New findings of Pleistocene fossil turtles (Geoemydidae, Kinosternidae and Chelydridae) from Santa Elena Province, Ecuador.

New Pleistocene fossilized turtle remains from five localities of western Ecuador (Santa Elena Province) are described here. All these shell (carapace and plastron) fossil remains come from the Tablazo Formation and belong to three different lineages of cryptodires ("hidden-necked" turtles). The most abundant remains belong to geoemydids, attributed here to the genus Rhinoclemmys (indeterminate species). Less abundant in occurrence are the kinosternidids, attributed to Kinosternon (indeterminate species), and the first fossil record of chelydrids, Chelydra(indeterminate species), in the entirety of Central and South America.

The fossil recodd of turtles in Colombia; a revew of the discoveries, researchh and future challenges / El registro fósil de las tortugas en Colombia; una revisión de los descubrimientos, investigaciones y futuros desafíos

This is a review article on the fossil record of turtles in Colombia that includes: the early Cretaceous turtles from Zapatoca and Villa de Leyva localities; the giant turtles from the Paleocene Cerrejón and Calenturitas Coal Mines; the early Miocene, earliest record of Chelus from Pubenza, Cundinamarca; the early to late Miocene large podocnemids, chelids and testudinids from Castilletes, Alta Guajira and La Venta; and the small late Pleistocene kinosternids from Pubenza, Cundinamarca. I also discuss here the current gaps in the fossil record of tropical South American turtles, as well as the ongoing research and future projects to be developed in order to understand better the evolutionary history of Colombian turtles.

En este artículo resumo el registro fósil de tortugas de Colombia, incluyendo las tortugas del Cretácico temprano de Zapatoca y Villa de Leyva, las tortugas gigantes del Paleoceno en las minas de carbón de El Cerrejón y Calenturitas, el registro más antiguo de Chelus, proveniente del Mioceno temprano de Pubenza (Cundinamarca), los grandes podocnémidos, chélidos, y testudínidos del Mioceno temprano a tardío de Castilletes en la Alta Guajira y La Venta, y los pequeños kinostérnidos del Pleistoceno tardío de Pubenza, Cundinamarca. En este artículo discuto también los actuales intervalos para los cuales no se conocen registro fósil de tortugas en la parte tropical de Suramérica, así como también las investigaciones que se están desarrollando actualmente, c también los futuros proyectos a desarrollar con el fin de entender mejor la historia evolutiva de las tortugas en Colombia.

Variation in osteocytes morphology vs bone type in turtle shell and their exceptional preservation from the Jurassic to the present.

Here we describe variations in osteocytes derived from each of the three bone layers that comprise the turtle shell. We examine osteocytes in bone from four extant turtle species to form a morphological 'baseline', and then compare these with morphologies of osteocytes preserved in Cenozoic and Mesozoic fossils. Two different morphotypes of osteocytes are recognized: flattened-oblate osteocytes (FO osteocytes), which are particularly abundant in the internal cortex and lamellae of secondary osteons in cancellous bone, and stellate osteocytes (SO osteocytes), principally present in the interstitial lamellae between secondary osteons and external cortex. We show that the morphology of osteocytes in each of the three bone layers is conserved through ontogeny. We also demonstrate that these morphological variations are phylogenetically independent, as well as independent of the bone origin (intramembranous or endochondral). Preservation of microstructures consistent with osteocytes in the morphology in Cenozoic and Mesozoic fossil turtle bones appears to be common, and occurs in diverse diagenetic environments including marine, freshwater, and terrestrial deposits. These data have potential to illuminate aspects of turtle biology and evolution previously unapproachable, such as estimates of genome size of extinct species, differences in metabolic rates among different bones from a single individual, and potential function of osteocytes as capsules for preservation of ancient biomolecules.

Giant boid snake from the Palaeocene neotropics reveals hotter past equatorial temperatures.

The largest extant snakes live in the tropics of South America and southeast Asia where high temperatures facilitate the evolution of large body sizes among air-breathing animals whose body temperatures are dependant on ambient environmental temperatures (poikilothermy). Very little is known about ancient tropical terrestrial ecosystems, limiting our understanding of the evolution of giant snakes and their relationship to climate in the past. Here we describe a boid snake from the oldest known neotropical rainforest fauna from the Cerrejón Formation (58-60 Myr ago) in northeastern Colombia. We estimate a body length of 13 m and a mass of 1,135 kg, making it the largest known snake. The maximum size of poikilothermic animals at a given temperature is limited by metabolic rate, and a snake of this size would require a minimum mean annual temperature of 30-34 degrees C to survive. This estimate is consistent with hypotheses of hot Palaeocene neotropics with high concentrations of atmospheric CO(2) based on climate models. Comparison of palaeotemperature estimates from the equator to those from South American mid-latitudes indicates a relatively steep temperature gradient during the early Palaeogene greenhouse, similar to that of today. Depositional environments and faunal composition of the Cerrejón Formation indicate an anaconda-like ecology for the giant snake, and an earliest Cenozoic origin of neotropical vertebrate faunas.