Stable isotope distribution in Maastrichtian vertebrates and paleosols from the Haţeg Basin, South Carpathians

Palaeogeography, Palaeoclimatology, Palaeoecology 293 (2010) 329–342

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Palaeogeography, Palaeoclimatology, Palaeoecology j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / p a l a e o

Stable isotope distribution in Maastrichtian vertebrates and paleosols from the Haţeg Basin, South Carpathians Ana-Voica Bojar a,⁎, Zoltan Csiki b, Dan Grigorescu b a b

Institute of Earth Sciences, Geology and Palaeontology, Karl-Franzens University, Heinrichstrasse 26, A-8010 Graz, Austria Department of Geology and Geophysics, Bucharest University, Bd. Bălcescu 1, R-010041 Bucharest, Romania

a r t i c l e

i n f o

Article history: Received 9 March 2009 Received in revised form 28 May 2009 Accepted 28 August 2009 Available online 10 September 2009 Keywords: Dinosaur Crocodilian Turtle Paleosols Calcrete Stable isotopes Clay mineralogy Palaeoenvironment Palaeoecology Haţeg Basin Maastrichtian

a b s t r a c t Located in the South Carpathians in Romania, the Haţeg Basin contains a thick sequence of Maastrichtian continental deposits yielding a rich dinosaur and mammalian fauna. Stable isotope analyses of both calcretes and dinosaur, crocodilian and turtle remains from two localities (Tuştea and Sibişel) were integrated in order to reconstruct environmental conditions during Maastrichtian time and to gain further insights into the metabolism and behaviour of the vertebrates. The large difference observed between the δ18O and δ13C of the eggshells and the surrounding mudstones, as well as the preservation of the 9‰ difference between the oxygen isotope composition of the Telmatosaurus eggshell and tooth enamel, indicate that diagenesis has not significantly altered the primary isotopic signal. The presence of smectite in the fraction less than 2 μm and the preservation of dinosaur eggshell structure also indicate that diagenesis was not significant in the studied outcrops. Stable isotope compositions of both calcretes and phosphatic remains suggest warmer conditions during the deposition of the Tuştea sequence (mean annual temperature of around 14 °C) than during the deposition of the Sibişel sequence (mean annual temperature of 10 °C). The intra-tooth δ18O patterns for Zalmoxes and Allodaposuchus show different magnitudes of isotopic variation, with lower values for Tuştea and higher for Sibişel. The calculated δ18Obody water enrichment for Kallokibotion bajazidi is similar to that found in living turtle taxa. By contrast, in the case of Allodaposuchus, the isotopic enrichment is higher than for recent taxa. This suggests that, for Allodaposuchus, the body water was less buffered by a watery environment, which probably indicates more time spent outside water (i.e. more terrestrial habit). The δ18O values for the teeth of Telmatosaurus and Zalmoxes are similar to those of Allodaposuchus, suggesting that, at the investigated sites, the body temperature of both dinosaurs was similar to that of the crocodile. The isotopic composition of calcretes, teeth and eggshells indicates a C3 vegetation and diet with δ13C values between − 27 and − 29‰ (PDB) and the absence of large-scale habitat partitioning between the dinosaurs. © 2009 Elsevier B.V. All rights reserved.

1. Introduction In the Haţeg Basin, there has been a long and interesting tradition of research activity on the Late Cretaceous faunal assemblages, which started with Franz von Nopcsa. Nopcsa studied the bone material discovered in his neighborhood and published several papers concerning the deposits and their dinosaur, pterosaur, turtle, and crocodilian assemblages (Nopcsa, 1900, 1902, 1914, 1926). After a long time gap, systematic research commenced again in the 1980s. Through these studies, the lithostratigraphy and chronostratigraphy of the deposits have been updated (Antonescu et al., 1983; Grigorescu, 1990; Grigorescu and Melinte, 2001; Grigorescu and Csiki, 2002). Several small theropods (Grigorescu, 1984; Weishampel and Jianu, 1996; Csiki and Grigorescu, 1998; Ősi and Főzy, 2007) and mammals (Grigorescu, 1984; Rădulescu and Samson, 1986; Grigorescu

⁎ Corresponding author. E-mail address: [email protected] (A.-V. Bojar). 0031-0182/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2009.08.027

and Hahn, 1987; Csiki and Grigorescu, 2000; Codrea et al., 2002) have been discovered as well, with a regular increase of the number of identified taxa. New discoveries also include dinosaur eggs and hatchlings (Grigorescu et al., 1990; Grigorescu, 1993; Codrea et al., 2002; Smith et al., 2002) along with remains of hatchlings of the hadrosaurid Telmatosaurus transsylvanicus (Weishampel et al., 1993). A giant pterosaur, Hatzegopteryz thambema, one of the largest flying creatures in the world, was also discovered in the region (Buffetaut et al., 2002). Besides dinosaurs, mammals and pterosaurs, various other vertebrates were reported, including frogs (Venczel and Csiki, 2003), albanerpetontids (Grigorescu et al., 1999; Folie and Codrea, 2005), turtles and crocodilians (Buscalioni et al., 2001; Martin et al., 2006), and their palaeontological relevance was reassessed. Csiki (2005) and Grigorescu (2005) and Csiki et al. (this volume) present a list of the faunal assemblage of the dinosaur-bearing deposits from the Haţeg basin, which included around 70 taxa. The faunal assemblage was found in continental deposits of Maastrichtian age, situated at that time at a subtropical latitude between two marine domains: the Penninic to the north and the

