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Patricia Vickers-Rich, Andrey Yu. Ivantsov, Peter W. Trusler, Guy M. Narbonne, Mike Hall, Siobhan A. Wilson, Carolyn Greentree, Mikhail A. Fedonkin, David A. Elliott, Karl H. Hoffmann, Gabi I. C. Schneider
Rangea is the type genus of the Rangeomorpha, an extinct clade near the base of the evolutionary tree of large, complex organisms which prospered during the late Neoproterozoic. It represents an iconic Ediacaran taxon, but the relatively few specimens previously known significantly hindered an accurate reconstruction. Discovery of more than 100 specimens of Rangea in two gutter casts recovered from Farm Aar in southern Namibia significantly expands this data set, and the well preserved internal and external features on these specimens permit new interpretations of Rangea morphology and lifestyle. Internal structures of Rangea consist of a hexaradial axial bulb that passes into an axial stalk extending the length of the fossil. The axial bulb is typically filled with sediment, which becomes increasingly loosely packed and porous distally, with the end of the stalk typically preserved as an empty, cylindrical cone. This length of the axial structure forms the structural foundation for six vanes arranged radially around the axis, with each vane consisting of a bilaminar sheet composed of a repetitive pattern of elements exhibiting at least three orders of self-similar branching. Rangea was probably an epibenthic frond that rested upright on the sea bottom, and all known fossil specimens were transported prior to their final burial in storm deposits.
The Dunleith Formation echinoderms lived on a shallow water carbonate platform (Benthic Assemblages outer 2 and 3 during the latter part of the Dunleith Regressive Cycle). The echinoderms were buried rapidly by storms or a volcanic ash bed in one example. The presence of complete specimens, entire crowns, attachment structures, and excellent preservation strongly suggests that these assemblages reflect in situ communities on the seafloor that have not been significantly mixed, transported, or concentrated in time. Most taxa are suspension feeders, namely 21 crinoids, one glyptocystitid rhombiferan, a paracrinoid, and two edrioasteroids, but a deposit feeding pleurocystitid rhombiferan is also common. Three assemblages are recognized and defined by their dominant taxa; in order of increasing depth, these are the Cotylacrinna sandra, Pleurocystites strimplei, and Cupulocrinus crossmani assemblages. Substrates ranged from hard- or firm-ground carbonates to soft carbonate and siliciclastic muds. Diverse attachment structures are recognized: the recumbent stems of calceocrinids, lichenocrinids on shells, small distal stem tips, and round to lobate calcite pads cemented to shells or the substrate, open distal stem coils directly on the seabed or coiled around soft objects thereon, and large conical and highly modified cirrus holdfasts on hard- or firm-grounds. The echinoderms were located at levels ranging from the seafloor to almost a meter above, with maximum diversity at about 50 mm above the seafloor. The size frequency distributions of food particles and the ranges of ambient current velocities for successful feeding by the juveniles and adults of the common crinoids are modeled using filtration theory. The food particle size distributions and the current velocities for feeding are correlated with the arm or filtration fan morphology of the crinoids. Differences between these parameters tend to partially separate the feeding ecologies of species located at the same elevation. Nevertheless, considerable overlap remains between species for small sized food particles and the lower ranges of ambient current velocities for feeding. Except for the Cotylacrinna sandra Assemblage, competition for space does not seem to have been important in regulating the ecological structure of the Dunleith crinoids. However, the deposit feeding pleurocystitids possibly competed for food and space in one example. The Dunleith assemblages are much more diverse with greater ecological complexity than seen in the relatively deep water fauna from the Upper Ordovician Trenton Group of the Walcott-Rust Quarry in New York (Benthic Assemblage 5).
A fusulinoidean taxonomic study of the Gurkovo and Kalinovo sections allows us to refine the biostratigraphy of the poorly studied Myachkovian (upper Moscovian) strata of the “N” Formation in the Donets Basin. Three fusulinid biozones, Hemifusulina graciosa–Fusiella spatiosa, Fusulina cylindrica–Fusulinella pseudobocki, and Fusulinella ? kumpani, are proposed in the interval from the top of Limestone M10 to the base of N3, and they are correlated with coeval strata in the historical type area of the Moscow Basin. A total of 33 fusulinid species and subspecies belonging to eight genera are described, including three new species: Hemifusulina gurkovensis n. sp., Beedeina innaeformis n. sp., and Fusulina sosninae n. sp. The main evolutionary trend in fusulinoidean morphology in the late Moscovian is the appearance of massive secondary deposits in the limestone of the “N” Formation.
Specific temporal and distributional patterns of the Middle Pennsylvanian fusulinoidean assemblages indicate variations in sea level stand. Variations are cyclic, with periods ∼600,000–1,000,000 years. A Hemifusulina-association indicates the beginning of transgression; the late transgression–high sea level stand is designated by the Beedeina–Neostaffella–Ozawainella–Taitzehoella assemblage which is successively replaced by the most diverse Fusulinella-dominant association, which occupied a progressively shallowing sea.
