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1.
A lower jaw of the mesonychian Hapalodectes is reported from Nongshanian sediments (Upper Doumu Formation; middle Paleocene) of the Qianshan Basin (Anhui Province, China). The fragmentary mandible is only the third specimen of Hapalodectidae discovered in Paleocene deposits, and the first in south east China; it is moreover the oldest, the two other specimens having been found in Gashatan (late Paleocene) localities. The premolars and molars of the new fossil are morphologically similar to Hapalodectes dux (late Paleocene of Mongolia), which has been considered to be the most primitive hapalodectid, but their relative proportions recall H. paleocenus and the Eocene Hapalodectes species. As a result, the fossil described herein appears to be different from the other previously described species of Hapalodectes in being morphologically intermediate between H. dux and the other Hapalodectes species, notably the Bumbanian Hapalodectes hetangensis and H. huanghaiensis from China; it is thus identified as a new species, Hapalodectes lopatini (possibly a male individual). Its discovery is important because it sheds light on the initial radiation of hapalodectids. The presence of one primitive hapalodectid in Mongolia previously suggested the Mongolian Plateau as the centre of origination of this carnivorous family, but the discovery of H. lopatini in older sediments from south‐east China challenges this hypothesis. In the earliest Eocene, Hapalodectes dispersed from Asia to North America; this event being part of the ‘East of Eden’ dispersals. This event resulted in the geographical separation of two distinct Hapalodectes groups, in North America and south‐eastern China respectively.  相似文献   

2.
The effects of faunal turnover on mammalian community structure are evaluated for 17 faunal zones of the North American Paleocene through early Eocene land mammal ages (Puercan through early Wasatchian). Generic disappearances were significantly high at the end of the Puercan, Torrejonian, and Tiffanian land mammal ages, but appearances were significantly high only during the early Puercan. Generic richness rose rapidly in the early Puercan, remained stable throughout most of the Paleocene, and increased from the late Paleocene into the early Eocene. The null hypothesis that generic turnover clustered preferentially according to dentally defined trophic or body size categories could be rejected or attributed to sampling problems for all but the early (Pu0) and late Paleocene (Ti5‐Cf2). Early Paleocene change in community structure most probably represented endemic radiation of mammals into previously unoccupied niches. Community restructuring in the late Paleocene reflected a complex of causes, including climatic wanning, intercontinental dispersal, and competition.  相似文献   

3.
This paper presents for the first time the inventory of the Paleocene and Lower Eocene foraminifers located in the North Pyrenean trough, between the Atlantic Ocean and the neighbourhood of the town Pau. They have been studied from three outcrops. The Bidart Beach section shows the Lasseube Formation from the Cretaceous/Paleogene boundary to the base of the P 3a zone. The Loubieng Quarry section, near Orthez, represents the upper P 3a zone and the lower P 3b zone as well as the Lasseube Formation / Pont Labau Formation boundary. The interval between the upper part of the P 3b zone and the upperest part of the P 5 zone crops out along the Gan - Rébénacq road with a hiatus located at the Paleocene / Eocene boundary, the whole interval belonging to the Pont Labau Formation. 394 taxons of foraminifers are present in this formations: 349 benthic and 45 planktonic species. The Velasco type benthic foraminifers show a middle bathyal depositional environment, with a paleobathymetry included between 500-600 m and 1000 m: Nuttallides truempyi, Osangularia velascoensis, Bulimina trinitatensis. The Midway type species which were transported by the turbidite currents from the lower to middle neritic environments are frequent as well as the Cretaceous reworked species. The species number is low: 29 in the iridium layer of the Cretaceous/Paleogene boundary (P 0 zone). Fauna grows rich quickly in the Pα zone reaching 129 species. The diversity grows up progressively from P α to the P 4a zone (NP 8). The disappearances are rare until his horizon, but their number is bigger than the number of appearances from the P 4b zone. It reaches their maximum between the P 4c zone and the P 5 zone. It shows that the decline of the Paleocene fauna begins around 2 million years before the thermal event of the Paleocene / Eocene boundary in the Aquitaine sections. The disappearances stay important in the Lower Eocene - Ypresian, but the appearance of lots of Eocene species show that the fauna renewal is located in this stage. The Cretaceous taxa dominate in the Paleocene benthonic fauna. The appearance or the disappearance of some species has a stratigraphic value in the Aquitaine region: the disappearance of Coryphostoma incrassata in the P 1b zone, the appearances of Plectina dalmatina, Elongobula grata (P α); Bulimina tuxpamensis (P 2); Tritaxilina cubensis, Thalmannita madrugaensis (P 3a); Svenia bulbosa (P 3b); Discorbis perovalis (P 4a/NP 7); Elongobula pulchra, E. pupa, Asterigerina bartoniana, Neorotalia gr. tuberculata (P 4a/NP 8); Bigenerina pannonica, Pentellina pseudosaxorum (P 5/NP 9-10).  相似文献   

