Print ISSN: 0031-0247
Online ISSN: 2274-0333
Révision des Rhombodontidae (Neoselachii Batomorphii) des bassins à phosphate du Maroc
Evolution et extinction des reptiles marins au Mésozoïque
La palichnofaune de vertébrés tétrapodes du permien supérieur du Bassin de Lodève .
Les oiseaux aquatiques (Gaviiformes à Anseriformes) de Saint-Gerand-le-Puy. Révision systématique.
A pangolin from the French Quercy phosphorites
Les Issiodoromyinae (Rodentia, Theridomyidae) de l'Eocène supérieur à l'Oligocène supérieur en Europe occidentaleClimate; Faunal turnover; Paleogene
Based on material from 30 localities, morphologic dental, cranial and biometric analyses have permitted the characterization of two parallel Issiodoromyine lineages, and also the definition of diverse species representing several evolutive stages. Thus it is that new lineages complete the contribution made by the Theridomyinae and Cricetidae and permit, for the Quercy in particular, additional precision in the biochronologic succession of the localities. One of the lineages is limited to the genus Pseudoltinomys LAVOCAT; the other evolves from the genus Elfomys HARTENBERGER to the genus Issiodoromys BRAVARD in GERVAIS. The latter is affected by profound anatomical changes due to a functional modification of the mastication apparatus. These changes seem to be able to be put in relation with the aridification and cooling of the climate at the end of the Eocene. At the end of the middle Oligocene, a new chewing structure is achieved. It is found in diverse living rodents that inhabit a rather arid steppe environment (Cavia, Pedetes, Ctenodactylus). To these supposed nearby ecologic conditions, these rodents have responded in a convergent fashion. It is possible to attribute to the extreme specialization of Issiodoromys its incapacity to adapt to the new climatic crisis of the end of the Oligocene. The arrival of immigrants may be considered as another cause of its disappearance at this time, complementary or not with the first.
Published in Vol. 07, Fasc. 1-2 (1976)