Shed Teeth Research Articles

Shed teeth from Portezuelo formation at Sierra del Portezuelo reveal a higher diversity of predator theropods during Turonian-Coniacian times in northern Patagonia

The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroidea, and one to Alvarezsauridae. Additionally, two of the morphotypes exhibit a combination of dental features typically found in megaraptorid and abelisauridtheropods. These results suggest a greater diversity of theropods in the original ecosystem than previously thought, including the presence of a second morphotype of megaraptorid and alvarezsaurid previously undocumented in this formation. Furthermore, the existence of Morphotype 6 indicates the potential coexistence of medium-sized abelisauroids alongside larger abelisaurids in the same ecosystem. These findings underscore the importance of future expeditions to the Sierra del Portezuelo locality to further our understanding of these previously unknown theropod species.

Biogeography of theropod dinosaurs during the Late Cretaceous: evidence from central South America

Abstract In central South America, theropod remains are relatively scarce in comparison to the southern part of the continent, with shed teeth being the primary fossils found in this region. We examined 179 isolated teeth from the Bauru Basin, Brazil, using linear discriminant analysis (LDA; N = 178) and phylogenetic analysis (N = 174). The LDA used eight measurements, and the phylogenetic analysis used seven morphotypes. Although the results of the LDA suggest the presence of various South American theropod clades, such as Carcharodontosauridae, Noasauridae, and Spinosauridae, the phylogenetic analysis using a constrained dentition-based matrix classified the morphotypes as Abelisauridae (morphotypes I–IV, VI, and VII) and Therizinosauria (morphotype V). Given the considerable number of homoplastic characters and missing data, the phylogenetic analyses could not precisely determine the taxonomy of morphotypes V, VI, and VII in the unconstrained dataset. Morphological comparisons, nevertheless, strongly suggest that all morphotypes should be classified as abelisaurid theropods. We propose that the palaeogeographical distribution of Abelisauridae in South America was influenced by climatic conditions. These apex carnivores are likely to have adapted well to increased climate changes that led to semi-arid conditions. Our research sheds light on the evolutionary and ecological aspects of theropod dinosaurs in this region, contributing to a better understanding of the ancient ecosystems of central South America.

Plesiosaurs from the fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and a review of non-marine plesiosaurs

Plesiosaurs were a long-lived and widespread group of marine reptiles, with a worldwide distribution and a temporal range from the Late Triassic to the Late Cretaceous. Most occur in marine deposits, but some occur in low-salinity, brackish to freshwater environments. We report plesiosaurs from the freshwater fluvial deposits of the mid-Cretaceous (?Albian–Cenomanian) Kem Kem Group of Morocco. Remains include numerous shed teeth, vertebrae, and a humerus. The humerus represents a young juvenile; vertebrae likely belong to sub-adults. Teeth show heavy wear, similar to teeth of co-occurring spinosaurids. While coeval plesiosaurs from the Bahariya Formation of Egypt are members of Polycotylidae, the Kem Kem fossils show features of Leptocleididae, small-bodied plesiosaurs that were widely distributed in nearshore and non-marine settings in the Early Cretaceous. These fossils are the first freshwater plesiosaurs from Morocco, and are among the youngest representatives of Leptocleididae. The Kem Kem leptocleidids could have been infrequent visitors from the sea, freshwater-tolerant, or even freshwater-adapted, as in modern river dolphins. The abundance of shed teeth in the Kem Kem Group supports the hypothesis that they had some degree of freshwater tolerance. Furthermore, leptocleidids occur almost exclusively in shallow nearshore, brackish, or freshwater environments, suggesting adaptation to shallow, low-salinity environments. Other plesiosaur groups and other Mesozoic marine reptiles, including teleosaurids and mosasaurids, also occur in freshwater settings, suggesting plesiosaurs and other marine reptiles frequently exploited non-marine environments.