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Tethys to the south (Camoin et al., 1993). The presence of smectites as the main clay minerals in the paleosols and the absence (or the minimal presence up to a few percent) of kaolinite also support a subtropical position. Several fossiliferous levels were identified within the red silty mudstones from Tuştea and in the Sibişel Valley, the paleosols from these sites being characterized by the presence of pedogenetic calcrete horizons (Bojar et al., 2005; Therrien, 2005). Since this study investigates the stable isotope composition of calcretes, dinosaur eggs, dinosaur and crocodilian tooth enamel and turtle shell, we will first provide a brief overview of the carbon and oxygen stable isotopes as contextual information in palaeoenvironmental and palaeoecologicals studies. Pedogenic calcretes are formed in paleosols under arid to semi-arid conditions. Retallack (1991) provides an extended discussion concerning the definition of paleosols (ancient soils), as well as the formation mechanisms of calcretes. The stable oxygen isotope composition of pedogenic calcretes is generally related to the composition of soil water, which is in turn relates to the isotopic composition of precipitation in the area and the mean annual temperature (MAT; Cerling and Quade, 1993). The presence of C3 versus C4 biomass (Park and Epstein, 1960) and the CO2 concentration in the air control the carbon isotopic composition of carbonate concretions (Cerling, 1984; Quade et al., 1989). Fluctuation of the carbon isotopic composition of a few permil may be induced by physiological effects of the plants, arid conditions leading to closing of stomata, and higher fractionation (Farquhar et al., 1989). Data from calcitic eggshells of dinosaurs, crocodiles and birds collected from contrasting climatic regions have shown that the δ18O of eggshells are linearly related to the δ18O of water ingested by the species and body water (Folinsbee et al., 1970; Erben et al., 1979; Sarkar and Bhattachary, 1991; Schaffner and Swart, 1991; Tandon et al., 1995; Johnson et al., 1998; Cojan et al., 2003), which is further related to the local meteoric water and MAT. The δ13C value of the eggshells is controlled by ingested or stored food, but is also strongly modified through metabolic fractionation (Folinsbee et al., 1970; von Schirnding et al., 1982; Freundlich et al., 1989; Schaffner and Swart, 1991; Hobson, 1995). Enamel, dentine and bones have inorganic/organic components in variable proportions between the different tissues. The organic component is present as collagen, a fibrous protein. The inorganic component is found as hydroxylapatite Ca5(PO4)3(OH), which also contains a small amount of carbonate substituting for phosphate and hydroxyl ions. The carbon and oxygen isotopic composition of phosphate have long been considered a potentially useful record of climate, diet, trophic level and migration. It has been demonstrated that tooth enamel is less porous than bone, contains less than 5% organic matter, and has larger apatite crystals (LeGeros, 1981). For this reason, enamel is more resistant to diagenesis and suitable for isotopic investigations and reconstructions of ancient conditions (Sharp et al., 2000). Luz et al. (1984) developed a mass balance equation based on the fact that the isotopic composition of body water depends on the total oxygen flux through the body for which: a) the principal oxygen inputs are atmospheric O2, liquid water and food; b) the principal outputs are oxygen in water (liquid and vapor) and CO2. So body water is a mixture between drinking water and metabolic water produced during the oxidation of food with oxygen from the atmosphere. The equation predicts a linear relationship between the composition of body water and that of ingested water for mammals that do not obtain the majority of the ingested water from plant leaves or other highly fractionated sources. Such relationships have been demonstrated for some groups of mammals (Luz and Kolodny, 1985; D'Angela and Longinelli, 1990; Ayliffe et al., 1992; Bryant et al., 1994; Chillion et al., 1994; Cormie et al., 1994; Huertas et al., 1995; Huertas et al., 1995; Longinelli, 1996; Reinhard et al., 1996; Kohn et al., 1996; Fricke and O'Neil, 1996; Stuart-Williams and Schwarz, 1997; Fricke

et al., 1998). Furthermore, since rain and drinking water are related to mean annual temperature (Dansgaard, 1964; Fricke and O'Neil, 1999), then the δ18O value of body water, via drinking water, is also related to the ambient temperature. Moreover, it has been shown that fossil teeth may preserve even short-term seasonal variations of drinking water, as well as those of feeding patterns (Fricke and O'Neil, 1996; Sharp and Cerling, 1998). The carbon isotopic composition found in mammal phosphates is mainly controlled by the proportion of C3 to C4 in their diet, trophic level, and spatial niche partitioning (Longinelli and Nutti, 1973; LeeThorp and van der Merwe, 1987; Quade and Cerling, 1990; Thackeray et al., 1990; Quade et al., 1992; Wang et al., 1993; Wang et al., 1994; MacFadden, 1994; MacFadden and Cerling, 1996; Koch, 1998; Thorp and Sponheimer, 2005). The oxygen isotopic compositions of biogenic apatite from crocodiles, turtles and dinosaurs, and their relationship to climate and physiology have been evidenced by several studies (Barrick and Showers, 1995; Kolodny et al., 1996; Barrick et al., 1999; Fricke and Rogers, 2000; Stoskopf et al., 2001; Straight et al., 2004; Amiot et al., 2007). To date, few attempts have been made to correlate the enamel δ13C to dietary resources of dinosaurs (Bocherens et al., 1988; Stanton Thomas and Carlson, 2004; Fricke and Pearson, 2008; Fricke, et al., 2008). One additional complication is that for dinosaurs, the δ18O of enamel phosphate depends on both body water and variations in body temperature. Several studies have addressed the issue of endothermy versus ectothermy of fossil vertebrates by studying inter- and intra-bone and enamel isotopic variability (Barrick and Showers, 1994, 1995; Barrick et al., 1996, 1998; Fricke and Rogers, 2000). More recent investigations provide evidence for intertooth temporal variations and related them to seasonality and/or changes in physiology (Straight et al., 2004; Stanton Thomas and Carlson, 2004). The main objectives of this study are to extract palaeoclimatic information (mean annual temperature, relative humidity) considering, besides lithofacial characteristics, the isotopic distribution of carbonates formed in paleosols and the stable isotope composition of vertebrate remains from the Haţeg Basin. We also sampled several teeth along their growth axis in order to get further information about growth rates and the amplitude of isotopic variation. Two outcrops were studied, one from Tuştea, in the northern part of the basin, and one along the Sibişel valley, in the southern part of the basin. The wellexposed outcrops are known for their rich vertebrate remains. Bojar et al. (2005) and Therrien (2005) described the facies characteristics of these outcrops, which indicate the presence of different depositional environments. 2. Geology of the region Stilla (1985) and Pop (1990) divided the Upper Cretaceous sequences within the Haţeg Basin (Fig. 1) into sedimentary groups, separated by local unconformities. In this volume, Melinte–Dobrinescu presents a detailed Upper Cretaceous stratigraphy. Since our study concerns only the latest part of this stratigraphical succession, we will review here the Maastrichtian to lower Palaeogene continental molasse deposits described as the Densuş–Ciula and the Sânpetru formations (Grigorescu et al., 1990; Grigorescu 1992). In the region, Late Cretaceous basin subsidence correlates with the stacking of the Getic nappe on top of the Danubian unit, as well as uplift of the surrounding areas and orogenic collapse (Bojar et al., 1998; Willingshofer, 2000; Willingshofer et al., 2001). In a regional frame, this phase corresponds to the Late Cretaceous so-called Laramide Orogeny (Săndulescu, 1984). Burial of Maastrichtian strata by younger deposits was limited to a few hundred meters. The Densuş–Ciula Formation crops out in the northwestern part of the basin and is divided into three members (Anastasiu and Csobuka, 1989; Grigorescu et al., 1990a). The lower Densuş–Ciula member

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Fig. 1. a) Geological map of the study area; b) Haţeg basin: the distribution of the Densuş-Ciula and Sânpetru formations are shown.

