Two somewhat “odd” taxa of theridomyid rodents, one formerly known (Bernardia marandati Vianey-Liaud, 1991) and the other new (Idicia vidalenci gen. et sp. nov.) are discussed from a taxonomical and taphonomical perspectives. These two rodents were found at Lavergne, a late middle Eocene (MP16) “phosphatière” from the Quercy (Southwest France). The genus Bernardia, being preoccupied by a scale insect (Bernardia Ashmead, 1881), is here renamed Burgia. We benefit from this nomenclatural change to describe additional new dental specimens of this patriotheridomyine species, including a previously undescribed locus (P4). The other theridomyid from Lavergne, Idicia vidalenci gen. et sp. nov., so far documented by a mandible preserving two teeth (m2-m3) is a new taxon of peculiar occlusal morphology, and whose subfamilial affinities remain unknown. These two peculiar theridomyids recorded at Lavergne are found nowhere else, whether in coeval localities in Quercy or elsewhere in Western Europe. We discuss the possible causes of their unique presence at Lavergne.
  

This paper provides a revision of the early and middle Eocene European rodents previously referred to as Ischyromyoidea, including taxa considered to be at the origin of the Theridomorpha. The use of an accurate dental terminology and a better understanding of the size and shape of their infra-orbital foramen (i.o.f.) led us to a substantial revision of this group, which allowed to better characterize them and to appreciate their variability. On these bases, phylogenetic analyses (cladistic and standard Bayesian
approaches) of early Ypresian to late Priabonian European rodent species were undertaken in order to highlight the root of the early Theridomorpha and its content. In this paper, the phylogeny was established based on 343 characters (338 dental) through 45 early Paleogene taxa using both cladistic and bayesian analyses. The ingroup included on one hand a few North American genera (Reithroparamys, Microparamys, and Acritoparamys) and European ones (Eogliravus, Ailuravus, Corbarimys, Meldimys, Euromys, Plesiarctomys, and Pseudoparamys) considered until now as being related with the North American superfamily Ischyromyoidea. On the other hand, it included genera close to the root of the Theridomorpha (Sparnacomys, Pantrogna, and Hartenbergeromys) and early Theridomyoidea (Masillamys, Protadelomys, and some Pseudosciuridae). The phylogenetic results obtained via the two
distinct reconstruction approaches are consistent in virtually all relationships. The proposed systematics here derives from these phylogenetic results. This phylogenetic context led us to change the suprafamilial, familial, subfamilial or generic attribution of several species. Characters of Theridomorpha, like the obliquely developed postprotocristid allied with the occurrence of a metalophulid I, have been found in genera previously considered as Ischyromyidae (Pseudoparamys, Euromys, Sparnacomys, Meldimys, Pantrogna, and Hartenbergeromys) as well as the large i.o.f., when preserved (Pseudoparamys, Hartenbergeromys, and Masillamys). Based on these morphological observations and new phylogenetic considerations, the content of the Theridomorpha clade is here enlarged, thereby extending back the first theridomorph radiations to the early Eocene. Aside, a new taxon (Reinomys rhomboides gen and sp. nov.) is described from Avenay. In addition, a new genus, Auroremys, is created for the species subita (Comte et al., 2012) from Chery-Chartreuve. 

Situated in the Cape region of the Republic of South Africa (RSA), the paleontological site of Langebaanweg is dated to 5.1 Myr and is famous for having yielded an abundant vertebrate assemblage, including numerous rodent species from the Mio-Pliocene transition. Based on molar morphology and skull anatomy, the single Gerbillinae taxon identified at Langebaanweg and described in this paper is allocated to Desmodillus, which is a modern monotypic South African endemic genus. It is significant in being the oldest representative of the genus in Africa. We describe here a new species of this genus which is larger than the modern D. auricularis, but nevertheless retains some of its main characteristics, namely the shape of the maxilla and mandible, the presence of poorly fused alternating cusps, and no longitudinal crest. This taxon differs from modern South African Gerbilliscus representatives in some mandibular and maxillary characters, in the m1 prelobe cusp, and in having less fused cusps. Two fossil Gerbillinae discovered in the Upper Miocene of Africa and Asia, Abudhabia and Protatera, have been compared with the new species. We discuss their relationships with modern and Plio-pleistocene Gerbillinae and conclude that Abudhabia could be the sister taxon of Desmodillus and that around 6-5 Myr a vicariance event allowed Gerbillinae to diversify into modern Desmodillus in South Africa, and Gerbilliscus in East Africa. The murine/gerbilline ratio, which is a good indicator of rainfall, supports other proxies which suggest that at 5.1 Myr the climate in the Langebaanweg region was more humid than today. 

