Paleobiogeographic Implications Research Articles

Paleobiota from the Deccan volcano-sedimentary sequences of India: paleoenvironments, age and paleobiogeographic implications

Paleobiotic assemblages from the Deccan infra- and intertrappean beds are reviewed in great detail. Three distinct paleoenvironments (fluvio-lacustrine/terrestrial, brackish water and marine) have been identified within the infra- and intertrappean biotic assemblages of peninsular India. Recently, marine incursions have been recorded in a few of the Deccan intertrappean beds exposed in central and south-eastern India. The intertrappean beds have yielded marine planktic foraminiferans and freshwater/brackish water ostracods. The affinities of the paleobiotas are commonly considered to show a mixed pattern resulting from the addition of Gondwanan and Laurasian elements to endemic Indian taxa. During the last four decades, various biogeographic models (southern and northern connections) have been proposed to explain the presence of anomalous biogeographic biota in the Late Cretaceous of India. Based on the recovered fauna and flora assemblages, the Cretaceous–Paleogene boundary has been marked and a Late Cretaceous to Early Paleocene age has been assigned to these Deccan volcano-sedimentary sequences.

First report of the giant snake Gigantophis (Madtsoiidae) from the Paleocene of Pakistan: Paleobiogeographic implications

We report here the discovery of madtsoiid snake remains from the early Paleocene Khadro Formation (Ranikot Group, Sindh, Southern Pakistan). These specimens consist of vertebrae and are referred to Gigantophis. This is the first report of Gigantophis from outside of Africa. The problem of the generic distinction between Gigantophis and Madtsoia is stressed. The specimens from Pakistan slightly differ from the single species (G. garstini) referred to the genus Gigantophis, but the available material does not allow further considerations and the fossil is referred to as Gigantophis sp. However, Gigantophis sp. from the Khadro Formation is more closely related to G. garstini, that is known only from the middle and late Eocene of northern Africa, than to any other species, thus suggesting dispersal between these two areas during the Paleocene or earlier. These results are consistent with the hypothesis of intermittent dispersals between the Indo-Pakistan Plate and Africa suggested by other fossil evidences.

Chaetophractus tarijensis (Xenarthra, Dasypodidae) ¿Un endemismo del Valle de Tarija (Bolivia)? Implicancias paleobiogeográficas

CHAETOPHRACTUS TARIJENSIS (XENARTHRA, DASYPODIDAE). AN ENDEMISM FROM THE TARIJA VALLEY (BOLIVIA)? PALEOBIOGEOGRAPHICAL IMPLICATIONS. Chaetophractus tarijensis (Ameghino) is a dasypodid restricted to the Pleistocene of the Tarija Valley (Bolivia). In this contribution we study the type specimen of C. tarijensis and referred specimens to this species, and establish comparisons with extant Dasypodidae Euphractinae. The analysis of the present study reveal that the characters used by Florentino Ameghino (e.g. the underdevelopment of the angular portion of the ramus of the mandible and the cylindrical shape of the last molariform) do not allow the differentiation with Chaetopractus (Desmarest). Also, a principal components analysis was performed with cranial measurements. All these evidence support the hypothesis that C. tarijensis is a synonym of C. villosus. From a paleobiogeographic point of view, these results are important because it indicates that C. tarijensis is not one of the few supposedly endemic species of the of the Tarija Valley.

A morphological intermediate between eosimiiform and simiiform primates from the late middle Eocene of Tunisia: Macroevolutionary and paleobiogeographic implications of early anthropoids

Although advanced anthropoid primates (i.e., Simiiformes) are recorded at the end of the Eocene in North Africa (Proteopithecidae, Parapithecidae, and Oligopithecidae), the origin and emergence of this group has so far remained undocumented. The question as to whether these primates are the result of a monophyletic radiation of endemic anthropoids in Africa, or several Asian clades colonizing Africa, is a current focus of paleoprimatology. In this article, we report the discovery of a new anthropoid from Djebel el Kébar in central Tunisia, dating from the late middle Eocene (Bartonian). This taxon, Amamria tunisiensis, new genus and species, currently known by only one isolated upper molar, is among the most ancient anthropoids to be recorded in Africa thus far. Amamria displays a suite of dental features that are primarily observed in Eosimiiformes (stem Anthropoidea). However, it is not allocated to any known family of that group (i.e., Asian Eosimiidae and Afro-Asian Afrotarsiidae) inasmuch as it develops some dental traits that are unknown among eosimiiforms, but can be found in African simiiform anthropoids such as proteopithecids and oligopithecids. With such a mosaic of dental traits, Amamria appears to be a structural intermediate, and as such it could occupy a key position, close to the root of the African simiiforms. Given its antiquity and its apparent pivotal position, the possibility exists that Amamria could have evolved in Africa from Asian eosimiiform or Asian "proto"-simiiform ancestors, which would have entered Africa sometime during the middle Eocene. Amamria could then represent one of the earliest offshoots of the African simiiform radiation. This view would then be rather in favor of the hypothesis of a monophyletic radiation of endemic simiiform anthropoids in Africa. Finally, these new data suggest that there must have been at least two Asian anthropoid colonizers of Africa: the afrotarsiids and the ancestor of Amamria.

