Search results for "Vertebra"

Le supra-occipital des Cétacés et des Rongeurs fouisseurs. Une convergence morphologique induite par le pôle post-céphalique ?

2000

A comparative study of the cranial morphologies of cetaceans and of rodents that use their incisors for burrowing brings out morphological convergences concerning the supra-occipital bone. These phyletically very remote groups are both subject to the same mechanical constraint, viz. the need for the spinal column to be aligned with the anteroposterior axis of the skull. This constraint, which is related to swimming in cetaceans and burrowing in rodents, entails three major points of convergence: 1) a clearly backward facing foramen magnum; 2) a shortened or even greatly shortened neck, sometimes with cervical vertebrae fused together; and 3) an uprighted or even forward tilted supra-occipit…

El registro fósil de vertebrados y patrimonio paleontológico más representativo de los pirineos occidentales

2019

Los Pirineos occidentales son un territorio con una notable diversidad geológica y un importante registro fósil, que constituye un gran archivo de paleobiodiversidad. En lo que respecta al registro fósil de vertebrados, los Pirineos occidentales (Región Vasco-Cantábrica, Cuenca de Pamplona y sector noroccidental de la Cuenca del Ebro) son relevantes tanto desde el punto de vista de los yacimientos paleontológicos como de las colecciones de fósiles procedentes de ellos. Varios yacimientos de vertebrados forman parte del Inventario de Lugares de Interés Geológico (LIG) con alto o muy alto interés paleontológico en la Comunidad Autónoma del País Vasco. Destacan los yacimientos de peces cretáci…

1988

The living freshwater gastropod Melanopsis dufouri (FERUSSAC) has two morphotypes. The study of chemical variation of trace-elements in this gastropod and its correlation with the environmental fluctuation are the aim of this paper. Due to the genus Melanopsis has an abundant fossil record during the Cenozoic, the results of the present work could be of paleoecological interest. Trace-elements are embodied in the shell during growth. The shell of M. dufouri has accretionary growth. There are several examples cited on circadian accretionary growth in invertebrate shells. However, in the present case and as a first conclusion, the accretion rate depends on the size of the shell. In a short-ti…

CASE REPORT: FRATTURE VERTEBRALI DA FRAGILITÀ E BPCO

2017

Ultraviolet vision and foraging in terrestrial vertebrates

2002

Tetrachromatic colour vision, based on four ‘main’ colours and their combinations, is probably the original colour vision in terrestrial vertebrates. In addition to human visible waveband of light (400–700 nm) and three main colours, it also includes the near ultraviolet part of light spectrum (320–400 nm). The ecological importance of ultraviolet (UV) vision in animals has mainly been studied in the context of intra- and inter-sexual signalling, but recently the importance of UV vision in foraging has received more attention. Foraging animals may use either UV cues (reflectance or absorbance) of food items or UV cues of the environment. So far, all diurnal birds studied (at least 35 specie…

Efficacy of Zero-Profile Device versus Plate and Cage Implant for Treatment of Symptomatic Adjacent Segment Disease After Anterior Cervical Diskectom…

2018

Taphonomical peculiarities and formation conditions of Baltic Devonian vertebrate fossil assemblages

2013

Devona mugurkaulnieku atrodņu tafonomiskais raksturojums un veidošanās apstākļi dienvidaustrumu Baltijā Pirmo reizi paleontoloģisko pētījumu vēsturē Baltijā ir veikta detalizēta Živetas, Franas un Famenas mugurkaulnieku atrodņu tafonomisko īpašību analīze, izmantojot mūsdienu metodiku. Savā starpā ir salīdzinātas vidējā un augšējā devona oriktocenozes Latvijas teritorijā, bet Baltijas (Galvenā devona lauka) fosiliju atrodnes ir salīdzinātas ar sakopojumiem Dienvidu Timanā. Ir secināts, ka, neskatoties uz tafonomisko pazīmju atšķirībām, Franas un Famenas klastiskās slāņkopas, kā arī vidus- un augšdevona mugurkaulnieku sakopojumu veidošanās mehānismi Baltijā ir bijuši visai līdzīgi. Ir noteik…

Variation in the risk of being wounded: an overlooked factor in studies of invertebrate immune function?

2003

In invertebrates, wounding can trigger an immune response, and will often expose organisms to parasites and pathogens. Here we show that in the amphipod Gammarus pulex, wounding abundance is negatively correlated with PhenolOxidase activity (a major component of the invertebrate immune response), and that the occurrence and abundance of wounding is extremely high and varies significantly between five natural populations. In some populations the prevalence and abundance of wounds also varied between sexes. Given that, using and maintaining an efficient immune system is costly, we suggest that the frequency of wounding may be an important selective pressure influencing an organism's optimal i…

Recent speciation and secondary contact in endemic ants

2014

Gene flow is the main force opposing divergent selection, and its effects are greater in populations in close proximity. Thus, complete reproductive isolation between parapatric populations is not expected, particularly in the absence of ecological adaptation and sharp environmental differences. Here, we explore the biogeographical patterns of an endemic ant species, Cataglyphis floricola, for which two colour morphs (black and bicolour) coexist in parapatry throughout continuous sandy habitat in southern Spain. Discriminant analyses of six biometric measurements of male genitalia and 27 cuticular hydrocarbons reveal high differentiation between morphs. Furthermore, the low number of shared…

Polymorphism in Developmental Mode and Its Effect on Population Genetic Structure of a Spionid Polychaete, Pygospio elegans

2012

Population genetic structure of sedentary marine species is expected to be shaped mainly by the dispersal ability of their larvae. Long-lived planktonic larvae can connect populations through migration and gene flow, whereas species with nondispersive benthic or direct-developing larvae are expected to have genetically differentiated populations. Poecilogonous species producing different larval types are ideal when studying the effect of developmental mode on population genetic structure and connectivity. In the spionid polychaete Pygospio elegans, different larval types have been observed between, and sometimes also within, populations. We used microsatellite markers to study population st…