Isolated elasmobranch teeth (sharks and rays) from the middle Eocene (Bartonian) Bandah Formation in the Jaisalmer District of Rajasthan, India are described. The remains improve our knowledge of the environment represented by this lithostratigraphic unit and the ecology preserved therein. Seventeen unequivocal taxa were identified, including Nebrius sp., Striatolamia aff. S. macrota, Brachycarcharias atlasi, B. lerichei, cf. Jaekelotodus sp., Carcharhinus mancinae, Rhizoprionodon sp., Physogaleus sp., Galeocerdo clarkensis, G. eaglesomei, Odontorhytis aff. O. pappenheimi, “Rhinobatos” sp., “Dasyatis” sp., Coupatezia sp., “Aetomylaeus” sp., “Rhinoptera” sp., and Ouledia aff. O. lacuna. Of these, “Aetomylaeus” sp., B. atlasi, C. mancinae, G. clarkensis, G. eaglesomei, cf. Jaekelotodus sp., Nebrius sp., Odontorhytis aff. O. pappenheimi, Ouledia aff. O. lacuna, and “Rhinoptera” sp. are reported from the middle Eocene of India for the first time. The Bandah Formation elasmobranch palaeofauna has close affinities to the Palaeocene-Eocene Tethyan/Paratethyan faunas of Africa, Madagascar, Asia, and Europe, and some taxa indicate a western hemisphere influence from North America. The Bandah Formation palaeofauna indicates that deposition occurred in a moderately shallow marine environment. The Bartonian age is primarily based on foraminifera but is corroborated by the presence of elasmobranch taxa that also occur in contemporaneous deposits elsewhere. The marine regression started during the early Palaeogene, and our study indicates that the sea completely withdrew from the Jaisalmer Basin after the deposition of the Bandah Formation. This event may have been synchronous with the middle Eocene uplift of the Himalayan-Tibetan Plateau. 

The tooth morphology of the Thalattosuchia (marine crocodilians from the Jurassic and the Early Cretaceous) is analysed. The Callovian from Poitou and the Kimmeridgian from Quercy have yielded many remains of Metriorhynchus, Steneosaurus and Machimosaurus. These remains allow us to study the variations of tooth morphology during ontogenic growth, tooth replacement and the location of the teeth. We have defined different tooth types for these genera. In Metriorhynchus, the two tooth types defined do not coincide with the two groups recognized in the Callovian (broad-skulled and narrow-skulled metriorhynchids) but reflect the prey preferences of these forms. In Steneosaurus and Machimosaurus the five tooth types deñned are in agreement with the main taxa known from the Bathonian to the Early Cretaceous. This study allows to precise the function and the prey preference of the Thalattosuchia during the Jurassic and the Early Cretaceous.

  

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 classifications of the recent vespertilionine bats were made wihtout taking in account the teeth morphology; this resulted in a reduction of the possibilities of comparison with the available fossils. The generalized use of dental formulae was abusive: this contributed to the admission of artificial genera. These conditions have long delayed the consideration of characters able to frame the phylogeny of the sub-family. In the first part of the study, the teeth morphologies are described and analysed. morphological reference types are established for each upper and lower tooth: they should make an easier elaboration of criteria for the differentiation at generic level. The position of the species in view of these criteria allows one to group them into homogeneous genera, and to appreciate the degree of relationship that the latter have between them. The second part of the study (next publicationà will develop inferences dealing with systematics and phylogeny 

The middle Palaeocene of São José de Itaboraí (State of Rio de Janeiro, Brazil) has yielded a very rich and diverse snake fauna which includes Madtsoiidae, Aniliidae s.l., Boidae, Tropidophiidae s.l., Booidea incertae sedis, and Russellophiidae. The present article (part I) deals with Madtsoiidae and Aniliidae s.l. Madtsoiidae are represented by many vertebrae and a few skull bones. They comprise one new species assigned to the genus Madtsoia (M. camposi sp. nov.). However, the definition of the genus Madtsoia is unsatisfactory and the generic allocation might be provisional. A few elements, vertebrae only, belong to the Aniliidae s. l. Two taxa are referred to this latter group: Coniophis cf. C. precedens and Hoffstetterella brasiliensis gen. et sp. nov. The forthcoming part II will deal with Boidae.

  

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. 