Actinocerid Cephalopods from the Ordovician of Myanmar, and their Paleobiogeographic Implications for Northern Gondwana

This paper describes a new actinocerid cephalopod fauna from the western part of the Shan Plateau in Myanmar (Sibumasu Block), and discusses its significance. The cephalopod fossils are preserved in shallow marine limestones of the Wunbye Formation (Pindaya Group) and its equivalent strata. The fauna consists of Ordosoceras theini sp. nov. (Floian or Dapingian, late Early or early Middle Ordovician age), Armenoceras myanmarense sp. nov. (Darriwilian, late Middle Ordovician), Paratunkuskoceras sp. (Darriwilian), and Wuti- noceras moeseini (Floian, late Early Ordovician). The presence of Ordosoceras, which was previously known only in the North China Block, and specific characters in the actinocerid fauna of Sibumasu indicate a strong linkage with that of North China during Early-Middle Ordovician time; in contrast, Sibumasu's affinity to the coeval Australian fauna is less definable. It is possible that an actinocerid faunal exchange took place between North China and Sibumasu over the shelf sea environment open to the Prototethys Ocean but this did not hap- pen to the inland seas of Australian Gondwana during the period.

New Records of Eutherian Mammals from the Goler Formation (Tiffanian, Paleocene) of California and Their Biostratigraphic and Paleobiogeographic Implications

ABSTRACT The Goler Formation is the only rock unit on the West Coast of North America that has yielded a diverse assemblage of Paleocene vertebrates. Intense prospecting of strata representing member 4 of the formation over the past two decades has resulted in recovery of over 70 specimens of eutherian mammals, representing 18 species. All specimens were recovered from member 4a and the lower part of member 4b, except an isolated tooth referred to Phenacodus cf. P. vortmani from member 4d in the uppermost part of the formation. Three taxa are new, the plesiadapid, Nannodectes lynasi, and two hyopsodontid condylarths, Promioclaenus walshi and Protoselene ashtoni. Also present are four species of Phenacodus, two species of Protictis, and single species representing Goleroconus, Mimotricentes, Lambertocyon, Ignacius, Paromomys, Bessoecetor, Thryptacodon, Dissacus, and a taeniodont. The mammalian fauna from member 4a and the lower part of member 4b is collectively referred to as the Goler Assemblage because t...

Early Miocene evolution of the genus Megacricetodon in Europe and its paleobiogeographical implications

The Megacricetodon material from Aliveri (Isle of Evia, Greece) was previously assigned to Megacricetodon primitivus, implying palaeobiogeographical relationship between south-eastern and south-western Europe. The material from Aliveri is here assigned to the new species Megacricetodon hellenicus sp. nov. This form has significant morphological differences compared to other Early Miocene species from Europe. This new evolutionary hypothesis of this genus has implications on the Early Miocene paleobiogeography of Europe. This work presents a new interpretation on the earliest European representative of the genus Megacricetodon from Aliveri localities. Analyses of the Megacricetodon material from MN 4 and MN 5 localities enable to propose a new palaeobiogeographical framework in which there are three main migration events of the genus Megacricetodon into Europe, each corresponding to different lineages that evolved independently. The new Greek taxon is considered the first migration wave from Anatolia, repr...