The similarity of fusulinoidean assemblages in the Moscow and Donets Basins and their cognate evolution trends reveal a connection between both regions at least during Podolskian–Myachkovian time.
A small assemblage of shelly fossils, dominated by the brachiopod Treptotreta jucunda and the bradoriid arthropod Mongolitubulus aspermachaera new species is described from a Furongian limestone of Västergötland, south-central Sweden. Mongolitubulus aspermachaera is represented in the assemblage by individual valves and numerous, ornamented spines. Valves and spines share identical ornament and microstructure leaving no doubt that the isolated spines were once attached to the bradoriid valves. Mongolitubulus aspermachaera adds to the increasing list of spinose Cambrian bradoriid arthropods, and Mongolitubulidae new family is erected here to incorporate the genera Mongolitubulus, Tubuterium and Spinospitella. Mongolitubulus aspermachaera represents the youngest member of the new family and supplements the biodiversity of bradoriids in the Furongian, an interval when bradoriid diversity is considered to be very much on the decline. The brachiopod Treptotreta jucunda described predominantly from the ‘middle' to ‘late' Cambrian of Australia is here documented for the first time from outside Gondwana, dramatically extending the biogeographical range of the species. Other elements of the faunal assemblage include typical Baltic Furongian representatives, such as the trilobite Parabolina, the agnostoid Agnostus and the phosphatocopids Hesslandona and Vestrogothia.
Shells and opercula of bithyniid gastropods assigned to Gabbiella are found in high abundance in the Pleistocene upper Burgi and KBS Members of the Koobi Fora Formation, Turkana Basin, northern Kenya. The systematic paleontology of the Turkana Basin Gabbiella is revised herein based on morphological comparison with the opercula of other Recent African bithyniids. The fossils from the upper Burgi and KBS Members are here assigned to Gabbiella roseaMandahl-Barth, 1968, a species not known from the Turkana fossil record before, but extant in this lake today. A sampling and taphonomic bias is identified which influences the relative abundance of Gabbiella shells and opercula, as a mesh size of 0.63 mm or less is necessary to capture all opercula preserved in the sediments. Accordingly, opercula were found to be significantly more abundant than shells, indicating a different preservation potential of shells and opercula, as the calcitic operculum is more robust than the aragonitic shell. In contrast to previous arguments that most shellbeds in the Turkana Basin sequence represent undisturbed life assemblages, a taphonomic bias is clearly evident reducing the fidelity of the Turkana Basin mollusk assemblages.
Fifteen limnic ostracodes species have been recorded in the Alagamar Formation, Potiguar Basin: Cypridea araripensisSilva, 1978a; Cypridea? sp., Harbinia sinuata (Krömmelbein and Weber, 1971); Harbinia crepata n. sp., Harbinia dimorphica n. sp., Harbinia altaAntonietto et al., 2012; Paracypria? elongata n. sp., Ilyocyprimorpha berthoui (Colin and Dépêche, 1997); Ilyocypris? sp., Brasacypris subovatum n. sp., Candona? sp., Theriosynoecum colini n. sp., T. guzzoi n. sp., T. silvai (Silva, 1978b) diagnosis emended by Do Carmo et al. (2004b); and Darwinula martinsiSilva, 1978c diagnosis emended by Do Carmo et al. (2004b). Nine of these species have also been recorded outside of the Potiguar Basin, either in other Cretaceous basins in Brazil or coeval strata in western Africa. Despite the controversy about dating the local Alagoas Stage and the relatively large range of the Zone Harbinia spp. 201–218, the material studied in this paper belongs to the interval corresponding to the well-defined palynological zone coded as P-270, which is mid-upper Aptian in age.
The discovery of a new species, Cyclolampas altus new species in the upper Callovian of Burgundy (France) leads to the systematic revision of the rare echinoid genus CyclolampasPomel, 1883. Two morphometric approaches are used jointly to describe and quantify variations in test shape: the analysis of linear measurements and the Elliptic Fourier shape analysis. Both analyses yield congruent results that highlight the amplitude of within-species variations and quantify the part due to allometry. Along with the description of C. altus, the systematic position of species formerly assigned to the genera PygorhytisPomel, 1883 and Cyclolampas is amended. Previously attributed to the genus Pygorhytis, Cyclolampas castanea (Desor, 1858) is reassigned to the genus Cyclolampas on the base of new observations. Conversely, the examination of the Bajocian species Pygorhytis kiliani (Lambert, 1909) and Pygorhytis gillieroni Desor in Desor and de Loriol, 1872, which were previously assigned to Cyclolampas now supports their taxonomic reassignment to the genus Pygorhytis. Finally, the two species Cyclolampas verneuili (Cotteau, 1870) and Cyclolampas cotteauiMintz, 1966 (nomen nudum) are considered junior synonyms of the genus type species Cyclolampas voltzii (Agassiz, 1839). The questioned origin date of the genus, estimated either to the Bajocian or to the Oxfordian, is now clearly established to be upper Callovian. These new results fit well with the overall scheme of atelostomate echinoid evolution and migration to deep-sea environments during the Middle and Upper Jurassic.
