The fluvial sediments of the Siwaliks in northern Pakistan preserve an exceptional geologic and paleontological record encompassing parts of the Oligocene and all of the Miocene and Pliocene. The sediments, which can be thousands of meters thick, have abundant vertebrate and invertebrate fossils from hundreds of different levels. Fossils were first discovered in the Siwaliks in 1832 and there are important collections of them in the Museum of the Geological Survey of India as well as in various European, British, and American museums. Renewed collecting has now added over 10,000 bovid fossils to a new collection held by the Geological Survey of Pakistan. The fossils include rare skulls and many isolated horn cores, as well as teeth and postcranials. Here we discuss material belonging to the hypsodontinae, boselaphini, and bovini. We recognize four hypsodontine and twenty-two bovine species, plus one species of uncertain subfamilial placement. Nineteen of the twenty-seven have previously been named, while another five have cranial material suitable for defining a new species. Two species, referred to as  ?Hypsodontinae sp. and Bovidae sp. 1, are distinctive but left unnamed. We are also uncertain about how distinctive what we refer to as Selenoportax aff. vexillarius is from Selenoportax vexillarius. Boselaphinines predominate in the fossil collections, both in terms of number of species and number of specimens. Most of the boselaphine genera are endemic to the Siwaliks, as are the hypsodontine Palaeohypsodontus and the possible bovini Pachyportax. The predominance of boselaphines together with the number of endemic taxa gives the Siwalik bovid fauna a distinctive aspect and collectively comprise the best-known Miocene record of the subfamily.
  

The Late Campanian Cerro del Pueblo Formation, located in southeastern Coahuila, Mexico, has produced a diverse array of vertebrate fossils. However, pterosaur remains from this unit are notably scarce. In this study, we describe new pterosaur material from the formation. The specimens include a fragmentary vertebra identified as belonging to an indeterminate, but derived pterodactyloid, along with the distal condyle of a left metacarpal, referable to an azhdarchoid pterosaur, and a left manus print. While these specimens provide additional evidence of pterosaur presence in the region during the Late Cretaceous, their fragmentary nature limits precise taxonomic and ichnotaxonomic identification. Nevertheless, they highlight the potential for future discoveries that could refine our understanding of the diversity and distribution of pterosaurs in Mexico.
  

Des prospections géologiques et paléontologiques sur les affleurements continentaux paléogènes du Complexe de Gour Lazib (Hammada du Dra, Algérie) nous ont permis de mettre en évidence plusieurs sites à vertébrés, sur une superficie de plus de cinq cents kilomètres carrés. La faune est constituée de nombreux vertébrés fossiles associant mammifères placentaires, poissons actinoptérygiens et protoptères, squamates, amphibiens, chéloniens, crocodiles et oiseaux. La flore de charophytes est également diversifiée. Les données bio-magnétostratigraphiques indiquent un âge compris entre l’Yprésien terminal et le Lutétien basal pour cet assemblage unique en Afrique. Les nombreux restes de mammifères récoltés ont une préservation exceptionnelle pour le Paléogène ancien arabo-africain et permettent une reconstitution paléoenvironnementale réalisée via une méthode couplant cénogramme et distribution pondérale des taxons arboricoles. Le profil du cénogramme, caractérisé par l’abondance des espèces de petite taille (insectivores, primates et rongeurs), la présence d’espèces de taille intermédiaire (hyracoïdes) et la rareté des grandes espèces (uniquement représentées par les hyracoïdes ; absence notable des proboscidiens et embrithopodes), met en évidence un milieu forestier assez fermé sous climat tropical. Par ailleurs, les données lithologiques et sédimentologiques indiquent un milieu fluviatile méandriforme où ont proliféré les charophytes. Plus hypothétique reste l’existence d’une saisonnalité dans les Gour Lazib, avec de possibles périodes temporaires modérément arides.
  