Tayassu pecari (Link, 1795) (Mammalia, Cetartiodactyla): comments on its South American fossil record, taxonomy and paleobiogeography

Tayassu pecari is widely distributed across the Neotropical region, from northern Argentina to south-eastern Mexico. However, its fossil record is scarce; it is recorded since the middle Pleistocene to Holocene in Argentina, Brazil and Uruguay. This paper aims to: (1) update the systematic synonymy of this species; (2) review and update its geographic chronologic distribution and provide a new Lujanian record of Tayassu pecari in Buenos Aires Province and (3) discuss the paleoenvironmental and paleobiogeographical implications of this record. Considering the quantitative analysis performed, the fossil here recorded clearly integrates the group of Tayassu pecari. This specimen corresponds to the first record of Tayassu pecari in the central-northern region of the Buenos Aires Province. During Late Pleistocene, Tayassu pecari was distributed southern to its recent range, probably evidencing different paleoenvironment conditions. This species is the better adapted peccary to tropical and subtropical rainforests, but may also be present in arid environments. Consequently, Tayassu by itself is insufficient to infer the prevailing environmental conditions. However, according to the fauna associated with the specimen described here, it is possible to infer an open or semi-open and arid or semi-arid environment for the central-northern Buenos Aires region by Late Pleistocene times.

A new ichthyodectiform (Pisces, Teleostei) from the Lower Cretaceous of South Korea and its paleobiogeographic implication

Here we report the first ichthyodectiform in the Jinju Biota from the Lower Cretaceous Jinju Formation, Shindong Group, at Hyojagyo, Jinju City, South Korea. It shows the following ichthyodectiform characters: 1) jaw teeth in single series; 2) coracoid expanded ventrally; 3) dorsal fin situated posteriorly, with its origin opposite to that of long anal fin. Besides, its caudal skeleton also exhibits certain features often seen in basal ichthyodectiforms and some other primitive teleosts. The fish is noticeably similar to the species referred to Chuhsiungichthys from the upper Lower Cretaceous Dobaru and Kumagai formations of the Wakino Subgroup of Kanmon Group in Kyushu, Japan, and Chuhsiungichthys tsanglingensis from the Jiangdihe Formation of similar age from Chuxiong, Yunnan Province, China. Chuhsiungichthys was, in turn, comparable with Mesoclupea showchangensis from the upper Lower Cretaceous Shouchang Formation in Shouchang and Linhai, and Guantou Formation in Zhuji, Zhejiang Province, China. The latter two genera also show the ichthyodectiform characters mentioned above. Nevertheless, the fish from Korea, those referred to Chuhsiungichthys from Japan and China, and Mesoclupea can easily be distinguished from other ichthyodectiforms in their higher body depth and shorter length; proportionally longer head; longer dorsal and anal fins; lower number of vertebrae, with abdominal less than caudal; vertebrae deeper than long. Among them the Jinju fish is distinct from the other two genera in even higher and shorter body, and presence of urodermal. In addition, the Jinju fish is different from Mesoclupea showchangensis in having a much longer dorsal fin and lower number of vertebrae, but different from Chuhsiungichthys tsanglingensis in having a much higher number of vertebrae and more ridges and grooves on the lateral face of vertebrae. Thus, the Jinju fish cannot be referred to either Chuhsiungichthys or Mesoclupea, and establishing a new genus and species for it is warranted. The Asian ichthyodectiforms, Mesoclupea, Chuhsiungichthys, and Jinjuichthys, may most probably form a monophyletic group – Chuhsiungichthyidae, known so far restricted to the upper Lower Cretaceous fresh and/or brackish waters of East Asia. The new ichthyodectiform materials from Korea are better preserved than those from Japan, thereby allowing a relatively complete description of the fish, providing more information for discussion of its phylogenetic position, enriching the diversity of the local fish fauna, and helping us better understand the paleobiogeographical distribution of the group and its geological background.

Paleoenvironmental and paleobiogeographical implications of a middle Pleistocene mollusc assemblage from the marine terraces of Baía Das Pipas, southwest Angola

Quaternary raised marine terraces containing the remains of diverse, shallow water marine invertebrate faunas are widespread across the coast of Angola. These deposits and faunas have not been studied in the same detail as contemporaneous features in northwest and southernmost Africa. We analyzed the fossil assemblages and sedimentology of two closely spaced middle Pleistocene marine terrace deposits in Baía das Pipas, southwest Angola. This revealed 46 gastropod and 29 bivalve species, along with scleractinian corals, encrusting bryozoans, polychaete tubes, barnacles, and echinoids. The fauna is characteristic of intertidal and nearshore rocky substrates and sandy soft-bottom habitats. Sedimentological analysis is consistent with faunal data and indicates an upper shoreface paleoenvironment along a gravel coast. This diverse fauna stands out as a rare example of a marine Pleistocene assemblage from over 6,000 km of the West African coast. The assemblage is dominated by extant tropical West African molluscs, including species from the “Senegalese fauna” that colonized northern Africa and beyond during Pleistocene interstadials. Additionally, as along the modern coast of the Namibe Desert, the influence of the cool-water Benguela Current is apparent in the paleofauna by the occurrence of a few temperate species. The distribution and thermal tolerances of extant species identified in the Pipas fauna indicate that this region experienced similar climatic and oceanographic conditions as that of the present during this interstadial. Seasonal temperature varied between ∼20 and 28°C and resulted from upwelling in this tropical setting.

