Eocene Faunas Research Articles

Illuminating the richness of the ascidian fossil record: a new exceptionally diverse assemblage of ascidian spicules from the Middle Miocene of Bosnia and Herzegovina

AbstractAscidians, or sea squirts, are sac‐like sessile tunicates commonly found in modern seas. Although the oldest ascidians, or at least ascidian‐like tunicates, are mid‐Cambrian in age, the quality of the ascidian fossil record is extraordinarily poor. It mostly consists of isolated finds or low‐diversity assemblages, often represented by mineral spicules. Our study reports the world's most diverse assemblage of ascidian spicules, originating from the Middle Miocene Bogutovo Selo near Ugljevik, Bosnia and Herzegovina. This material includes 31 spicule types, with four assignable to species (Lissoclinum cf. perforatum, Polysyncraton cf. bilobatum, Didemnum cf. vexillum and D. cf. leopardi) and 10 to genera, all belonging to aplousobranchiate ascidians. Comparing our findings with those of two other studies that use modern biological nomenclature, our assemblage shows a closer resemblance to the distant Eocene Australian assemblage than to the Miocene ascidians from Eastern Paratethys. This suggests the persistence of a once‐homogeneous and widely distributed Eocene fauna into the Miocene, while the Eastern Paratethyan basin developed an endemic fauna after the isolation of Eastern Paratethys from the open sea. Some taxa of our assemblage currently inhabit the Mediterranean Sea. The discovery of one species in distant South African waters suggests that tectonic and environmental changes during the Late Miocene, including the closure of the Gibraltar Strait and prior disconnection from the Indian Ocean, may have limited its survival to remote refugia. The study underscores the importance of including spicules in reconstructing ascidian faunas in the geological past, an area that has been surprisingly understudied.

Fish otoliths from the basal Oligocene Viborg Formation in Denmark

The Viborg Formation is the lowest part of the early Oligocene in Denmark and represents the upper part of nannoplankton zone NP21. Here we describe a small assemblage of otoliths from the Viborg Formation obtained from five localities that yielded 88 specimens of nine species. The composition of the otolith-based f ish species is transitional between the terminal Eocene (Priabonian) faunas from the Latdorf Formation of northern Germany and its equivalents and the middle and upper Rupelian. The Viborg otolith association witnessed the first arrivals of the subsequently dominant Gadidae (Trisopterus elegans) and the migration of certain species of the merlucciid genus Palaeogadus from the Eastern Paratethys through the Polish gateway. Furthermore, the otoliths from the Viborg Formation f ill an important gap in the previous knowledge of late Eocene and early Oligocene otolith associations in the North Sea Basin and thus facilitate some refinement of their biostratigraphic usage.

Updated cranial and mandibular description of the Late Cretaceous (Maastrichtian) baenid turtle Saxochelys gilberti based on micro-computed tomography scans and new information on the holotype-shell association

Saxochelys gilberti is a baenid turtle from the Late Cretaceous Hell Creek Formation of the United States of America known from cranial, shell, and other postcranial material. Baenid turtles are taxonomically diverse and common fossil elements within Late Cretaceous through Eocene faunas. Detailed anatomical knowledge is critical to understanding the systematics and morphological evolution of the group. This is particularly important as baenids represent an important group of continental vertebrates that survived the mass extinction event associated with the Cretaceous/Paleogene boundary. High-resolution micro-computed tomography scanning of the holotype skull reveals additional anatomical details for the already well-known Saxochelys gilberti. This includes the revision of some anatomical statements from the original description, but also detailed knowledge on internal anatomical features of the braincase and the description of a well-preserved axis (cervical vertebra 2). Our new detailed description and previous work on the shell and postcrania make Saxochelys one of the best-described, nearly complete baenid turtles, which are often only known from either isolated shell or cranial material. A revised phylogenetic analysis confirms the position of Saxochelys gilberti as a derived baenid (Eubaeninae) more closely related to Baena arenosa than to Eubaena cephalica.

