The principles and practices employed in establishment and recognition of South American land mammal ages are reviewed along with previous and present concepts of distinguishing time, rock, and faunal units. Previous chronological arrangements of South American Tertiary land mammal faunas are appraised on the basis of recent geological and paleontological data. Twelve South American Tertiary land mammal ages are here recognized [from oldest to youngest, Riochican (middle to late Paleocene); Casamayoran (early Eocene); Mustersan (middle Eocene); Divisaderan (late Eocene); Deseadan (early [to middle?] Oligocene); Colhuehuapian (late Oligocene); Santacrucian (early Miocene); Friasan (middle Miocene); Chasicoan (late Miocene); Huayquerian (latest Miocene); Montehermosan (early to middle Pliocene); and Chapadmalalan (late Pliocene)]. As all except the Friasian were originally defined on the basis of Argentine faunas, these are discussed first and at length, and each is reviewed with discussion of type locality, stratigraphy, type fauna, and faunal correlations. Non-Argentine faunas are then discussed country by country in alphabetical order.

     A review is given of radioisotope dates obtained on volcanic rocks (i.e., basalts, tuffs) associated with mammalbearing beds in Argentina. Based on these age determinations and on correlation of the late Tertiary land mammals involved in the interchange between North and South America, a chronology of South American land mammal ages correlated with North American land mammal ages and European marine stages is proposed.

It is concluded that South America was an island continent through most of the Tertiary Period (ca 65 to about 3 Ma). As a result, the land mammal fauna of South America developed in isolation and was dominated by autochthonous endemic groups. Toward the end of the Tertiary (i.e., middle Miocene) a unique faunal balance had been achieved by the descendants of the ancient inhabitants (notoungulates, litopterns, condylarths, astrapotheres, edentates, marsupials) and of later (late Eocene) waif immigrants (caviomorph rodents, platyrrhine primates). A prominent feature of this mammal fauna was the combination of carnivorous and omnivorous marsupials with native placental herbivorous ungulates, subungulates, and edentates.

Sometime during the late Miocene, a limited but important interchange of mammalian taxa between North and South America took place. Procyonids (raccoons and their allies), a group of North American origin, first appear in South America in strata of Huayquerian Age, while members of the extinct South American ground sloth families Megalonychidae and Mylodontidae first appear in North America in early Hemphillian time. These groups dispersed along island arcs before the appearance of the Panamanian land bridge in the Pliocene (ca 3.0 Ma). Cricetine rodents, a group of North American origin, are first known in South America in strata of Montehermosan Age. The known taxa are too advanced and diversified to be considered the first of this group to invade South America. lt is believed by some workers that these rodents arrived before the Montehermosan, possibly in the late Miocene or earlier, by waif dispersal from North America.

The isolation of South America ended with the appearance of the Panamanian land bridge, which provided a direct, dry land connection between the two Americas. Across this portal an extensive interchange of terrestrial faunas occurred, and the fossil record documents an intermingling of these long-separated land mammals faunas.

      The beginning of this interchange by land route in South America is marked by the appearance of mammals which evolved from North American emigrants in the Chapadmalal Formation of Argentina. These include a mustelid (Conepatus), a tayassuid (Argyrohyus), and four genera (Akodon, Dankomys, Graomys, Reithrodon) of cricetine rodents. The appearance of this contingent of northern animals favors the existence of the Panamanian land bridge by this time. Likewise, a large number of terrestrial vertebrates of South American origin appear in North America in beds of late Blancan Age date around 2.7 Ma. Among the mammals are Neochoerus, Erethizon, Glyptotherium, Glossotherium, Kraglievichia, and Dasypus. 

