Palaeobiodiversity and Palaeoenvironments最新文献

The first fossil harvestmen (Arachnida: Opiliones) from the Messel Pit in Hesse, Germany, are described as ?Leiobunum messelense sp. nov. and ?Leiobunum schaali sp. nov. This is the first formal description of fossil harvestmen from the Eocene (ca. 47 Ma) of Messel, and one of the few non-amber records of harvestmen in the Cenozoic. Remarkably, these new specimens show iridescent, metallic colouration. This was previously unknown in the arachnid fossil record, but is seen often in insect fossils from Messel. The new harvestmen exhibit the typical ‘daddy long legs’ morphotype, with small, rounded bodies and long, slender legs. In detail, most of the dorsal opisthosomal tergites appear to be fused together into a single large scute, or scutum parvum, which strongly suggests the modern family Sclerosomatidae, especially in combination with a pectinate pedipalp claw. The iridescent colouration further implies that these fossils can be referred to either the subfamilies Gagrellinae or Leiobuninae, some of which also have a characteristic metallic lustre. Iridescence of the body is more typical for tropical sclerosomatids and is not known from extant European sclerosomatids, with the exception of a single, probably invasive, Leiobunum species. The warmer temperatures during the Eocene might have allowed exchange of early iridescent sclerosomatids between Eurasia and North America, which led to their wide present day distribution and diversity. A few not very well preserved harvestman fossils from Messel are recorded and/or figured for completeness as Leiobuninae / Gagrellinae indet. and Opiliones indet.

New Zealand has a diverse and highly endemic fauna of dance flies (Empididae) with much of its diversity found in the tribe Hilarini. Here we report the first fossil of a dance fly from New Zealand from lacustrine diatomites of the earliest Miocene Foulden Maar Fossil-Lagerstätte in Otago. Hilarempis otagoensis sp. nov. is described from a single male specimen and assigned to the tribe Hilarini based on characters of the wing venation. This new species represents the first fossil record of the predominantly southern temperate genus Hilarempis Bezzi and the second fossil record of the subfamily Empidinae from the Southern Hemisphere. The articulated preservation suggests that Hilarempis otagoensis sp. nov. lived among riparian vegetation on the shore of the Foulden Maar palaeolake and probably drowned while skimming the water surface in search for prey or nuptial gifts.

Mixed siliciclastic-carbonate deposits of Lower Devonian (Lochkovian-Emsian) age are exposed in the northeastern part of the Reggane Basin (Touat region). Based on lithological, sedimentological and palaeontological data, these deposits are subdivided into four distinct lithological units: Unit A characterises the Silurian-Devonian transitional zone; Unit B consists of a thick succession of Lochkovian-Pragian age, whereas Units C and D both document Emsian deposits. The studied section exhibits low to moderate ichnodiversity consisting of 14 ichnotaxa: Arenicolites isp., Chondrites isp., Curvolithus multiplex, Lockeia siliquaria, Monomorphichnus isp., Neonereites bisserialis, Neonereites uniserialis, Ophiomorpha isp., Palaeophycus isp., Planolites isp., Psilonichnus upsilon, Skolithos linearis, S. verticalis, and Thalassinoides isp. Both Curvolithus multiplex and Psilonichnus upsilon are documented for the first time from Palaeozoic deposits of the Saharan platform. These ichnofaunas are commonly ascribed to the Skolithos and Cruziana ichnofacies. Five distinct ichnoassemblages (Ichnoassemblages A to E) were defined, reflecting palaeoenvironmental changes from the foreshore to upper offshore zones, with frequent storm influence. Ichnofabric analysis of the section studied reveals six levels with different bioturbation intensities showing different palaeoecological conditions in various environmental settings (Monospecific Planolites, Lower combined Skolithos-Arenicolites, Combined Skolithos-Thalassinoides, Monospecific Skolithos, and Upper combined Skolithos-Arenicolites and Reburrowed Chondrites ichnofabrics). The vertical evolution of these deposits displays the successive deepening and shallowing trends recorded during the Lower Devonian in this area.

