Paleobiogeographic Implications Research Articles

Middle Pleistocene Hippopotamus amphibius (Mammalia, Hippopotamidae) from southern Europe: Implications for morphology, morphometry and biogeography

Hippopotamuses were present in Western Europe during the Pleistocene with at least two continental species: Hippopotamus antiquus and H. amphibius. The former was the large European hippopotamus, which appeared in the fossil record around 2 Ma and successfully spread across Europe before its last appearance datum (LAD) in Portugal and Greece, dated to 0.4 Ma. The extant hippopotamus, H. amphibius, first occurred in Africa around 1.5 Ma, and was well-established in Europe during the Late Pleistocene; however, its first occurrence datum (FOD) in Europe is still highly debated. Most of the H. amphibius remains collected from Middle Pleistocene localities are either badly preserved and fragmented or lacking clear stratigraphical data, in turn leading to doubtful specific attributions. A well-preservedmandible herein described, collected from Fosso Malafede (Latium, central Italy), allows to re-assess the occurrence of H. amphibius and to critically revise its earliest records. The morphological and morphometric characters of the studied remain, such as the general robustness of the studied mandible, the convex ventral profile of the mandibular corpus, the length of the teeth series, and the shape of the sagittal cross section of the mandibular symphysis, allow us to ascribe it to Hippopotamus amphibius. Fosso Malafede has been chronologically assigned to MIS 7 (∼0.25 Ma) and represents one of the best preserved H. amphibius specimen of the Middle Pleistocene of the European mainland. Accordingly, we discuss biochronological and paleobiogeographic implications, suggesting a critical revision of several remains from the Middle Pleistocene of southern Europe.

An overview of Miocene to Pleistocene methane-seep faunas from Taiwan: Paleoecology and paleobiogeographic implications

The invertebrate macrofauna of four methane-seep deposits of Miocene to Pleistocene age from Taiwan is taxonomically evaluated. The Neogene faunas, with one example each from the early and late Miocene and the Pliocene, consist exclusively of one or two large, infaunal lucinid bivalve genera per site, namely Meganodontia and Lucinoma. The former includes the large, charismatic Pliocene ‘Loripes’ goliath, which is here identified as belonging to the widespread, Neogene to Recent genus Meganodontia. The Pleistocene seep fauna is more diverse, includes extant species like the mytilid Gigantidas horikoshii and Meganodontia aff. acetabulum, unidentified species belonging to Lucinoma and the vesicomyid Isorropodon, and specimens resembling the enigmatic bivalve Sisonia frijellanae, described so far only from the late Miocene of the Philippines; the gastropods could not be identified below family level. The two Miocene seep faunules formed on the shelf of the Eurasian plate, the Pliocene faunule in an upper offshore setting in the Tainan foreland basin, whereas the Pleistocene site with its more diverse fauna formed closer to the shelf edge of the Tainan foreland basin. We suggest that water depth is the most likely driver of this difference in species diversity. The very negative δ13C signature of the seep carbonates of all fossil sites indicates the seepage of mostly biogenic rather than thermogenic methane, analogous to the extant seep sites around Taiwan. Biogeographically, the Miocene seep faunas show, with Meganodontia, links to seep faunas from lower to mid-latitudes worldwide (Caribbean Sea, Mediterranean Sea, Philippines, and New Zealand). From the Pliocene onward, biogeographic ties are more restricted to areas in the central Indo-West Pacific Ocean.

New Sinoalidae (Hemiptera, Cercopoidea) in Cenomanian Kachin amber, with notes on its paleobiogeographic implications

The froghopper extinct family Sinoalidae shows high paleo-diversity in mid-Cretaceous Kachin amber biota. The sinoalid genus Cretadorus Chen, 2020 is revised in this study. Araeoanasillus Poinar et Brown, 2023, tentatively placed in Sinoalidae with subfamily and tribe incertae sedis in original paper, is proposed herein to be synonymized under Cretadorus, leading to Cretadorus leptosomus (Poinar et Brown, 2023) comb. nov. A new species of this genus, Cretadorus qingyui sp. nov., is described and illustrated on the basis of an almost complete fossil trapped in Kachin amber. The Gondwanan origin of Burma Terrane suggests that Sinoalids in Kachin amber are likely one of residual groups of Gondwanan biotae, and so this family had wide paleobiogeographic distribution on the earth in the Jurassic. In the Early Cretaceous, the distribution range of Sinoalidae has reduced: it at least probably disappeared in northeastern Eurasia. This hemipteran lineage was extinct in the late Mesozoic owing to food crisis after the angiosperm floristic revolution.

