Ichnofossils, cracks or crystals? A test for biogenicity of stick-like structures from vera rubin ridge, mars

New images from Mars rover Curiosity display millimetric, elongate stick- like structures in the fluvio-lacustrine deposits of Vera Rubin Ridge, the depositional environment of which has been previously acknowledged as habitable. Morphology, size and topology of the structures are yet incompletely known and their biogenicity remains untested. Here we provide the first quantitative description of the Vera Rubin Ridge structures, showing that ichnofossils, i.e., the product of life-substrate interactions, are among their closest morphological analogues. Crystal growth and sedimentary cracking are plausible non-biological genetic processes for the structures, although crystals, desiccation and syneresis cracks do not typically present all the morphological and topological features of the Vera Rubin Ridge structures. Morphological analogy does not necessarily imply biogenicity but, given that none of the available observations falsifies the ichnofossil hypothesis, Vera Rubin Ridge and its sedimentary features are here recognized as a privileged target for astrobiological research

Prehistoric stone disks from entrances and cemeteries of north-eastern Adriatic hillforts|Prazgodovinski kamniti diski z vhodov in grobi[; na gradi[;ih na severovzhodnem Jadranu

The paper presents a group of four, approximately 0.5m large, stone disks from entrances or cemeteries of two protohistoric hillforts of north-eastern Adriatic. The disks, having a sparse chronology with the exception of one dated to the Middle Bronze Age, show flat and plain surfaces or covered with sub-circular depressions. One disk shows two larger cup-marks at the centre of both faces. They are interpreted as ritual artefacts based on the association with sacred settlement locations and comparisons with similar coeval stones found mainly close to citadel entrances, burials and thresholds in the Aegean area and Anatolia

Padrão geográfico de diversidade genética em populações naturais de Pau-rosa (Aniba rosaeodora), na Amazônia Central

Rosewood (Aniba rosaeodora Ducke, Lauraceae) is an Amazonian evergreen tree and a source of the purest linalool, the main component of its essential oil, which is very valuable in the international perfumery market. After decades of over-exploitation it is currently considered as threatened. We evaluated the genetic diversity and its distribution in four populations in Central Amazonia. Thirty-five reliable RAPD markers were generated, of which 32 were polymorphic (91.4%). Variation was higher within the populations (76.5%; p < 0.0001) and geographic distribution contributed to population differentiation (23.4%; p < 0.0001). The Amazon River had a small influence on gene flow (3.3%; p < 0.0001), but we identified evidence of gene flow across the river. There were significant differences in marker frequencies (p < 0.05), in agreement with the low gene flow (Nm = 2.02). The correlation between genetic distance and gene flow was - 0.95 (p = 0.06) and between geographic distance and gene flow was -0.78 (p = 0.12). There was a geographic cline of variability across an East-West axis, influenced as well by the Amazon River, suggesting the river could be a barrier to gene flow. Although threatened, these Rosewood populations retain high diversity, with the highest levels in the Manaus population, which has been protected for over 42 years in a Reserve.O Pau-rosa (Aniba rosaeodora Ducke, Lauraceae) é uma árvore amazônica fonte do mais puro linalol, o qual é o principal componente do seu óleo essencial e muito valioso no mercado internacional de perfumaria. Após várias décadas de intensa exploração, a espécie foi levada à categoria de ameaçada de extinção. Quatro populações naturais distribuídas na bacia Amazônia Central foram avaliadas quanto ao nível e a distribuição da diversidade genética. Trinta e cinco marcadores RAPD reprodutíveis foram gerados, dos quais 32 foram polimórficos (91,4%). A diversidade foi maior dentro das populações (76,5%; p < 0,0001) e a distribuição geográfica contribuiu para a diferenciação entre as populações (23,4%; p < 0,0001). A AMOVA indicou que pode haver uma influência parcial do Rio Amazonas no fluxo gênico (3,3%; p < 0,0001), mas foram identificadas evidências de fluxo gênico atravessando o rio. Houve diferenças significativas nas freqüências dos marcadores (p < 0,05) e o fluxo gênico estimado foi relativamente baixo (Nm = 2,02). A correlação entre a distância genética e o fluxo gênico foi de - 0,95 (p = 0,06) e para a distância geográfica e o fluxo gênico foi de - 0,78 (p = 0,12). Houve um padrão geográfico de variabilidade ao longo do eixo Leste - Oeste, influenciado também pelo Rio Amazonas, o que sugere que o rio poderia funcionar como uma barreira para o fluxo gênico. Apesar de ameaçadas, estas populações de Pau-rosa possuem alta diversidade, com o maior valor na população de Manaus, que vem sendo protegida por 42 anos em uma reserva