4.
Arctostylopids are enigmatic mammals known from the Paleocene and Early Eocene of Asia and North America. Based on molar similarities, they have most often been grouped with the extinct Notoungulata from South and Central America, but tarsal evidence links them to Asian basal gliriforms. Although Palaeostylops is the best-known arctostylopid genus, some points of its content and species level taxonomy remain uncertain. Here we report 255 upper and lower jaw fragments of Palaeostylops, five calcanea, three astragali, as well as the first known arctostylopid distal tibia. This new material was collected from the late Paleocene of the Flaming Cliffs area in Mongolia, in a single lens almost exclusively containing arctostylopid remains. Our study of the morphology and size of the new Palaeostylops dental material confirms the validity of two species, P. iturus and P. macrodon, and illustrates their morphological and biometrical variability and diagnostic differences. The distal tibia of Palaeostylops is relatively unspecialised and resembles the Asian gliriforms Pseudictops and Rhombomylus. We also review the relevance of the historically important genus Palaeostylops in view of other, more recently described but less abundant arctostylopid genera. Palaeostylops remains the reference taxon for the arctostylopid anterior dentition and postcranial morphology. For both anatomical regions, arctostylopids differ significantly from notoungulates, and present a mosaic of characters also seen in basal gliriforms. The notoungulate-like molars of Palaeostylops are highly specialized for arctostylopids and the arctostylopid molar morphotype is therefore better illustrated by the early middle Paleocene Asiostylops. This morphotype does not present any similarities to notoungulates, but shares a number of derived characters with basal gliriforms. Among gliriforms, the primitive arctostylopid morphotype is most similar to Astigale from the early Paleocene of South China, and we suggest that Arctostylopidae may therefore be more closely related to Astigalidae than to any other group.  相似文献   

5.
Oxyaenid creodonts are extinct carnivorous mammals known from the Paleogene of North America, Europe, and Asia. The genus Palaeonictis is represented by three species that together span the late Paleocene to early Eocene of North America, and at least one species from the early Eocene of Europe. Previously, only a single trigonid of Palaeonictis was known from the interval encompassing the Paleocene-Eocene Thermal Maximum (PETM) in North America. We describe Palaeonictis wingi sp. nov. from the PETM in the Cabin Fork drainage, southeastern Bighorn Basin, Wyoming, based on associated right and left dentaries with P2-M2. Palaeonictis wingi sp. nov. is substantially smaller than the other North American congeners, making it similar in size to P. gigantea from the earliest Eocene of Europe and the previously described PETM specimen. We suggest that a form similar to the large-bodied late Paleocene P. peloria from North America gave rise to two smaller species in the earliest Eocene of North America (P. wingi) and Europe (P. gigantea). Palaeonictis wingi may have given rise to P. occidentalis following the PETM in North America. Dispersal of Palaeonictis to Europe coincided with rapid global warming of 5–10°C and related geographic range shifts in plants and other animals during the PETM. It has been suggested that certain mammalian lineages decreased in body size during the PETM, possibly in response to elevated temperature and/or higher CO2 levels. Results from a dietary analysis of Palaeonictis indicate that it was an omnivore that primarily consumed meat. This suggests that the decreased nutritious quality of vegetation caused by increased CO2 levels was not the direct contributing factor that caused body size reduction of this lineage during the PETM. Other selective pressures such as temperature, aridity, and prey size may have also contributed to the smaller body size of carnivorous mammals during this interval, although the presence of smaller species could also be explained by latitudinal range shifts of mammals during the PETM.  相似文献   