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contains coarse volcanoclastic deposits with interbedded lacustrine marls, which lie discordantly on top of uppermost Campanian flysch deposits (Grigorescu and Melinte, 2001; Melinte–Dobrinescu, this volume). The middle Densuş–Ciula member, with a total thickness of 2 km, is represented by matrix-supported conglomerates, cross-bedded sandstones and massive red and grey mudstones. These mudstones contain fossil dinosaur eggs, bones, teeth, mollusc shells and plant remains (Grigorescu et al., 1990; Grigorescu et al., 1994; Csiki and Grigorescu, 1998). A Maastrichtian age is indicated by freshwater gastropod assemblages, including Bauxia bulimoides, Gastrobulimus munieri, Rognacia abreviata, Ajkaia cf. gregaria, and a palynological assemblage, with Pseudopapilopollis praesubhercynicus (Antonescu et al., 1983; Pană et al., 2002; Bojar et al., 2005; Van Itterbeeck et al., 2005). The dinosaur assemblage includes Magyarosaurus dacus, Zalmoxes robustus, Zalmoxes shqiperorum, Telmatosaurus transsylvanicus, and Euronychodon, among others (Grigorescu and Csiki, 2002, Weishampel et al., 2003). The (possibly Palaeogene) deposits of the upper Densuş–Ciula member contain neither volcanoclastic material, nor dinosaur remains. The Sânpetru Formation is restricted to the central and southern parts of the basin and is represented by a wide range of terrigenous deposits ranging from conglomerates to mudstones. The lower part of the succession is predominantly red and brown, while the upper part is predominantly dark gray (Grigorescu, 1992). In fact, the middle Densuş–Ciula member and the Sânpetru Formation, represent end members of a transition between a facies dominated by the development of an alluvial plain with low sedimentation rates and frequent paleosol levels, and a facies dominated by the presence of alluvial channels and adjacent alluvial plains (Van Itterbeeck et al., 2004; Bojar et al., 2005; Therrien, 2005). In the Haţeg Basin, the transition from Maastrichtian to Lower Palaeogene deposits (mostly represented by conglomerates) is inaccessible; therefore no direct observation regarding this aspect could be made.

3. Methods and material studied Isotopic analyses of carbonates were performed using an automatic Kiel II preparation line and a Finnigan MAT Delta Plus Mass Spectrometer. The reaction with H3PO4 (with a density of 1.95) was carried out at 70 °C. NBS-19 and an internal laboratory standard were continuously analyzed for accuracy control. The standard deviation of NBS-19 and the internal laboratory standard was 0.1‰ for both δ18O and δ13C. All isotopic results are reported in per mil, relative to SMOW and PDB, respectively. Eggshell fragments were cleaned in an ultrasonic bath and sampled using a 0.5 mm drill. We analyzed several well-preserved teeth of two herbivorous dinosaurs (Telmatosaurus and Zalmoxes) and a crocodilian (Allodaposuchus), as well as shell material of a turtle (Kallokibotion bajazidi). In order to document intra-tooth variations, serial measurements along the tooth growth direction were made for several teeth, since enamel is considered the best material to analyze in order to obtain the unaltered isotopic signal. The stable carbon and oxygen isotope analysis of fossil tooth enamel was performed using the laser ablation GC-IRMMS (gas chromatography–isotope ratio monitoring mass spectrometry) technique, as described by Cerling and Sharp (1996). The δ18O and δ13C data given in Tables 2 and 3 represent the oxygen isotopic composition of the (PO4)3− and (CO3)2− ions, respectively. The tooth surface was first cleaned using abrasion and an ultrasonic bath. The stable isotope data are summarized in Tables 1, 2 and 3, as well as in Figs. 4 and 5. Cathodoluminescence investigations on calcretes and dinosaur egg shells were done using a Citl Cold Cathodoluminescence 8200 mk3 electron gun, a vacuum chamber with windows, and stage X–Y

Table 1 Stable isotope composition of carbonates. Location

Sample

Sample description

δ18O δ13C (SMOW) (PDB)

ma1

Mudstone (calcite cement) Mudstone Mudstone Mudstone Mudstone Mudstone Mudstone Mudstone Mudstone Dinosaur egg, calcite Egg Egg Egg Egg Egg Egg Egg Egg Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete

26.7

− 6.8

24.1 24.2 24.2 19.4 23.7 23.2 23.7 23.2 29.8 29.9 30.8 30.5 29.5 29.6 30.1 29.9 30.3 24.6 24.6 24.8 24.4 24.7 25.0 24.5 24.1 24.7 24.8 24.7 24.4 24.9 24.9 24.6 24.3 24.6

− 8.2 − 8.2 − 7.6 − 14.6 − 7.4 − 8.4 − 7.4 − 8.4 − 13.8 − 13.7 − 14.1 − 14.1 − 13.3 − 12.6 − 14.6 − 14.2 − 15.0 − 8.6 − 8.6 − 8.5 − 8.5 − 8.3 − 8.6 − 8.7 − 8.3 − 8.1 − 8.2 − 8.5 − 9.0 − 8.3 − 8.2 − 8.5 − 8.5 − 8.5

23.1 23.0 23.9 24.1 22.7 22.9 22.9 22.9 23.8 24.9 24.3 23.1 24.2 23.7 21.5 21.1 23.2

− 9.0 − 9.4 − 11.3 − 11.1 − 8.4 − 9.4 − 10.3 − 10.2 − 10.1 − 11.8 − 10.4 − 11.4 − 7.7 − 7.9 − 8.4 − 8.8 − 9.7

Tuştea

ma2 ma3 ma4 m4.1 m4.2.2 m4.3 m4.2.2 m4.3 egg1 egg1a egg2 egg2a egg3 egg3a egg2 egg2 egg2 CO3 CO3 CO2 CO1 c2.1 m2.1 c2.2 c4.1 c4.2.1 c4.2.2 c4.3.1 c4.3.2 c4.3.3 c4.4.1 c4.4.2 c5.2–2003 Mean value calcretes Location 6 Sibişel V. 18.1 18.2 18.3 18.4 20 22 22.8 22.9 22.10 25.1 25.2 25.3 27.1 27.2 29.1 29.2 Mean value calcretes

Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete Calcrete

movement. The stage is coupled to an Olympus BH-2 optical microscope. The measurement conditions were 17 kV and 450 mA. 4. Stable isotope distribution in calcretes and vertebrate remains At the Tuştea quarry, the 10 m vertical escarpment comprises two levels of massive red mudstones intercalated with conglomerates and cross-stratified sandstones. The bottom of the sequence consists of a massive red mudstone, followed by 4-meter-thick coarse-grained, poorly sorted sandstones and conglomerates with trough-cross to parallel stratification. The channel bodies show laterally crosscutting and alternating sandstones and conglomerates, which indicate unstable flow with discharge fluctuations. The coarse facies is interpreted as deposited from a stream flow. The inter-channel

A.-V. Bojar et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 293 (2010) 329–342 Table 2 Stable isotope composition of vertebrate remains. Location

Sample

Sample description

δ18O (SMOW)

δ13C (PDB)

Tuştea

Telmatosaurus Zalmoxes (2) Allodaposuchus Zalmoxes (1) Kallokibotion bajazidi Mean value

Tooth Tooth Tooth Tooth Shield

22.3 22.1 22.1 21.7 20.4 21.7

− 10.8 − 8.3 − 9.4 − 12.3 − 11.3 − 10.4

Telmatosaurus Zalmoxes Allodaposuchus Allodaposuchus Allodaposuchus Mean value

Tooth Tooth Tooth Tooth Tooth

19.1 22.2 19.9 21.7 20.7 20.7

− 10.8 − 9.3 − 12.3 − 12.2 − 10.6 − 11.0

Sibişel

areas were sites of pedogenesis. The soils show a red mud horizon with blocky structure characterized by the presence of welldeveloped vertical roots and burrows and a level with calcareous concretions. Paleosols can be classified as calcic oxisols (Mack and James, 1994). There are seven levels of calcretes with thickness and lateral continuity indicating moderately developed soils (Retallack, 2001). In the fraction less than 2 µm, smectite, a swelling clay mineral, dominates with up to 94 mass %. Other clay minerals present in very small amounts are illite in the range of 4 to 10 mass %, and kaolinite 2 to 4 mass % (Bojar et al., 2005). Several carbonate concretions were studied in thin section under cathodoluminescence, a powerful technique for distinguishing secondary diagenetic effects. These analyses revealed a brown, nonluminescent massive micritic groundmass, throughout which detrital grains of feldspar and quartz are dispersed (Fig. 2e). The carbonates show a narrow range of isotopic compositions, with δ18O values between 24.1 and 25.0‰ (SMOW) and δ13C between 8.1 to −8.9‰ (PDB) (Fig. 4a). Associated with one of the concretion layers, just

Table 3 Measurements across teeth (See Fig. 5). Location

Sample

Sample description

δ18O (SMOW)

δ18O (PDB)

δ13C (PDB)

Tuştea

Zalmoxes

Tooth

Allodaposuchus

Tooth

22.0 21.9 21.9 21.3 21.1 21.9 22.2 21.9 22.2 21.6 22.1 22.9 21.9 19.9 21.9 22.3 22.3 22.7 21.7 21.2 19.8 20.0 19.1 20.3 19.6 21.6 22.5 22.3 20.8

− 8.7 − 8.7 − 8.7 − 9.4 − 9.5 − 8.8 − 8.4 − 8.8 − 8.4 − 9.0 − 8.5 − 7.7 − 8.7 − 10.7 − 8.7 − 8.3 − 8.4 − 7.9 − 8.9 − 9.4 − 10.8 − 10.6 − 11.4 − 10.3 − 11.0 − 9.0 − 8.2 − 8.4 − 9.8

− 15.0 − 13.6 − 13.4 − 12.4 − 12.8 − 10.5 − 11.1 − 8.6 − 11.1 − 9.5 − 9.7 − 9.5 − 8.00 − 12.8 − 12.1 − 12.4 − 12.1 − 13.9 − 11.4 − 10.8 − 10.3 − 10.7 − 10.7 − 11.0 − 10.1 − 10.5 − 10.8 − 11.0 − 10.5

Sibişel

Allodaposuchus

Tooth

Allodaposuchus

Tooth

333

above it, dinosaur nests, together with embryonic/hatchling skeletal remains, were found. Based on these remains, the eggs are considered to belong to the hadrosaurid Telmatosaurus transsylvanicus (Grigorescu et al., 1994; Weishampel et al., 1993). Scanning electron micrographs and examination of thin sections under polarized light indicate that both the internal multistratified growth structure of the eggs and the external structure have been entirely preserved, with the eggshell showing a tubocanaliculate type of structure (Fig. 2a, b, c). Cathodoluminescence revealed a brown, non-luminescent mass (Fig. 2d). The eggshells yielded δ18O values between 29.5 and 30.5‰ (SMOW) and δ13C between −13.0 and −14.0‰ (PDB). Further evidence supporting the hypothesis that the initial isotopic ratios of the eggshells were not severely affected by diagenesis is that their δ18O and δ13C values are different from those of the associated sedimentary matrix, which in turn has an isotopic composition similar to that of the calcretes (Table 1). It is thus unlikely that any significant diagenetic alteration affected the eggs, since such effects tend to homogenize the isotopic composition between shells and matrix. Several teeth (Fig. 3) and a turtle shell fragment were analyzed, and the oxygen and carbon isotopic compositions of the phosphates are given in Table 2, 3 and Figs. 4, 5. The enamel δ18O data for Telmatosaurus transsylvanicus, Zalmoxes robustus and Allodaposuchus vary within a narrow range, between 21.7 and 22.3‰ (SMOW). Kallokibotion bajazidi shows a lighter signature of 20.4‰ (SMOW). The Sânpetru Formation crops out mainly along the Sibişel and Râul Mare valleys. The Sibişel valley opens from the center of the basin toward the south, yielding a profile with progressively younger deposits and with a vertical thickness reaching approximately 2 km. At location 6, in addition to the channel facies, sheets of parallelbedded sandstones up to 1 m thick are observed. The bottoms of the sand bodies show little erosion and are laterally associated with channel deposits. Floodplain sedimentation is represented by paleosols, for which the following horizons may be distinguished: a red horizon with parallel lamination and a level with moderate to welldeveloped concretions (up to 10 cm) underlined by parallel stratified mudstones with the color changing progressively from red to mottled textures involving grey-green and red drab-haloes. Paleosols from this outcrop are dominated by calcisols, and vertisols without a calcic horizon are found only sporadically. Smectite is the most frequent clay mineral, 55 to 68 mass %; subordinate chlorite and illite are also present. Both oxygen and carbon isotopic composition of calcretes show considerable variation, between 24.1 and 22.1‰ (SMOW), and −7.7 and −11‰ (PDB) respectively. The oxygen isotopic composition of dinosaur teeth varies between 19.1 and 22.2‰, the carbon between − 9.3 and −10.8‰. The oxygen isotope composition of Allodaposuchus varies between 19.9 and 21.7‰, that of the carbon isotope between − 10.6 and −12.3‰.