Welcome to the 18th conference of the EAVP, the first online meeting of our association. The pandemic emergency made it impossible to organize the in-person meeting in Benevento as we all had hoped. However, we couldn’t miss another EAVP meeting. Therefore, this year we are meeting online, trying to make the experience the closest to the in-person meeting possible, in order to offer the delegates the opportunity to share knowledge, build new networks and reinforce the old ones. We have received 137 communications, with more than 150 delegates from 24 countries. All the abstracts have passed a peer review process and are part of this special volume of Palaeovertebrata, the official journal of the EAVP. This year we are also offering a variety of workshops, roundtables and symposia on different topics. These include the annual “Pride EAVP: An LGBTQ+ Roundtable” and “Women in Palaeontology Roundtable Discussion”, together with the workshops on “Gendered Perspective in Palaeontological Research: from Definition to Action”, “International Palaeontology Education: Virtual Teaching and Real-World Learning”, “Stepping out of Academia: Why, When and How?”, “Introduction to Hypothesis Testing in Statistics”, “The Early-Middle Pleistocene Transition: Marked Mammal Turnover and Ecosystem Dynamic” (included in the early event for the XXI INQUA Congress in Rome 2023, “A Mediterranean Perspective on Quaternary Sciences”). To conclude, we are hosting two symposia on “Palaeoart: Diversity on and behind the Canvas” and “3D fossils, Robotic and Experimental Palaeontology”. We wish you all a happy and productive meeting. And see you in Benevento next year! 

Macrauchenia patachonica was among the largest litopterns. It had a long neck with elongated cervical vertebrae, unique among endemic South American ungulates. We calculated the pattern of stress in the joints between the vertebral centra along the neck of the recently-extinct litoptern mammal M. patachonica for various hypothetical neck postures to determine which one is optimal. We also determined the zygapophyseal alignment positions for the neck, assuming a wide range of values for the thickness of the intervertebral discs. We concluded that a vertical posture is the one that best meets the requirements of nearly constant stress. This upright posture was probably a frequently adopted posture by M. patachonica while feeding or standing. It is also possible that occasionally it could adopt a gerenuk-like posture. In almost any other position, the standard deviations of stress values (SD) divided by mean stress (MS) have values between 0.4 and 0.5. Since it was a mixed feeder, M. patachonica probably used different postures to reach resources at different heights. However, an almost horizontal posture was required for the optimal articulation of the neck vertebrae. It probably represents the posture during fast locomotion, as suggested in a previous biomechanical study of locomotion. 

There are very few birds in the site of Sainte-Néboule. They belong to three species already known in the "Phosphorites" : Paraortyx brancoi, Aegialornis broweri, Cypselavus gallicus, and to one new species, Recurvirostra santaeneboulae. The comparison of some different bones of the genus Cypselavus with some Apodiformes and Caprimulgiformes shows that this genus must be classified in the order Apodiformes. 

Book of Abstracts of the XXII Annual Meeting of the European Association of Vertebrate Palaeontologists, 30 June–5 July 2025, Kraków, Poland. 