Macrofaunal communities and microfacies analysis of the upper Campanian-Maastrichtian Sudr Formation at the Galala Plateaus, north Eastern Desert, Egypt: paleoenvironmental and paleobiogeographical implications

Macrofaunal communities and microfacies analysis of the upper Campanian-Maastrichtian Sudr Formation at the Galala Plateaus, north Eastern Desert, Egypt: paleoenvironmental and paleobiogeographical implications

Miocene Stromboid Gastropods (Superfamily Stromboidea Rafinesque, 1815) from the Dwarka Basin, Western India and their Paleobiogeographic Implications

Miocene Stromboid Gastropods (Superfamily Stromboidea Rafinesque, 1815) from the Dwarka Basin, Western India and their Paleobiogeographic Implications

New data on Silurian (Llandovery) sinacanthids from Wuhan, South China and their biostratigraphic and paleobiogeographic implications

Sinacanthids are a group of Silurian spine-based mysterious taxa, probably representing a lineage of stem chondrichthyans. New sinacanthid fossils attributed to Sinacanthus wuchangensis, S. triangulatus, Sinacanthus sp., Neosinacanthus planispinatus, Tarimacanthus bachuensis, Eosinacanthus shanmenensis, and fin spine morphology 1, 2 and 3 are identified from the upper member of the Qingshui Formation and the Fentou Formation (Telychian, Llandovery) of Wuhan, South China. These sinacanthid fin spines are similar to those from the Rongxi Formation in northwestern Hunan and the Ymogantau Formation in the northwestern Tarim. This study provides further evidence for the presence of diverse sinacanthid faunas from the South China plate. As the part of the Zhangjiajie Vertebrate Fauna of China, they have great significance in the paleogeographic division of vertebrates and the regional stratigraphic division and correlation. The Silurian sinacanthids from China were mainly grouped into three assemblages, i.e., the Wentang/Tataertag assemblage (early Telychian), the Fentou/Ymogantau assemblage (middle Telychian), and the Maoshan assemblage (middle to late Telychian). In addition, the sinacanthids from the South China plate, Tarim plate, and Qiongzhong block belong to the Zhangjiajie Vertebrate Fauna and there was certain extent of migration of sinacanthids among these areas during the Telychian, Silurian.

Late Cenomanian–early Turonian ammonite successions of north Eastern Desert, Egypt: biostratigraphy and paleobiogeographic implications

The upper Cenomanian-lower Turonian sequence of Egypt yield a remarkably diverse and plentiful ammonite fauna. Three stratigraphic sections located on Wadi Araba, north of the Southern Galal Plateau were investigated. Lithostratigraphically, the measured sections are subdivided from base to top into the Malha (pre-Cenomanian), Galala (Cenomanian) and Maghra El Hadida (Turonian) formations. Over a hundred well-preserved and nearly complete ammonite internal molds were collected. The studied ammonites are systematically classified as Vascoceratidae, Pseudotissotiidae, Acanthoceratidae and Engonoceratidae. Vascoceratidae and Pseudotissotiidae comprise 75% of the identified ammonites. Twelve ammonite species have been identified. Six late Cenomanian-early Turonian ammonite biozones are proposed herein: Neolobites vibrayeanus, Vascoceras gamai, Vascoceras cauvini, Vascoceras proprium, Choffaticeras segne, and Wrightoceras munieri. The identified ammonite biozones are correlated with NW European standard zonation and the Tethyan biostratigraphical schemes was performed. The first occurrences of Vascoceras proprium, as well as the first occurrences of the inoceramids Mytiloides kosmati and Mytiloides puebloensis define the Cenomanian-Turonian boundary. The diversity and abundance of studied fossil groups varied dramatically over the C/T transition. In the latest Cenomanian, all identified Cenomanian species had become extinct. Only three species have reached the Turonian time. The paleobiogeographic implications of the descried ammonites are thoroughly discussed. The paleogeographic distribution of the studied ammonite fauna shows that the majority of the described species are restricted to the shallow shelf of the southern Tethys.

