphere and biosphere. This is particularly true for the role the biosphere played in the inceptual formation of atmospheric oxygen, and subsequently in its potential role in the evolution of higher life forms. Quantifying the change in atmospheric oxygen with geol...

The climate shift of the Last Glacial Maximum (LGM) strongly impacted the vegetation cover and related trophic chains of western Europe. Harsh, cold and dry conditions then prevailed in most regions, strongly impacting migrations and survival of human beings. Nonetheless, environments suitable for mammalian fauna to survive persisted in SW Europe t...

We investigated the environmental conditions that prevailed in continental ecosystems recorded in sedimentary deposits of Japan during the Cretaceous through the analysis of oxygen and carbon isotope compositions of phosphate (δ¹⁸Op) and apatite-bound carbonate (δ¹⁸Oc and δ¹³Cc) of vertebrate teeth and bones. Local surface water δ¹⁸Ow values were c...

The Roman Warm Period (from ≈300 BCE to ≈300 CE) is a climatic optimum, which had a key role in the development of the Roman civilization. This study provides new Mean Air Temperatures (MATs) inferred from the oxygen isotope composition of 80 bones and teeth apatite from 8 humans and 8 animals of the Gallic site of Thézy-Glimont, Picardie, France,...

Millions of mummified birds serving for religious purpose have been discovered from archeological sites along the Nile Valley of Egypt, in majority ibises. Whether these birds were industrially raised or massively hunted is a matter of heavy debate as it would have a significant impact on the economy related to their supply and cult, and if hunted...

d2H and d18O values of precipitations follow an empirical linear relationship at the global scale that is called the Global Meteoric Water Line (GMWL) and characterized by a slope of 8. However, Local Meteoric Water Lines (LMWL) may have different slopes S depending on their geographic situation. Monthly d2H and d18O of precipitation have been comp...

For the first time, we present a decadal-scale stable isotope record (δ18O, δ13C) of sixty-seven speleothem calcite samples coming from an artificial tunnel network located in Graz, Austria. Stable isotope data are interpreted with the help of Time Series (TS) analysis of mean air temperatures (MAT) and mean annual precipitations (MAP) that have be...

Stable isotope compositions of ancient halite fluid inclusions have been recognized to be valuable tools for reconstructing past environments. Nevertheless, in order to better understand the genesis of halite deposits, it could be of great interest to combine both δ2H and δ18O measurements of the water trapped as inclusions in the defects of the mi...

The late Permian dicynodont Endothiodon is characterized by its specialized feeding system, most notably manifested in its long rows of post-canine teeth and corresponding keratinous surfaces. This specialisation has fuelled discussion of not only the masticatory biomechanics in Endothiodon but also of its diet and ecology. To shed light on the lat...

Earth's atmosphere was not always rich in oxygen and the timeframe for proliferation of free oxygen remains unresolved. Without oxygen, metazoan life would not have evolved and nor would the explosion of vertebrate fossils have occurred. The rise of free oxygen is a key to life on Earth. Mid-proterozoic BIF's provide a time constraint for Earth's f...

Minerals of the apatite group, especially hydroxylapatite Ca5(PO4)3OH, are valuable archives for reconstructing environmental conditions occurring throughout the Earth's history (e.g., Joachimski et al. 2009). Apatite oxygen isotope compositions have proved useful in studies of conodonts as well as fish and mammalian teeth and bones. Secondary ion...

Oxygen concentration in the Precambrian atmosphere-ocean system is currently estimated from a series of geochemical proxies that depend on the concentration of redox-sensitive trace elements or their isotopic ratios measured in organic-bearing marine shales. This research has indicated that atmospheric oxygen content throughout the Precambrian was...

The Canary Islands, east of the North Atlantic Ocean (27°N-29°N), are under the influence of the Canary Current, the descending branch of the North Atlantic Gyre, which is modulated by coastal upwelling off North-West Africa. They constitute strategic sites for palaeoclimatic reconstructions, especially for the Last Interglacial (LIG, 129 to 116 ky...