Three marsupial species are present in Palaeogene assemblages from south-eastern Serbia, Amphiperatherium minutum (Aymard, 1846), A. exile (Gervais, 1848–1852) and a species of Peratherium Aymard, 1850. These species are common in the late Eocene and early Oligocene of Western and Central Europe and their presence in South-Eastern Europe indicate that by the end of the Eocene, the eastwards dispersal of these marsupial species was already a fact. The presence of the same marsupial species in Serbia and in Western Europe is surprising, as the difference in composition between the Serbian and Western European rodent faunas indicates a limited faunal exchange between these areas in the late Eocene and early Oligocene. In marsupials, the stylar shelf of the upper molars shows a large morphological variation. A lesser-known variation is the presence of a transverse crista in the stylar shelf. These occur in various marsupial species, but so far were not known to be present in Amphiperatherium minutum. In our opinion, the large morphological variation of the stylar shelf is thus better not used to define a new species.

Abstract

Triassic and Jurassic strata are thick and widely distributed in the Sichuan Basin, South China. In particular, the continental Upper Triassic Xujiahe Formation is well-exposed in this region, yielding rich assemblages of fossil plants. Here, a new Rhaetian fossil assemblage is reported from Zilanba in the Guangyuan area, northern Sichuan Basin. In this locality, 29 species of fossil plants belonging to 17 genera have been newly collected and identified within Member III of the Xujiahe Formation. Based on the floral assemblages and previous magnetostratigraphic and palynostratigraphic studies, the host strata are considered Rhaetian in age. This flora in the Guangyuan area is dominated by Cycadales and Bennettitales but also contains abundant ferns and less common sphenopsids, conifers and other gymnosperms. The occurrence of some climate-diagnostic plants, such as Dipteridaceae, Anthrophyopsis and Ptilozamites, indicate that this area experienced a humid and warm tropical or subtropical climate during the Rhaetian.

During excavations at Koridornaya Cave (Pompeevskiy Ridge, Russian Far East) in 2017–2018 numerous skeletal elements of late Quaternary mammals were recovered for the first time in Priamurye. The aim of this work is to determine the shrew (Soricidae) species and to estimate their abundance. In the deposits of Koridornaya Cave, 890 cranial remains of shrews were found belonging to 10 species from genera: Sorex, Neomys, Beremendia, and Crocidura. The formation period of the deposits is determined as the Last Glacial Interstadial (MIS 3), and the upper part of the deposits contains also Holocene (MIS 1) components. The studied Late Pleistocene communities of shrews of the Pompeevskiy Ridge included modern inhabitants of this territory (S. caecutiens, S. isodon, S. unguiculatus, S. daphaenodon, S. roboratus, S. minutissimus, N. fodiens, and C. lasiura) and S. tundrensis; C. ex gr. suaveolens appeared in the Holocene. Sorex gracillimus, which currently lives here, was not recorded either because it was absent during the time of deposition of the fauna or it was extremely rare. Because of remaining uncertainties, within the framework of this study, B. minor is not considered a part of the Late Pleistocene fauna of Far Eastern shrews. The dominant species in the shrew communities in the Last Glacial Interstadial at the Pompeevskiy Ridge was S. caecutiens, just as in the shrew communities during Late Pleistocene to Holocene in the southern Sikhote-Alin Mountains and in most of modern shrew communities in the south of the Russian Far East.

Palynological investigation was conducted to reconstruct the palaeodepositional and palaeoclimatic conditions of the late Eocene Kopili Shale of Assam-Arakan Basin (AAB), India. The palynoassemblage (PA) comprises particulate organic matters (POMs), dinoflagellate cysts (DCs), pteridophytic spores (PSs), angiospermous pollen (APs), acritarchs, fungal remains (FRs) and foraminiferal linings (FLs). Amorphous organic matter (AOM), making up 55 to 97 % of the PA, is the predominant form of organic matter (OM) among the POMs. The palynoflora is dominated by DCs comprising 5 genera (Cordosphaeridium, Hystrichosphaeridium, Heteraulacacysta, Glaphyrocysta and Thalassiphora) and 22 referable species. The PSs are assigned to 3 families (Polypodiaceae, Matoniaceae and Osmundaceae) and 8 referable species. The APs are characterised by 3 families (Arecaceae, Fabaceae and Gunneraceae) and 9 pollen species. The palynological data reveal that the Kopili Shale was deposited in a marginal-marine to shallow marine environment under suboxic-anoxic basin condition having influx of coastal elements into the depositional basin. The palaeoclimatic condition during the deposition of the Kopili Shale was tropical-subtropical and warm-humid.