Abdominal contents reveal Cretaceous crocodyliforms ate dinosaurs

Crocodylians are among Earth’s most successful hyper-carnivores, with their crocodyliform ancestors persisting since the Triassic. The diets of extinct crocodyliforms are typically inferred from distinctive bite-marks on fossil bone, which indicate that some species fed on contemporaneous dinosaurs. Nevertheless, the most direct dietary evidence (i.e. preserved gut contents) of these interactions in fossil crocodyliforms has been elusive. Here we report on a new crocodyliform, Confractosuchus sauroktonos gen. et sp. nov., from the Cenomanian (92.5–104 Ma) of Australia, with exceptionally preserved abdominal contents comprising parts of a juvenile ornithopod dinosaur. A phylogenetic analysis recovered Confractosuchus as the sister taxon to a clade comprising susisuchids and hylaeochampsids. The ornithopod remains displayed clear evidence of oral processing, carcass reduction (dismemberment) and bone fragmentation, which are diagnostic hallmarks of some modern crocodylian feeding behaviour. Nevertheless, a macro-generalist feeding strategy for Confractosuchus similar to extant crocodylians is supported by a morphometric analysis of the skull and reveals that dietary versatility accompanied the modular assembly of the modern crocodylian bauplan. Of further interest, these ornithopod bones represent the first skeletal remains of the group from the Winton Formation, previously only known from shed teeth and tracks, and may represent a novel taxon.

Lagged Weighted Quantile Sum Regression

BACKGROUND AND AIM: We aim to develop a method for identifying critical exposure windows relating exposure to environmental mixtures and health outcomes that may differ by subject characteristics (e.g., sex). We extend weighted quantile sum (WQS) regression with its variations (e.g., stratified interaction WQS regression) to a lagged version that accommodates heterogeneous exposure times for each subject. METHODS: Briefly, time-specific weights are estimated and the weighted index calculated (i.e., WQS(t)) across the time frame with at least moderate sample sizes. Then a reverse distributed lagged model (rDLM) is similarly parameterized and estimated using a nonlinear mixed model. The rDLM allows for different exposure times per subject while correcting for within-subject correlated observations. Critical windows are identified where the family-wise confidence intervals for the association parameter(s) exclude zero. RESULTS:The approach is illustrated using perinatal exposures measured in shed teeth with later life health effects in a lagged stratified interaction WQS model. CONCLUSIONS:Identifying environmental chemicals of concern in critical exposure windows, that may vary by subject characteristics, may be useful in intervention strategies to protect public health. KEYWORDS: chemical exposures, mixtures, critical windows

Comparative study of B content and δ11 B in the enamel of isolated teeth from brothers in the same family.

The quantity of boron (B) and its isotopic ratios in tooth can provide information on dietary habits and oral health of individuals. These metrics are gradually being used in stomatology, environmental science and geochemistry. This study measured the B concentration and δ11 B in the enamel of isolated teeth from brothers in the same family living in high-B-exposure areas at different times using inductively coupled plasma mass spectrometry (ICP-MS) and multicollector ICP-MS. The results demonstrate that B content in tooth samples of two brothers is related to the time of shedding. The earlier the time of shedding, the lower is the B content in tooth. The B content increased from 20.5μg/g of the central incisor (6-7years old) of the younger brother to 50.4μg/g of the second molar (10-12 years old). And B content for the elder brother increased from 28.7 to 58.3μg/g at the same positions. In the same family, the diet and environmental input of B is basically similar, and the B exposure is basically the same every year. The annual growth rate of B for the younger brother in this experiment is about 4.98 μg/g per year and that for the elder brother is about 4.93 μg/g per year. The δ11 B of shed teeth at different times from the same person is basically similar, but different from person to person. The δ11 B of shed teeth from the elder brother varies from 15.5‰ to 17.9‰ and from the younger brother varies from 5.2‰ to 6.7‰. The δ11 B is quite different for the brothers in the same family who had the same food and environmental intake of B. The experimental data confirmed the relationship between the information of B (B content and δ11 B) in shed teeth and B exposure. They provided an experimental basis using modern human teeth to apply B-isotope paleo-environmental significance.