Résumé :
L’étude des rongeurs Theridomorpha permet de suivre le déroulement d’une radiation adaptative pendant toute sa durée (Eocène moyen-Oligocène terminal), sur un territoire restreint à l’extrémité ouest de l’Europe Occidentale. Dans ce papier, la phylogénie de ce groupe est établie à partir d’une analyse cladistique reposant sur l’examen de 315 caractères (310 dentaires). Le groupe d’intérêt comprend 110 des 132 espèces (24 genres) de Theridomyoidea et deux genres encore inclus jusqu’ici dans les Reithroparamyinae qui rejoignent les Theridomorpha. Les groupes externes comprennent des Glires basaux, Cocomys, Tanquammys et 16 Ischyromyiformes. Un cadre phylogénétique robuste est produit, qui permet de clarifier la systématique des Theridomorpha. La position des Remyoidea (nov. sup.fam.) au sein des Ischyromyiformes, extérieure aux Theridomorpha, est confortée. Les Protadelomys et Tardenomys sont à la base des Theridomyoidea, avant la séparation en deux clades correspondant aux familles Pseudosciuridae et Theridomyidae. Les sous-familles sont consolidées : Pseudosciurinae et Sciuroidinae pour les Pseudosciuridae ; Issiodoromyinae, Oltinomyinae, Columbomyinae, Theridomyinae, auxquelles s’ajoute au moins une nouvelle sous-famille (Patriotheridomyinae), pour les Theridomyidae. La topologie des chrono-espèces (sensu Simpson), traitées antérieurement comme lignées évolutives, apparaît dans la plupart des cas sous forme de clades successifs dans lesquels les espèces sont le plus souvent arrangées de manière pectinée, émergeant dans l’ordre stratigraphique. L’analyse des caractères aux principaux nœuds permet de consolider les caractères diagnostiques des taxons et les tendances évolutives, ainsi que de discuter des divers parallélismes et convergences dans l’évolution des structures et patrons dentaires (e.g., émail des incisives unisérié chez les Issiodoromyinae et les Patriotheridomyinae, ou pseudo-multisérié chez les Blainvillimys les plus hypsodontes, les Protechimys et Archaeomys ; patrons dentaires téniodontes ; allongement des dents déciduales chez les Patriotheridomyinae, Issiodoromyinae et Theridomyidae ; sélénodontie ou lophodontie). Les dynamiques évolutives traduites par les changements morphologiques sont mises en relation avec les variations environnementales. Enfin, les implications biochronologiques de l’évolution des Theridomyoidea sont discutées.
Abstract:
The adaptive radiation of the rodents Theridomorpha occurred during a limited time window (middle Eocene to late Oligocene), on an area restricted to Western Europe. In this paper, the phylogeny of this group is established via a cladistic assessment of 315 morphological characters (310 dental). The group of interest encompasses 110 upon 132 species (24 genera) of Theridomyoidea, and two genera formerly included within the Reithroparamyinae, and which are included here within the Theridomorpha. The outgroups include basal Glires, Cocomys, Tanquammys and 16 Ischyromyiformes. A robust phylogenetic frame is produced, which allows clarifying the systematics of the Theridomorpha. Within the Ischyromyiformes, the Remyoidea (nov. supfam.) are set apart from the Theridomorpha. Protadelomys and Tardenomys represent the earliest offshoots of the Theridomyoidea, before the dichotomy between Pseudosciuridae and Theridomyidae. It supports the former subfamilies Pseudosciurinae and Sciuroidinae within the Pseudosciuridae; and for the Theridomyidae: the Issiodoromyinae, Oltinomyinae, Columbomyinae, Theridomyinae, with at least one new subfamily (Patriotheridomyinae). The topologies of the chronospecies (sensu Simpson), formerly considered as evolutionary lineages, appear in most cases as successive clades, in which the species are generally pectinately arranged and emerging in the stratigraphic order. The analysis of characters supporting the main nodes allow consolidating the diagnosic characters of the taxa and their evolutionary trends, as well as discussing the various cases of parallelism and convergence in the evolution of structures and dental patterns (e.g., uniserial incisor enamel for Issiodoromyinae and Patriotheridomyinae, or pseudo-multiserial for the most hypsodont Blainvillimys, Protechimys and Archaeomys; taeniodont dental patterns; lengthening of deciduous premolars for Patriotheridomyinae, Issiodoromyinae and Theridomyidae; selenodonty or lophodonty).
Evolutionary dynamics are analysed with respect to environmental changes. Finally, biochronological implications of the evolution of Theridomyoidea are discussed.
  