Three collections of clam shrimp from the Lower Devonian (upper lower Emsian) Klerf Formation of Willwerath and Waxweiler in the western Eifel Mountains are herein studied. Four discernible morphotypes are present in the Willwerath assemblage. These morphotypes correspond to the previously described species from this locality: Pseudestheria diensti (Gross), Pseudestheria subcircularis Raymond, and Palaeolimnadiopsis? eifelensis Raymond. The fourth morphotype also closely corresponds to Pseudestheria diensti, but is slightly different in outline. Asmussia willweratica (Novozhilov) is an objective synonym of Pseudestheria subcircularis. In the Willwerath clam shrimp sample, it is difficult to disentangle taphonomic/preservational versus ontogenetic/sexual variation. If taphonomic/preservational causes could be confirmed, all the Willwerath specimens may represent just one taxon and Pseudestheria subcircularis and Palaeolimnadiopsis? eifelensis would be potential subjective synonyms of Pseudestheria diensti. However, we refrain from a formal taxonomic act, which requires a larger number of specimens to be analysed.

In addition, we investigated two samples from Waxweiler, which originate from distinct centimetre-thick layers and therefore represent associations. One of these associations comprises two discernible clam shrimp morphotypes. Because of limited preservation of morphological characters, one is here left in open nomenclature as Spinicaudata incertae sedis, whereas the other is recognised as a new species of the family Palaeolimnadiopseidae, Palaeolimnadiopsis frankeorum sp. nov. The second association from Waxweiler comprises at least four, possibly six different clam shrimp taxa. In addition to Pseudestheria diensti, Palaeolimnadiopsis sp., and poorly preserved Asmussia- and Ulugkemia-like specimens, two taxa can be described as new, namely the vertexiid Cornia wasvilrensis sp. nov. and the leaiine Eicheleaia wenndorfi gen. nov. et sp. nov. Altogether, the Klerf Formation at Waxweiler yields a total of at least five (possibly eight) clam shrimp taxa. The palaeoenvironment of these early clam shrimp from the Klerf Formation is interpreted as a non-marine, relatively proximal deltaic setting with no or very minor marine influence, such as a deltaic freshwater pond or lake. The comparatively high diversity of these lower Devonian clam shrimp suggests a considerably earlier origin and cryptic evolution of the group.

Abstract

The Miocene succession (Allala River Sandstones and Tenes Blue Marls Formation) that crops out in the Tenes area, situated in the northeast of the Lower Chelif Basin in NW-Algeria, contains a low-diversity assemblage of trace fossils. Fifteen (15) ichnogenera were identified: Arenicolites, Beaconites, Cylindrichnus, Diplocraterion, Macaronichnus, Ophiomorpha, Palaeophycus, Parahaentzschelinia, Planolites, Rosselia, Skolithos, Taenidium, Teichichnus, Thalassinoides and Zoophycos. Ethologically, these ichnogenera chiefly display dwelling and feeding activities. The presence of thick, deep-tier, scattered, mainly vertical dwelling burrows attributed to the Skolithos ichnofacies indicates high energy conditions, normal oxygenation and soft substrate. Moreover, elements of the Cruziana ichnofacies show more varied behavioural strategies and higher inchnodiversity with the dominance of horizontal burrows of deposit-feeders. This ichnological study supports the palaeoenvironmental interpretation based on sedimentological analysis of a wave-dominated siliciclastic platform (backshore to offshore), allowing a more precise zonation of the shoreface zone (middle/upper and lower shoreface). In addition, this study allows evaluation of variable degrees of storm influence in response to the contrasting palaeogeomorphology of the coastline.