Crocodylian princess in Taiwan: Revising the taxonomic status of Tomistoma taiwanicus from the Pleistocene of Taiwan and its paleobiogeographic implications

AbstractToyotamaphimeia is an extinct crocodylian lineage whose name is derived from a mythological Japanese princess. Here, we re-examine the type specimens of a long-forgotten species: Tomistoma taiwanicus from the Pleistocene of Tainan (Taiwan) and revise its taxonomic status to Toyotamaphimeia taiwanicus n. comb., leading to the first recognized species of Toyotamaphimeia outside Japan. Our phylogenetic analyses also support this taxonomic assignment and, more interestingly, further suggest an East Asian lineage. In addition, Toyotamaphimeia taiwanicus n. comb. represents a tropical species, resolving a long-standing puzzle of why Toyotamaphimeia only inhabited a much higher latitudinal area (Japan). Given the large body size of Toyotamaphimeia taiwanicus n. comb. (~7 m) and the fact that it is geologically older than Toyotamaphimeia machikanensis from Japan, we propose a novel evolutionary scenario: the genus Toyotamaphimeia originated in Taiwan and evolved to a large body size with gigantothermic physiology, which resulted in migration out of Taiwan and dispersal farther north to Japan. Our taxonomic identification shows the presence of an extinct endemic crocodylian species from the Pleistocene of Taiwan with large-scale paleogeographic implications. This study, with our recent progress in vertebrate paleontology in Taiwan, should provoke more in-depth paleontological research on the Pleistocene extinction.

Appraisal of middle Floian (Lower Ordovician) conodont diversity of the Precordillera and Cordillera Oriental, Argentina: Paleobiogeographical implications

In this paper we compare the diversity of Floian (Lower Ordovician) conodonts from the Precordillera with that of the Cordillera Oriental, Argentina. The comparative analysis is restricted to the middle Floian Stage Slice (Fl2) from correlative intervals: Oepikodus evae Zone (Juanognathus variabilis Subzone) in the Precordillera and the Gothodus andinus Zone in the Cordillera Oriental. For the comparative analysis, absolute frequency tables of the conodont data from published articles and collections under study, were prepared. These include four sections of the Precordillera with 13 samples recovered from the middle section of the carbonate San Juan Formation, and six sections of the Cordillera Oriental with 28 samples from the middle-upper section of the shaly Acoite Formation. Diversity patterns and indices were generated from absolute frequencies using the software PAST 4.03. Remarkable differences in the species richness and diversity between coeval communities of referred basins are displayed. Comparisons with other basins elsewhere suggest that the paleolatitudinal gradient is not a major factor controlling changes in diversity, which may be due to a response to the complex interaction of biological and physico-chemical factors.

Northward expansion of the southern-temperate podocarp forest during the early Eocene: Palynological evidence from the NE Tibetan Plateau (China)