The dentitions as well as one complete and several partial skeletons of Equoids from the Eocene lignite beds of the Geiseltal locality are revised. Instead of 13 species distinguished up to now 3 chronoclines with 5 species and 3 separate species are recognized (text. fig. 1). Propalaeotherium hassiacum HAUPT, 1925 is evolving into Propalaeotherium isselanum (CUVIER, 1824) between the levels of the « obere Unterkohle ›› and the « untere Mittelkohle ›› of the Geiseltal section. Propalaeotherium argentonicum GERVAIS, 1849 is shown to be present in the « untere Unterkohle ››, whereas Lophiotherium pygmaeum (DEPERET,1901) occurs in the « obere Mittelkohle ›› and in the « oberes Hauptmittel ››. Plagiolophus cartieri STEHLIN, 1904 appears during the transition from the « Mittelkohle ›› into the « Oberkohle ›› as the earliest true Palaeothere. Therefore the « Oberkohle ›› is already regarded as Upper Eocene. This is corroborated by the occurrence of a phyletic descendant of Propalaeatherium parvulum (Propalaeotherium n.sp.) in the middle and upper "Oberkohle " because this species appears otherwise for the first time at the mammal level of Lissieu. On the other hand Propachynolophus gaudryz (LEMOINE, 1878) described by Matthes (1977) from the « untere Unterkohle ›› turns out te be in fact a Phenacodont. Thus the decisive argument for classifying the « untere Unterkohle ›› as Lower Eocene has to be dropped. Biostratigraphically the « Unterkohle ›› and the «Basishauptrnittel ›› correspond with the lower Middle Eocene (mammal level of Messel), whereas the «unteres Hauptmittel ›› and the « untere Mittelkohle ›› are equivalent to the middle part of the middle Eocene (mammal level of lssel), and the « obere Mittelkohle ›› together with the « oberes Hauptmittel ›› coincide with the upper Middle Eocene (mammal level of Bouxwiller). 

La poche à phosphorite de Sainte-Néboule (Lot) a livré au cours des récentes campagnes de fouilles effectuées dans le cadre de la Rep 311 une douzaine de dents ou fragments de dents de paléothéridés à rapporter à 3 taxons. 

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 first lists of Insectivores (Erinaceidae, Talpidae and Soricidae) from the Pliocene beds of Southern France and North-East Spain are given in this paper. The material from twelve localities is studied. These localities are geographically situated in Languedoc (Celleneuve, Vendargues, Nîmes, Sète, Balaruc 2 and Seynes), in Roussillon (Terrats, Serrats-d'en-Vacquer, Château d'eau and Mont-Hélène) and in North-East Spain (Layna, Medas Islands and Puebla de Valverde). These faunas correspond to the Early, Middle and Late Pliocene. 1 to 8 taxa are identified in these localities and 14 specific taxa are presently listed for this period in this area. Two new specific taxa are described as Galerix depereti nov. sp. from all the Early Pliocene localities in the North-Pyrenean area and as Desmanella gardiolensis nov. sp. from Balaruc 2. For this small mammals, two faunal assemblages are recognized. The first one is dated from the Early Pliocene (F 1, 2 and 3 zones in Aguilar et Michaux) and is characterized by Galerix depereti and rare and little diversified Soricids. The second one is Late Pliocene in age (zones G 2 and G 3). The fossils of the genus Talpa are relatively abundant and the Soricids are diversified and very abundant. The Middle Pliocene (zone G 1) is a transitional period. ln these faunas, most of the insectivore genera are known from the European Late Miocene beds (8 on 10). This fact demonstrates a relative continuity between the invectivore faunas from the Late Miocene to the Early Pliocene. In conclusion, somme paleoecological considerations are suggested.
  

The recent discovery of several mandibular toothplates of a chimaeroid fish at a dig in the area of the Landover Mall, near Landover, Prince Georges County, Maryland, brings to our attention a new species of the chimaeroid, Ischyodus.
 Although superficially reminiscent of the European chimaeroid toothplates of Ischyodus thurmanni (cf. text-fig. 2), I. williamsae nov. sp. probably has a more closer relationship to I. bifurcatus CASE, 1978, of the Upper Cretaceous of New Jersey and Delaware. 

The revision of the old collections of fossil birds from the “Phosphorites du Quercy” and the study of new material give the following results (Gruiformes, Cariamae) :  The humeri and most of the carpometacarpi described under the name Filholornis belong in Elaphrocnemus. The ulnae ascribed to Fïlholornis belong in Idiornis. Most of the post-cranial elements of the genera Elaphrocnemus and Idiornis are described and show great similarities with recent Cariamidae and Opisthocomidae, and fossil Bathornithinae.  A new genus and a new species, Oblitavis insolitus, are created in the sub-family Idiornithinae; two new species are described in the genera Elaphrocnemus (E. brodkorbz) and Idiornis (I. itardiensis), and the species Elaphrocnemus gracilis is transferred to the genus Idiornis.  The genus Propelargus Lydekker is transferred from the family Ciconiidae to Cariamidae.  A new generic name, Occitaniavis, is created for the species Geranopsis elatus, which belong in Cariamidae, while the type-species of the genus, Geranopsis hastingsiae, is a member of the Gruidae.  The affinities between the Quercy avifauna and the Neotropical one is emphasized by the occurrence of Phorusrhacidae, previously known only from the Cenozoic of South America and the Late Pliocene or Early Pleistocene of North America. Thanks to the material collected during the new excavations, the stratigraphical position of most of the species is stated precisely, and evolutionary lineages are outlined. This study shows that the suborder Cariamae, presently restricted to two South American genera, was already extremely diversified during the Eocene, and widespread in Europe and North America. 