The early Eocene green lacewings (Neuroptera, Chrysopidae) of the Okanagan Highlands deposits of McAbee, and Driftwood Canyon, British Columbia (Canada) and Republic, Washington (U.S.A.) are treated in detail for the first time. At least six genera are present, one unnamed, three new, with at least 10 new species, six named: Protochrysa fuscobasalis n. sp. (McAbee) (Limaiinae, the youngest known record of the subfamily), Okanaganochrysa coltsunae n. gen. n. sp. (McAbee), Adamsochrysa aspera n. gen. n. sp. (McAbee), A. wilsoni n. gen. n. sp. (Republic), Archaeochrysa profracta n. sp. (McAbee), and Pseudochrysopa harveyi n. gen. n. sp. (Driftwood Canyon) (all Nothochrysinae, the latter provisionally). The four unnamed species include one assigned to Pseudochrysopa, two likely belonging to Adamsochrysa, and one of an unknown nothochrysine genus. Microtholi are detected on the abdominal sclerites of Adamsochrysa wilsoni, and the spermatheca and spermathecal duct in the abdomen of Pseudochrysopa harveyi, the first reported occurrences of these preserved in fossil Chrysopidae. Structures were detected on the apical wing margins of some species that appear similar to trichosors, which are unknown in Chrysopidae, but are present in some other neuropteran families. This is the richest described assemblage of the family anywhere in the fossil record. Okanagan chrysopids were also morphologically and presumably ecologically diverse, including large species with rich venation and well as those with simplified venation and the smallest known fossil species. This is the oldest reported occurrence of the family in North America.
Fossil mayfly larvae (cf. Heptageniidae) are reported for the first time in the Cretaceous of Canada. The new fossils come from the latest Campanian part of the Wapiti Formation, which crops out in west-central Alberta, near the British Columbia border. These sediments represent mixed lentic and lotic fluvial environments consistent with modern heptageniid ecology. This discovery helps fill a significant temporal gap in heptageniid evolution between the Eocene and their earliest appearance in the Turonian.
The caracaras belong to a group of falconids with widespread geographical distribution in the Western Hemisphere, particularly in South America. Here we report fossil remains of a new species attributed to the genus Caracara from the late Pleistocene of Uruguay. This bird would have had an estimated body mass of 3700 grams, a value that greatly exceeds the maximum body mass reported for living falconids. Apparently, it would have had flying capabilities, in contrast to another paleospecies recently described from the Holocene of Jamaica. This fossil bird was found in association with mammal megafaunal remains and could offer new insights about the role of carnivorous birds in late Pleistocene environments of South America.
A new microconchid tentaculitoid, Microconchus utahensis new species, is described from the Lower Triassic (Spathian) Virgin Formation of two localities (Hurricane Cliffs and Beaver Dam Mountains) near St George, Utah. This small encrusting tubeworm, previously referred to erroneously as Spirorbis, has a laminated shell microstructure containing minute pores (punctae). The population from deeper water facies of the Beaver Dam Mountains is more abundant than that from Hurricane Cliffs and the tubes are significantly larger in size. Although represented by only one species (M. utahensis), microconchids are by far the most dominant component of the otherwise impoverished sclerobiont assemblage of the Virgin Formation, which also includes rare cemented bivalves and probable foraminifers. Whereas the remainder of the Virgin fauna is quite diverse, the low diversity of encrusters suggests a slow recovery from end-Permian mass extinctions. Indeed, more typically Mesozoic sclerobiont assemblages dominated by cyclostome bryozoans and serpulid polychaetes did not appear until the Late Triassic, probably Rhaetian.
Crinoid faunas from the Lower Devonian of South America are poorly known. Two new taxa are described from the Emsian Icla Formation at Cerro Kochis in the Cochabamba Department: the rhodocrinitid, Lutocrinus boliviaensis n. gen. n. sp. and Griphocrinus pirovanoi n. sp. Two additional camerates are reported from the Emsian Belèn Formation of the Altiplano region in the La Paz Department, including Ctenocrinus branisai n. sp. and Boliviacrinus isaacsoniMcIntosh, 1988. In addition, a specimen of the blastoid, Pachyblastus dicki Bremier and Macurda, 1972, was recovered from the Altiplano region. These crinoids and material previously collected by Leonardo Branisa, including specimens of C. branisai n. sp., Apurocrinus sucreiMcIntosh, 1981, B. isaacsoniMcIntosh, 1988, and L. boliviaensis n. sp., are described and revised. The specimens give new insights into the Lower Devonian Malvinokaffric Realm of Bolivia, a relatively new frontier in crinoid paleontology.
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