Investigations of the Clinchfield Formation (middle Eocene, upper Bartonian) exposed at the Hardie Mine (Wilkinson County, Georgia, USA), produced 4,768 actinopterygian otoliths representing 14 taxa and increased the number of bony fishes threefold from the site. The somewhat limited richness was characterized by bonefishes, mud eels, conger eels, sea catfishes, cusk-eels, snooks, grunts, drums and croakers, and porgies. The assemblage had a relatively even distribution with Ophidiidae, Congridae, and Sciaenidae most common. Included in the otolith taxa was a new sciaenid genus and species, Eosciaena ebersolei, with unknown relationships to other Sciaenidae. The Clinchfield otoliths were compared to other middle and late Eocene in age otolith assemblages in Alabama, Mississippi, and Louisiana utilizing percentage similarity measurements. Analysis indicated that the Clinchfield otoliths were not greatly similar or greatly unlike the Moodys Branch and Yazoo Clay otolith assemblages. However, the Clinchfield showed little relationship to the slightly older Lisbon Formation in adjacent Alabama and is postulated to be related to global climatic and plate tectonic events. Biostratigraphically, the Clinchfield otolith taxa are essentially the same as the other formations except for the Lisbon, which has at least ten unique species. Abundances of Clinchfield otolith taxa indicate a possible sub-bioprovince in the eastern Gulf Coastal Plain. The Clinchfield otoliths indicate a tropical to perhaps subtropical, soft substrate, mainly normal marine to slightly reduced salinities, inner shelf (0–20 m) paleoenvironment with indications of proximal continental coastlines. This investigation represents an initial step in addressing the immensely understudied Paleogene otolith assemblages in Georgia.
  

Fourteen distinct phyletical lineages which belong at least in three families: Ischyromyidae ALSTON, 1876, Gliridae THOMAS, 1896 and Theridomyidae ALSTON, 1876, have been identified after the study of more than 3600 rodent dental remains from about twenty Early and Middle Eocene european localities. A systematical and phylogenetical revision of these rodents has been achieved. Nearly all the specific and generic diagnosis are emended. Several new combinations and synonymies are proposed. Four new species and two new genera, Euromys nov. (Ailuravinae) and Hartenbergeromys nov. (Microparamyini), are named and described. Euromys nov. gen. is known by three distinctive ypresian (MP 7 to MP 10 european reference levels) chronospecies. This new lineage is thought to be the direct ancestor of Meldimys MICHAUX, 1968 and Ailuravus RUTIMEYER, 1891. A new species of the genus Plesiarctomys BRAVARD, 1850, Pl. lapicidinarum from Condé-en-Brie (MP 8-9 reference level), allows to relate the Plesiarctomys lineage to the Pseudoparamys MICHAUX, 1964 one. The taxa Sparnacomys HARTENBERGER, 1971, Pantrogna HARTENBERGER, 1971, and Corbarimys MARANDAT, 1989 are erected to genus rank; the last one is not thought to be an Ischyromyidae. A new chronospecies of Pantrogna, P. marandati nov. sp. from the locality of Prémontré (MP 10 reference level), is described. This lineage is at the origin of two others, namely Masillamys TOBIEN, 1954, including M. mattaueri (HARTENBERGER, 1975) nov. comb. (MP 10 reference level), and Hartenbergeromys nov. gen., known from MP 10 (H. hautefeuillei nov. sp.) and MP 11 (H. parvus TOBIEN, 1954) reference levels. The phylogenetical position of Hartenbergeromys nov. gen., at the origin of the european family Theridomyidae, is discussed. The systematical and phylogenetical status of two probable Paramyinae, "Paramys" woodi MICHAUX, 1964 and an unnamed genus and species, are discussed. New populations of the primitive Gliridae Eogliravus HARTENBERGER, 1971 and of the primitive Theridomyidae Protadelomys HARTENBERGER, 1968, are described and assigned to previously known species.

  

Prolagus sardus is the last representative of the diverse lineages of European endemic ochotonids. It is also the most abundant in the collections. The previous studies made of this species have established rather well its dental morphology, its phylogenetic position, its geographic and temporal distribution, and its intraspecific individual variation. On the other hand, no osteologic study has fully utilized the superb material from Corsica and Sardinia  collected by Forsyth Major.
Nearly all of the parts of the skeleton are represented in this material; they are here described and figured. Comparisons are made with Ochotona, the only surviving genus of the family, as well as with the living leporids, in particular Romerolagus, Oryctolagus and Lepus. A brief examination of the dentition reveals some particular characters of the incisors. The osteologic study allows limited interpretations to be advanced concerning the posture, mastication. locomotion and some other adaptive features of P. sardus.
P. sardus appears as an incontestable ochotonid, but it differs from Ochotona by some characters which are found in leporids. Certain of the characters are here judged primitive for lagomorphs. The genus Ochotona therefore can no longer be considered as the image of a primitive lagomorph, because in spite of the lack of cursorial adaptations which differentiate it from leporids, it presents other specializations which are common to it alone. 