Taxonomic revision of the giant marine snake genus Pterosphenus Lucas, 1898, based on new fossil material from the middle Eocene (Bartonian) Harudi Formation of Kachchh (Kutch) Basin, India

ABSTRACT Fossil snakes of the family Palaeophiidae are primarily known from rare, isolated vertebrae, leading to a poor understanding of the intra- and inter-columnar variation within a palaeophiid species. This leads to ambiguity in the taxonomic identity of these snakes, as in the case of the Eocene-age marine snakes of the genus Pterosphenus, in which the majority of species have been described by characters of problematic taxonomic value. Here, we propose a taxonomic revision of the genus based on an articulated to semi-articulated section of the vertebral column at the anterior to mid trunk-transition of Pterosphenus schucherti discovered from the middle Eocene (Bartonian) Harudi Formation, Kachchh (Kutch) Basin. The characters that separate Pterosphenus schucherti from ‘Pterosphenus schweinfurthi’ and ‘Pterosphenus biswasi,’ viz., the height of the pterapophysis and the anterior concavity of the zygosphene, have been found to be non-diagnostic, and the latter two species have been synonymized with the type species. Additionally, we utilized 2D and 3D landmark-based geometric morphometry to determine the morphometric affinity of palaeophiids amongst the alethinophidian snakes. The body size of the snake was estimated based on extant snakes with a morphometric affinity to Palaeophiidae. The cosmopolitan distribution of Pterosphenus schucherti is modelled based on the sea surface temperature (SST) constraints of the modern cosmopolitan snake Hydrophis platurus, and the known fossil localities of the species. The present findings provide crucial insights into the global paleoecological landscape of the Eocene, and the interactions of Pterosphenus schucherti with other palaeophiid snakes as well as the other Eocene fauna.

A remarkable diversity of waterfowl (Aves: Anseriformes) from the Upper Eocene and Lower Oligocene of Kazakhstan

ABSTRACT Evolutionarily advanced waterfowl (the modern family Anatidae and its stem members in the order Anseriformes) are a successful bird group, well represented in faunas globally since the late Oligocene. However, the pre-late Oligocene history of the evolutionary lineage of Anatidae remains largely unexplored, as these birds are very rare in earlier faunas. This paper describes a remarkable diversity of waterfowl from the lower Oligocene of Kazakhstan (Central Asia), which includes two members of Anatidae, as well as stem-anatids referred to Romainvilliidae and Paranyrocidae. The latter family is represented by the enigmatic swan-sized Cygnopterus, the genus revised here, with new materials confirming its ordinal and familiar assignment. Anatidae are represented by the globally oldest diagnosable taxa for this family, including species in the fossil genus Mionetta, previously known from upper Oligocene–Middle Miocene strata. The paper further addresses two upper Eocene anseriform taxa from Kazakhstan. These data show that diverse assemblages of advanced anseriforms existed in Asia as early as early Oligocene. The presence of several stem-anatid taxa in the late Eocene faunas of Central Asia supports the hypothesis of a possible Eurasian (or Northern Continents) origin of Anatidae, although the subsequent diversification of the group could have occurred in the Australian region.

New early and middle Eocene artiodactyls from the Erlian Basin, Inner Mongolia, China

ABSTRACT Eocene artiodactyls from Asia were considered less diverse and abundant than the contemporary perissodactyls, especially in the Eocene faunas from the Mongolia Plateau and Central Asia. By contrast, artiodactyls are highly diverse and endemic from the Eocene deposits of Europe and North America. Here we report two new genera and three new species of small- to medium-sized artiodactyls preserved by fragmentary materials from the Early and Middle Eocene of the Erlian Basin, Inner Mongolia, China. Paraphenacodus gabuniai sp. nov. represents the first record of artiodactyls from Arshantan Asian Land Mammal Age, and shows some more primitive characters than Paraphenacodus solivagus from the Middle Eocene of the Zaysan Depression of Kazakhstan. Although Paraphenacodus with generally bunodont teeth shows some similarities with both Early Eocene Tsaganohyus from Mongolia and early cebochoerid Gervachoerus from Europe, its affinities with other artiodactyls remain obscure. Two new genera and species, Irdinodon bicuspidata gen. et sp. nov. and Aliusuellus laolii gen. et sp. nov., from the Irdinmanhan ALMA represent new taxa of Lantianiinae and Tapirulidae, respectively. Irdinodon is characterized by twinned metaconules and entoconids on the upper and lower molars in lantianiines. Aliusuellus is characterized by a large size and a distinct ridge raised along the posterolingual side of the paracone to its apex on M2. These new artiodactyl materials from the Erlian Basin, as well as recently reported tapirulids and bunodont Erlianhyus, increase the diversity of the Eocene artiodactyls from the Mongolia Plateau, and provide new clues on the origin and dispersal of some early artiodactyls.