Mammal‐bearing gastric pellets potentially attributable to Troodonformosus at the Cretaceous Egg Mountain locality, Two Medicine Formation, Montana, USA

AbstractFossil gastric pellets (regurgitalites) have distinct taphonomic characteristics that facilitate inferences of behavioural ecology in deep time, despite their rarity in the fossil record. Using the taphonomic patterns of both extant and fossil small mammals from more recent geologic deposits as a guide, we assess the taphonomy of three unusual multi‐individual aggregates of mammal skeletons from palaeosols at Egg Mountain, a dinosaur nesting locality from the Upper Cretaceous Two Medicine Formation, Montana, USA. One aggregate consists of two individuals of the multituberculate Filikomys primaevus. This specimen is characterized by brecciated crania, articulated postcrania, and an absence of digestive markings, all suggestive of a non‐predatory origin. Two additional aggregates consist of 3 and 11 individuals, respectively, primarily of the marsupialiform Alphadon halleyi. High proportions of crania and indigestible elements (e.g. teeth), extensive disarticulation and breakage, digestive corrosion patterns, and the absence of a phosphatic ground mass are indicative of regurgitalites and align with features of extant prey in diurnal raptor gastric pellets. We interpret these specimens as the oldest known mammal‐bearing regurgitalites. The discrepancy in taphonomic features implies behavioural separation between the two mammalian taxa at the locality. Abundant shed teeth and nesting evidence at the locality favours the non‐avian theropod Troodon formosus as the predator responsible for the regurgitalites, congruent with previous inferences of a small‐bodied prey diet, manipulation of prey during feeding, heightened metabolic processes, and potential nocturnality for this taxon.

The easternmost occurrence of Saurornitholestes from the Judith River Formation, Montana, indicates broad biogeographic distribution of Saurornitholestes in the Western Interior of North America

ABSTRACT Small-bodied dromaeosaurid and troodontid theropod dinosaurs are present in most of the terrestrial Late Cretaceous formations of the North American Western Interior, but are represented predominantly by shed teeth and more rarely by isolated skeletal elements and associated skeletons. The eudromaeosaurian dromaeosaurid Saurornitholestes is among the most commonly recovered small theropods from North America, known from abundant shed teeth, isolated cranial and postcranial elements, and several partial or near-complete skeletons from the Campanian aged Two Medicine Formation of Montana and the Dinosaur Park Formation of Alberta. Conversely, few Saurornitholestes specimens beyond shed teeth have been recovered from temporally equivalent units of the Judith River Formation of Montana. This study reports the first cranial material, a near-complete frontal, referable to Saurornitholestes from the Judith River Formation of Montana. This specimen is the easternmost occurrence of this taxon and was recovered approximately 400 km east of the localities which have produced referred Saurornitholestes specimens in the Two Medicine Formation, proximal to the Cordilleran thrust front. As such, this new specimen indicates that Saurornitholestes was biogeographically widespread and occupied both inland and coastal environments across the northern portions of the Late Cretaceous Western Interior of North America.

Taxonomic identification of isolated theropod teeth: The case of the shed tooth crown associated with Aerosteon (Theropoda: Megaraptora) and the dentition of Abelisauridae