Late Triassic ammonoid Sirenites from the Sabudani Formation in Tokushima, Southwest Japan, and its biostratigraphic and paleobiogeographic implications

AbstractDiscovery of Sirenites senticosus (Dittmar) in the upper part of the Sabudani Formation of the Kurosegawa Belt, Kito area, Tokushima Prefecture, Japan, establishes a late Early Carnian age for this part of the stratigraphic unit. Because S. senticosus was mainly distributed in the Tethyan region, its occurrence provides evidence that Late Triassic ammonoids of Japan had strong affinities with those of the Tethyan faunas. This finding clearly differs from the biogeographic distribution of contemporary bivalves in the region, which are referred to as the Kochigatani bivalve faunas, and show strong affinities to faunas of the Boreal region.

Quaternary ostracodes and molluscs from the Rukwa Basin (Tanzania) and their evolutionary and paleobiogeographic implications

Much of the spectacular biodiversity of the African Great Lakes is endemic to single lake basins so that the margins of these basins or their lakes coincide with biogeographic boundaries. Longstanding debate surrounds the evolution of these endemic species, the stability of bioprovinces, and the exchange of faunas between them over geologic time as the rift developed. Because these debates are currently unsettled, we are uncertain of how much existing distribution patterns are determined by modern hydrological barriers versus reflecting past history. This study reports on late Quaternary fossils from the Rukwa Basin and integrates geological and paleoecological data to explore faunal exchange between freshwater bioprovinces, in particular with Lake Tanganyika. Lake Rukwa's water level showed large fluctuations over the last 25ky, and for most of this period the lake contained large habitat diversity, with different species assemblages and taphonomic controls along its northern and southern shores. Comparison of fossil and modern invertebrate assemblages suggests faunal persistence through the Last Glacial Maximum, but with an extirpation event that occurred in the last 5ky. Some of the molluscs and ostracodes studied here are closely related to taxa (or part of clades) that are currently endemic to Lake Tanganyika, but others testify to wider and perhaps older faunal exchanges between the Rukwa bioprovince and those of Lake Malawi and the Upper Congo (in particular Lake Mweru). The Rukwa Basin has a long history of rifting and lacustrine conditions and, at least temporarily, its ecosystems appear to have functioned as satellites to Lake Tanganyika in which intralacustrine speciation occurred. Paleontological studies of the Rukwa faunas are particularly relevant because of the basin's important role in the late Cenozoic biogeography of tropical Africa, and because many of the molecular traces potentially revealing this history would have been erased in the late Holocene extirpation.

Late Pliocene vegetation and orbital-scale climate changes from the western Mediterranean area

The Late Pliocene is a very interesting period as climate deteriorated from a warm optimum at ca. 3.3–3.0Ma to a progressive climate cooling. Simultaneously, the Mediterranean area witnessed the establishment of the Mediterranean-type seasonal precipitation rhythm (summer drought). These important climate changes produced significant vegetation changes, such as the extinction of several thermophilous and hygrophilous plant taxa from the European latitudes. Besides these long-term trends, climate was also characterized by cyclical variability (i.e., orbital changes) that forced vegetation changes (forested vs. open vegetation). In the Mediterranean area, cyclical changes in the vegetation were mostly forced by precession. In this study we analyzed pollen from a Late Pliocene maar lake core from NE Spain. An increase in aridity is observed as well as cyclic variations throughout the studied sequence. Cyclicity was mostly forced by precession but also by obliquity and eccentricity. Precipitation seems to be the main factor controlling these cycles. These data allowed estimating a sedimentary rate of ca. 0.19mm/yr and the time duration covered by the studied core, close to 200ka. The combination of biostratigraphy, palaeomagnetism and cyclostratigraphy allowed for a very precise dating of the sediments between ca. 3.3 and 3.1Ma. Climate and paleobiogeographical implications are discussed within the context of the Late Pliocene Northern Hemisphere glacial intensification.