Since the 19th century, thousands of footprints were observed in the geological series of the French Mesozoic. All are located in the Triassic and Jurassic. After a promising beginning, in France, it is only a few papers which will be published in the first half 20th century, unlike the USA and of others countries of Western Europe. One ought to wait about 1950 for a revival and now they are nearly 200 papers which were devoted to the ichnofossils. The literature abundance and the renewed interest of the naturalists for the palichnologic studies decided to us to write a synthesis work. This one begins with a stratigraphic inventory in which, localisation, age and paleontological contents of about 180 fossiliferous sites are specified. After having pointed out the followed methods, the footprints paleontological interpretation is then approached in detail and the results obtained are replaced in stratigraphy to deduce the fauna evolution during the Mesozoic. So, it appears that Ichnologic data, more varied and rich in the Triassic and Liassic than those relating to the bones, very rare for the considered periods, are very informative. The middle Triassic (Anisian-Ladinian), thus reveals Cotylosauria, Lepidosauria, Crurotarsi with Rauisuchia, Ornithosuchidae, Crocodylia and Dinosauromorpha more the "Prodinosauria": Dinosamiforme whose skeletons are known in Argentina but only in Ladinian. The rather fast domination of Dinosaurs during Norian is also as well shown. The almost exclusive presence of their footprints, up to fifty cm long, in the Lower Hettangian indicates their supremacy in the environments. Footprints characterise not very deep life places located between inter-supratidal limits and often out of water. Sedimentologic and Palaeontologic studies showed that they were great coastal spaces during Middle Triassic, flood-plain with sebkhas while Upper Triassic, and a large !!coastal marsh!! in Grands-Causses during Liassic in which, mainly, fine stromatolithic layers were deposited. During the same periad, bay beaches spread in Vendée. During the Middle Jurassic, they are also brackish to lacustrine environments and recifallagoons in- the Upper Jurassic. Numerous measurements of the footprints and trackways directions showed that the animaIs moved there in weil defined directions, for long periods. They seem due to the palaeotopography of the life environments relatively stable. Also, the discovery of vegetal radicular networks and small footprints far away from the continental borderlands has suggested that the animals continuously lived in these palaeoenvironnements, belonging to large ecosystems, where the sedimentation rate was weak. This explains that thebadies could not fossilize there but only their footprints through the cyanobacterian action in main cases. From the vertical distribution of different ichnospecies, defined with adapted statistical methods, explained in this work, a palichnostratigraphy was established for the Middle Triassic. Although the footprints are also abundant in Hettango-Sinemurian of "Grands-Causses" and the Vendée, it was not possible, up to now, to establish any zonation in this series; Probably because the palichnofauna is too little diversified there, currently reduced to a majority of Theropods II-IV tridactyl traces.
  

The late Cretaceous Auca Mahuevo nesting site (Neuquén Province, Argentina) has produced a large number of sauropod eggs, many of them containing the remains of embryos. Research at this site has generated important information about the development of the embryos, the morphology and eggshell microstructure of the eggs, and the reproductive behavior of sauropod dinosaurs. Cranial features present in the embryos have allowed their identification as those of titanosaurian sauropods. Differences in the texture of the sediments that contain some of the egg-clutches have illuminated their nest architecture. Microstructural studies of eggshells have expanded our knowledge of their variability and the incidence of pathologies within a reproductive titanosaurian population. Maps showing the spatial distribution of eggs and clutches. the stratigraphic distribution of the egg-beds, and the sedimentological context in which they are contained, have provided the basis for several inferences about the nesting behavior of these dinosaurs. 

Confident attribution of bipedal tridactyl dinosaur tracks to theropods or ornithopods can be challenging. Here we describe trackways produced by tetanuran dinosaurs, previously attributed to hadrosaurs, from Coahuila State, northeastern Mexico. Multiple trackways headed in the same direction suggest gregarious behaviour in these late Campanian theropods.  