Shed teeth are usually the most abundant theropod material on a dinosaur fossil site and are constantly reported in the literature. Although new quantitative techniques have emerged to identify isolated theropod teeth with better accuracy, they remain difficult to assign to a certain family-level or genus-level taxon because of the presence of rampant homoplasy in their morphology and the lack of thorough descriptions. Here we test three methods to investigate the phylogenetic position of a tooth previously considered to be part of the holotype of the megaraptoran Aerosteon riocoloradensis (MCNA-PV-3137): a cladistic analysis performed on a dentition-based data matrix scored across 105 theropod species and using a backbone topology as constraint, as well as discriminant and cluster analyses conducted on a dataset of non-avian theropod crown measurements. Even though the cladistic technique appears to be the most reliable method to investigate the phylogenetic affinities of theropod teeth, we recommend using the three techniques conjointly to corroborate the identification of isolated dental material. The results of the cladistic and discriminant analyses support the assignment of the tooth associated with MCNA-PV-3137 to an abelisaurid theropod. It should therefore be excluded from the holotype of Aerosteon. A thorough description of the dental anatomy of Abelisauridae is also provided. The current study is the first to evaluate different methodological tools to identify isolated theropod teeth. With the added detailed description of the dental anatomy of Abelisauridae, it will also assist future authors to investigate the systematic palaeontology of isolated theropod teeth with more confidence.

Mitochondrial DNA haplotype diversity and origin of captive sand tiger sharks (Carcharias taurus)

The sand tiger shark (Carcharias taurus) is listed as globally vulnerable with geographically confined and disrupted global populations with little or no gene flow between them. Captive breeding in aquaria of these sharks would reduce the need to populate displays with wild-caught individuals, however, sand tigers are notoriously difficult to breed in captivity. In this study we analysed 520bp of the mitochondrial D-loop to assess the haplotype diversity of 19 captive sand tiger sharks, from UK and US aquaria sampled in a non-invasive fashion through DNA extracted from shed teeth. Data obtained were compared to known geographically mapped wild haplotypes to establish whether individuals from different global populations are being housed together. We were able to identify the haplotype of a minimum of ten of the 19 sharks, detecting four different haplotypes, with a previously undescribed haplotype (Haplotype K) found from a captive sample. A major genetic subdivision between the haplotypes of the North West Atlantic and the other global populations has been previously shown from population genetic analyses. Our results indicate that captive sharks can be from either side of this subdivision and occasionally these can be co-housed in the same aquarium. Since sharks with highly divergent genetic ancestry are being kept together, these findings have implications for conservation efforts regarding the individual needs of sand tiger shark populations and for captive breeding program success rates.

Sex differences in sensitivity to prenatal and early childhood manganese exposure on neuromotor function in adolescents

IntroductionWhile studies have suggested that exposure to manganese (Mn) may be associated with neurodevelopment in school-age children, there is limited information on prenatal and postnatal Mn exposures and tremor or motor function in children. MethodsWe measured Mn levels in dentine of shed teeth, representing prenatal, early postnatal, and cumulative childhood exposure windows, from 195 children (predominantly right-handed, 92%) in Italy. Pursuit Aiming, Luria Nebraska Motor Battery, as well as Tremor and Sway system from Computerized Adaptive Testing System (CATSYS) were administered at 11–14 years old. We examined the relationships of tooth Mn (ln-transformed) with motor function using multivariable linear regressions and generalized additive models, adjusting for age, sex, and socioeconomic status index. Effect modification by sex was also examined. ResultsWe found that higher prenatal Mn was associated with better body stability in boys in a number of sway tests (including mean sway, transversal sway, sagittal sway, sway area, and sway intensity), while Mn was associated with poorer performance in girls on all of these metrics (all p for Mn × sex interaction < 0.05). Higher prenatal Mn was also modestly associated with better hand/finger and eye-hand coordination in boys compared to girls in sex-stratified analyses, although interaction models did not reach statistical significance. For tremor, on the other hand, higher early postnatal Mn was associated with increased right-hand center frequency in girls (p for interaction < 0.01), but increased Mn level at the later postnatal period was associated with increased center frequency in boys (p for interaction = 0.01). ConclusionsThis study, which used a direct measure of prenatal and childhood Mn exposure, suggested sex-specific critical windows of early life Mn exposure in relation to neuromotor function in adolescents. The sex-specific associations might be strongest with measures of whole body stability, for which the critical exposure window was during the prenatal period.