Les Carnivores Fissipèdes de Sainte-Néboule appartiennent tous au genre Cynodictis et semblent constituer une population homogène. Celle-ci se distingue suffisamment des espèces déjà décrites pour constituer un taxon particulier : Cynodictis lacustris neboulensis n. s. sp. . L'étude des variations à l'intérieur de cette population nous a conduit à reconsidérer les critères utilisés pour définir les espèces existantes et à regrouper certaines d'entre elles. Il semble qu'il demeure cependant trois lignées distinctes dans le genre Cynodictis mais le matériel nous paraît encore insuffisant pour traduire cette remarque en termes de systématique. 

A new Propalaeotherium species, clearly distinct from the genus Eurohippus, is described. It is characterized by having a similar size as P. voigti from the German Geiseltal localities (MP 11 to MP 13 reference-level), but differs in several features suggesting a slighty more derived morphology. It presents indeed less brachyodont crowns with less prominent and less elevated cingula, slightly larger relative surface of premolars, and a more marked metaconid splitting on cheek teeth. This new species is unknown from other European localities except the nearby Saint-Martin de Londres locality which has been considered older than the MP 13 level. 

The mammalian faunas of the Paleogene of Europe and their localities are reviewed with comments on problems of European stratigraphy (epoch, stage and substage limits) and on the possibilities of faunal migrations. Radiometric dating is discussed. A stratigraphic scale for the Paleogene is presented, as well as a refined system of sequential faunal levels. 

The discovery of new hippopotamid material from the late Miocene Baynunah Formation (Abu Dhabi, United Arab Emirates) has prompted the revision of the existing material of this as yet unnamed fossil taxon. The Baynunah hippopotamid appears to be distinct from all other contemporary and later species in having a relatively more elongate symphysis, a feature similar to the earlier (and more primitive) Kenyapotamus. Yet, the Baynunah hippopotamid presents a dentition typical of the Hippopotaminae. It is therefore a distinct species attributed to the later subfamily, described and named in this contribution. This species provides further evidence for a ca. 8 Ma evolutionary event (termed “Hippopotamine Event”) that initiated the spread and ecological significance of the Hippopotaminae into wet habitats across Africa and Eurasia. The morphological affinities of the new species from Abu Dhabi suggest that the Arabian Peninsula was not a dispersal route from Africa toward southern Asia for the Hippopotamidae at ca. 7.5 Ma to 6.5 Ma. 

The Late Miocene site of Gritsev (MN 9, Ukraine) has yielded a very rich bat fauna, the remains of which are well preserved. Compared to other Neogene bat assemblages of Europe, the Gritsev bat community is unique in preserving plecotine bats, which are rare from Neogene sites. Some peculiar and new bat species, including a large plecotin Otonycteris, already were described from the Gritsev mammal site. Here we report new records of small plecotin bats from Gritsev, including a new taxon, Barbastella maxima nov. sp. This is the earliest reliable fossil record of this genus and it differs from more recent species of Barbastella in being considerably larger. The evolutionary patterns in the odontology within the tribe Plecotini, supported by biostratigraphical distribution of fossil records of Plecotus are discussed. The morphological peculiarities of the new fossils of plecotine bats from Gritsev are discussed in connection with its possible taxonomical affinity. 

Pangolins have never shown a high taxic diversity and their fossil record is scarce. We report here the first discovery of a partial humerus from late Oligocene deposits in Pech du Fraysse (MP28, France). The new specimen from Pech du Fraysse is described and compared to various extant and extinct species of pangolins. It shows a suite of morphological features very similar to the humeri discovered in Saint-André (MP 26), Solnhofen (Burdigalien), and Saulcet (Aquitanian), attributed here to Necromanis franconica. The description of the specimen from Pech du Fraysse allowed us to discuss the systematics of Paleogene and Neogene pholidotans. The differences between PFY 4051 and N. franconica on the one side, and N. quercyi on the other side, might be sufficiently important to justify a generic distinction. A comparison with extant species showed that N. franconica was likely terrestrial and fossorial based on its humeral morphology. 