δ²H were measured in water present in tiny primary fluid inclusions trapped in Mesoproterozoic (≈1.4 Ga) and Neoproterozoic (≈0.8 Ga) halite crystals. While the hydrogen concentrations range from 300 to 1500 ppm for the whole sample collection, δ²H values range from −74‰ to −54‰ (VSMOW) for the Mesoproterozoic halite sampled from the Sibley Group,...

Recurrent long-and short-term Neanderthal occupations occurred in the Abric Romaní rock shelter (Capellades, Barcelona, Spain) for more than 20,000 years. This provides an opportunity to enhance our understanding of the evolution of behavioral strategies of these human groups. The site has a long and high-resolution sequence with 17 levels complete...

Reconstructing the living environment of extinct vertebrates is often challenging due to the lack of proxies. We propose a new proxy to the living environment based on the combined oxygen and sulphur stable isotope analysis of vertebrate hydroxyapatite. We tested this isotopic proxy to 64 biogenic apatite (bones) samples that represent a wide spect...

Teleosauridae and Metriorhynchidae were thalattosuchian crocodylomorph clades that secondarily adapted to marine life and coexisted during the Middle to Late Jurassic. While teleosaurid diversity collapsed at the end of the Jurassic, most likely as a result of a global cooling of the oceans and associated marine regressions, metriorhynchid diversit...

Abstract: This paper aims to provide some elements of reflection focus on the use of radiocarbon and the design of the different hypotheses about the establishment of North African populations in the Canary Islands. In addition, a set of carbon 14 dates from some funeral contexts of Gran Canaria are presented. These new dates, together with others...

The study of paleoclimates enables us to improve and better constrain climate models in order to forecast future climate variations. Marine Isotope Stage 11 (MIS11), which began around 425,000 yr BP and lasted about 65,000 yr, is a warm isotope stage of paramount importance, because the astronomical configuration was similar to the one characterizi...

Fossiliferous bioclastic calcarenites of fluvial-aeolian origin were deposited between 4.3 ± 0.7 Ma and 3.78 ± 0.71 Ma in Lanzarote, Canary Archipelago. Climate was characterized by warm and steppic conditions. The fossil assemblage contains land snail shells that recrystallized into calcite as revealed by Raman spectroscopy. Carbon and oxygen isot...

The Abrahamskraal Formation of South Africa has a diverse middle Permian (Guadalupian) fossil tetrapod fauna comprising largely basal therapsids and pareiasaurian parareptiles. Knowledge on the paleoecology of these animals is limited because inferences of many ecological traits in mid-Permian tetrapods are based on deductions from morphology. Whil...

In addition to the collagen and phosphate components of bones and teeth, the stable carbon and oxygen isotope compositions of skeletal carbonate are frequently measured to determine diet, environmental conditions, and populational or individual migration in bioarchaeological research. A standardized method for the stable isotopic analysis of skelet...

The large range of stable oxygen isotope values of phosphate‐bearing minerals and dissolved phosphate of inorganic or organic origin requires the availability of in‐house produced calibrated silver phosphate of which isotopic ratios must closely bracket those of studied samples. We propose a simple protocol to synthesise Ag3PO4 in a wide range of o...

Small mammals, especially rodents, constitute valuable proxies for continental Quaternary environments at a regional and local scale. Recent studies have demonstrated the relation between the stable oxygen isotope composition of the biogenic phosphate from rodent teeth (δ18Op), and the oxygen isotope composition of meteoric waters (δ18Omw), which i...

The chemical and isotopic compositions of biogenic apatite are important geochemical markers, which can suffer modifications during fossilisation. Compared with modern ones, fossil apatites generally exhibit variations in carbonate content, enrichment in fluorine, incorporation of trace elements and an increase in crystallinity parameters. Detailed...