The Causses" is a near 3400 km2 large plateau located in the south of France. Here the first dinosaur footprints where found in 1935. After this, this area has yielded an ever-increasing number of ichnites now in excess of 500 specimens. These latter, 15 to 50 cm long, tridactyl or tetradactyl footprints of generally biped animals, were discovered at the surface of Hettangian to lower Sinemurian dolomite layers within 4 distinct stratigraphic units. The 35 sites bearing ichnites are located on the plateau margin. For the first time, morphologic characters studied through descriptive statistic methods with the usual parameters and classical Student and Snédecor tests, allowed us, to divide the whole set of biped traces into 6 ichnospecies. Their definitions are further constrained by multivariate statistical results using Principal Component Analysis (PCA), Factor Analysis of correspondances (FAC) and Discriminant Analysis (DA). All have confirmed the morphologic observations. So that now, the following taxa are identified : Grallator variabilis, G. lescurei, G. sauclierensis, G. minusculus, Eubrontes giganteus, Dilophosauripus williamsi, cf. Moraesichnium, Orníthopus fabrei nov ichnosp. The more immediately visible differences relate to the interdigital II-IV divarication and the digit length ratio. To this panel, we must add Batrachopus deweyi and shapes suggesting Trisauropodichnus and/or Anomoepus. Among all ichnite associations described in the lower Liasic, the New England assemblage presents the most affinities with ours. It shows the ichnotaxa Grallator, Dilophosauripus, Eubrontes, Batrachopus without forgetting Ornithopus fabrei nov. ichnosp. which is close to Ornithopus gallinaceus from the Massachusetts and Connecticut basins. On comparing the present early Jurassic ichnofauna of the Causses with the ones of the Middle and Upper Triassic formations of the eastem border of the Massif Central (France), it appears that tridactyl footprints become more and more numerous and large from Triassic to Early Jurassic. In the Causses, these latest are prevalent but in Quercy (France), Poland, Italy, USA, they are also associated with Omithopoda, Thyreophora and Sauropoda ichnites. Footprint areas considered here were generaly under an arid climate. Animals that passed by were heavy and bulky possible Megalosaur trackmakers, and lighter and slender Coelophysids or Ceratosaurs. For all, these areas were pathways as the orientations of the trackways seem point out. The directions followed by these reptiles were without any important variation during the Hettango-Sinemurian stages. These areas were also used from time to time by Crocodilomorpha and may be tetradactyl (I-IV) bipedal avian Theropods. However, the number of such trackways in sites, sometimes substantial, should not lead us to overestimate the trackmakers populations. These last were probably relatively moderately abondant in this inter-supratidal swamp environment. In the Causses, ichnites are connected with former algo-laminated deposits (Algal mats) which were rapidly hardened by means of calcitisation of cyanobacteria. The result has been a moderate depth of footprints; autopodia disturbing only a few cm of the carbonate substrate. Other fossils have been discovered : invertebrates with thin bivalve and gastropod shells, crustaceans tests and plants. These latter suggest the existence of paleomangroves like environments but also continental vegetation periodically overruning the swamp environment during regression/transgression cycles. At these times, wooded parts of it, could become protecting, feeding, resting and nesting places.

  

Les Pistes de Vertébrés du Stormberg Supérieur ("Trias terminal à Rhétien"), ou Quthingien

Si les zones du Stormberg inférieur se sont révélées contenir de nombreuses traces, surtout dans les faciès dits "Molteno moyen et supérieur", représentant apparemment la base du Keuper, il est frappant de voir pratiquement l'ensemble de cette grosse faune "Molteno" disparaître avec la fin de cette période, que nous avons appelée le "Maphutsengien".

Dès les premières zones du Stormberg supérieur, que nous nommons le"Quthingien" la zoocénose et la phytocénose, en même temps que les données d'ensemble manifestées par l'environnement, sont modifiées. Nous ne verrons plus guère de dépôts marécageux à flore riche et variée, parfois même luxuriante. Les fougères elles-mêmes ont disparu. Elles sont remplacées par de maigres plantes, aux feuilles très souvent filiformes qui paraissent témoigner d'un climat continental. Le sol est devenu de plus en plus rouge, avec des variations latérales beaucoup plus accusées. Les fleuves amenant des galets des monts du "Grand Sud" ont tari. La faune va en subir les conséquences. Certaines des espèces se révèleront sautillantes ou coureuses, pour un grand nombre plus légères et pour la quasi-totalité d'apparence carnivore ou entomophages, les phytophages devant se contenter d'un régime ingrat,difficile ou à tout le moins irrégulier,les dépôts le montrent.

C'est dans ces conditions que s'inaugure notre Etage nouveau,quelque peu discordant sur les zones A/5, A/6 ou A/7 du Stormberg inférieur (Maphutsengien). Le Stormberg supérieur (ou Quthingien) commence avec le paléopaysage remarquable dit de Moyeni, que nous allons maintenant étudier, typologiquement, avec ses homologues du même âge. Quelques 38 types d'animaux tous nouveaux vont défiler à nos yeux lors de la zone de base de cet Etage, ou zone B/1.

L'on nous avait proposé d'intituler ce Ile Tome de la série : "La grande Dalle de Moyeni et ses homologues. Paléo-spectacles, scènes et paysages animaux au Lesotho à l'approche du Trias finissant". Nous avons préféré garder le sous-titre plus haut, peut-être plus prosaïque.

Un llle Tome est en préparation : "Les développements ultérieurs et terminaux de la faune du Gondwana".