5. Discussions At Tuştea, the red color of the fine-grained sediments, the presence of calcretes with micritic texture and the deeply penetrating vertical root traces indicate that the soils formed above the water table under oxidizing, alkaline conditions (Retallack, 1991). These conditions were favorable for the preservation of egg and bone material. The thickness and distribution of the calcrete levels indicate multiply buried, moderate to strongly developed soils (Retallack, 1998), most probably formed on a stable terrace, close to the basin border. The soils point to vertical aggradations due to slow deposition of fine material and progressive burial, this pedofacies type is described as multiple buried soils (Daniels, 2003). The distance between the calcrete layers is not larger than 40 cm, and since there is no evidence for erosion, this suggests that the concretion layers formed at a depth less than 40 cm. According to Retallack (2001), this indicates that the mean annual rainfall did not exceed 600 mm. The preservation of

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Fig. 2. Telmatosaurus transsylvanicus. a) Egg surface; b) and c) Microscopic studies in parallel light indicate that the internal multistratified growth structure of the eggs have been entirely preserved; d) Cathodoluminiscence of a thin section perpendicular to the egg surface reveals a brown non-luminiscent mass; e) Thin section trough a calcrete nodule showing micritic texture with dispersed detrital grains.

smectites in the fraction less than 2 μm was also favored by generally dry climatic conditions (Chamley, 1989). The dinosaur nests lie just on top of a calcrete layer probably because the dinosaurs dug until they met the hard calcitic ground at a maximum depth of 40 cm. The red color of the mudstones from Tuştea, the presence of smectite, and the preservation of hematite suggest that the nesting dinosaurs preferred rather dry, well-oxygenated, finegrained sediments in order to maintain oxygen circulation through the eggshell canals. Burial of the eggs probably provided protection against mechanical damage and dehydration, as previously suggested by Erben et al. (1979) for Late Cretaceous dinosaur nesting sites in France. Similarly, present-day turtles also bury their eggs, in order to protect them from drying out. The profiles from Tuştea and from location 6 on the Sibişel valley show a similar type of soils, although those from Sibişel developed under much cooler and more humid conditions (Bojar et al., 2005). In the following section, we assess how the isotopic composition of sedimentary rocks and fossil remains from the investigated localities

constrain their genetic conditions and allow insights into the physiology of the Maastrichtian vertebrates.

5.1. Growth rates for dinosaur eggs and crocodile and dinosaur teeth The interpretation of the isotopic pattern for eggs and teeth must also take growth rates into account. Eggshell formation in birds (e.g. Gallus) is known to last for less than one day (Carpenter, 1999). Mean eggshell thickness in the Telmatosaurus eggs from Tuştea is reported to be 2.3–2.4 mm (Grigorescu et al., 1994), about 7 to 8 times thicker than in Gallus. Based on this difference, eggshell formation was probably more protracted, but still within the range of a few days. Similar to other biominerals, it is assumed that for birds, eggshell calcite reflects the oxygen isotopic composition of body water (Clarke et al., 2006). For modern birds, the time needed to reset the isotopic signature of the δ18O of ingested water and δ13C of food is about two weeks (Folinsbee et al., 1970; Hobson, 1995). Thus, we can assume

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Fig. 3. Tuştea Quarry: a) Zalmoxes teeth; b) Telmatosaurus transsylvanicus tooth; c) Allodaposuchus tooth.

that the dinosaur eggs represent practically an “instantaneous” record of the isotopic composition of drinking water and food. Crocodile (and generally archosaur) teeth grow continuously by incremental layers. For example, in Alligator mississippiensis the tooth replacement rate changes with body length, with the 1.5 meter

crocodiles having a replacement rate of 150 days (Erickson, 1996a,b). Studies on incremental lines in dinosaur teeth (Erickson, 1996a,b) indicate that a tooth of an adult hadrosaurid Maiasaura formed in 281 days. Erickson also shows that the tooth formation rate is generally dependent on mean crown volume. Taking this into account, we can assume that an adult Zalmoxes tooth formed in about 200 days. 5.2. Oxygen stable isotopic composition of calcretes and dinosaur eggs

Fig. 4. Stable isotopic composition of a) calcretes and b) vertebrate remains collected at Tuştea and at Sibişel.

For Maastrichtian times, the temperature distribution map compiled by Chumakov et al. (1995) shows values between 25 and 30 °C for the palaeolatitudes of the Haţeg Basin. These temperatures are too high for the types of paleosols already described, where smectite is the main clay mineral. Amiot et al. (2004) calculated the Late Campanian–Middle Maastrichtian latitudinal gradient using the δ18O record of phosphates from continental vertebrates. Their work suggested temperatures around 20 °C for a subtropical site at 30° latitude. The stable isotopic composition of calcretes is controlled by both mean annual temperatures (MAT) and the isotopic composition of the precipitation, the latter being also temperature dependent (Dansgaard, 1964). Hays and Grossman (1991) and Dworkin et al. (2005) used the calcite-water equation of O'Neil et al. (1969) and the meteoric water δ18O versus temperature relationship in order to obtain an equation for meteoric carbonate versus temperature during genesis. We estimated the MAT for Haţeg using the isotopic composition of pedogenic carbonates, the equation of Hays and Grossman (1991) and a Late Cretaceous δ18O value of seawater of –1‰ (Shackleton and Kennett, 1975). Considering the mean δ18O value of calcretes for Tuştea (24.6‰) and for Sibişel Valley (23.2‰), the calculated MATs are 14 °C and 10 °C, respectively. Using the equation of Dworkin et al. (2005), the calculated MATs for Tuştea and Sibişel are 14 °C, and 9 °C, respectively. These values are comparable to those calculated previously, but lower than the temperatures estimated by Amiot et al. (2004). As the different methods (Hays and Grossman, 1991; Amiot et al., 2004) give different mean annual temperatures, we considered a minimum and a maximum MAT for both Tuştea and Sibişel valley. For Tuştea, the minimum is 14 °C

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Fig. 5. Results of the isotopic analysis of the material collected at a) Tuştea and b) Sibişel. Measured oxygen values of teeth, eggs, calcretes (left) and calculated values (right) for soil and rain water. The values for body water were obtained using the value of soil water, MAT and the measured isotopic composition of teeth. Measured carbon values of teeth, eggs, calcretes (left) and calculated values (right) for isotopic composition of vegetation and food.