Foraminifera of the Eocene Shitakara Formation in eastern Hokkaido, with the designation of neotype specimens of Yoshida (1957)

Forty-three species belonging to thirty-seven genera of benthic foraminifera were differentiated from the Eocene Shitakara Formation in the eastern part of the Kushiro Coalfield, eastern Hokkaido. The foraminiferal assemblages show upward transgression from the inner to outer sublittoral condition. They contain abundant agglutinated and calcareous hyaline benthic species, including Labrospira crassiformis, Haplophragmoides subamakusaensis, and Cribroelphidium sorachiense, indicating similarity to the Eocene fauna in central Hokkaido. Two planktonic species Chiloguembelina ototara and Tenuitella insolita also indicate a late Eocene age. Neotype specimens of Cyclammina pacifica var. kushiroensis, Nonion kushiroense, and Nonion sorachiense var. konbumoriense described by Yoshida (1957) have been designated as replacements for holotype specimens that were lost in a fire in May 1965. A taxonomical reexamination based on the neotypes and topotypes indicates that Cyclammina pacifica var. kushiroensis is a distinct species, whereas Nonion kushiroense and Nonion sorachiense var. konbumoriense are junior synonyms of Cribroelphidium sorachiense (Asano 1954). All foraminiferal taxa are illustrated with taxonomical notes.

Organic petrography and depositional environments of the upper Eocene Kopili Shale, Bengal Basin, Bangladesh

Mudrock samples of the upper Eocene Kopili Shale, taken from the outcrops in the northeastern Sylhet Trough areas, and drilled cores from the Indian Platform in the northwestern Bangladesh, were investigated in order to present an overview of the depositional environment. Several techniques such as organic petrography, thin section petrography, X-Ray fluorescence (XRF) elemental analysis, X-Ray diffraction (XRD) mineralogical analysis, and lithologic observations were combined to draw the best possible conclusions.Organic petrographic analysis shows higher proportion of vitrinite along with liptinitic materials in the northeastern samples, suggesting deposition in an upper deltaic environment, whereas the northwestern samples show abundance of inertinite, indicating deposition in a lower deltaic environment. Thin section petrographic analyses, which reveal planktonic foraminifers, bioturbated fabrics, pyrite framboids, sand lenses and flame structures; and XRD and XRF analyses reveal abundance of quartz and illite in Kopili Shale, all of which suggest deposition in shallow marine reducing environments.The fauna in the Kopili Shale can be correlated to upper Eocene faunas of the Tethys Sea around the Indian subcontinent. Organic petrographic analysis suggest provenance from a low-relief crystalline Indian craton located adjacent to the west, rather than the Himalayan or Indo-Burman ranges to the north and east of the Bengal basin. Taken together, the present results suggest that the Kopili Shale of the Bengal basin is a silty mudrock, which was deposited during rapid marine transgression and regression, in a deltaic near-shore setting.