Murids and gerbillids (Rodentia, Mammalia) recovered from four Upper Siwalik localities; Moginand (around 3.5-4.5 m.y.), Kanthro (around 2.5 m.y.), Ghaggar (around 2 m.y.) and Nadah (around 1.8-2 m.y.) are described herein. A comparison of Mus linnaeusi sp. nov. reveals its close relationship towards the house mouse Mus musculus. In contradiction to earlier proposals that Golunda migrated to the Indian subcontinent from Africa sometime during Late Pliocene, it is suggested here that Golunda (in the form of Golunda tatroticus sp. nov.) evolved from Parapelomys robertsí of Late Miocene deposits of Siwaliks. Golunda tatroticus sp. nov. exhibits a progressive relationship to the extant Indian Bush Rat Golunda ellioti through Golunda kelleri and Golunda sp. Tatera pinjoricus sp. nov. is considered here to be a link between the extinct Abudhabia kabulense and the extant Tatera indica.

  

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. 

Some new material of percrocutas from the late Miocene of Axios valley (Macedonia, Greece) is studied. They have been found in the locality of "Pentalophos 1" (PNT). The material has been described and compared with the known late Miocene percrocutas of Eurasia. This comparison indicates that it can be identified as Dinocrocuta gigantea (SCHLOSSER, 1903). A maxilla of a percrocuta, named ”Hyaena" salonicae, was found in the same area (Andrews, 1918). "Hyaena" salonicae is smaller than the PNT material. It is also compared with other material from Eurasia while its taxonomic and age problems are discussed. It belongs to Dinocrocuta and shows close relationships with D. robusta and D. senyureki; its age can be considered as late Vallesian-early Turolian. The age of the locality PNT is also discussed and a possible Vallesian age is proposed for it. 

The dentition of selachians is characterized by an often very pronounced heterodonty involving a great morphological diversity. Despite this fact, the dentitions of selachians can be grouped in a rather reduced number of dental types corresponding to trophic adaptations: grasping, tearing, cutting, crushing, grinding and grasping-grinding type. The numerous exemples of convergence and parallelism that can be observed in fossil selachians and between Recent and fossil ones is the result of this reduced number of dental types. These dental specialisations allow to try a reconstruction of the way of life of fossil forms. 

A detailed comparative study of a complete skeleton of Bachitherium and a cladistic analysis of the sub-order Neoselenodontia lead us to propose a cladogram and a new classification of this group. The Tylopoda are the sister-group of the Ruminantia, which are chiefly defined by the fusion of the cuboid and navicular. Within this infra-order, Amphimeryx is the sister genus of a tetraselenodont group, in which the Hypertragulidae are well-separated group from a monophyletic group defined by the loss of trapezium, fusion of capitatum and trapezoid, and the isolation of the hypoconid on lower molars. The most primitive genera of this group, Lophiomeryx and Iberomeryx still have an open trigonid on the lower molars, but this is lingually closed in Archaeomeryx, sister-genus of the higher Ruminantia which have fused metatarsals and more evolved milk teeth. We divide them into two pan/orders : Tragulina (including the recent and miocene Tragulidae, and the North-American Leptomerycidae), and Pecora, with reduced lateral metacarpals and a new crest (telocristid) on the lower premolars. Within the Pecora, the upper molars of Gelocus are more primitive than those of Bachitherium (a genus with many autapomorphies in the dentition) itself more primitive than the group Prodremotherium + Eupecora, with fused metacarpals. We consider the Eupecora (including several genera without frontal appendages) to be monophyletic. 

Eosimiid and amphipithecid primates document a long and significant history of primate evolution throughout the Eocene in Southeast Asia. Despite the absence of a comprehensive post-Eocene fossil record, it was generally hypothesized that both families left no descendant in Asia. Recently, two new small-bodied taxa, Bugtipithecus and Phileosimias, have been recovered in early Oligocene coastal deposits from the Bugti Hills (Balochistan, central Pakistan) and referred to the families Amphipithecidae and Eosimiidae, respectively, on the basis of dental fossil remains. In this paper, we provide more exhaustive description, comparison, and discussion of these taxa. As for tarsiid and sivaladapid primates, the persistence of eosimiids and amphipithecids into the Oligocene clearly demonstrates that low latitudes of South Asia provided a continuous access to tropical refugia during the climatic deterioration characterizing the late Eocene-early Oligocene interval, which was seemingly lethal for primate communities elsewhere across the Holarctic continents. As a contribution to the ongoing phylogenetic debates regarding the position of eosimiids and amphipithecids on the primate family tree, we have performed a cladistic analysis in a high-level primate systematic context in order to assess the position and the role of these new taxa in that phylogenetic issue. Our results support the view according to which eosimiids and amphipithecids (and by extension Phileosimias and Bugtipithecus, respectively) are stem anthropoids. These fossils from Pakistan document an unsuspected Oligocene phase of the evolutionary history of anthropoid primates in southern Asia, which clearly enhances the extent of the anthropoid radiation in this province during the Paleogene. Several phylogenetic and paleobiogeographic aspects are discussed, notably the intra- and inter-relationships between Paleogene Asian and Afro-Arabian anthropoids, and the resulting potential dispersal models between both land-masses during the Paleogene. 