(calculated using the isotopic composition of calcretes) and the maximum is 20 °C (after Amiot et al., 2004). For Sibişel, the minimum is 10 °C and, allowing the same variation range as for Tuştea, we consider the maximum as 16 °C. The isotopic composition of the soil water in equilibrium with calcite can be calculated using the measured oxygen isotopic composition of calcretes and the inferred temperatures (O'Neil et al., 1969). For Tuştea,

the calculated values of soil water range from −6.4‰ (for 14 °C) to −5.1‰ (for 20 °C), while for Sibişel these vary from −8.8‰ (for 10 °C) to −7.3‰ (for 16 °C). Independently, using the linear relationship between soil carbonate and meteoric water deduced from actual pedogenic carbonate concretions (Cerling and Quade, 1993), the rainwater in equilibrium with the carbonate concretions gives similar values and varies for the different locations between −8 and −6‰ (for

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Tuştea) and −10 and −8‰ (for Sibişel) (Table 4). In order to simplify further calculations, we assumed that soil water and drinking water have similar isotopic values. Another way of calculating temperature differences between the two continental sites is based on the fact that MAT has antagonistic effects on the δ18O of carbonate. This is expressed in the slope for the relationship between δ18O of meteoric water and mean annual temperature (MAT) of ~+0.6‰ per °C (Dansgaard) and the slope for the relationship between δ18O of calcite and formation temperature of ~− 0.23‰ per °C (O'Neil et al., 1969). Thus the difference of 1.4‰ in the mean δ18O values of calcretes between sites can be translated in MAT variations of 3 to 4 °C. This is similar with the MAT variation between sites calculated before using Hays and Grossman (1991) and Dworkin et al. (2005). Using the empirical relationship between ostrich eggshells and drinking water oxygen isotope composition (Johnson et al., 1998), we estimated the δ18O of the water drunk by the taxon laying the eggs found at Tuştea as −1‰. This indicates a 4 to 5‰ difference between eggshell δ18O (drinking water) and paleosol carbonates (precipitation). One possible explanation for this difference is the seasonal distribution of humidity. At that time, the Haţeg area was at a subtropical latitude (Camoin et al., 1993). Using the International Atomic Energy Agency/ World Meteorological Organization (IAEA/WMO, 2001) database, we compiled all localities with precipitation between 100 and 800 mm/ year, situated at latitudes between 25 and 35° North or South, and at elevations less than 1000 m. For practically all stations, the seasonal δ18O variation of rainwater is up to 5‰. The predominant pattern is represented by cases where the heavy isotopic composition occurs during the dry, warm season (14 stations). For only six stations, mostly related to monsoon-type climates, does the amount effect dominate over the temperature effect. Consequently, in the case of the Haţeg Basin, the 18O-enriched rain was most likely related to the warm season. During Maastrichtian times, the Haţeg Basin was not close to an open oceanic domain but near to a land-surrounded marine domain, at a subtropical site, so there is no reason to infer strong monsoondominated climatic conditions. Monsoon conditions also imply winds that regularly change directions with a minimum of 120°, winds which

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are present nowadays between 5° and 25° latitude (Goudie, 2002). As noted above, Haţeg at that time was situated outside this region. We must consider further how seasonality could be related to the observed 4–5‰ differences between drinking water (calculated using the δ18O values of the eggshells) and rainwater (calculated using the δ18O of the calcretes). 1. The heavier isotopic values calculated for drinking water could be because the eggs preserved the signature of the drinking water at the time they formed, which might have been during the period characterized by heavier isotopic compositions of rain. High δ18O values of rainwater were associated with warm, dry or wet, seasons. In contrast, carbonate concretions formed during a longer period of time, from 10 to 100 ky, thus reflecting the long-term δ18O average value of rainwater. On the other hand, δ18O profiles for the Allodaposuchus and Zalmoxes teeth at Tuştea (Fig. 6) show variations less than 1‰. Taking into account the fact that tooth growth lasts a maximum of 200 days, only 1‰ differences between drinking water (calculated using the δ18O of the eggshells) and rainwater (calculated using the δ18O of the calcretes) can be related to seasonal variation. 2. In comparison with typically warm-blooded vertebrates, there is an additional variable for dinosaurs — body temperature. For vertebrates, the δ18O value of the body water is 4 to 8‰ higher than that of the drinking water (Luz and Kolodny, 1985; D'Angela and Longinelli, 1990). The enrichment observed at Tuştea between δ18Oeggshell and δ18Ocalcrete could be because for dinosaurs the δ18Obody water −δ18Odrinking water difference is larger than for ostriches, or because the fractionation between δ18Ocalcite −δ18Obody water was larger for dinosaurs. For example, it has been reported for reptiles that the phosphate δ18O value is higher than in mammals having the same 18 Obody water, assuming that MAT is lower than the mammal's body temperature (Kolodny et al., 1996); a similar δ18O offset, although of a lesser magnitude, is to be expected in dinosaurs, characterized by ectothermy (similar to crocodiles) or an intermediate-grade metabolism different from the fully endothermic, tachymetabolic birds.

Table 4 Calculated values for oxygen and carbon isotope fractionation. Loc.