Crocodylian assemblage from the middle Eocene Ikovo locality (Lugansk Province, Ukraine), with a discussion of the fossil record and geographic origins of crocodyliform fauna in the Paleogene of Europe

The known fossil record of crocodyliforms in Europe during the Paleogene is significantly biased, in that the fauna of Western Europe is far better sampled and understood compared to that of Eastern Europe. We describe in detail all known crocodyliform remains from the middle Eocene (Lutetian) Ikovo locality in Ukraine. We conclude that at least two taxa were present: a moderate to large-sized Tomistominae indet. similar to the basalmost known tomistomines, and the small-sized basal alligatoroid cf. Diplocynodon sp. Despite its scarcity, this is the first basal alligatoroid material reported from Eastern Europe (as part of post-Soviet countries) and the easternmost record of diplocynodontines in Europe so far. An allegedly freshwater cf. Diplocynodon sp. contributes a rare faunal element to the vertebrate assemblage of the Ikovo locality, otherwise dominated by resident or facultative marine taxa. The fossil record and historical paleobiogeography of crocodyliforms from the Paleocene and Eocene of Europe are reviewed. As it has been already known, the middle Eocene fauna of crocodyliforms proves to be taxonomically diverse and complex. Its constituent lineages geographically originated in Asia or North America (Diplocynodontinae, Asiatosuchus-like crocodyloids, Planocraniidae), North America (derived alligatorines), Africa (Tomistominae), and Gondwana (ziphodont mesoeucrocodylians Iberosuchus and Bergisuchus), with possible subsequent speciation in Europe. We propose a novel hypothesis of Asian origins of European diplocynodontines, which will be explicitly tested in future studies. The revealed similarities between crocodylians and turtles from the Ikovo locality and those from Western Europe support the presence of a single Pan-European biogeographical zone during the middle Eocene, distinct from that of Asia.

Diversity and renewal of tropical elasmobranchs around the Middle Eocene Climatic Optimum (MECO) in North Africa: New data from the lagoonal deposits of Djebel el Kébar, Central Tunisia

Bulk sampling of an indurated glauconic sandstone horizon from Djebel el Kebar, Central Tunisia, yielded a moderately diversified assemblage of elasmobranchs (sharks and rays), dating from the late Middle Eocene (mid Bartonian). Here, 10 new taxa (nine new species and three new genera) are described among a total diversity of 33 species. These new taxa highlight the rise of mid-large predator lineages of modern nearshore seas and fill a substantial gap in the sporadic fossil record of the late Middle Eocene. Comparisons of this assemblage with other Middle-Late Eocene faunas from the Tethys seaway indicate that this Tunisian fauna shares more similarities with Late Eocene than with early Middle Eocene assemblages. This suggests that the major shift observed in tropical elasmobranch communities from the Late Eocene, with for instance the appearance of large Carcharhinids replacing Lamniforms, began during the late Middle Eocene. Such a biotic shift could be linked to the warm conditions recorded ca. 41 Ma, known as the Middle Eocene Climatic Optimum (MECO), which was characterized by a short temperature increase of all marine waters.

The Earliest Asian Duck (Anseriformes: Romainvillia) and the Origin of Anatidae.

A new species of the extinct duck Romainvillia from the Upper Eocene of Kazakhstan is described. This is the earliest duck from Asia, the first record of Romainvillia beyond France and the first reliable evidence of the presence of Romainvilliinae (regarded here as family) in Asia. This occurrence shows a wide range of Romainvillia and suggests a greater similarity of Late Eocene faunas of Western Europe and Asia than it was previously thought. The origin of Romainvilliidae and their presumable descendants Anatidae may be connected with adaptation to a new biotope, the shallowing Late Eocene epicontinental Asian basins (due to a global decrease in sea level).

New records from Banks Island expand the diversity of Eocene fishes from Canada’s western Arctic Greenhouse

Eocene vertebrates from the Canadian Arctic, including sharks, bony fishes, turtles, crocodylians, birds, and mammals, have provided strong evidence for relatively warm ice-free conditions in the Arctic during the Eocene Greenhouse interval. Recent expeditions to Banks Island (Northwest Territories) in the western Arctic have recovered a relatively more marine-influenced Eocene fauna, including sand tiger sharks, bony fishes, turtle shell fragments, and a single crocodylian specimen. We report here on new additions to this fauna, including diagnostic large scales that confirm the presence of Amia in the western Arctic. One very large lateral line scale corresponds to a fish approximately 1.4 m in total length, larger than the maximum size for extant Amia calva. We also recovered approximately 100 distinctive teeth that we assign to the teleost genus Eutrichiurides, which is otherwise known from lower latitude Paleogene sites in the United States, India, Africa, and Europe. The genus is interpreted as an a...