6.
Two new species of pseudorhyncocyonid, Fordonia lawsoni sp. nov. and Leptictidium prouti sp. nov. from the UK earliest Eocene, described here, are older than any previously recorded member of the family. They are represented by teeth from numerous loci, which allow a better understanding of the sparsely known dentitions of currently known pseudorhyncocyonids. This facilitates the recognition of two further species of Leptictidium, L. listeri sp. nov. from the Middle Eocene of Germany and L. storchi sp. nov. from the Late Eocene of France. Study of occlusal relationships also helps to fill gaps in our knowledge of missing tooth loci. Cladistic analysis of pseudorhyncocyonids with their previously judged closest relatives, the Leptictidae, Pantolesta and Palaeanodonta, shows that two European species, Diaphyodectes prolatus and Palaeictops? levei, formerly thought to be leptictids, are instead primitive pseudorhyncocyonids, extending the range of the family further back in time to the Middle Paleocene. Plevei is placed in the new genus Phakodon gen. nov. The analysis also shows that the Pseudorhyncocyonidae are sister group to the other three groups combined and that family‐level differentiation in this probable clade took place as early as the earliest Paleocene.  相似文献   

7.
Abstract: Among the new dental remains from the late Early Eocene of Chambi (Kasserine area, Tunisia) is a large‐sized upper molar of a new bat species, Witwatia sigei nov. sp. (Chiroptera, Vespertilionoidea, Philisidae), described herein. The locality of Chambi has revealed evidence for an early appearance of two modern microchiropteran superfamilies in Africa: Dizzya exsultans, a Philisidae, which is considered to be an archaic Vespertilionoidea, and an indeterminate Rhinolophoidea. In addition to D. exsultans, the new species, W. sigei, is the second representative of the Philisidae in this locality. W. sigei extends back to the late Early Eocene the occurrence of the genus Witwatia, which was previously only reported from the early Late Eocene of the Fayum (BQ‐2, Egypt). By analogy with the largest extant microbats, the large size of Witwatia suggests a tendency to the opportunistic diet of this taxon, thereby contrasting with the strict insectivory characterizing primitive bats found in other continents in the same epoch.  相似文献   

8.
This work summarizes biostratigraphic and paleogeographic data on Paleocene ostracods from the Senegalese-Mauritanian, West African and North African basins. In the Senegalese-Mauritanian basin, late Paleocene ostracods of high diversity suffered a mass extinction in the early Eocene. Comparison between Senegalese faunas and others of the Gulf of Guinea, Sahara and North African basins shows great similarities, with 10 common species identified: Bairdia ilaroensis Reyment and Reyment, Buntonia apatayeriyerii Reyment, Bfortunata Apostolescu, B. tichittensis Apostolescu, Cytherella sylvesterbradleyi Reyment, Dahomeya alata Apostolescu, Isohabrocythere teiskotensis Apostolescu, Phalcocythere vesiculosa (Apostolescu) Quadracythere lagaghiroboensis (Apostolescu) and Trachyleberis teiskotensis (Apostolescu). I. teiskotensis and P. vesiculosa are restricted to the upper Paleocene and are good stratigraphic markers for these basins. Faunal exchanges between West African, trans-Saharan and North African basins are highlighted. The directions of migration of some species are specified. Many West African species migrated to North Africa at the end of the Paleocene-Early Eocene. Migrations are related to climatic and paleobathymetric changes of the Paleocene-Eocene Thermal Maximum (PETM) that occurred during the Paleocene-Eocene transition.  相似文献   

9.
Modern penguins are typically small to medium-sized birds, and nearly all known modern specimens are smaller than the most archaic Paleogene relatives. Here we report an incomplete humerus, associated femur and tibiatarsus of a new spheniscid, Crossvallia unienwillia nov. gen. and sp., from the Late Paleocene (~55 million years, Myr) of Antarctica, extending the record of spheniscids by about 15 Myr. Its large size (length ~140 cm) supports the idea that large body size in penguins was acquired independently at different times (Late Paleocene and Late Eocene) under dramatically different environmental conditions. Comparison of its osteological anatomy suggests that the new taxon is closely related to the extinct Anthropornithinae rather than to other penguin lineages.  相似文献   