  

The complex taxonomic history of the paramyid rodent genus Ailuravus is reviewed. It has been described as Hyracotherium, as a creodont carnivore and as a lemuroid primate - errors at the ordínal level that are most unusual for a rodent. The genus is a member of the poorly known subfamily Ailuravinae, probably derived from some European Early Eocene species of Paramys. Aíluravus was a large arboreal paramyid with highly rugose cheek teeth, very well developed hypocone, and a remarkably weak lower incisor. It was tropical to subtropical. Three named species are recognized, A. macrurus from the Lutetian of Messel; the genotype, A. picteti, from Egerkingen, Buchsweiler and the Geiseltal, slightly later in the Lutetian; and A. stehlinschaubi, new name, from the Bartonian of Mormont-Eclépens and Robiac. One or more unnamed species are present in the Ypresian of Cuis. The species are close to a phyletic sequence. No later representatives of the genus are known. The late Eocene to earliest Oligocene North American paramyid Mytonomys, whose relationships have been obscure, is tentatively referred to the Ailuravinae. 

A peculiar new rodent, Malpaisomys insularis nov. gen., nov. sp., is described from subfossil deposits of the eastern Canary Islands. The species shows some highly specialized skull features although its molars exhibit a mixture of primitive and derived characters among which a partial stephanodonty is most notable. A comparison of the new rodent with several Miocene to Holocene Muridae shows that Malpaisomys possibly shares a common ancestor with Acomys and Uranomys. 

The utilization of screen-washing and attack by dilute acetic acid has permitted the collecting, in the Miocene of the department of Hérault (France), of a very rich ichthyofauna. This fauna is presently comprised of about 60 studied species, of which 11 are new, and represents, in the present state of knowledge, the most varied Miocene selachian fauna described in the world.
The abondance of material has allowed an overall revision to be made; it has thus been possible to complete the description and the figuration of species that were poorly known until now, and to synonymize species that were established on simple morphotypes. Paleo-ecologic study of the ichthyofauna has permitted conclusions to be drawn relative to climate and bathymetry; it was thus possible to show that the Miocene fauna of Hérault was a fauna of a subtropical sea, essentially neritic with rare pelagic contributions.
Knowing the stratigraphic position of the localities, it has been possible to distinguish three faunal assemblages based on associations of species. Some hypotheses on the evolution of certain lineages have been expressed.
The comparison of this fauna with that of other regions permitted the relationships of two diflerent faunal provinces to be specified: the first belongs to the northern domain, characterized by a fauna still subtropical but with numerous temperate water elements; the leoond belongs to the Mesogean domain characterized by warm water forms. It has also lhovm that contemporary faunas could be very different according to the bathymetric zone in which they lived, which furnishes valuable information for the paleogeographic reconstruction of sedimentary basins.
  

Sirenians are among the common marine fossil remains found in the Faluns deposits of western France. We describe new material of a Dugongidae sirenian from the middle Miocene Savignean facies of La Morfassière quarry (Indre-et-Loire, northwestern France) that includes a well preserved and almost complete skull associated with its mandible, several vertebrae and ribs. The cranial remains exhibit features that allow to attribute them to Metaxytherium medium, a species recorded from the middle and early late Miocene of European and Mediterranean coasts. The discovery of an associated skull and mandible of this species is unusual in this area and deserves to be reported, mostly because its preservation contributes to a better knowledge of the variable structure of its skull and teeth anatomy. For the first time the body size and weight of M. medium can be assessed through regression equations based on skull measurements. The particularly good condition of the material can be explained by the calm and deep marine environment in which it was deposited.
  

Fossils of the endangered sturgeons and peddlefishes are widely distributed. We here report for the first time the presence of one of the extinct osteichthyes genus Cylindracanthus (Liedy 1856a) from the Early Eocene lignite-bearing successions of the Kutch Basin, India. The present well preserved rostrum is characterised by numerous wedge-shaped components encircling the central canal that runs along its length, paired at the base and each wedge contributing to the formation of a ridge. The rostrum lacks teeth. The present find extends the palaeobiogeographical distribution of Cylindracanthus considerably and supports its Eocene age as dental remnants preserved in Cylindracanthus sp. shows a decrease in remanent dentition and tooth bases from the Cretaceous to the Eocene. Cylindracanthus is an useful palaeoenvironmental indicator as it has been found associated typically with deposits of nearshore marine environments. 