The debated vegetation response to climate change can be investigated through palynological fossil records from past extreme climate conditions. In this context, the early Eocene (53.3 to 41.2 million years ago (Ma)) is often referred to as a model for a greenhouse Earth. In the Xining Basin, situated on the Northeastern Tibetan Plateau (NETP), this time interval is represented by an extensive and well-dated sedimentary sequence of evaporites and red mudstones. Here we focus on the palynological record of the Early Eocene Climatic Optimum (EECO; 53.3 to 49.1 Ma) and study the fossil gymnosperm pollen composition in these sediments. In addition, we also investigate the nearest living relatives (NLR) or botanical affinity of these genera and the paleobiogeographic implications of their occurrence in the Eocene of the NETP. To reach our objective, we complemented transmitted light microscopy with laser scanning- and electron microscopy techniques, to produce high-resolution images, and illustrate the morphological variation within fossil and extant gymnosperm pollen. Furthermore, a morphometric analysis was carried out to investigate the infra- and intrageneric variation of these and related taxa. To place the data in context we produced paleobiogeographic maps for Phyllocladidites and for other Podocarpaceae, based on data from a global fossil pollen data base, and compare these with modern records from GBIF. We also assessed the climatic envelope of the NLR. Our analyses confirm the presence of Phyllocladidites (NLR Phyllocladus, Podocarpaceae) and Podocarpidites (NLR Podocarpus, Podocarpaceae) in the EECO deposits in the Xining Basin. In addition, a comparative study based on literature suggests that Parcisporites is likely a younger synonym of Phyllocladidites. Our findings further suggest that the Phyllocladidites specimens are derived from a lineage that was much more diverse than previously thought, and which had a much larger biogeographical distribution during the EECO than at present. Based on the climatic envelope of the NLR, we suggest that the paleoclimatic conditions in the Xining Basin were warmer and more humid during the EECO. We conclude that phylloclade-type conifers typical of the southern-temperate podocarp forests, had a northward geographical expansion during the EECO, followed by extirpation.

An enigmatic giraffid from the latest Miocene of Italy: Taxonomy, affinity, and paleobiogeographic implications

The origin and evolution of endemic species characterizing the Oreopithecus-faunal assemblages of the Tusco-Sardinian archipelago remain a matter of debate. An emblematic case is the enigmatic giraffid Umbrotherium azzarolii, represented by a single specimen from the type locality of Casteani (Tuscany) and by several isolated teeth and fragmentary mandibles from the locality of Fiume Santo (Sardinia). An exhaustive diagnosis of Umbrotherium has not been firmly established, and its systematic and phylogenetic position remain unresolved. Unpublished remains of giraffids, including an almost complete mandible, several isolated teeth, and other cranial remains are described for the first time in the present work. The specimens were collected from the locality of Botro della Canonica (Pisa), located at the northernmost portion of the Tusco-Sardinian archipelago. The new material sheds light on the morphological and morphometric variability of Umbrotherium, thereby enabling a comparison between specimens collected from different Tusco-Sardinian Miocene localities spanning from the V1 to the V2 Oreopithecus-Zone Faunas and allowing the establishment of the new species U. engesserii sp. nov. from Fiume Santo (Sardinia). This study also reveals that Umbrotherium was more closely related to Decennatherium than to other Late Miocene continental giraffids, suggesting a dispersal of its ancestor from the Iberian Peninsula. Accordingly, a new paleogeographic and biochronological framework is proposed herein for the Tusco-Sardinian archipelago, hypothesizing a fragmentation of the area into several domains, with sporadic reconnections, and the establishment of different faunal assemblages.

A reappraisal of the lost suids from the Late Miocene of Gravitelli (Sicily, Italy) and paleobiogeographical implications