Bajaichthys elegans from the Eocene of Bolca (Italy) and the overlooked morphological diversity of Zeiformes (Teleostei, Acanthomorpha)

AbstractThe Eocene (Ypresian) fauna of Bolca, Italy yields a famous assemblage of marine tropical teleosts. One of the most anatomically distinctive teleosts from Bolca is the enigmatic †Bajaichthys elegans, generally interpreted as a member of Lampridiformes (oarfishes and their allies). Re‐examination of the type and only specimen of †Bajaichthys contradicts this attribution, and we propose that its original description as a member of Zeiformes (dories) was in fact correct. †Bajaichthys bears numerous derived features of zeiforms not found in lampridiforms, including: a pelvic spine, a first vertebra closely associated with the neurocranium, and a reduced metapterygoid not contacting the quadrate. Lampridiform‐like attributes, including a greatly elongated ascending process of the premaxilla, are known to be convergent between this group and Zeiformes. Using a combination of morphological and molecular data, we confirm this revised interpretation and resolve the position of †Bajaichthys within zeiform phylogeny. In terms of overall shape, the very elongate †Bajaichthys contrasts with deep‐bodied Zeiformes and probably had distinctive ecological habits. Our inferred placement of †Bajaichthys and other fossil taxa with extended caudal peduncles (e.g. †Archaeozeus) suggests that the elongate morphotype is ancestral for Zeiformes as a whole, and that the deep‐bodied geometry typical of extant taxa probably appeared several times independently. However, these inferences must be considered preliminary due to low support for patterns of relationships within Zeiformes. The systematic reattribution of †Bajaichthys expands the taxonomic diversity of the Bolca fauna as well as the morphological and ecological diversity of the zeiform clade.

Biting Midges (Diptera: Ceratopogonidae) from Cambay Amber Indicate that the Eocene Fauna of the Indian Subcontinent Was Not Isolated.

India’s unique and highly diverse biota combined with its unique geodynamical history has generated significant interest in the patterns and processes that have shaped the current distribution of India’s flora and fauna and their biogeographical relationships. Fifty four million year old Cambay amber from northwestern India provides the opportunity to address questions relating to endemism and biogeographic history by studying fossil insects. Within the present study seven extant and three fossil genera of biting midges are recorded from Cambay amber and five new species are described: Eohelea indica Stebner & Szadziewski n. sp., Gedanohelea gerdesorum Stebner & Szadziewski n. sp., Meunierohelea cambayana Stebner & Szadziewski n. sp., Meunierohelea borkenti Stebner & Szadziewski n. sp., and Meunierohelea orientalis Stebner & Szadziewski n. sp. Fossils of species in the genera Leptoconops Skuse, 1889, Forcipomyia Meigen, 1818, Brachypogon Kieffer, 1899, Stilobezzia Kieffer, 1911, Serromyia Meigen, 1818, and Mantohelea Szadziewski, 1988 are recorded without formal description. Furthermore, one fossil belonging to the genus Camptopterohelea Wirth & Hubert, 1960 is included in the present study. Our study reveals faunal links among Ceratopogonidae from Cambay amber and contemporaneous amber from Fushun, China, Eocene Baltic amber from Europe, as well as the modern Australasian and the Oriental regions. These findings imply that faunal exchange between Europe, Asia and India took place before the formation of Cambay amber in the early Eocene.