Leños Fósiles De Leguminosas de la Formación Ituzaingó, Entre Ríos, Argentina: Implicancias Paleoecológicas y Paleobiogeográficas

Abstract. FOSSIL WOODS OF LEGUMINOSAE FROM THE ITUZAINGO FORMATION, ENTRE RIOS, ARGENTINA: PALEOECOLOGICAL AND PALEOBIOGEOGRAPHIC IMPLICATIONS. The family Fabaceae is among the best represented in the fossil record of the Cenozoic of Argentina and in particular of the Ituzaingo Formation. This paper describes four types of permineralized by silicification woods related to this family, Menendoxylon vasallensis Lutz, Anadenantheroxylon villaurquicense Brea, Acenolaza y Zucol emend., Prosopisinoxylon americanum sp. nov. and Gleditsioxylon paramorphoides sp. nov. Two new fossil species were recognized and the diagnosis of Anadenantheroxylon villaurquicense was amended. The specimens were found in the Ituzaingo Formation (Pliocene—Pleistocene), Entre Rios, Argentina, and have only preserved the anatomy of secondary xylem. Some anatomical features were related with the presence of a seasonal and dry climate. From paleogeographic and paleoecological features of distribution of most related extant genera, it is p...

Late Messinian rodents from Verduno (Piedmont, NW Italy): Biochronological, paleoecological and paleobiogeographic implications

The stratigraphic and paleoenvironmental context of the Verduno fossil vertebrate locality is discussed herein based on its rodent record. The Verduno section crops out in the southern part of the Tertiary Piedmont Basin (TPB), and can be included in the Messinian post-evaporitic Cassano Spinola Fm., chronologically corresponding to the so-called Lago-Mare event. Rodents are represented by a relatively rich assemblage. Murids are by far the most diverse and abundant, with at least four taxa, including the common Centralomys benericettii and Paraethomys meini, and the rare Apodemus gudrunae and Occitanomys sp. Cricetids are represented by a single species, Apocricetus cf. A. barrierei. Muscardinus aff. M. vireti appears to be the only glirid present at Verduno. The Verduno rodent assemblage shares some taxa with other Messinian post-evaporitic localities from Italy bearing continental vertebrate remains, such as Brisighella (central Italy) and Moncucco Torinese (NW Italy) (e.g., C. benericettii, P. meini) and, possibly, with Ciabòt Cagna (NW Italy). However, the general structure of these four Messinian assemblages displays substantial differences, which may reflect different palaeoenvironmental conditions.

A fossil Dendrocygninae (Aves, Anatidae) from the Early Pliocene of the Argentine Pampas and its paleobiogeographical implications

In the present paper, the distal end of a humerus referable to a Dendrocygninae anseriform bird is reported. The specimen was collected at the Monte Hermoso Formation (early Pliocene) of the Farola Monte Hermoso locality (Buenos Aires Province, Argentina). This record constitutes one of the oldest for the group in South America and elsewhere. The overview of the anseriform record in South America indicates a similar pattern to that of other localities across the world. Paleogene localities are dominated by non-Anatinae taxa, whereas more recent faunas are dominated by anatines. Following this pattern, in South America the Anatinae appears in the fossil record as recently as in the Pleistocene, probably arriving from North America during the Great American Biotic Interchange. Pleistocene and Recent anseriform avifaunas are dominated by Anatinae taxa, and this dominance is probably due to some “key characters” regarding reproductive biology. In fact, the anatines exhibit a high reproductive success probably due to the capability of having two molts per year, and that the parental care of the downy young is only conducted by the female. The combination of characters may have allowed anatines to dominate most aquatic environments, surpassing in diversity more plesiomorphic taxa.

Fruits ofHemitrapa(Trapaceae) from the Miocene of eastern China, their correlation withSporotrapoidites erdtmaniipollen and paleobiogeographic implications