Abstract
 The validity of Propachynolophus Lemoine, 1891, supposedly an intermediate between Hyracotherium Owen, 1841 and Pachynolophus Pomel, 1847, has been questioned for a long time. A detailed analysis of features on which this genus is based further supported by a formal cladistic analysis demonstrates that Propachynolophus is not a valid taxon. The type species, “Propachynolophus gaudryi Lemoine, 1891” shall be assigned to Propalaeotherium Gervais, 1849, under the new combination Propalaeotherium gaudryi (Lemoine, 1891). “Pachynolophus maldani Lemoine, 1878”, later assigned to Propachynolophus, typifies the new genus Orolophus, under the binomen Orolophus maldani (Lemoine, 1878). The other referred species, “Propachynolophus levei Hooker, 1994” and “P. remyi Checa-Soler, 1997” are poorly documented, and both species shall be provisionally referred to as “Hyracotherium” levei (Hooker, 1994) and “Hyracotherium” remyi (Checa-Soler, 1997), pending new discoveries.
 
  

Le Quercy est aujourd 'hui un vaste plateau calcaire, parcouru par un réseau karstique actif, profondément
entaillé par des vallées aux falaises abruptes, comme celles du Lot ou du Célé. Sur un sol peu épais domine la forêt de chênes, accompagnés de cornouillers, érables, genévriers. La faune est pauvre, peu diverse, et les nombreux chasseurs se satisfont de gibier d'élevage ...

Il y a trente cinq millions d'années environ, le paysage était bien différent. La période de l'Eocène supérieur, qui s'achevait, avait été chaude et humide, si l'on se réfère à la fois aux paléotempératures (calculées à partir de sédiments marins extra·européens) et aux restes fossilisés de végétaux typiquement tropicaux. 

 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. 

Morphological descriptions are given of Eocene mammals from the locality Toru Ajgyr (NEKyrgyzstan) that were excavated in 1997 and 1998 in a cooperation between the Martin-Luther-University Halle (Germany), the Zoological Institute in St. Petersburg (Russia) and the Seismological Institute in Bishkek (Kyrgyzstan). The species found belong mostly to perissodactyls, as Lophialetes sp., Teleolophus sp. and brontotheres. The primitive ungulate family Olseniidae is represented by a complete foot skeleton of cf. Olsenia sp. In addition, postcranial materials of Gobiatherium mirificum (Dinocerata) and of artiodactyls have been collected and are described herein. Based on mammals, the locality is part of the Asian Land Mammal Age Arshantan and is stratigraphically equivalent with the Bridgerian Land Mammal Age in North America and with the lower and middle Geiseltalian of the European Middle Eocene. 

The genus Cryptomeryx SCHLOSSER, 1886, inusited during a long period, has been discovered in Lower and Middle Oligocene localities of the Quercy region (South-West France). This new material, as well as specimens from the old collections referred to Cryptomeryx, are described; their study, allows us precising the definition of the genus, and confirming its allocation to the Tragulidae family. The type species of the genus, Crypmmeryx gaudryi (= Lophiomeryx gaudryi FILHOL, 1877), occurs in several localities at the base of the Middle Oligocene (Itardies, La Plante 2, Roqueprune 2, Soulce, Herrlingen 1). The new species C. matsoui n. sp. has been defined in the older locality of Mas de Got (top of Lower Oligocene). It is possible that the species Pseudamphimeryx decedens STEHLIN, 1910 pertains to the same genus. Also to the Tragulids must be referred the monospecific genus Iberomeryx (I. parvus GABOUNIA, 1964) from Upper Oligocene of Benara (Georgie, URSS), with which Cryptomeryx is related. These genera are not direct ancestors of Miocene tragulids; their occurrence in the Western European Oligocene results from a first immigration wawe of the family. These Tragulids are one of the most archaic groups of Ruminants. They are probably derived from a primitive stock which had acquired in Asia the selenodont condition of the dentition. 

La poche de Ste-Néboule, commune de Béduer (Lot), 15 km environ à l'WSW de Figeac, fait partie du groupe le plus septentrional des gouffres creusés par les ruissellements du Paléogène dans les calcaires jurassiques de la bordure sud-ouest du Massif Central et qui furent comblés à la même époque par des argiles sidérolithiques accompagnées de phosphate de chaux concrétionné ainsi que des restes de la célèbre faune dite «des phosphorites du Quercy» . 

The litoptem Proterotheriidae are extinct endemic South American ungulates frequently used as an example of evolutionary convergence with the horses. They were considered to be exclusively Tertiary representatives with the youngest record being in the late Pliocene, before the appearence of the equids and cervids during the Great American Interchange. Two undoubted Pleistocene records in Argentina and the specimen here described from Uruguay, confirm the persistence of the proterotherids into that period. In the Quaternary, these ungulates are found outside the typical pampean region and probably were confined to a few northern and warmer more forested relictual microhabitats.