Early Pleistocene (Calabrian) clays of the Lindos Bay Formation have been uplifted and are exposed today on the eastern coast of Rhodes (Hellenic forearc, Greece). The hemipelagic origin of these sediments and the excellent preservation of the microfossils they contain, make the Lindos Bay Formation a unique element in the eastern Mediterranean, wh...

The Toarcian oceanic anoxic event (T-OAE; 183 Ma) was accompanied by severe biotic and geochemical perturbations that are considered as some of the most severe of the Mesozoic era. Nevertheless, paleoceanographic conditions during the T-OAE in the Tethyan domain remain poorly understood owing to the relatively low number of marine successions from...

The Vocontian Basin (SE France) which presents lower Aptian expanded successions characterized by major lithological changes, is particularly suitable to determine palaeoenvironmental changes occurring across the OAE 1a. A multidisciplinary study (sedimentology, CaCO3, TOC, carbon and oxygen stable isotopes, micropalaeontology, cyclostratigraphy) w...

How to gain insight into past climate and ecology from plant fossils has been a major concern of palaeobotanists during the last decades. Prof. Chaloner was one of the main leading minds in this field, leaving a heritage of innovation and creative thinking in the use of plant fossils as palaeoproxies. His legacy has inspired numerous research lines...

The relationship between palaeoclimate warming and cyclone frequency is still poorly understood, even though tempestites (i.e. storm deposits) may be abundant in Greenhouse period deposits. The Kimmeridgian marl-limestone alternations of the North Aquitaine Platform include abundant tempestites that formed in shallow to moderate-depth marine enviro...

The late Capitanian mass extinction (˜260 million years ago) represents one of the greatest biotic perturbations of the Phanerozoic and was the earliest mass extinction to affect terrestrial tetrapods and ecosystems. In the past, this extinction has been largely associated with taxonomic loss and ecological restructuring in marine environments but...

66 million years ago, sea temperatures rose rapidly as a result of environmental perturbations

The fish-to-tetrapod transition-followed later by terrestrialization-represented a major step in vertebrate evolution that gave rise to a successful clade that today contains more than 30,000 tetrapod species. The early tetrapod Ichthyostega was discovered in 1929 in the Devonian Old Red Sandstone sediments of East Greenland (dated to approximately...

The study outlined in this article was carried out within the framework of ESA's PROSPECT programme, which will provide both a sample drill and miniaturised mass spectrometer system for flight on-board the planned Russian Luna-27 mission to the lunar south pole. There, it aims to collect samples of regolith, containing water ice and other volatiles...

Brachiopods are usually attached benthic marine invertebrates with a shell (exoskeleton) that archives modifications of the environment via chemical proxies. Growth lines regularly occurring (i.e. excluding random ones) at the shell's surface reflect phenotypically controlled interruptions or changes in secretion (Williams et al., 1997). Modificati...

The late Capitanian mass extinction (~260 million years ago) represents one of the greatest biotic perturbations of the Phanerozoic and was the earliest mass extinction to affect terrestrial tetrapods and ecosystems. In the past, this extinction has been largely associated with taxonomic loss and ecological restructuring in marine environments but...

Earthquakes or explosive eruptions generate tsunami, which are at the origin of thick and chaotic coastal sediments. These commonly fossiliferous deposits are formed instantaneously at the historical or geological timescale and therefore have the potential to provide snapshot records of past climates. In Crete, near the city of Palaikastro, crops o...

Deep-sea vent communities live on a limited area characterised by sharp physico-chemical (temperature, salinity, pH) gradients. Around the vent, the fauna is distributed accordingly, showing characteristic niche partitioning for different groups of animals. In this study we investigate shell microstructure, minor elements and stable isotope composi...

Quantification of paleoprecipitation during the Last Glacial is a key element to reconstruct palae- oclimates. Recently, fossil calcite granules have been identified in loess sequences with high contents in specific horizons. In this study, we explored for the first time the potential of this new bio-indicator as a climatic proxy for precipitation...