Tooth Matrix Biomarkers of Pre- and Postnatal Manganese Exposure and Motor Function in Adolescents

INTRODUCTION: While studies have suggested that exposure to manganese (Mn) may be associated with neurodevelopment in school-age children, there is limited information on prenatal and postnatal Mn exposures and tremor or motor function in children. METHODS: We measured Mn levels in dentine of shed teeth, representing prenatal, early postnatal, and cumulative childhood exposure windows, from 192 children in Italy. Pursuit Aiming, Luria Nebraska Motor Battery, as well as Tremor and Sway system from Computerized Adaptive Testing System (CATSYS) were measured at 11-14 years old. We examined the relationships of tooth Mn (log-transformed) with motor function using generalized linear models and generalized additive models, adjusting for age, sex, and socioeconomic status index. Effect modification by sex was also examined. RESULTS: We found that higher prenatal Mn was associated with increased number of correct aiming dots (β=10.8, p=0.02) on the Pursuit Aiming test, particularly in boys (p for Mn × sex interaction=0.04). In contrast, higher cumulative childhood Mn was associated with poorer accuracy as indicated by the ratio of correct-to-total number of aiming dots (β=−0.04, p=0.04), particularly in girls (p for interaction=0.05). Higher prenatal Mn was also associated with lower tremor intensity of non-dominant hand (β=−1.16, p=0.048). We did not observe significant effect estimates of prenatal or postnatal Mn on Luria battery or Sway test. Conclusions: Our findings suggest that higher prenatal Mn levels measured in tooth dentine, a novel biomarker that provides reliable information on the timing of exposures to Mn, may be associated with better eye-hand coordination, particularly in boys. On the other hand, higher postnatal Mn was inversely associated with eye-hand coordination in girls. These data potentially support the existence of two distinct critical windows (prenatal vs. postnatal) of Mn exposure in relation to motor function.

Characterization of neurons from immortalized dental pulp stem cells for the study of neurogenetic disorders

A major challenge to the study and treatment of neurogenetic syndromes is accessing live neurons for study from affected individuals. Although several sources of stem cells are currently available, acquiring these involve invasive procedures, may be difficult or expensive to generate and are limited in number. Dental pulp stem cells (DPSCs) are multipotent stem cells that reside deep the pulp of shed teeth. To investigate the characteristics of DPSCs that make them a valuable resource for translational research, we performed a set of viability, senescence, immortalization and gene expression studies on control DPSC and derived neurons. We investigated the basic transport conditions and maximum passage number for primary DPSCs. We immortalized control DPSCs using human telomerase reverse transcriptase (hTERT) and evaluated neuronal differentiation potential and global gene expression changes by RNA-seq. We show that neurons from immortalized DPSCs share morphological and electrophysiological properties with non-immortalized DPSCs. We also show that differentiation of DPSCs into neurons significantly alters gene expression for 1305 transcripts. Here we show that these changes in gene expression are concurrent with changes in protein levels of the transcriptional repressor REST/NRSF, which is known to be involved in neuronal differentiation. Immortalization significantly altered the expression of 183 genes after neuronal differentiation, 94 of which also changed during differentiation. Our studies indicate that viable DPSCs can be obtained from teeth stored for ≥72h, these can then be immortalized and still produce functional neurons for in vitro studies, but that constitutive hTERT immortalization is not be the best approach for long term use of patient derived DPSCs for the study of disease.