Systematics of the GenusPalaeictopsMatthew, 1899 (Mammalia: Leptictidae), with the Description of Two New Species from the Middle Eocene of Utah and Wyoming

ABSTRACT Palaeictops is a genus of Early Cenozoic Leptictidae, currently comprising six species known from Eocene faunas in the United States and Canada. Two new species, Palaeictops altimontis and P. robustus, are represented by nearly complete skulls and mandibles from the Tepee Trail (Middle Eocene) and Uinta (Middle Eocene) formations of Wyoming and Utah, respectively. They are similar to other species of Palaeictops in having a single sagittal crest, small suprameatal foramen, and an expanded cochlear fossula. Phylogenetic analysis recovered a monophyletic Palaeictops and a sister relationship of P. bicuspis and P. multicuspis with P. matthewi sister to this clade. The subfamily Leptictinae is herein recognized to comprise Blacktops, Leptictis, Megaleptictis, and Palaeictops. This group is distinctive in having a number of features that indicate a less sectorial cheektooth dentition than in the nonleptictine Prodiacodon and Myrmecoboides. The leptictines Palaeictops and Leptictis are also known from ...

Early Eocene rodents (Mammalia) from the Subathu Formation of type area (Himachal Pradesh), NW sub-Himalaya, India: Palaeobiogeographic implications

Based on isolated upper cheek teeth, two new early Eocene rodents (Subathumys solanorius gen. et sp. nov. and Subathumys globulus gen. et sp. nov.) and three others (Birbalomys cf. sondaari, Birbalomys sp., cf. Chapattimys sp.) are recorded from the lower–middle part of the Subathu Formation of the type area in Himachal Pradesh, northwestern sub-Himalaya (India). The new rodents exhibit morphological features most similar to the unified ctenodactyloid family Chapattimyidae (including Yuomyidae), which is also represented in the assemblage from the upper part (middle Eocene) of the Subathu Formation. The associated lower cheek teeth are provisionally described as three indeterminate chapattimyid taxa. The new Subathu rodents are somewhat younger than the previously documented early Eocene assemblages from the Indian subcontinent, and are chronologically intermediate between the early Eocene ailuravines from Gujarat in the western peninsular India and the middle Eocene chapattimyids from northwestern India and Pakistan. They suggest that chapattimyids originated in the sub-Himalayan region during the Ypresian, which is earlier than previously believed. The absence of ailuravines in this as well as younger rodent assemblages from the subcontinent seems to suggest that ailuravines (Ischyromyidae), within a relatively short time after their appearance in the peninsular India in the early Eocene, may have been replaced by the indigenous chapattimyids. The co-occurrence in the early Eocene Subathu assemblage of three or more chapattimyids indicates their early radiation and dominance during the early and middle Eocene. This record of rodents opens the possibility of recovery of other small mammal remains in older levels of the Subathu Formation, which will be important for understanding linkage with early Eocene faunas from peninsular India, Europe and North America.

Paleogene mammals from the Iwaki Formation in Japan: Their implications for the geologic age and paleobiogeography of this formation

The mammalian fauna and geologic age of the Iwaki Formation of the Paleogene Shiramizu Group (Iwaki, southern Fukushima, northeastern Japan) are reviewed and previously undescribed specimens are described. The Iwaki mammalian fauna consists of three artiodactyl species: Bothriogenys sp. cf. B. hui (Anthracotheriidae), Entelodon gobiensis (Entelodontidae), and cf. Notomeryx sp. (Ruminantia). These three genera indicate an Ergilian Asian Land Mamma Age (=late Eocene [Priabonian] equivalent) correlation for the Iwaki Formation, demonstrating that the Eocene–Oligocene boundary exists within the Shiramizu Group. These three genera have never co-occurred in a single formation, although in Asia they have been recorded only in the late Eocene. In Asia, Bothriogenys has been recorded in the southern and middle regions, Entelodon has been mostly recorded in the northern and middle regions with one exception from the southern region, and Notomeryx has been recorded in the southern region. The co-occurrence of these three genera in the Iwaki Formation implies that Bothriogenys, Entelodon, and perhaps also Notomeryx can be useful late Eocene indicators in terrestrial eastern Asia. It also suggests that the Iwaki mammalian fauna is paleobiogeographically located between the northern and southern late Eocene faunas of eastern Asia, showing some faunal mixture. The Iwaki fauna is also unique in comprising diverse faunas of marine sharks and seashore birds together with terrestrial mammals. The Iwaki vertebrate fauna is key for reconstructing the faunas of the eastern coastal margin of the Asian Continent during the late Eocene.

