Geology and taphonomy of a unique tyrannosaurid bonebed from the upper Campanian Kaiparowits Formation of southern Utah: implications for tyrannosaurid gregariousness

Tyrannosaurids are hypothesized to be gregarious, possibly parasocial carnivores engaging in cooperative hunting and extended parental care. A tyrannosaurid (cf. Teratophoneus curriei) bonebed in the late Campanian age Kaiparowits Formation of southern Utah, nicknamed the Rainbows and Unicorns Quarry (RUQ), provides the first opportunity to investigate possible tyrannosaurid gregariousness in a taxon unique to southern Laramidia. Analyses of the site’s sedimentology, fauna, flora, stable isotopes, rare earth elements (REE), charcoal content and taphonomy suggest a complex history starting with the deaths and transport of tyrannosaurids into a peri-fluvial, low-energy lacustrine setting. Isotopic and REE analyses of the fossil material yields a relatively homogeneous signature indicating the assemblage was derived from the same source and represents a fauna living in a single ecospace. Subsequent drying of the lake and fluctuating water tables simultaneously overprinted the bones with pedogenic carbonate and structurally weakened them through wet-dry cycling. Abundant charcoal recovered from the primary bone layer indicate a low temperature fire played a role in the site history, possibly triggering an avulsion that exhumed and reburied skeletal material on the margin of a new channel with minimal transport. Possible causes of mortality and concentration of the tyrannosaurids include cyanobacterial toxicosis, fire, and flooding, the latter being the preferred hypothesis. Comparisons of the RUQ site with other North American tyrannosaur bonebeds (Dry Island-Alberta; Daspletosaurus horneri-Montana) suggest all formed through similar processes. Combined with ichnological evidence, these tyrannosaur mass-burial sites could be part of an emerging pattern throughout Laramidia reflecting innate tyrannosaurid behavior such as habitual gregariousness

Caught in the Act: A Case Study on Microscopic Scale Physicochemical Effects of Fossilization on Stable Isotopic Composition of Bone

Geochemical zoning in a partially fossilized Pleistocene artiodactyl metapodial was contrasted with a fully fossilized Cretaceous ceratopsian femur as distinct stages along the fossilization process to investigate the physicochemical effects of fossilization and fossilization mechanisms. Bone fragments were analyzed via laser ablation ICP-MS, FT-IR, and stable isotope microanalysis to determine zoning patterns in trace elements, relative carbonate content and collagen contents,and stable isotopes of both the CO3 and PO4 components (δ13CCO3, δ18OCO3, and δ18OPO4). The Pleistocene sample shows a pronounced step in U concentration from high values (up to 90 ppm) within 1 mm of the outer bone surface and inner medullary cavity to ppb-level concentrations typical of in-vivo bone in the interior (inner ~6 mm). High U broadly coincides with reduced collagen, higher δ13CCO3, and lower δ18OCO3. Rare earth elements (REE), however, show typical exponential decreases from bone edges inward, and δ18OPO4 shows no clear trend. The Cretaceous bone shows high REE and U contents throughout, a complete absence of collagen, and relatively uniform isotope compositions. The Pleistocene data, especially U zoning, implicate a diffusion-reaction (DR) fossilization mechanism, in which collagen degradation facilitates a recrystallization front that propagates as a front towards the bone interior, reducing OH-site CO3 content, and shifting δ13CCO3,δ18OCO3,and δ18OPO4. Disequilibrium O-isotope partitioning between the CO3 and PO4 components in the interior of the Pleistocene bone suggests that both the CO3 and PO4 components have exchanged with diagenetic waters, likely through abiotic and microbially-induced exchange, respectively. Strong partitioning between apatite and soil water, coupled with uptake of REE in apatite from surrounding sediment matrix during fossilization, leads to exponential decreases in concentrations, which are passively recorded in apatite in the bone interior. The Cretaceous data do not implicate a unique fossilization mechanism but instead reflect the consequences of protracted fossilization and the final state that the Pleistocene bone might eventually have reached had the bone not been excavated. That is, the Cretaceous bone fossilization history resulted in no collagen, reduced or no OH-site CO3, and more uniform isotopic compositions. The multi-analytical methods employed in this study may benefit studies of diagenetic alteration of other apatitic tissues, e.g., tooth enamel

Data from: Endothermic mosasaurs? Possible thermoregulation of Late Cretaceous mosasaurs (Reptilia, Squamata) indicated by stable oxygen isotopes in fossil bioapatite in comparison with coeval marine fish and pelagic seabirds