The Tafna Basin corresponds to the lowlands, which are located in front of Tessala and Traras ranges, below the Tlemcen mountains, Algeria. This basin displays a complete sedimentary cycle dominated by lagoonal-fluvial and marine deposits. The continental formations located at the base of these deposits are mainly composed of alternating sandstones and clays. An early late Miocene age has been previously attributed to them, based on direct correlations with marine deposits. Search for micromammal fossils led to the discovery of three different rodent species from a single level of the Djebel Guetaf section, located at the bottom of these deposits. The rodent assemblage indicates a late Miocene age. Combined magnetostratigraphical and biostratigraphical investigations were carried out to provide a more accurate age control of these continental deposits. Sixty-four oriented rock samples were collected for a magnetostratigraphic study along a 92 meters thick section including the fossiliferous layer. Rock magnetic investigations indicate the presence of both high and low coercivity minerals. Specimens subjected to progressive thermal demagnetization procedures show that the samples exhibit a high temperature magnetization component and display a normal polarity. Based on biostratigraphic constraints, the Guetaf section is correlated with Chron C4An, indicating an age ranging from
9.1 to 8.7 Myr.
  

The Oligocene deposits of the Ulantatal area in Inner Mongolia (China) contain among the richest mammalian faunas from Asia. To date, only some parts of the rodent faunas have been described. Here, we propose to review the rodent faunal lists for each site, including the description of a few new rodent specimens. We describe three additional rodent species: the Cylindrodontidae Anomoemys lohiculus, the Eomyidae Asianeomys sp., and the Dipodidae Litodonomys huangheensis. This study allows us to constrain the stratigraphic range of Anomoemys lohiculus, which ranged from the late Early Oligocene to the early Late Oligocene in this area. Asianeomys sp. and Litodonomys huangheensis are dated from the latest Oligocene. These Oligocene deposits consist now of more than 70 species of mammals if we include the fauna from Kekeamu. This latter corresponds to the basal part of the Ulantatal Formation and could be dated biochronologically from the earliest Oligocene. When compared to the faunas from the Valley of Lakes in Central Mongolia, the Ulantatal faunas present a great majority of rodents, and this difference can be partly explained by sampling and description biases regarding macro-mammals. This study also shows that variations existed between Inner and Central Mongolia, especially regarding the composition of the rodent paleocommunities. However, the assessment of their evolutionary history in this part of Asia with respect to the important climate and environment changes, require further precisions and more material than current data allow. 

The subfamilies Murinae and "Dendromurinae" both include 4 species at Chorora. Among the former, while Preacomys nov. gen. seems to be a forerunner of Acomys, the affinities of the remaining, poorly known taxa, are more difficult to evaluate. The bulk of the fauna, remarkably, consists of Dendromurines. Their similarities with those of Ngorora tends to pull the site back in time, but the large size and diversity of Murines fit better an age more recent than the very beginning of the Late Miocene.