10.
11.
A small collection of fossil catarrhines was recovered from the early Miocene locality of Meswa Bridge in western Kenya between 1978 and 1980. The associated fauna from Meswa Bridge indicates an age older than 20 Ma. Much of the material has been briefly described previously, and its taxonomic status considered. The material can be assigned to a minimum of four individuals, all of which are infants or juveniles. Although the specimens were shown to belong to a distinct species of Proconsul, the taxon was not named, primarily because many of the specimens belonged to immature individuals. Nevertheless, the combined morphological features of the deciduous and permanent teeth allow the diagnosis of a new species of Proconsul, which is formally named here as P. meswae. It is a large-sized species, similar in dental size to P. nyanzae. The main features distinguishing it from all other previously named species of Proconsul are: incisors and deciduous incisors relatively low crowned; upper deciduous canines relatively higher crowned and more robust; molars and deciduous premolars relatively broader and higher crowned, with a more pronounced degree of buccolingual flare and better developed cingula; size differential between molars not as marked; dP4 with a longer mesial fovea and smaller hypoconulid and distal fovea; P4 relatively broader, with a better developed buccal cingulum; lower molars less rectangular with a longer mesial fovea, smaller distal fovea, more restricted talonid basin, and a tendency for a smaller hypoconulid; dP4 and upper molars with strongly buccolingually splayed roots; mandibular corpus in infants relatively deeper and more slender; maxilla with a well developed canine jugum and fossa. The broader and more flared molars with better developed cingula indicate that the Meswa Bridge species is more primitive than other species of Proconsul. The inference that it is a stem member of the Proconsul clade is consistent with the estimated age of the material.  相似文献   

12.
Allelopathy plays a crucial role in providing competitive advantage to several alien invasive species, and assists in their establishment beyond native boundaries. Role of allelopathy in the invasion success of the alien weed, Parthenium hysterophorus is well established; however, the ecological and evolutionary factors that could affect its allelopathic interactions are relatively unexplored. In our earlier findings, we suggested the presence of two morphotypes (PA and PB) in the population of P. hysterophorus, with variable morphology, physiology, and level of ecological impacts. Here, we hypothesize that phenotypically distinct morphotypes of P. hysterophorus may vary in their phytotoxicity and allelochemistry, thereby producing differential ecological impact. To test this hypothesis, effects of rhizospheric soil (RS) and plant amended soils (PAS) of the two morphotypes of P. hysterophorus (PA and PB) were studied on selected dicot (Bidens pilosa and Senna occidentalis) and monocot species (Phalaris minor and Avena fatua). Also, the composition of allelochemicals in PA and PB was assessed using Liquid Chromatography and Mass Spectrometry (LC-MS). The study revealed that the phytotoxic effect of PB was greater than PA in all the parameters measured for dicot species and in most of the parameters studied in monocot species. A generalized dose-dependent response was observed in the test species (PAS0 < PAS10 < PAS20 < PAS40) and the effect of RS was comparable to PAS20 and PAS40. A greater number of allelochemicals were reported from PB, which is in accordance with the growth studies. The study concludes that intraspecific variations account for differential phytotoxicity and allelochemistry in P. hysterophorus.  相似文献   

13.
The earliest euprimates to arrive in North America were larger‐bodied notharctids and smaller‐bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small‐ and increasingly mid‐sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P4 displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P4 can also provide important paleoecological insights. We analyzed the P4 from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two‐dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P4 than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P4 disparity and convergent evolution of the semimolariform condition in the largest omomyines. P4 morphology relates to diet in early euprimates, although patterns vary between families. Am J Phys Anthropol 153:15–28, 2014. © 2013 Wiley Periodicals, Inc.  相似文献   

14.
A humerus and a coracoid from the Early Eocene Wasatch Formation in the Washakie Basin of south‐western Wyoming are the oldest materials (by ~2 million years) of the pelecaniform Limnofregata (Aves) and represent a new large species, Limnofregata hutchisoni sp. nov. This fossil is the oldest known member of the frigatebird lineage. Other than its large size relative to Limnofregata azygosternon and Lhasegawai, the new material is very similar morphologically to other known Limnofregata specimens. The size of this new species is comparable to the largest living species (e.g. Fregata minor and Fregata magnifiscens) and much larger than the two described species of Limnofregata. This fossil indicates that the hard minimum date previously advocated for molecular calibration of the split between Fregatidae and Suloidea is an underestimate by approximately two million years. The presence of early pelecaniform bird lineages (represented by Limnofregata and Masillastega) in limnic ecosystems prior to their known occurrences in marine deposits/habitats appears to indicate that some clades of pelecaniform birds may have undergone an evolutionary transition from freshwater to marine habitats in a pattern reminiscent of what has been suggested during the evolution of pinnipeds or that their palaeoecology included broader niches ranging across a variety of aquatic habitats. That transition in habitat occupation and the origin of many of the characteristic biological aspects present in the crown frigatebird clade likely occurred during a significant temporal gap (> 45 million years) in the fossil record of the frigatebird lineage after these earliest occurrences in the Early Eocene and before the oldest records of the extant Fregata species in the Pleistocene.  相似文献   