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. 

A comparative bone histological study of the three known genera of the endemic European ornithopod dinosaur family, Rhabdodontidae, is presented here in an ontogenetic context. Investigated specimens were assigned to different ontogenetic stages based exclusively on the histological indicators of osteologic maturation during diametrical bone growth; an entirely size-independent method as opposed to most previous studies. Qualitative comparison of bone histology of corresponding ontogenetic stages and elements among the three valid rhabdodontid genera, Mochlodon, Zalmoxes, and Rhabdodon, revealed some consistent patterns. Genus specific histological differences within Rhabdodontidae are most expressed between Rhabdodon and the Mochlodon-Zalmoxes clade. These indicate a prolonged phase of fast growth and a less constrained cyclicity in the growth dynamics of Rhabdodon, as opposed to the slower and more regulated growth strategy reflected in the bones of Mochlodon and Zalmoxes. These genus specific differences are consistent with the phylogenetic interrelation of the genera and are most probably related to the pronounced differences in body size. However, when compared to other ornithopods, most detected histological features in rhabdodontids do not seem to reliably reflect either phylogenetic relations or body size. A notable common feature of all rhabdodontid genera irrespective of body size is the ontogenetically early onset of cyclical growth and secondary remodelling; a pattern that more resembles the condition found in derived ornithopods than that described in more basal taxa which are closer relatives of rhabdodontids. The recognition of taxon-specific histological patterns as well as patterns indicative of ecological and thereby functional traits clearly requires more accurate, preferably quantitative evaluations.   

Based on isolated teeth two new scyliorhinid shark species, Scyliorhinus biformis nov. sp. and Scyliorhinus suelstorfensis nov. sp., are described from the Sülstorf Beds, early-middle Chattian, of Mecklenburg, northeastern Germany. They form part of a speciose assemblage of necto-benthic sharks and batoids which populated the warm-temperate to subtropical upper shelf sea of the south-eastern North Sea Basin. 

New records of terrestrial mammals from the Qasr el Sagha Formation, Fayum Depression, Egypt are reported, and the stratigraphic occurrences of these fossils noted. These include additional specimens of Moeritheríum, Barytherium, and anthracotheres, as well as the oldest record of a hyracoid in the Fayum.These Eocene mammals occur almost exclusively in the alluvial deposits of the Dir Abu Lifa Member of the Qasr el Sagha Formation and show close affinities to the faunas from the lower sequence of the Jebel Qatrani Formation. There is no evidence of a more marked faunal discontinuity between the Qasr el Sagha and Jebel Qatrani Formations than there is across any of the three major breaks in sedimentation that exist within the Jebel Qatrani Formation. The faunal similarities between fossils of the lower sequence of the Jebel Qatrani Formation and of the upper part of the Qasr el Sagha Formation is consistent with recent paleomagnetic dating that suggests that these rocks differ in age by only one to two million years. 

An interpretation of the marine reptile fossil record, based on the existing litterature and complemented by the review of ancient collections and the study of new material, permits a better understanding of Mesozoic marine ecosystems. An inventory of the marine reptiles known from the Lower Triassic to the Paleocene is presented: 46 families, about 200 genera and 400 species have been recorded. This data base includes commentaries about systematics, stratigraphical ranges and geographical distribution of taxa. Marine reptiles include a mosaic of not necessarily closely related groups: ichthyosaurs, thalattosaurs, hupehsuchians, pachypleurosaurs, placodonts, nothosaurs, plesiosaurs, pliosaurs but also crocodiles, lizards, snakes, turtles. The diversity studies reveal that the fossil record of marine reptiles has been punctuated by two mass extinctions, during the Middle-Upper Triassic transition and at the Cretaceous-Tertiary boundary. The Jurassic-Cretaceous and Cenomanian-Turonian boundaries (the latter marked by the disappearance of ichthyosaurs) are potential crisis periods, but current data are not sufficient to reach conclusions. The Ladinian-Carnian transition is characterized by the disappearance of 64 % of families and affects essentially coastal forms. This extinction coincides with an important regressive phase. During the Upper Triassic, a faunal reorganisation within marine reptiles leads to the progressive disappearance of near-shore forms and to the development of pelagic groups. During the Maastrichtian-Danian crisis, 36% of families died out. Large-sized pelagic forms such as mosasaurs and elasmosaurs were the most affected and their extinction seems to have been rather sudden. On the other hand, pliosaurs and protostegid turtles became extinct, but were already declining. The survivors were near-shore forms such as crocodiles, snakes and some turtles and they may have taken refuge in freshwater environments. A break in the food chain based on phytoplankton is proposed as an extinction scenario for pelagic forms.