  

 A new genus of hystricognath rodent with two new species, Soriamys gaimanensis and Soriamys ganganensis, from the Colhuehuapian Age (Early Miocene), Sarmiento Formation, of Patagonia is described. The first species comes from the south barranca of the valley of Rio Chubut, near Gaiman locality (Chubut Province). It is known through a great number of dental remains in different stages of wear. The teeth are protohypsodont, with cement in the principal valleys. P4 are simpler, more oval inoutline and without a differentiated hypocone-hypoflexus. Upper molars are pentalophodont in early stages of wear and become bilobated in middle and advanced stages; M3 have a temporary third posterior lobe due to the maintenance of the braquiflexus on the posterior wall of the tooth. Lower teeth have a completely asymrnetrical pattern in relation to the uppers. The molars are trilophodont, with only one complex crest in the trigonid composed of the fusion of the anterolophid and mesolophid. The dp4 have a derived pentalophodont pattern due to the loss or fusion of the mesolophid and the development of an accessory transverse crest between the anterolophid and metalophid. The second species is known through a complete skull and jaw and other skull fragments with the dentition, proceeding from Pampa de Gan Gan, Chubut province. Respect to the first species, the teeth are higher crowned, with an earlier occlusal simplification and a third posterior lobe of M3 more developed and persistent. The skull and jaws show many chinchilloid characters, such as jugal bone with an ascending process, concave palate, very prominent dorsal shelf of the masseteric fossa, nasolachrymal duct opened laterally on the maxillary and very developed lateral mandibular fossa. Moreover, Soriamys is closely related to Cephalomys by sharing a similar asymmetric dental pattern and other dental and mandibular characters. These two genera constitute a natural group, the Cephalomyidae, with peculiar dental characters, like the asymmetric pattem of the upper and lower teeth; Cephalomyopsis, and probably Litadontomys, can be considered part of this group. Scotamys and Perimys constitute a distinct lineage (the Neopiblemidae or Perimyidae), more closely related to the chinchillids. Many characters shared by cephalomyids, eocardiids and caviids suggest a closer affinity between the Chinchilloidea and the Cavioiidea as a whole. Abrocoma shows also an asymmetric dental pattern and other chinchilloid features that suggest some degree of relationship with the cephalomyids, still not well determined. 

The genus Parasteiromys AMEGHINO, 1904 is revalidated, and P. friantae sp. nov. (Hystricognathi, Erethizontidae) from Colhuehuapian (early Miocene) sediments of the southern cliff of Colhue-Huapi Lake (Province of Chubut, Argentina), is described. The molar morphology of these taxa and of living porcupines adds new elements to understand the dental evolution of the Erethizontidae, and to propose the hypothetical ancestral molar pattern for this family. This pattern does not correspond to any of the morphologies traditionally proposed as ancestral for South American hystricognathous rodents. The proposed pattern is characterized by a metaloph disconnected from the posteroloph and oriented towards the hypocone, and the third loph incompletely developed with the lingual portion homologous to the mesolophule of Baluchimyinae (Chapattimyidae) from the Miocene of Pakistan. The inferred steps of the molar evolution of erethizontids towards the pentalophodont condition, considered derived for the family, are illustrated. This study strengthens the hypothesis placing erethizontids in a basal position among rodents of the suborder Hystricognathi.

  

Besides Dendromurids and Murids, the Chorora Rodents include 7 taxa, two of which are new. Afaromys nov. gen. is a Cricetodontine with very complicated lower molars, certainly isolated for a long time from Eurasian species. A Paraphiomys, with tetralophodont upper molars, is also quite different from other East African species, and its roots should probably he searched in the middle Miocene. Other taxa are less original, and more similar to the South Asiatic ones. 