The fruits of the extinct genusHemitrapaMiki (Trapaceae) are described from the Miocene Shanwang Formation, representing its first fossil record in the Cenozoic of China. Bearing a fusiform, relatively small fruit body with a very long stalk and four sub-equal, strongly ascending, horn-like arms, the Chinese fossil fruits are described asH. shanwangensisQ. Wang new species. Prior to this discovery, a dispersed, trapaceous pollenSporotrapoidites erdtmanii(Nagy) Nagy was documented from the same formation. Recent paleobotanical and palynological studies in Europe demonstrated thatHemitrapawas closely related toS. erdtmanii, so the co-occurrence ofHemitrapafruits andS. erdtmaniipollen at Shanwang implies that they may stem from the same parental plant population.Hemitrapafruits have been widely recognized from the Miocene of mid-latitudes in France, Austria, the Czech Republic, Kazakhstan, Russia, Korea, Japan and the U.S.A. as well as from the late Oligocene–Miocene of Germany and the late Eocene of the Czech Republic. In contrast, dispersedS. erdtmaniipollen has been recovered from the Miocene in central Europe as well as from the late Eocene to the Pliocene of eastern Asiatic shelf basins near the Bohai Sea, Yellow Sea, East China Sea, and the Sea of Japan. Overall, the microfossil and macrofossil records demonstrate that the parental plants ofHemitrapamight have begun to diversify from the mid-latitudes of Eurasia since the Eocene, flourished in eastern Asia and Central Europe during the Miocene, and become extinct after the Pliocene.

A new species of the snake Madtsoia from the Upper Cretaceous of India and its paleobiogeographic implications

ABSTRACT We report the discovery of a new species of the snake Madtsoia from infratrappean horizons of Late Cretaceous age in Pisdura, central India. Recovered vertebrae are large (1.83 cm long; 4.35 cm tall) and pertain to a snake that was ca. 5 m long. Discovery of Madtsoia in India extends the geographic distribution of the genus and represents only the second species known from the Cretaceous. Vertebrae of Madtsoia pisdurensis sp. nov. are strikingly similar to those of M. bai and M. camposi (South America) and M. madagascariensis (Madagascar), but can be distinguished from them by a unique process on the hemal keel, which is low, flat, and triangular in outline. Whereas the eastern Gondwanan species of Madtsoia (M. madagascariensis, M. pisdurensis) are Late Cretaceous in age, the western Gondwanan species (M. bai, M. camposi) are Paleogene in age. Geophysical evidence suggests that land connections between South America, Madagascar, and Indo-Pakistan were severed by at least 100–90 Ma, which implies that Madtsoia achieved its broad geographic distribution either by (1) origin and dispersion before the end of the Turonian; or (2) the presence of an unrecognized land connection persisting into the latest Cretaceous. Both hypotheses predict that Madtsoia will be discovered in Mesozoic strata of South America, where it survived the Cretaceous-Paleogene mass extinction.

Late Pliocene Glyptodontinae (Xenarthra, Cingulata, Glyptodontidae) of South and North America: Morphology and paleobiogeographical implications in the GABI

Abstract Knowledge of the main aspects of the Great American Biotic Interchange (GABI) concerning the glyptodontine Glyptodontidae (Xenarthra) is very scarce. A bidirectional dispersal process was recently proposed for this clade, with the presence of the North American genus Glyptotherium Osborn recognized in latest Pleistocene sediments of northern South America (Venezuela and Brazil). However, the earliest stages of this paleobiogeographical process remain poorly understood, mainly because of the limited fossil record on this clade in late Pliocene sediments. The goals of this contribution are: a) to present and describe the first record of a glyptodontine glyptodontid from the late Pliocene of northern South America, tentatively assigned to a new species of Boreostemma Carlini et al. Boreostemma ? sp. nov); and b) to analyze its paleobiogeographical implications with respect to the GABI. This new material was recovered from the San Gregorio Formation (late Pliocene, prior the GABI) in northern Venezuela, where it is represented by several osteoderms of the dorsal carapace. A comparison among the three known late Pliocene glyptodontine glyptodontids of a) southern South America Paraglyptodon b) northern South America Boreostemma and c) southern North America ( Glyptotherium ), reveals a series of shared characters between (b) and (c), not present in (a). The most important of these shared characters in (b) and (c) are: all the osteoderms present a great development of the central figure, which is always larger than the peripherals; the sulcus that delimits the central and peripheral figures is narrower and shallower; and all the osteoderms present are relatively thin. This evidence suggests that the lineage of Glyptodontinae which participated in the GABI and subsequently diversified in North America originated in northern South America. Moreover, the evident morphological differences between these glyptodontines with respect to the southern South American forms show a significant separation of both lineages since at least latest Miocene-early Pliocene.

Silurian rugose corals from the Kurosegawa Terrane, Southwest Japan, and their paleobiogeographic implications

Silurian rugose corals from the Kurosegawa Terrane, Southwest Japan, and their paleobiogeographic implications