Manganese in teeth and neurodevelopment in young Mexican–American children

IntroductionManganese (Mn) is an essential nutrient but higher exposure has been associated with poorer neurodevelopment in children. MethodsWe measured Mn levels in prenatal (Mnpre) (n=197) and postnatal (Mnpost) dentin (n=193) from children's shed teeth using laser ablation inductively coupled plasma mass spectroscopy and examined the relationship with children's scores on the Mental Development Index (MDI) and Psychomotor Development Index (PDI) on the Bayley Scales of Infant Development at 6, 12, and 24-months. We explored non-linear associations and interactions by sex, blood lead concentrations and maternal iron status during pregnancy. ResultsA two-fold increase of Mnpost levels in dentin was associated with small decreases in MDI at 6-months and 12-months of age. We also observed a non-linear relationship between Mnpost levels and PDI at 6-months. We found effect modification by sex for Mnpost levels and neurodevelopment at 6-months with stronger effects among girls for both MDI (−1.5 points; 95% Confidence Interval (CI): −2.4, −0.6) and PDI (−1.8 points; 95% CI: −3.3, −0.3). Girls whose mothers had lower hemoglobin levels experienced larger decreases in MDI and PDI associated with Mnpre levels than girls whose mothers had higher hemoglobin levels (pinteraction=0.007 and 0.09, respectively). We did not observe interactions with blood lead concentrations or any relationships with neurodevelopment at 24-months. ConclusionsUsing Mn measurements in tooth dentin, a novel biomarker that provides prenatal and early postnatal levels, we observed negative transient associations between postnatal Mn levels and early neurodevelopment with effect modification by sex and interactions with prenatal hemoglobin.

Prenatal and postnatal manganese teeth levels and neurodevelopment at 7, 9, and 10.5 years in the CHAMACOS cohort

BackgroundNumerous cross-sectional studies of school-age children have observed that exposure to manganese (Mn) adversely affects neurodevelopment. However, few prospective studies have looked at the effects of both prenatal and postnatal Mn exposure on child neurodevelopment. MethodsWe measured Mn levels in prenatal and early postnatal dentine of shed teeth and examined their association with behavior, cognition, memory, and motor functioning in 248 children aged 7, 9, and/or 10.5years living near agricultural fields treated with Mn-containing fungicides in California. We used generalized linear models and generalized additive models to test for linear and nonlinear associations, and generalized estimating equation models to assess longitudinal effects. ResultsWe observed that higher prenatal and early postnatal Mn levels in dentine of deciduous teeth were adversely associated with behavioral outcomes, namely internalizing, externalizing, and hyperactivity problems, in boys and girls at 7 and 10.5years. In contrast, higher Mn levels in prenatal and postnatal dentine were associated with better memory abilities at ages 9 and 10.5, and better cognitive and motor outcomes at ages 7 and 10.5years, among boys only. Higher prenatal dentine Mn levels were also associated with poorer visuospatial memory outcomes at 9years and worse cognitive scores at 7 and 10.5years in children with higher prenatal lead levels (≥0.8μg/dL). All these associations were linear and were consistent with findings from longitudinal analyses. ConclusionsWe observed that higher prenatal and early postnatal Mn levels measured in dentine of deciduous teeth, a novel biomarker that provides reliable information on the developmental timing of exposures to Mn, were associated with poorer behavioral outcomes in school-age boys and girls and better motor function, memory, and/or cognitive abilities in school-age boys. Additional research is needed to understand the inconsistencies in the neurodevelopmental findings across studies and the degree to which differences may be associated with different Mn exposure pathways and biomarkers.

Structure and mechanical properties of normal and anomalous teeth in the sand tiger shark Carcharias taurus.

This study reports and characterises an anomalous condition in teeth of captive sand tiger sharks Carcharias taurus . Abnormal shed teeth from captive sand tiger sharks which were soft to the touch were structurally and chemically characterised and compared to the structure and composition of normal teeth of the species. Normal specimens exhibited the expected tooth morphology with a well-developed tooth crown consisting of a central cusp and two lateral cusplets with smooth and sharp margins, while in the anomalous specimens the crown height was much reduced and the overall shape did not follow this pattern. Lateral cusplets were also considerably reduced in size and with blunt margins. Scanning electron images showed a distinct absence of crystalline structures in the anomalous specimens. Raman microscopy analysis confirmed the low volume of fluoroapatite in the outer layers of the anomalous teeth, while the composition of the inner layers corresponding to dentine was comparable to the normal tooth specimens. Nanoindentation-derived mechanical properties showed significant differences between the anomalous and normal teeth. The mean values for enameloid elastic modulus and hardness of all three normal teeth were 75.92±3.4 GPa and 3.27±0.41 GPa, respectively. On the other hand, mean values of elastic modulus and hardness for anomalous teeth were 7.81±3.27 GPa and 0.39±0.25 GPa, respectively. However, mechanical property values of the dentine of normal and anomalous teeth were similar. The mean values of dentine elastic modulus and hardness of the normal teeth were 25.66±2.14 GPa and 0.89±0.01 GPa, respectively, while mean values for the anomalous teeth were 25.34±1.54 GPa and 0.83±0.03 GPa. Although the morphological, mechanical and chemical differences between the normal and anomalous teeth are quite evident, establishing the causes of this condition are not possible at this stage.