Leonardo da vinci, the founding father of ichnology

Science historians separated the scientific origins of ichnology and body fossil paleontology; the birth of body fossil paleontology is attributed to the Renaissance, whereas the beginnings of ichnology are placed in the 19th century. The present study shifts the boundaries of the history of paleontology and provides new information on an obscure chapter of scientific thought: the ichnological studies of Leonardo da Vinci. This report examines the ichnological observations of Leonardo da Vinci by (1) interpreting the Codex Leicester and the ichnosites described therein, and (2) studying the ichnological drawing included in the Codex I. This paper demonstrates the modernity and correctness of the observations and interpretations made by da Vinci, who used trace fossils to complement his hypothesis concerning the relationship of body fossils to the host sediment. The result from new information presented here is the establishment of a line of continuity between the two main branches of paleontologytrace fossils and body fossilsthat emerge united by the genius of Leonardo da Vinci, the founding father of ichnology. Copyright © 2010, SEPM (Society for Sedimentary Geology)

Depositional processes and environmental settings in rock shelters: The case of the prehistoric Oscurusciuto site (Southern Italy)

Clastic successions in rock shelters commonly host important archaeological findings, especially of prehistoric and protostoric times. The understanding of depositional and post-depositional processes in these environments is crucial to understand the lifestyle settings of humans, as well as the reliability of archaeological data obtained during excavations. Rock shelters are genetically related to caves, but while depositional processes in caves are generally well known, less information is available concerning the depositional processes active in rock shelters. This paper tries to contribute to this issue, describing the sedimentary succession exposed at the Oscurusciuto rock shelter (Ginosa, Southern Italy). This is one of the most important Middle Palaeolithic sites of the Italian peninsula, and its sedimentary infill hosts witnesses of very late Neanderthal populations that lived in Italy just before their total decline and complete replacement by Modern Humans (MH). This work presents the results of a sedimentologically based study integrated with an ichnological study of selected beds. The combination of these two methodologies allowed us to: (i) define the main depositional processes active in the rock shelter environment, as well as the relationships between different processes; (ii) discuss the meaning of peculiar ichnofabrics recognized at the site, and (iii) discuss the meaning of structureless strata at an archeological site in the framework of human trampling vs bioturbation as a cause of the obliteration of primary sedimentary structures

Ulisse Aldrovandi (1522-1605): The study of trace fossils during the Renaissance

The Renaissance was a time of flourishing for literature, art and science. A prominent figure in Renaissance science was the Italian naturalist Ulisse Aldrovandi, considered today to be one of the founding fathers of modern paleontology. Aldrovandi is known to have widely studied body fossils, but his work on trace fossils has yet to be explored by science historians. This paper proposes to critically analyze Aldrovandi's approach to trace fossils, based on his writings (most of which are still unpublished) and on the illustrations that accompany them. In his studies, the Bolognaborn naturalist accurately describes such ichnological celebrities as Gastrochaenolites and Cosmorhaphe and discusses a few theoretic principles on the trace-making process. The study of the works of Aldrovandi brings to light a fascinating and little-known source of the history of ichnology. © Taylor &amp; Francis Group, LLC

NETWORK THEORY IN ICHNOLOGY: FROM BEHAVIOURAL TOPOLOGY TO THE DEPOSITIONAL ENVIRONMENT

This study aims to (1) develop quantitative approaches for the study of ichnological systems; (2) model, for the first time, ichnosites as networks; (3) analyze the response of ichnological systems to global dynamics, with particular regard to Late Paleozoic fluvial-influenced settings. In this regard, the modern peritidal environments of the Grado lagoon (Italy, Adriatic Sea), the Nurra ichnosite (Permian-Triassic; Italy) and the Pramollo ichnolagerst\ue4tte (Carboniferous-Permian; Italy) have been selected for developing, applying and testing network analysis for the study of ichnological systems. Results show that network theory is able to depict the traces-environment relationships both for modern and fossil ichnological systems. It is therefore suggested that network theory may have great potential for understanding Phanerozoic bioturbation patterns