The thermoregulatory style of Late Cretaceous mosasaurs has become a highly controversial subject in vertebrate palaeontology. These extinct marine reptiles have previously been described as poikilothermic, endothermic or gigantothermic. Here we analyse three genera of mosasaurs from the Mooreville Chalk in Alabama (USA) of differing body mass, and compare their δ18OPO4 derived body temperatures (Tb) with those of coeval poikilothermic fish (Enchodus) and endothermic pelagic seabirds (Ichthyornis). Results show that all mosasaurs, Clidastes (Tb = 33.1°C), Platecarpus (Tb = 36.3°C), and Tylosaurus (Tb = 34.3°C), had elevated average body temperatures in relation to those of the fish (Tb = 28.3°C) and were closer to those of Ichthyornis (Tb = 38.6°C). The temperatures calculated for Enchodus compare well with previously reported temperature estimates for the Mooreville Chalk and the Tb of Ichthyornis compares well with temperatures that have been reported for modern seabirds, suggesting that this method provides accurate results. Finally, although there are small differences of body temperature among mosasaur genera, these are independent of size, and thus inferred body mass, suggesting that mosasaurs were not gigantotherms, but rather endotherms

Paleoecología y paleoclima del Cretácico Superior del Grupo Chubut (Patagonia Central): el uso de isótopos estables en dientes de vertebrados fósiles

El análisis de isótopos estables en vertebrados mesozoicos es utilizado en el exterior, pero en Argentina es aún infrecuente. Esta contribución presenta resultados preliminares del análisis de isótopos estables de oxígeno (δ18OPO4 y δ18OCO3-VSMOW) y carbono (δ13CCO3-VPDB) realizados en el esmalte de cinco dientes de Sauropoda, seis de Theropoda, dos de Crocodyliformes, pertenecientes a las formaciones Bajo Barreal (Cenomaniano–Turoniano) y Lago Colhué Huapi (Coniaciano–Maastrichtiano), Grupo Chubut, Cuenca del Golfo San Jorge, depositados en la Colección de Paleontología de Vertebrados del repositorio de la Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB-PV).Fil: Alvarez, Bruno Nicolás. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; Argentina. Universidad Nacional de la Patagonia Austral. Centro de Investigaciones y Transferencia Golfo San Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia Golfo San Jorge. Universidad Nacional de la Patagonia "San Juan Bosco". Centro de Investigaciones y Transferencia Golfo San Jorge; ArgentinaFil: Casal, Gabriel A.. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; ArgentinaFil: Ibiricu, Lucio Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; ArgentinaFil: Suarez, Celina A.. University of Arkansas for Medical Sciences; Estados UnidosXII Congreso de la Asociación Paleontológica ArgentinaArgentinaAsociación Paleontológica Argentin

La familia como factor influyente en la formación del gaminismo en Cartagena

Tesis (Trabajadora Social) -- Universidad de Cartagena. Facultad de Ciencias Sociales y Educación. Programa de Trabajo Social, 1978Causas y características del gaminismo en Cartagena, presentando alternativas de solución para solventar en parte este problema, mediante la atención que deben brindar las diferentes instituciones de bienestar social

A Chronostratigraphic Assessment of the Moenave Formation, USA Using C-Isotope Chemostratigraphy and Detrital Zircon Geochronology: Implications for the Terrestrial End Triassic Extinction

The Late Triassic is a period of abrupt climate change associated with a disruption to the global carbon cycle usually ascribed to the emplacement of the Central Atlantic Magmatic Province (CAMP). Geochronologic, paleontologic, and geochemical studies have shown that the CAMP was likely the major factor for the end-Triassic extinction (ETE), however, difficulties correlating and dating terrestrial strata has left the nature of the terrestrial extinction in question. The lacustrine Whitmore Point Member (WPM) of the Moenave Formation is ideal for investigating these details because it is reported to be Late Triassic to Early Jurassic. However, currently there are conflicting age constraints between biostratigraphy and magnetostratigraphy. In this study we attempt to elucidate the ETE by incorporating C-isotope chemostratigraphy and detrital zircon geochronology. Detrital zircon geochronology suggests the upper part of the Dinosaur Canyon Member (DCM) is younger (201.33 ± 0.07/0.12/0.25 Ma) than the ETE (201.564 Ma) suggesting the ETE is in the middle to lower DCM, in agreement with track biostratigraphy (first occurrence of Eubrontes, Anomoepus, and Batrachopus). Meanwhile a distinct negative carbon isotope (NCIE) excursion (−5.5‰) occurs at the base of the WPM at Potter Canyon, AZ with a more subtle NCIE at the base of the WPM at Black Canyon, UT (−2.0‰) that may correlate to the initial NCIE at the ETE. However, the WPM NCIE is correlated to the preservation of organic C (relative %C) suggesting it may be either related to local lake productivity and biases in organic matter preservation or may be a negative CIE in the Jurassic Hettangian stage. With the addition of the detrital zircon data, we suggest the M2r reversal at the base of the WPM is a reversal in the Hettangian (the H24r, H25r, or H26r) and the ETE is within the DCM. Additional C-isotope analysis of the DCM is necessary to determine if the initial NCIE that is the hallmark of the ETE occurs in terrestrial strata in western Pangea. However, our WPM C-isotope record is the most complete C-isotope record from terrestrial strata of western Pangea to date and in addition to detrital zircon geochronology, magnetostratigraphy, and biostratigraphy, will be used to provide a framework for future chronologic and paleoclimatic studies