Sample

Tuştea Telmatosaurus Zalmoxes (2) Allodaposuchus Zalmoxes (1) Kallokibotion bajazidi Telmatosaurus

Sample description

Body water enrichment δ13C (PDB) δ18Obodyw−δ18Odrinkingw (SMOW)‰ ‰

Tooth

5.9

− 29 (diet)

Tooth Tooth Tooth Shield

5.7 5.7 5.3 4

− 27 (diet)

Tooth-diet: − 18‰ (Fricke et al. (2008) Fricke et al. (2008)

− 30 (diet)

Fricke et al. (2008)

Egg

5.9

− 29 (diet)

4.1 7.2 4.9 6.7 5.7

− 29 (diet) − 27 (diet)

Calcretes

14 °C (MAT) (Hays and Grossman, 1991) − 6.4‰ (δ18O soil water) (O'Neil et al., 1969) − 7‰ (δ18O rainwater) (Cerling and Quade, 1993)

Fractionation for δ13C

Egg-diet: − 15‰ (Hobson, 1995) − 25 (vegetation) Calcrete-vegetation: − 16‰ (Cerling and Quade, 1993)

Sibişel Telmatosaurus Tooth Zalmoxes Tooth Allodaposuchus Tooth Allodaposuchus (1) Tooth Allodaposuchus (2) Tooth Calcretes

10 °C (Hays and Grossman, 1991) −8.8‰ (soil water) (O'Neil et al., 1969) − 10‰ (rainwater) (Cerling and Quade, 1993)

Fricke et al. (2008) Fricke et al. (2008)

− 27 (vegetation) Cerling and Quade (1993)

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Fig. 6. Isotopic variations across teeth at Tuştea and Sibişel. The white spots represent the locations of the analysis point using laser ablation technique. Each measurement point from the graphic represents the average of four to five measurements.

5.3. Oxygen stable isotopic composition of phosphate The δ18O values measured for the tooth enamel and turtle shell are relative high, ranging from 22.3 to 19.3‰. These high values are compatible with the low latitudinal position of the Haţeg Basin during the Maastrichtian. For example, Fricke and Rogers (2000) analyzed crocodile and theropod tooth enamel from different latitudes and obtained similar high values for sites situated at about 30° N latitude. Several authors have shown that the dentine from teeth reflects the isotopic composition of ambient water and implicitly the MAT for both mammals and dinosaurs. For endotherms, the body temperature is constant. In contrast, ectotherms, or animals with intermediate-grade metabolism, have variable body temperatures that are assumed to mirror MAT for a given site (Fricke and Rogers, 2000). For ectotherms, the δ18Ophosphate depends on body water and on MAT, as body temperature is not constant. Further studies on recent ectotherms, such as crocodilians and turtles, show that the δ18O values of enamel

phosphate increase linearly with the δ18O of drinking water (Barrick et al., 1999; Amiot et al., 2004), which in turn increases linearly with MAT (Fricke and O'Neil, 1999). For captive ectotherms (for example crocodilians), if the δ18O value of drinking water is kept constant, then the δ18O of enamel phosphate decreases with increasing ambiental temperature (Kolodny et al., 1996; Amiot et al., 2004). We consider that the first case is applicable for this study, since the investigated material does not come from captive animals with access to drinking water of constant isotopic composition. The oxygen isotope values of tooth enamel (inter- and intra-tooth values) show less variation for Tuştea, between 21.7 and 22.3‰ (0.5‰), than for Sibişel, between 19.1 and 22.2‰ (3.1‰). These variations are in the same range as those for the δ18O values of the calcretes, for Tuştea from 24.1 to 25‰ (0.9‰) and for Sibişel from 21.1 to 24.9 (3.8‰). Since the paleosol calcrete layer formed in a time of 10,000 to 100,000 years, the larger variation found at Sibişel may be related to larger variation in the isotopic composition of rainwater

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during deposition of the sequence. The mean δ18O values for phosphates and carbonates measured at Tuştea is lower than the δ18O values for Sibişel, which supports both a lighter isotopic composition of the precipitation and lower temperatures during the deposition of the local sedimentary sequence. Serial sampling for δ18O measurements of the Allodaposuchus and Zalmoxes teeth was done from the base to the apex of the tooth (Table 3). We interpret the larger intra-tooth variation of 3‰ found in the Sibişel samples to reflect larger seasonal variation than for Tuştea, where only 1‰ intra-tooth variability was measured. At Sibişel, the amplitude of intra-tooth variation is similar for both teeth (they are from different levels of the outcrop), although the patterns are different. The phosphate–water temperature equation of Longinelli and Nutti (1973), as modified by Friedman and O'Neil (1977), is: T°(C) = 114.4 − 4.3(δ18Op − δ18Obw + 0.5), where T°(C) is the body temperature in degrees centigrade, δ18Op the isotopic composition of bone phosphate, and δ18Ow the isotopic composition of body water. Furthermore, we assumed that the drinking and the soil waters have similar δ18O values and that the body temperature of the species studied reflects ambient temperatures (Fricke and Rogers, 2000). We also assumed that the investigated species (turtles, crocodiles, dinosaurs) consumed the same drinking water. For Tuştea, considering temperature variations between 14 and 20 °C, we calculated the δ18Obody water and the δ18Obody water − δ18Odrinking water. For each species, the body water is temperature-dependent, but the difference δ18Obody water− δ18Odrinking water is practically constant over the given temperature range (Table 4, Fig. 7). For phosphates and carbonates grown in equilibrium, for example from the same body water, δ18Ocarbonate egg − δ18Ophosphate enamel is not temperature-dependent and has a constant value of 9‰ (Iacumin et al., 1996), values which represent the difference measured for Telmatosaurus between egg and teeth oxygen isotopic composition. This is a further argument that the eggs and the enamel largely preserve their initial isotopic signature. Considering the mean differences for the isotopic compositions of teeth and calcretes at Tuştea and Sibişel, the differences

Fig. 7. Calculated δ18O values for drinking water, body water and body water enrichment δ18Obody water −δ18Odrinking water.