Lalieudorhynchus gandi gen. nov. and sp. nov. is a new caseid synapsid from the Permian of the Lodève Basin, Occitanie, France. This new taxon is represented by a partial but well-preserved postcranial skeleton, and is characterized by the following apomorphies: a transverse section of the sacral and anterior caudal neural spines with a very thin keel-like process anteriorly, a slender dorsal tip of the dorsal and caudal spines, a narrow distal end of the first sacral rib, a fossa on triceps process of metacoracoid, and a very large distal tarsal 1 of same width than the astragalus, with nearly all sides being shallowly concave.
The skeleton corresponds to a sub-adult individual that was excavated from the La Lieude Formation dated as Roadian-Capitanian (Guadalupian). A sedimentological and taphonomical analysis of the type locality, together with preliminary osteohistological observations, suggest that this new French caseid was rather aquatic, as already hypothesised for other large forms.
A phylogenetic analysis of caseids is performed to test the position of this new taxon and to better understand the evolution of the clade: interestingly, Lalieudorhynchus gandi gen. nov. et sp. nov. is closer to the NorthAmerican “Cotylorhynchus” hancocki than to the other French caseids Ruthenosaurus and Euromycter from the Artinskian of the geographically closer Rodez Basin. These two last caseids document the Artinskian radiation of the clade, which remained diverse until Olson’s extinction. Caseids survived, as Lalieudorhynchus is one of the youngest representatives of the clade, and may have used novel ecological strategies to access their vegetarian food sources.

  

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.
  

Dichobunoid artiodactyls are described in this paper from the middle Eocene Geiseltal lignite deposits near Halle (Sachsen-Anhalt, Germany). The genera Eurodexis and Parahexacodus are established based on odontologica1 studies. The type-species are E. ceciliensis (FRANZEN & KRUMBIEGEL, 1981) and P. germanicus n. sp. from the "obere Mittelkohle" (see text), MP 13. The genera are referred to the new subfamily Eurodexeinae (Dichobunidae, Artiodactyla, Mammalia), which also contains the monospecific genus Eygalayodon SUDRE & MARANDAT, 1993. These new genera show many features similar to North American homacodontids and antiacodontids. They exemplify a high degree of diversity in European dichobunids. Moreover, the family Dichobunidae includes the Dichobuninae and the Hyperdichobuninae. The connection of the posthypocristid with the postentocristid, the shift of a medial to a lingual position of the hypoconulid on the lower molars and the development of a large, caniniform P1 are regarded as the principal tendencies of the eurodexeines. The entoconid is larger and more mesially situated compared to that of Diacodexis. The hypoconulid has a lingual position on a broad postcingulid. The elongation of the premolars and the presence of diastemata are considered associated with extension of the muzzle. This and the acute tubercles of the molars could indicate a limited degree of insectivory. Protodichobune cf. oweni and Diacodexis cf. varleli, first reported here from the "untere Unterkohle" (MP 11) of the Geiseltal, demonstrate the existence of forms in the basal part of the middle Eocene, that are direct descendants of lower Eocene ones. Eurodexis russelli n. sp. from MP 10 of Premontre is the most primitive representative of Eurodexis. A further part of this lineage could be Messelobunodon sp. from MP 11 of Messel (Germany). Another form from Premontre, referred to Eurodexeinae indet., represents the origin of the lineage to Parahexacodus germanicus n. sp. from the Geiseltal (MP 13). The identification of several lineages in MP 10 is evidence of an adaptive radiation during this time. Unfortunately the history of the earlier species of Diacodexis is not known well enough to exclude earlier diversifications. Our study shows the independent development of artiodactyls at the end of the lower Eocene in Europe, North America (and maybe in Asia) with much convergence. The question of the geographic origin of the genus Diacodexis is still open.