Extensive collecting in previously known and new Middle Eocene rodent localities in the Subathu Group of the Rajauri and Reasi districts, Jammu and Kashmir (northwest Himalaya, India) has yielded over 500 isolated cheek teeth, numerous incisors and cheek tooth fragments, and two mandibular fragments with M/1-M/3. An analysis of this additional material and a restudy of that reported earlier from the Metka (Rajauri) area has revealed the presence of diverse Middle Eocene ctenodactyloid rodents in India. The assemblage comprises six genera and twelve species, viz.., Bírbalomys woodi, B. ibrahimshahi, B. sondaari, Basalomys vandermeuleni, B. ijlsti, B. lavocati, Chapattimys wilsoni, C. debruijni, Gumbatomys asifi, cf. Advenimus bohlini, cf. Petrokoslovia sp. indet. 1 and cf. Petrokoslovia sp. indet. 2. Most species of this assemblage are endemic to the Indian subcontinent and are referred to the Family Chapattimyidae. However, at least three taxa, viz.., cf. Advenimus bohlini, cf. Petrokoslovia sp.indet. 1 and cf. Pezrokoslovia sp. indet. 2 show close affinities with their Central and Eastern Asiatic contemporaries and are attributed to the Family Yuomyidae. The dentitions of most of the Middle Eocene rodents from India are described here in better detail thus providing more precise characterization than was available earlier. The taxonomie status of Basalomys, formerly a subgenus of Birbalomys has been raised to that of a genus. Basalomys vandermeuleni is here designated as the type species of Basalomys in place of B. ijlsti. The rodent assemblage from the Subathu Group is specifically similar to that from the coeval Kuldana Formation of Pakistan. The absence of Birbalomys ibrahimshahi and cf. Advenimus bohlini in Pakistan is related to sampling bias. The identifications of the Early Eocene rodents from Barbara Banda, Pakistan have been reexamined and the familial assignments of some of the Early and Middle Eocene rodents from Central and Eastern Asia have been discussed and reviewed in the light of recent discovery of early rodents in Mongolia.

  

A new hypothesis for the phylogenetic relationships of recent anomalurids and graphiurids is proposed, based on information from evolutionary lineages of Paleogene European rodents, particularly Gliridae, and Eocene Algerian Zegdoumyidae. Differences in first occurrences, in paleogeography, and in infraorbital structure in glirids (protrogomorphy and pseudomyomorphy) and graphiurids (hystricomorphy) separate Graphiuridae from Gliridae (Graphiurinae is here raised to family rank). Similar considerations, and dental morphology, suggest that Anomaluridae (appearing in the late Eocene) and Graphiuridae (appearing in the Pliocene) are related to early Eocene Zegdoumyidae. 

A partial skull of Ardynomys russelli sp. nov. (Rodentia, Cylindrodontidae) is described. This was collected in the late Eocene of Alag Tsab locality in the eastem Gobi Desert, Mongolia. Ardynomys russelli sp. nov. is characterized by small size, brachyodont molars, and retention of P3. It represents the earliest record of the genus Ardynomys MATTHEW & GRANGER, 1925, in Asia. 

The earliest North American rodents occur in basal Clarkforkian beds of the Fort Union Formation at Big Multi Quarry near Bitter Creek, northern Washakie Basin, Sweetwater County, Wyoming, and in closely correlative Fort Union beds formerly accessible in the Eagle Coal Mine near Bear Creek, northern Clark's Fork Basin, Carbon County, Montana. Two new species of early Clarkforkian rodents, Paramys adamus and Alagomys russelli, are described from Big Multi Quarry. Paramys adamus is represented by virtually complete upper and lower dentitions, which demonstrate that this species is one of the most primitive North American paramyids yet discovered. These specimens form the basis for a reevaluation of the content and stratigraphic range of P. atavus, which is known with certainty only from Bear Creek. Alagomys russelli is the first North American record for the enigmatic rodent family Alagomyidae, otherwise known from ?late Paleocene-early Eocene localities in Mongolia and China. Phylogenetic analysis of dental and gnathic traits suggests that Alagomyidae form the sister group of all other undoubted rodents. At least two rodent clades, alagomyids and basal paramyids, seem to have invaded North America from Asia at the beginning of Clarkforkian time, but only the paramyids persisted to undergo a significant evolutionary radiation in North America. 