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δ18Ocarboante concretion − δ18Ophosphate enamel for both outcrops are similar (2.9 and 2.5‰) and independent of ambient temperature (see also Fig. 7). For the turtle Kallokibotion bajazidi, the calculated value δ18Obody water − δ18Odrinking water is similar to the values documented for emydid turtles by Barrick et al. (1999), which suggests that the body-water is enriched by 3.7‰ relative to the ambient water. Amiot et al. (2007) found that aquatic crocodiles have δ18Obody water − δ18Odrinking water values of 1.7 ± 0.3‰. They interpret the small δ18Obody water − δ18Odrinking water values as a result of the fact that crocodiles, being semi-aquatic reptiles, have their body water isotopically buffered by a large flux of ambient water. In our case, for the crocodilian Allodaposuchus we calculated a δ18Obody water −δ18Odrinking water difference ranging between 4.9 and 5.7‰. These different isotopic enrichments may suggest that the crocodilians from Haţeg spent more time in a fully terrestrial environment, so that the buffering offered by a water environment was less pronounced. For dinosaurs, δ18Obody water − δ18Odrinking water vary at Tuştea between 5.3 and 5.9‰. For the Sibişel valley, we can limit δ18Obody water − δ18Odrinking water between 4.1 and 7.2‰, the variation rather reflecting material availability (larger variation within the outcrop, teeth and calcretes not coming from exactly the same layer). Between the outcrops, no specific trend between the crocodile and dinosaur δ18O enamel is observed, unlike the situations reported by Fricke and Rogers (2000), for example. The δ18O of body water varies little with temperature, for both dinosaurs and crocodilians. For Tuştea, since the δ18O of the tooth enamel shows little variation, and assuming that the dinosaurs and crocodilians shared the same drinking water, then the body water enrichment for the temperature range previously assumed will be similar. This might support the idea that, like the crocodilians, Telmatosaurus and Zalmoxes were both largely ectotherms. 5.4. Carbon isotopic composition of calcretes and dinosaur eggs Plants using the C3 pathway have δ13C values between −32 and −21‰ with an average of − 27‰ (Cerling and Quade, 1993). At Tuştea, the carbon isotopic composition of calcretes varies between − 8 and − 9‰ and indicates an ecosystem with δ13C isotopic composition of plants around − 25‰ (Cerling and Quade, 1993). The measured δ13C signatures of Telmatosaurus eggs range between −13 and − 15‰. Considering that the 13/12C ratio of herbivorous birds is 15‰ heavier than that of the food material (Johnson et al., 1998), the calculated food carbon isotopic composition diet for Telmatosaurus is −29‰. Carbon incorporated into biogenic hydroxylapatite by dinosaurs has an enriched isotopic composition by 18‰ relative to diet (Fricke et al., 2008). This fractionation factor is larger than for carbon incorporated into hydroxylapatite of herbivorous mammals, which is isotopically enriched by 14‰ relative to diet (Sullivan and Krueger, 1981; Lee-Thorp and van der Merwe, 1987; Cerling and Harris, 1999). For Tuştea the diet value calculated using the eggshells and tooth gives a similar isotopic composition of ~ −29‰. For both Telmatosaurus and Zalmoxes the calculated δ13C values of the diet vary between − 27 and −30.3‰ (Table 4). The values are lower than the carbon isotopic values of the vegetation calculated using the isotopic composition of calcretes. This may be because the calcretes give the isotopic composition of the vegetation grown at a local site. In contrast, the dinosaurs acquire their food over a larger area, possibly extending over several microhabitats, which would contain different isotopic vegetation composition. The 3–4‰ inter-tooth and intratooth variation observed may reflect, in the case of a C3 vegetation, variability from either different environmental conditions over an area (Aucour et al., 2008) or intra-site variability for single plant species (McKee et al., 2002; Wooller et al., 2003). The lack of systematic differences in carbon isotopic composition between the different herbivorous species suggests that these shared a similar

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habitat (Fricke and Pearson, 2008). The mean δ13C values of carbonate and phosphate are higher at Tuştea than in the Sibişel valley The differences in δ13C may reflect possible differences in vegetation type, most probably related to differences in humidity for the two localities, since C3 plants growing under water-stressed conditions have higher C3 values from the closing of leaf stomata which control the CO2 flux into the plant (O'Leary, 1988; Farquhar et al., 1989). Such environmental conditions between the two areas have been suggested previously by sedimentological studies (Bojar et al., 2005; Therrien, 2005). 6. Conclusions For the localities investigated in this study, the stable isotope signal is largely preserved, as indicated by the differences in the isotope composition of the mudstones, calcretes and dinosaur eggs at Tuştea, as well as the preservation of the differences between the eggs and teeth of the same taxon (Telmatosaurus transsylvanicus). The presence of smectite in the clay fraction less than 2 μm and the dinosaur egg internal and external structure also indicate that diagenesis was not significant at the studied outcrops. It is thus possible to use the stable isotope composition patterns observed in the paleosol and vertebrate remains to derive palaeoecological and palaeophysiological information. Palaeotemperatures calculated using the stable isotope composition of calcretes indicate a MAT of 14 °C for Tuştea and of 10 °C for Sibişel. The δ18O values measured for the tooth enamel and turtle shell are relatively high, with the range of values being consistent with the low latitudinal position of the Haţeg Basin during the Maastrichtian. The stable isotope compositions of calcrete and vertebrate remains do not only depend on the palaeogeographic position, but are also related to tectonic and climatic changes within the basin. The intra-tooth δ18O patterns for Zalmoxes and Allodaposuchus show lower variations at Tuştea compared to Sibişel during the normal period of tooth growth (i.e. at a season-scale). Teeth and calcretes record intra-annual to 100,000 years temperature variations, which suggest more constant temperatures during the deposition of the sequence at Tuştea than at Sibişel. The calculated body water enrichment δ18Obody water −δ18Odrinking water is not temperature-dependent. For Kallokibotium bajazidi the body water enrichment is similar to that in present-day turtles. In contrast, Allodaposuchus had higher body water enrichment than present-day crocodiles perhaps explained by different behaviors or by higher metabolic rates of Allodaposuchus. Telmatosaurus and Zalmoxes have a δ18O value of body water comparable to that observed in Allodaposuchus, supporting a similar body temperature for the herbivorous dinosaurs and the crocodilian at the investigated sites. The isotopic composition of calcretes, teeth and eggshells supports the presence of a C3-based vegetation and corresponding diet with δ13C ranging between −27 and −29‰ (PDB). The similar δ13C values recorded for Zalmoxes and Telmatosaurus suggest the absence of largescale habitat partitioning between these herbivorous dinosaurs. For Tuştea, the difference between the carbon isotopic composition of vegetation, as represented by the calcretes, and that of the diet is larger than for the Sibişel valley. This may be because Tuştea was a rather dry, well-drained site situated in a terrace position close to the basin border, where the dinosaurs preferred to lay their eggs. One possible explanation may be that calcretes reflect the local vegetation at this rather dry site, while the carbon isotopic composition of the teeth and eggs represent the vegetation over a much larger area, which also included more humid microhabitats and which represented the feeding range of the herbivorous dinosaur from the Haţeg Basin. Acknowledgements We acknowledge the financial support from FWF P16258. Gratitude is extended to the stable isotope facility at New Mexico

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