Multi-Taxa Isotopic Investigation of Paleohydrology In the Lower Cretaceous Cedar Mountain Formation, Eastern Utah, U.S.A.: Deciphering Effects Of the Nevadaplano Plateau On Regional Climate

We investigate the regional climatic effects of the formation of the “Nevadaplano” plateau during the Sevier Orogeny in an overall warming world. Paleohydrology was reconstructed from 590 individual measurements of phosphate O isotopes in continental faunas of the Lower Cretaceous Cedar Mountain Formation, Utah, U.S.A. Semi-aquatic (turtles, crocodiles) and terrestrial (dinosaurs) taxa are compared to coeval pedogenic carbonates to interpret changing water sources over time. Samples were grouped into four stratigraphic faunas (lower Yellow Cat, upper Yellow Cat, Ruby Ranch, and Mussentuchit members). Resulting isotopic values were converted to δ18Owvalues using established δ18Op–δ18Ow and δ18Oc–δ18Ow relationships. At a formation scale, turtles (δ18Op  =  14.1 to 15.7‰ V-SMOW) and crocodiles (δ18Op  =  15.0 to 19.2‰) document water compositions of −8.1 to −6.1‰ and −7.7 to −4.2‰, respectively, within the zonal range for formation-scale meteoric water at 34° N paleolatitude (−7.1 to −4.8‰) established by pedogenic carbonates (δ18Oc  =  22.0 to 23.5‰ V-SMOW). These data suggest that, like soil carbonates, turtle and crocodile phosphate isotopes can be used as proxies for meteoric water isotopic composition. Dinosaur δ18Op(sauropods: 19.7 to 21.9‰, ornithischians: 16.6 to 21.7‰, small theropods: 16.9 to 18.2‰, and large allosauroids: 19.1 to 20.3‰) values generally exceed those of semi-aquatic taxa. Using mass-balance equations for modern terrestrial animals adjusted for size and inferred dinosaur physiology, ingested water is calculated for the above dinosaur groups. On a member scale, when meteoric-water values are compared with calculated dinosaur drinking water, values are equal to or lighter than meteoric water for most herbivorous groups (as low as −15.5‰ for ornithischians) and equal to or heavier than meteoric water for most carnivorous groups (as high as −2.0‰ for allosauroids). Changes in δ18Ometeoric water, δ18Odinosaur ingested water, faunal assemblages, and sedimentology, from member to member, correlate to thrusting events of the Sevier Orogeny. High elevations in the orogeny attenuated the influences of Pacific moisture, causing rainshadow-induced aridity on the leeward foreland basin during upper Yellow Cat time, and hosted seasonal snow accumulation by the end of Ruby Ranch time, as suggested by 18O-enriched water (e.g., up to an average of −2.0‰ from an allosauroid tooth) and extremely 18O-depleted water (e.g., −15.5‰ for ornithischians) in the Ruby Ranch Member. By Mussentuchit-time, delivery of the Western Interior Seaway–dominated moisture to the region, despite continued rise of the Sevier Mountains

Data from: The ‘Last Hurrah of the Reigning Darwinulocopines’? Ostracoda (Arthropoda, Crustacea) from the Lower Jurassic Moenave Formation, Arizona and Utah, USA

An ostracod fauna is described from lacustrine sediments of the Hettangian, Lower Jurassic Whitmore Point Member of the Moenave Formation. The Moenave is well known for its rich, Late Triassic?–Early Jurassic fossil record, which includes fossil fishes, stromatolites, ostracods, spinicaudatans and a diverse ichnofauna of invertebrates and vertebrates. Four ostracod species, all belonging to the suborder Darwinulocopina, were recovered from these sediments: Suchonellina globosa, Suchonellina stricta, Whipplella? sp. 1 and Whipplella? sp. 2. The diversity and composition of the Whitmore Point Member ostracod fauna agree with previous interpretations about Lake Dixie and nearby paleoenvironments as shallow lakes, where darwinulocopine species which survived the effects of the Central Atlantic Magmatic Province and the subsequent End-Triassic extinction quickly recolonized these areas thanks to asexual reproduction by parthenogenesis. The Lake Dixie region, in its geographical isolation, may represent the last episode of darwinulocopine dominance in non-marine environments before the Late Jurassic diversification of the cypridocopine/cytherocopine modern ostracods