Reigechimys octodontiformis gen. et sp. novo and R. plesiodon sp. novo are described. They represent the frrst record of the family Echimyidae for the Cerro Azul Formation (Huayquerian Age, Late Upper Miocene) at La Pampa Province, central Argentina. Both species have hypsodont cheek teeth with an eight-shaped occlusal design. This dental morphology represents a noticeable case of convergence to octodontids and indicates that these echimyids inhabited open environments. 

Enamel microstructure in the incisors of Old- and New World hystricognath rodents:

The incisor enamel microstructure in more than 100 genera of fossil and Recent hystricognath and sciurognath rodents was studied. A multiserial schmelzmuster is present in the Hystricognathi, the Ctenodactylidae, advanced Chapattimyidae, and in Pedetes. A redefinition of pauciserial and multiserial HSB is given that makes the two enamel types unambiguously distinguishable which apparently represent well defined evolutionary levels. In the pauciserial Schmelzmuster the IPM is thicker than in the multiserial one. In pauciserial HSB the IPM always surrounds each prism, and the crystallites of the IPM run parallel to prism direction; transition zones between HSB are lacking; the inclination of the HSB is normally very low and the prism cross sections are not flattened but somewhat irregular. The number of prisms per HSB is no good distinctive character for pauciserial and multiserial HSB, since there exists a wide overlap. The pauciserial schmelzmuster is primitive, the multiseiial derived because: 1. the pauciseiial schmelzmuster appears earlier in the fossil record in the most primitive rodents (Paramyids s.l. and Ctenodactyloids); 2. the Eocene Ctenodactyloidea show pauciserial HSB but the Oligocene and younger ones are characterized by multiserial HSB; 3. in the outgroup comparison, the Eurymylidae (Mixodontia) show pauciserial HSB; 4. biomechanically, multiserial HSB strenghten the enamel better than pauciserial HSB, since their IPM runs nearly always in an angle of 45° or more to the prisms.

In multiseríal HSB three subtypes can be distinguished which are differentiated by the IPM orientation. Primitive is a (rarely strict) parallel or acute angular, anastomozing IPM, and derived is an interrow sheet-like ("plattenartige") IPM. This evolutionary polarity is indicated by enamel evolution in the Ctenodactylidae which show an acute angular IPM in the Oligocene and a rectangular interrow sheet-like IPM since the Miocene. Among the Caviomorpha a rectangular interrow sheet-like IPM is restricted to the Octodontoidea; therefore they must be considered derived in terms of their enamel structure. The first multiserial HSB in rodent incisors appear in phiomyids or chapatrimyids from the Upper Eocene of Algeria. The IPM is acute angular and anastomozing. The worldwide next younger multiserial HSB are found in Lower Oligocene phiomyids of Fayum, Egypt There already a rectangular interrow sheet like IPM is present (in Metaphiomys) besides the acute angular anastomozing IPM.

The first Caviomorpha from the Deseadan (Oligocene-Miocene) likewise show already acute angular anastomozing IPM (e.g. Scozamys) and rectangular interrow sheet-like IPM (Platypittamys). Therefore the first Caviomorpha cannot be positioned close to a transition from pauciserial to multiserial HSB. In none of the potential caviomorph ancestors from southern North America multiserial HSB or transitional stage between pauciserial and multiserial HSB could be found. The similarities between the enamel types of the Fayum rodents and the rodents from the Deseadan of South America make a derivation of the Caviomorpha from Paleogene North African phiomorph rodents or their direct ancestors most probable. This supports at the same time a descent of the platyrrhine Primates from North African anthropoids.
  