The long-lost mammal fauna from Gravitelli (Messina, Sicily, Italy) represents one of the most important records for investigating faunal dynamics during the Late Miocene of the Mediterranean, although it is unfortunately only known from descriptions carried out in the early 1900s, as the original collection was lost during the Messina Earthquake of 1908. Gravitelli suids have been referred to Propotamochoerus sp. after the redescription of the casts of two specimens that survived to the present day. However, there is further material that has not been considered, which makes that of Gravitelli one of the most abundant samples of Late Miocene suids from Italy, with a minimum number of four individuals represented. A reappraisal of all Gravitelli suids allows to ascribe them to Propotamochoerus provincialis (Suinae, Dicoryphochoerini), following a comparison with related Late Miocene to Pliocene species from Eurasia. Moreover, the re-examination of the geological setting of the locality reveals that the mammal fauna of Gravitelli occurred well below the pre-evaporitic deposits of the Tripoli Formation, whose base is dated in Sicily at ∼7 Ma. Therefore, Gravitelli fauna either dates to the late Tortonian or, at most, to the earliest pre-evaporitic Messinian, corresponding to MN 11 or MN 12 in terms of mammal biochronology. This implies that the occurrence of P. provincialis at Gravitelli is the earliest in Italy and that emerged land masses connected Sicily with the European mainland earlier than 7 Ma. Available dates support a diachronous dispersal of Propotamochoerus in western Europe during the Turolian, being first known from the Balkans ∼8.3 Ma, then from Gravitelli prior to 7 Ma, and then from the Iberian Peninsula since ∼6.2 Ma. A similar pattern is known for Mesopithecus (Cercopithecidae). Although often discussed in light of its potential significance for Afro-Eurasian dispersals, only a fraction of the mammal fauna of Gravitelli has been reconsidered systematically. Notwithstanding the necessity of such dedicated studies, the faunal elements identified so far have an almost entirely European character and no species is shared with Cessaniti (Calabria), despite the two faunas have often been considered part of a paleobioprovince documenting a connection between southern Italy and northern Africa. At Gravitelli, the only species of African origin is the endemic hippo Hexaprotodon? siculus, but the extensive fossil record of insular hippopotamids testifies to their ability to colonize islands even in the absence of land bridges. Gravitelli hippos are nonetheless noteworthy, as the revised age of the site implies that they represent the earliest hippopotamids known outside Africa.

ARMADILLO OSTEODERMS ALTERED BY DIGESTION AND HOW TAPHONOMY CAN HELP TAXONOMY

ABSTRACTDiverse modifications of the original morphological features occur throughout the taphonomic history of osteological remains, which may lead in erroneous interpretations about the formation of an accumulation as well as taxonomic misidentifications. Here, we present a neo-taphonomic study in order to analyze and interpret the modifications generated by digestion on osteoderms of the armadillo Dasypus novemcinctus obtained from scats produced by Puma concolor. Results reveal intense breakage and modifications of the articular and broken edges, dorsal surface, bone tissues, and ornamentation pattern of the osteoderms. This work describes for the first time the modifications caused by digestion in armadillo osteoderms, improving the knowledge of preservation of this type of skeletal element and providing a modern analog that can be used to distinguish archeological and paleontological accumulations formed by predators from those generated by other processes. The recognition that digestion modifies the original ornamentation pattern is particularly significant because ornamentation features are used in nearly all taxonomic and phylogenetic studies of fossil cingulates. We use this new information to re-evaluate osteoderms recovered from carnivore coprolites of the classic Middle Miocene La Venta site (Colombia), which formed the basis for recognizing and characterizing the dasypodid species Nanoastegotherium prostatum. We highlight the importance of knowing with certainty the origin and taphonomic history of remains since, in the particular case of cingulates, taxonomic identification also has important biostratigraphic, paleoecological, paleoenvironmental, and paleobiogeographical implications.

The vertebrate fossil record from the Feliz Deserto Formation (Lower Cretaceous), Sergipe, NE Brazil: paleoecological, taphonomic, and paleobiogeographic implications

The Feliz Deserto Formation (Berriasian–Valanginian, Sergipe–Alagoas Basin, NE Brazil) preserved some of the earliest South American fossil records of the rifting stages which resulted in the Gondwana supercontinent break-up during the Early Cretaceous. Recently, the first spinosaurid theropod record of this formation was described, based on a tooth recovered from Canafístula 01 locality in Sergipe State. We add herein twenty-seven isolated specimens to the fossil record of the Lower Cretaceous Feliz Deserto Formation. The new material includes seven isolated spinosaurid theropod teeth of the spinosaurine clade, as well as an indeterminate theropod preungual pedal phalanx. In addition, we describe an isolated crocodyliform osteoderm, as well as eighteen isolated teeth, some of which were taxonomically identified in three distinct morphotypes of neosuchian crocodyliforms. These findings expand the Gondwanan fossil record of both spinosaurine theropods and neosuchian crocodyliforms. Despite the fragmented nature of the specimens, these new fossils allowed the characterization of their general taphonomic features with low fluvial transport of bioclast prior to the burial. The depositional paleoenvironment of the Canafístula 01 locality is compatible with the deltaic system unit, that characterizes part of the Feliz Deserto Formation during the Early Cretaceous. These fossil findings exemplify the co-occurrence of spinosaurid dinosaurs and more than one taxon of crocodyliforms in the deltaic-lacustrine paleoenvironment represented by the Feliz Deserto Formation. These new occurrences reinforce the fossiliferous potential of the Canafístula 01 locality, especially related to the paleovertebrates from the Lower Cretaceous of Brazil.