Biomarkers of manganese exposure in pregnant women and children living in an agricultural community in California.

Manganese (Mn) is an essential nutrient but at high exposure levels is a neurotoxicant. There is no well-validated biomarker to assess perinatal Mn exposure. A total of 75 mother-child pairs provided blood, urine, and/or deciduous tooth samples. We analyzed Mn in dentin and enamel of shed teeth; maternal, cord, and child blood; and maternal and child urine and examined the interrelationships of Mn levels in all matrices. We observed higher Mn levels in prenatal than postnatal dentin (geometric mean (GM) = 0.51 vs 0.16 Mn:Ca, p < 0.001), maternal blood at delivery than 26 weeks gestation (GM = 20.7 vs. 14.6 μg/L, p = 0.001), and cord blood than child blood at 24 months of age (39.9 vs 25.0 μg/L, p = 0.005). There were no significant correlations between Mn in dentin and Mn concentrations in maternal blood or maternal or child urine. Levels of Mn in prenatal dentin, prenatal maternal blood, and 24 month urine were higher (p < 0.05) among mothers and children living with a farm worker. Prenatal Mn levels in dentin were correlated with Mn loadings and concentrations in prenatal house dust. Levels of Mn measured in tooth dentin constitute a promising biomarker of perinatal exposure.

Manganese in Levels in Tooth Dentin and Neurodevelopment in a Cohort of Young Mexican- American Children

Manganese in Levels in Tooth Dentin and Neurodevelopment in a Cohort of Young Mexican- American ChildrenAbstract Number:2289 Robert Gunier*, Manish Arora, Michael Jerrett, Asa Bradman, Kim Harley, Nina Holland, Alan Hubbard, Brenda Eskenazi Robert Gunier* University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author , Manish Arora Mount Sinai School of Medicine, United States, E-mail Address: [email protected] Search for more papers by this author , Michael Jerrett University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author , Asa Bradman University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author , Kim Harley University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author , Nina Holland University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author , Alan Hubbard University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author , and Brenda Eskenazi University of California, Berkeley, United States, E-mail Address: [email protected] Search for more papers by this author AbstractIntroduction: Manganese (Mn) is an essential nutrient but can be neurotoxic at high exposure levels. Previous studies have observed associations between Mn exposure and children’s neurodevelopment, primarily using concurrent exposure measurements in blood or hair. Prenatal and postnatal Mn exposures have not been evaluated together in a prospective study of neurodevelopment in young children.Methods: We measured Mn levels in prenatal and postnatal dentin from children’s shed teeth. We examined the relationship between prenatal and postnatal exposure and children’s performance at 6, 12 and 24-months of age on the Bayley Scales of Infant Development mental and psychomotor development indices. We explored the possibility of an inverted U-shaped association with neurodevelopment since Mn is an essential nutrient. We also evaluated potential interactions between Mn exposure and blood lead concentrations as well as maternal iron status during pregnancy.Results: We observed a negative association between postnatal Mn levels in dentin and psychomotor development at 6-months of age. The relationship followed an inverse U- shaped association with the strongest effect observed when comparing the highest tertile of Mn levels in teeth to the middle tertile of Mn levels in teeth (-3.6 points; 95% Confidence Interval: -6.9, -0.2). Prenatal Mn levels in dentin were associated with both mental and psychomotor development at 6-months only among children whose mothers’ were iron deficient during pregnancy. We did not observe a significant interaction with prenatal or postnatal blood lead concentrations in this cohort. There was no relationship between Mn levels in dentin and mental or psychomotor development at 12 and 24 months of age.Conclusions: We report a modest decrease in psychomotor development at 6-months of age with early postnatal Mn exposure. Iron status during pregnancy was an important effect modifier of prenatal Mn exposure and neurodevelopment at 6-months of age.

