0000000000009807
AUTHOR
Frédéric Courant
Note sur l'ontogenèse crânienne et les hétérochronies chez Gorilla gorilla et Pan troglodytes
Resume La comparaison par les methodes Procrustes de l'ontogenese crânienne de Pan troglodytes et de Gorilla gorilla precise la dynamique et la chronologie de leur developpement. Les arbres phenetiques confirment un gradient morphologique du nouveau-ne a l'adulte, avec un dimorphisme d'origine sexuelle plus accuse chez le gorille. La quantification des changements morphologiques par des champs vectoriels permet de visualiser et de comparer l'organisation spatiale de la croissance cranio-faciale des deux especes. On en deduit que des heterochronies du developpement (acceleration, pre-deplacement, hypermorphose par acceleration et hypermorphose par post-deplacement) sont a l'origine des varia…
La notion d'espace morphologique,outil d'analyse de la morphodiversité des organismes
Resume L'analyse de la morphologie des organismes est une base essentielle dans la mise en evidence des changementsevolutifs. La morphologie est maintenant frequemment abordee par des procedures quantitatives, dont certaines permettent de construire de veritables cartes morphologiques ou les dissemblances et ressemblances de formes entre les organismes sont directement lisibles et quantifiees. La notion d'espace morphologique, illustree ici par differents exemples, se revele particulierement feconde pour comprendre comment la diversite morphologique d'un ensemble d'organismes (stades ontogenetiques, populations, clades) se structure, et par consequent pour interpreter en termes evolutifs ou…
Le supra-occipital des Cétacés et des Rongeurs fouisseurs. Une convergence morphologique induite par le pôle post-céphalique ?
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…
Quantification de révolution morphologique du crâne des Hominidés et hétérochronies
Abstract Comparisons of adult skulls of various species of great apes, fossil hominids and modern humans in the sagittal, Francfort and ortho-sagittal planes reveal a series of three separate organisation plans: ‘Great Ape’, ‘Australopithecine’ and ‘Homo’, the latter including primitive men ( Homo ergaster-erectus-neandertalensis ) and modern humans ( Homo sapiens ). Morphological changes between these plans are quantified for the first time here by vector fields. This study confirms the existence of cranio-facial contraction, which occurs as a series of leaps. The juvenile morphology of the great ape skull is broadly preserved in adult Homo sapiens, suggesting that numerous heterochronies …
Quantification of cranial convergences in arvicolids (Rodentia)
Cranial convergence in nine species of arvicolids is quantified phenetically using geometric morphometry. In a preliminary step, a hypothesis about phyletic relationships is proposed as a framework against which to examine morphological comparisons. The cranial morphology is then depicted in three series of 37, 20 and 13 landmarks characterizing the lower, upper and lateral sides of the skull respectively. Superimposition (Procrustes) methods are used to quantify shape differences and establish phenograms for the three sides of the skull. The phenogram obtained for lateral sides reveals a strong connection between skull profile and mode of life: surface dwelling forms have elongated skulls …
Karyological and dental identification of Microtus limnophilus in a large focus of alveolar echinococcosis (Gansu, China).
International audience; A study of voles (Arvicolidae, Rodentia) from Gansu (China) designed to identify a potential host of Echinococcus multilocularis, responsible for human alveolar echinococcosis, leads to a general analysis of Microtus limnophilus population karyotypes, M1 of M. oeconomus populations from all of Eurasia and of M. limnophilus of Mongolia. The Microtus of Gansu belonging to the nominal subspecies M. limnophilus limnophilus (2n = 38; NF = 58) differs markedly in size and shape of M1 from the M. limnophilus of Mongolia, which must therefore be considered as a new subspecies M. limnophilus of malygini nov. ssp. (2n = 38; NF = 60) and the M. oeconomus of Mongolia should be r…