The morphologic and paleobiogeographic implications of a new early Silurian echinoid from Anticosti Island, Quebec, Canada

The Ordovician and Silurian are an exceptionally important interval of time for understanding the effects of ancient climate change on the paleobiodiversity of echinoderms. Despite this importance, the fossil record of many echinoderm groups during this interval is sparse. The echinoids, or sea urchins, are no exception; and new fossil finds are necessary to better understand their initial diversification during the lower Paleozoic. We herein report on material from a new genus and species of echinoid, Anticostiechinus petryki gen. et sp. nov., from the Silurian of Anticosti Island, Canada. The morphology of the tubercles and spines of A. petryki are atypical for echinoids, and the surfaces for spine articulation consist of rounded, concave indentations. Additionally, the bases of the spines are subspherical. Furthermore, A. petryki belongs to the family Echinocystitidae, which increases the known diversity and distribution of this family during the Silurian and provides insight into the biogeography of echinocystitids from the Silurian to Devonian.

New data on the new micromammalian localities of Afoud (Aït Kandoula Basin, Morocco) at the Mio-Pliocene boundary: Biochronological, paleoecological and paleobiogeographic implications

Small mammal remains have been discovered in three new outcrops from the Afoud locality. This site is significant from a paleontological point of view because it has yielded fauna of European affinities (Castillomys, Occitanomys, Stephanomys, Eliomys, and Prolagus). The presence of two different species of Arvicanthis from the Afoud locality represents the oldest record in North Africa. The association of small mammals from the AF12-2 deposits provides an approximate view of the local environment and climate at the time of the formation of this locality. This faunal assemblage indicates a warm, temperate, semi-arid climate and an open vegetation cover of wooded savannah. Fossil assemblages documented in this paper expand our knowledge on the Late Miocene–Early Pliocene small mammal communities of the Aït Kandoula Basin. This study provides useful data for understanding the paleobiogeography of the Mediterranean region and faunal exchanges between North Africa and the Iberian Peninsula that took place before the Messinian Salinity Crisis.

The first record of mosasaurs (Squamata: Mosasauridae) from the West Indies and its paleobiogeographical implications

Remains of Cretaceous vertebrates have been scarce in the fossil record of Cuba, but recent exploration of Upper Cretaceous outcrops in the central part of the island has led to the discovery of new fossil-bearing deposits from nearshore depositional environments. Here, we report upon two isolated marginal teeth, which we identified as belonging to the genus Mosasaurus. The specimens described here, recovered from two upper Campanian – lower Maastrichtian outcrops in central Cuba, represent the first record of mosasaurs from the West Indies, and along with other marine fossils suggest that the Caribbean played an important role in the faunal interconnection across seaways and oceans in the region.

Lanternfish otoliths (Myctophidae, Teleostei) from the Miocene of Japan

Lanternfishes (Myctophidae) are one of the most common groups of fishes in the mesopelagic zone of the world ocean, and their otoliths have been dominant in pelagic sediments since at least Miocene times. Many species have a wide geographic distribution, with several being circumglobal. This wide distribution makes myctophid otoliths potentially useful for supraregional stratigraphic purposes. The Sea of Japan and the Northwest Pacific is an important region for investigations into the diversity and evolution of the Myctophidae. Here, we describe a large collection of myctophid otoliths from the late early to early middle Miocene (late Burdigalian to early Langhian) from six localities on western and central Honshu, which were under warm water influence during that time. A total of 22 species are recognized, of which eight are new. In the order in which they are described, the new species are Bolinichthys higashibesshoensissp. nov., Ceratoscopelus brevissp. nov., Lampadena eximasp. nov., Lampanyctus lenticularissp. nov., Lampanyctus tsuyamaensissp. nov., Stenobrachius ohashiisp. nov., Diaphus epipedussp. nov., and Diaphus watatsumisp. nov. At least nine species are also known from coeval sediments outside of Japan, most notably New Zealand and Europe. This distribution reflects the extraordinary geographic spread of myctophid species already in the early Miocene and indicates the potential for their future use for biostratigraphic purposes. The paleoecological and paleobiogeographical implications of the studied myctophid otolith assemblages are discussed. Furthermore, the stratigraphic ranges of the observed species are discussed and compared with data from other regions of the world in an attempt to outline the potential future application of myctophid otoliths for supraregional biostratigraphic purposes.