Prenatal and Postnatal Manganese Exposure and Neurodevelopment at 7, 9, and 10.5 Years in the CHAMACOS Cohort

Background: Manganese (Mn) is an essential nutrient, but is also neurotoxic at high doses. Many studies have examined the relationship between childhood Mn exposure and neurodevelopment, but few have looked at the effects of prenatal and postnatal Mn exposure. Methods: We measured prenatal and postnatal dentine Mn concentrations in shed teeth and assessed their association with cognition, attention, memory, and motor functioning in children aged 7, 9, and 10.5 years from CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas), a cohort study among farmworker families living near agricultural fields treated with Mn-containing fungicides in California. We used generalized linear models and generalized additive models to test for linear and nonlinear associations, and generalized estimating equation models to assess longitudinal effects. Results: Postnatal dentine Mn concentrations were associated with small improvements in fine motor coordination in the dominant hand at 7 years of age, immediate and delayed visual memory scores at 9 years, and Perceptual Reasoning and Working Memory intellectual quotient (IQ) scores at 10.5 years. Longitudinal models showed a weak but positive association between postnatal dentine Mn concentrations and Perceptual Reasoning, Working Memory, and Full Scale IQ scores at 7 and 10.5 years. We did not observe any associations between prenatal teeth Mn concentrations and the neurodevelopmental domains of interest. We did not find interactions between teeth Mn concentrations, maternal iron status or lead concentrations during pregnancy, or child sex. Conclusions: Previous studies have reported associations between childhood Mn exposure and negative neurodevelopmental effects, but we found small and positive relationships between postnatal dentine Mn and fine motor coordination, memory, and cognition in children aged 7, 9, and 10.5 years. We did not observe any association between prenatal dentine Mn and neurodevelopment.

A small, exquisitely preserved specimen of Mosasaurus missouriensis (Squamata, Mosasauridae) from the upper Campanian of the Bearpaw Formation, western Canada, and the first stomach contents for the genus

ABSTRACTA new, exquisitely preserved specimen of a small mosasaur, referable to Mosasaurus missouriensis, is reported from the Bearpaw Formation (ca. 75 Ma, upper Campanian) of southern Alberta, Canada. Many calcified cartilaginous elements, including tracheal rings and the sternum, are preserved. The sternum most closely resembles that of Clidastes propython, bearing five shallow sternal rib facets on each side. Our comparative study of the new material with the holotype, referred material, and the genotype M. hoffmannii is congruent with the preexisting hypothesis that M. missouriensis and M. hoffmannii are phylogenetically more closely related to each other than to the other congeners, in spite of a temporal gap of nearly 10 million years between them. Also preserved with the mosasaur, inside its ribcage and around the specimen, are well-preserved aulopiform fish bones, including a skull. The fish skull is punctured and its centra truncated, suggesting macrophagy was employed by M. missouriensis despite the apparent lack of tooth wear. A sympatric specimen of Prognathodon overtoni is known to have consumed a sea turtle as well as fishes, and consistently exhibits apical wear across marginal teeth. We hypothesize that coexistence of these apex predators in the Bearpaw Sea was possible because of niche partitioning. Finally, the mosasaur carcass was likely scavenged by at least three lamniform sharks, based on their shed teeth and a series of truncated transverse processes on the mosasaur tail.