The mammalian assemblage of Mazan (Vaucluse, France) and its position in the Early Oligocene European palaeobiogeography

The locality of Mazan (Provence, South-Eastern France) yielded numerous remains of vertebrates, including numerous isolated teeth and a few bone fragments of mammals. A preliminary faunal list was published by Triat et al; the present systematic revision of the mammalian remains and the description of new specimens reveal that the assemblage comprises 18 taxa belonging to 7 orders and 10 families. Among the mammalian remains, the theridomyids and cricetids are the two most abundant groups. This revision confirms the ascription of the locality to the biochronological unit MP21, which corresponds to the very beginning of the Oligocene. As this locality overlies the Late Eocene faunas of Mormoiron, it clearly illustrates the drastic changes induced by the European ‘Grande-Coupure’ in Southeastern France like in the rest of Europe. A palaeobiogeographic analysis based on a comparison with 22 other Early Oligocene localities allows deciphering the European mammalian palaeobiogeography at the beginning of the Oligocene. The mammalian assemblage of Mazan shows significant affinities with other localities from Western Europe (especially French and Spanish localities), while localities from the eastern part of Europe (Anatolian, Bavarian and Bohemian localities) are noticeably different, even though these were not subjected to strong palaeobiogeographic differentiation nor endemism. The locality of Paguera 1 (Majorca)–possibly already insular in the Early Oligocene–shows peculiar affinities with Anatolian and Bavarian localities rather than with those in Western European. This, together with the absence of strong endemism, suggests the existence of land connections with the Anatolian region, but also between the Anatolian and the Bavarian regions, permitting faunal exchanges.

Mesozoic and Cenozoic squamates of Europe

Squamates first appeared in Europe in the Middle Jurassic. They were lizards that already included some crown-group members. Faunas of the Late Jurassic and Early Cretaceous were more or less a continuation of the Middle Jurassic assemblage. The early Late Cretaceous was characterised by a peculiar fauna of marine pythonomorphs, while terrestrial forms were rare. In the subsequent levels of the Late Cretaceous, marine forms were mainly mosasaurids; terrestrial assemblages heralding modern ones began to take form during the Campanian–Maastrichtian. The Cretaceous–Tertiary event did not strongly affect squamates in Europe. After poor Paleocene faunas, a big wave of dispersals reached Europe during a marked rise in temperature at the beginning of the Eocene (MP 7). The Eocene fauna was rich, diverse and of tropical type. In western Europe, a sharp extinction event (‘Grande Coupure’) eliminated most squamates at the end of the Eocene, but its impact in central and eastern Europe is unknown. The Oligocene fauna was transitional between the ‘old’ Eocene and the modern Miocene faunas. By the late early Miocene (MN 3–MN 4), the fauna markedly changed when an important wave of dispersals entered Europe during a climatic optimum. From the late middle Miocene onward, the temperature has dropped. As a consequence, faunas became less rich and regionalisation occurred. Numerous extinctions and withdrawals took place during the late Pliocene and early Pleistocene, leaving an impoverished fauna in Europe.

Amphibians and squamates from the middle Eocene of Namibia, with comments on pre-Miocene anurans from Africa

Three middle Eocene localities (Silica North, Silica South, Black Crow) recently discovered in Namibia have produced terrestrial faunas that rank among the few known from the period of insulation of Africa (Aptian-early Miocene). Collectively, the three localities have yielded anuran amphibians (one pipid frog, the earliest assemblage [three taxa] of ranoid frogs in Africa, one indeterminate family) and squamate reptiles (an amphisbaenian ‘lizard’, a snake that likely represents a colubroid, and two indeterminate ‘lizards’). These Eocene faunas suggest that ranoids, colubroids and African pipids are autochthonous to Africa. However, whereas pipids are vicariants inherited from West Gondwana, ranoids and colubroids (if really autochthonous) originated in Africa from unknown stems. Silica North and Silica South correspond to aquatic environments, permanent fresh water being present in the first locality; the environment of Black Crow was drier.