Taxonomy and paleobiogeographic implication of Glabrobournonia Morris and Skelton (Hippuritida, Radiolitidae) from the Late Cretaceous Yigeziya Formation, southwestern Tarim Basin

A re-examination of the specimens that were identified as Biradiolites minor Pojarkova from the late Campanian to early Maastrichtian middle member of the Yigeziya Formation of southwestern Tarim Basin reveals that they should be assigned to the genus Glabrobournonia Morris and Skelton. Glabrobournonia is a genus of radiolitids characterized by indented radial bands, salient ridges on the shell margins and absence of fine ribs on the surface of the right valve. Apart from southwestern Tarim Basin, Glabrobournonia minor (Pojarkova) has also been recorded from the late Campanian of Fergana and Alai basins. The central Asian, late Campanian to early Maastrichtian G. minor differs from the late Campanian to Maastrichtian, eastern Arabian type species Glabrobournonia arabica Morris and Skelton in the flat left valve and an additional fourth ridge on the junction of the dorsal and posterior sides of the right valve. Biradiolites ingens (Des Moulins) could be the direct ancestor of Glabrobournonia. The paleogeographic distribution of Glabrobournonia suggests that this genus dispersed to central Asia from the late Campanian time, becoming widely distributed in the eastern Tethyan region rather than endemic to eastern Arabia. Correspondingly, specimens belonging to Gyropleura yielded from the same bed as G. minor in southwestern Tarim Basin, are similar to the specimens which were attributed to the eastern Arabian Gyropleura sp.; Campanian to early Maastrichtian Osculigera specimens described from the Yigeziya Formation are comparable with those known from the Campanian–Maastrichtian of Iran, Afghanistan and eastern Arabia. The similarity of the rudist assemblages between central Asia and eastern Arabia suggests a faunal connection and affinity between the north and south margins of the eastern Tethyan realm during Campanian to early Maastrichtian times.

The ‘grooved’ Hildoceras ammonite fauna from the Lower Jurassic (Toarcian) of the Apennines. Overview and proposal for a new species

ABSTRACT It is historically renown that morphotypes referred to Hildoceras bifrons from the Apennines (Italy) and other Mediterranean localities differ in many ways from the typical species of the Central and North-West Europe. Besides overall smaller size (usually < 40 mm), Mediterranean specimens attain marked whorl embracement, comparable to that of the kin species Hildoceras semipolitum (albeit retaining a less compressed whorl section). Relatively larger (and rare) morphotypes may show slight 'uncoiling' (resembling the typical Hildoceras bifrons), though limitedly to the final part of the adult-stage last whorl. Both the common (small-involute) and rare (larger-slightly uncoiled) morphotypes thus reveal of ambiguous taxonomic attribution either as Hildoceras bifrons or as Hildoceras semipolitum. In front of this ambiguity, the new species Hildoceras appenninicus sp. nov. is proposed for grouping 'bifrons-like' Hildoceras occurring in the Apennines and other Mediterranean localities. In contrast with previous works on this subject, definite ranges for whorl compression indexes relative to whorl diameter and embracement are provided, by this attempting at a more objective distinction of this new species from both Hildoceras bifrons and Hildoceras semipolitum. Finally, along with some biostratigraphic remarks, possible evolutionary and paleobiogeographic implications concerning the arising and spreading of Hildoceras species are outlined. lsid: zoobank.org:pub:5C2C159E-61CA-4EE0-996D-D098618B3790