15.
There is a dearth of diagnostic human remains securely associated with the Early Aurignacian of western Europe, despite the presence of similarly aged early modern human remains from further east. One small and fragmentary sample of such remains consists of the two partial immature mandibles plus teeth from the Early Aurignacian of La Quina-Aval, Charente, France. The La Quina-Aval 4 mandible exhibits a prominent anterior symphyseal tuber symphyseos on a vertical symphysis and a narrow anterior dental arcade, both features of early modern humans. The dental remains from La Quina-Aval 1 to 4 (a dm1, 2 dm2, a P4 and a P4) are unexceptional in size and present occlusal configurations that combine early modern human features with a few retained ancestral ones. Securely dated to ∼33 ka 14C BP (∼38 ka cal BP), these remains serve to confirm the association of early modern humans with the Early Aurignacian in western Europe.  相似文献   

16.
The early Eocene locality of La Borie is located near the village of Saint-Papoul, in southwestern France. It consists of clay deposits that have yielded numerous vertebrate fossils, including remains of the giant flightless bird Gastornis. These remains were initially attributed to the species G. parisiensis, which is otherwise recorded from the late Paleocene and earliest Eocene of the North Sea Basin. New fossil birds collected in the La Borie clay pit in 2018 include an almost complete mandible of Gastornis. We describe a new species of Gastornis based on this mandible and we show that the previously described remains from La Borie must be assigned to this new species. The new species differs from other species of Gastornis in the morphology of the mandible, maxilla and quadrate. The morphological diversity of the genus Gastornis, which existed in Europe for at least 17 million years, is emphasized.LSID of publication: urn:lsid:zoobank.org:pub:10E7938B-C972-4127-94DC-169D35977B11.  相似文献   

17.
We present here the earliest known Asian fossil records of the Menispermaceae based on fossil fruits from Paleocene and Eocene localities in South China. A new genus and species, Paleoorbicarpum parvum sp. nov., and two new species of Stephania Loureiro, S. ornamenta sp. nov. and S. geniculata sp. nov., are recognized from Paleocene deposits of the Sanshui Basin, Guangdong, and a new occurrence of the widespread Eocene species Stephania auriformis (Hollick) Han & Manchester is recognized from the Maoming Basin, Guangdong. The Paleocene Stephania specimens described here represent the earliest fossil endocarp record of the Menispermaceae in eastern Asia. This discovery shows that the moonseed family had arrived in tropical and humid South China by at least the middle Paleocene, which provides important evidence for the origin and phytogeographic history of the family.  相似文献   