Rodents from the new localities of Châteauredon (Alpes-de-Haute-Provence) and La Denise (Bouches-du-Rhône) show more similarities with the rodents known from the Czecho-Slovak locality of Franzenbad than with the species found in contemporaneous Lower Miocene faunas located westward of the present Rhône Valley. This is another data wich support the existance of several biogeographical provinces in Southern France during Lower Miocene. The correlations which have been settled down allow new datations of several formations in Provence and give new information on the Aquitanian and Burdigalian paleogeographies of this region. More precise stratigraphical allocations are given to some other localities of Central Europe. 

Cranial anatomy of a late Miocene rhizomyid, Brafhyrhizomys cf. B. pilgrimi, provides new evidence on the origin of the dorsal, round infraorbital foramen of living rhizomyines. Primitive rhizomyids retain a myomorphous keyhole foramen with a long ventral slit that retracts upward during the evolutionary history of the Rhizomyidae. The primitive condition of the elongated ventral slit is represented by Kanisamys sivalensis. Among later burrowers the foramen shows progressive dorsal migration, the ventral slit terminating midway up the snout in B.tertracharax and B. choristos ; well above the midline of the snout in Brachyrhizamys cf. B. pilgrimi. Apparently this transformation began earlier among Rhizomyinae than among Tachyoryctinae and continued to a more derived stage in rhizomyines. ln living Rhizomyx the ventral slit is absent and only a high round hole remains at the anterior end of the zygomatic arch. 

The review of material recently collected in the new localities from the “Phosphorites du Quercy", and different localities from the South of France, bring new informations on the genus Eucricetodon THALER. 1966, and Pseudocricetodon  THALER,  I969 (Middle and Upper Oligocene. Western Europe). Thanks to Eucricetodon huerzeleri VIANEY-LIAUD, 1972, which were unsufficiently known until now, is proposed. During the middle Oligocene Eucricetodon atavus  MISONNE, 1957 seems to give rise to two lineages. One of them led to Eucricetodon huberi,which however exhibits a larger size and a development of progressive characters on the teeth. The other would be Eucricetodon huerzeleri well differentiated at the “Mas de Pauffié" standard level (beginning of the upper Oligocene). The ornementation of lower incisors is described, when possible. Though the fossils are not abundant, it seems that the ancestral lineage, Eucriretodon atavus, remains in  the upper Oligocene (Boningen standard level). evolving into Eucricetodon praecursor SCHAUB, 1925 (Rickenbach standard level). The characters of Eucricetodon dubius  (SCHAUB. 1925), represented by a numerous population in Pech Desse and Pech du Fraysse (Quercy). confirm that this species and Eucricetodon praecursor  belong to two different lineages. As Eucricetodon dubius shows more primitive features, this species could not originale from Eucricetodon atavus -Eucricetodon huberi. The appearance of this species at the level of Mas de Pauffié could be the result of an immigration. A new definition of Pseudocricetodon incertus (SCHLOSSER. 1884) is given. This species has been found in several localities, where it had not been identified until now. lts comparison with Pseudocricetodon moguntiacus  (BAHLO. l975), found at several localities from the standard level of Antoingt (end of middle Oligocene). shows a parallel evolution to that of Pseudocetodon incertus, which is  of larger size and with a less complicated pattern of teeth. 

The new fauna of Collet Redon (Bouches-du-Rhône, France) is dated by three rodents: Megacricetodon aff. bavaricus, Democricetodon affinis mutilus and Peridyromys cf. hamadryas. They correlate this locality with Oggenhof and Ohningen in Bavaria (Western Germany). As the radiometric age of Ohningen is estimated between 14 and 13 M.Y., these three localities are of Serravallian age. This datation brings a complete readjusment of the stratigraphy of the section of Collet Redon formerly described by Collot and Combaluzier. The marine deposits with underly the continental formation with the mammal fauna, are Burdigalian. The angular unconformity between the marine and the continental deposits gives evidence of an episode of emersion on the margin of a sedimentary basin, with deformation and erosion. Owing to the newly discovered fauna, this geodynamical event is clearly settled within the regional geographical and chronological context. Lacustrine and continental deposits of such an age were up to now unsuspected in this area.