18.
《Comptes Rendus Palevol》2019,18(7):747-763
Glyptosaurine lizards (Glyptosaurinae, Anguidae) are an extinct group of heavily armored lizards known from North America, Europe and Asia. Glyptosaurine lizards, taxa that possess fully developed tuberculated dermal armor, appear to have been established in North America by late early Puercan time (To3). “Proxestops,” a taxon distinguished by a combination of vermiculate and tuberculated osteoderm sculpturing, is considered to be a non-glyptosaurine, a sister taxon of the Glyptosaurinae. Known from only fragmentary remains, its wide chronostratigraphic distribution suggests that “Proxestops” is a form genus that, in all probability, represents more than one taxon, that ranges from the middle Paleocene to the early Eocene of North America. Moreover, the taxa Odaxosaurus piger, Parodaxosaurus sanjuanensis and “Proxestops” are best considered “proto-glyptosaurines”. “Melanosaurins” and glyptosaurins were well-established by the early Eocene, especially in North America, and are here documented by their type species and chronostratigraphic levels. Both tribes are present in Europe (MP7), too, but the record is not as estensive as that of North America. The North American taxon Gaultia silvaticus (Wa0) is transitional between a “melanosaurin” and glyptosaurin. Because it lacks the well-defined hexagonal osteoderms that characterize the Glyptosaurini, it is removed from that group and considered to be a “melanosaurin”. The “melanosaurin” taxon “Xestopssavagei (Wa4–Wa6) cannot be referred to Xestops (Br2) based on non-corresponding elements and because superficial similarity does not justify assignment to this taxon. Arpadosaurus sepulchralis (Wa6?), whose holotype is a fragmentary right frontal, is considered a subjective junior synonym of A. gazinorum, based on minor differences in the epidermal scale pattern that probably represent individual variation. “Glyptosaurusagmodon (Wa6?), based on a partial right maxilla, cannot be referred to Glyptosaurus (sensu stricto), and the material upon which this taxon is based bears strong resemblance to material identified as cf. “?Paraglyptosaurusyatkolai (Wa5–Wa6). “Glyptosaurusrhodinos (Wa5) is based on an incomplete parietal, and its reference to Glyptosaurus is considered problematic. Eoglyptosaurus donohoei (Wa7) is probably valid and is re-established here. Glyptosaurus (sensu stricto) is known solely from the middle Eocene (Br2) by G. sylvestris. Dimetoposaurus wyomingensis (Br3) is removed from Xestops vagans because its synonymy was based on superficial similarities. Helodermoides tuberculatus, the largest and last glyptosaurin (Ch3), is restricted to the Chadronian of North America. Only the “melanosaurin” Peltosaurus granulosus (Or2–Or3), which includes the species P. abbotti, seems to have crossed the Eocene-Oligocene boundary, and appears to be largely restricted to the Orellan, but extended into the Arikareean. European glyptosaurines are also represented by both glyptosaurins and “melanosaurins” early in the Eocene (MP7). Placosauriops-like “melanosaurins” are known from Dormaal (MP7), and the glyptosaurin taxon?Placosaurus ragei occurs at the same level. “Placosauriops abderhaldeni” has been identified from the Grube Messel (MP11), but this assignment remains dubious because the species has not been adequately diagnosed, and the holotype species is from the Geiseltal (MP13), which is some 4.5 million years younger. Placosauriops weigelti (MP13) is the only valid species of this genus. Paraxestops stehlini (MP14) is not referable to the North American taxon Xestops, and its relationship to Placosauriops has not been studied. The late Eocene glyptosaurins Placosaurus estesi (MP17) and P. rugosus (MP18) are the last glyptosaurines known from Europe and appear to have gone extinct at the Eocene-Oligocene boundary, casulties perhaps of the “Grande Coupure”. Asian glyptosaurines are known solely from one species, Stenoplacosaurus mongoliensis, from the middle Eocene (Sharamurunian) of China. Glyptosaurines most likely originated in North America, diversified by late Paleocene time, and rapidly spread across the North Atlantic into Europe by the early Eocene. Both “melanosaurins” and glyptosaurins took a foothold in Europe by the early Neustrian, but the glyptosaurins, aside from one occurrence (Dormaal, MP7), were conspicuously absent for most of Neustrian through early Robiacian time. In North America, glyptosaurins diversified during the early and middle Eocene, while in Europe small “melanosaurins” were a prominent part of the paleoherpetofauna, and glyptosaurins are unknown for most of the Neustrian through the Geiseltalian, in both the fossilferous Lagerstätten of Messel and Geiseltal. Stenoplacosaurus is the only known glyptosaurin glyptosaurine from Asia, and its abrupt appearance during the late Eocene suggests the possiblity of a Beringian dispersal from North America into Asia.  相似文献   

19.
Orthophragminids are a key biostratigraphic proxy for Paleocene–Eocene sequences in western Tethys, but poorly known in eastern Tethys. The orthophragminids were previously misinterpreted as Paleocene's orbitoidiform foraminifera in the Indus Basin, Pakistan. This study focuses on detailed taxonomy and biostratigraphy of orthophragminids. Nine species/subspecies of orthophragminids are identified, including Discocyclina ranikotensis, D. archiaci bakhchisaraiensis, D. a. ex. interc. staroseliensis bakhchisaraiensis, D. dispansa hungarica, D. d. taurica, D. d. broennimanni and Orbitoclypeus schopeni ramaraoi, and two new species Discocyclina pseudoranikotensis n. sp. and Discocyclina debalensis n. sp. are described. The identified orthophragminid taxa represent the orthophragminid zones OZ2-3, corresponding to the shallow benthic zones SBZ5-7 of early Ypresian (early Eocene), which are correlated with those in western Tethys. However, we found that the first appearances of D. d. hungarica and D. d. taurica occur in the OZ3 or SBZ7 in this study instead of the OZ5 or SBZ10 as in western Tethys. The possible paleoecological setting for the occurrences of recognized species is interpreted as inner to middle shelf.  相似文献   

20.
The Upper Paleocene of E-Tademaït and W-Tinrhertis characterized by a new macrofauna and the appearance of Ranikothalia bermudezi. This is followed by Lower Eocene (Lowermost Ilerdian) Nummulites fraasi and N. deserti, in E-Tademaït.We note in relation with the uplifting of Saharo-Nubianshelf a regressive evolution towards the North, where successively later Nummulites species (deserti, globulus, rollandi, gizehensis) appear during the Lower Eocene.  相似文献   

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