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Trilobites of this suborder from Europe and North America have not been studied in detail, in contrast to the attention given to relationships within the orders Agnostida and Ptychopariina. The basis of the Corynexochina is the type species of Corynexochus from the middle Cambrian of Sweden. The type material redescribed here is only the cranidium, and is inadequate for diagnosis of the genus. A species attributed to this genus occurring in the Cambrian of southern France is represented by entire dorsal exoskeletons and is urgently in need of redescription. Similar material is recorded in northern Spain. Both complete exoskeletons and growth stages of Corynexochina have been described from Cambrian strata in Russia, Australia, Morocco and China, showing the wide geographical range and varied morphology of the Suborder. The type species of two genera from boulders of middle Cambrian age found in Quebec, Canada, are redescribed from exceptionally well preserved, though small, specimens. They appear to represent a distinct group related to some of the Zacanthoididae. Families of Corynexochina are inadequately discriminated one from another, so that a family name can only be used with question. Until this is remedied, diagnosis of a new group is not possible.
In the Conglomerate Mesa area in the southeastern Inyo Mountains, east-central California, a series of distinctive fusulinid assemblages ranging in age from late Artinskian to Kungurian or Roadian was developed in units 7–10 of the sedimentary rocks of Santa Rosa Flat (part of the Owens Valley Group). The fauna of unit 7 shows some eastern Klamath Mountains affinity, but most of the species in unit 7 and the lower half of unit 8 are highly endemic and comprise three new genera with 12 new species, two unusual unassigned forms, and two other new species assigned to previously described genera. New taxa include: Crenulosepta new genus with five new species, C. inyoensis, C. delicata, C. fusiformis, C. rossi, and C. wahlmani; Nigribaccinus new genus with three new species, N. giganteus, N. elegans, and N.? nestelli; and the new genus Inyoschwagerina with four new species, I. magnifica, I. elayeri, I. elongata, and I.? linderae. CuniculinellaSkinner and Wilde, 1965, is represented by one new species, C. parva, and SkinnerellaCoogan, 1960 by one new species, S.? mcallisteri. Faunas from the upper half of unit 8, unit 9, and unit 10 have a strong West Texas affinity. New species from these units are Skinnerella davydovi, S. hexagona, Parafusulina cerrogordoensis, P. complexa, P. halli, P. owensensis, and P. ubehebensis.
The basal Cambrian marks the beginning of an important chapter in the history of life. However, most paleontological work on the basal Cambrian has been focused on skeletal animal fossils, and our knowledge about the primary producers—cyanobacteria and eukaryotic phytoplankton (e.g., acritarchs)—is limited. In this research, we have investigated basal Cambrian acritarchs, coccoidal microfossils, and cyanobacteria preserved in phosphorites and cherts of the Yanjiahe Formation in the Yangtze Gorges area (South China) and the Yurtus Formation in the Aksu area (Tarim Block, northwestern China). Our study confirms the occurrence in these two formations of small acanthomorphic acritarchs characteristic of the basal Cambrian Asteridium–Comasphaeridium–Heliosphaeridium (ACH) assemblage. These acritarchs include abundant Heliosphaeridium ampliatum (Wang, 1985) Yao et al., 2005, common Yurtusia uniformis n. gen. and n. sp., and rare Comasphaeridium annulare (Wang, 1985) Yao et al., 2005. In addition, these basal Cambrian successions also contain the clustered coccoidal microfossil Archaeophycus yunnanensis (Song inLuo et al., 1982) n. comb., several filamentous cyanobacteria [Cyanonema majus n. sp., Oscillatoriopsis longaTimofeev and Hermann, 1979, and Siphonophycus robustum (Schopf, 1968) Knoll et al., 1991], and the tabulate tubular microfossil Megathrix longus L. Yin, 1987a, n. emend. Some of these taxa (e.g., H. ampliatum, C. annulare, and M. longus) have a wide geographic distribution but occur exclusively in basal Cambrian successions, supporting their biostratigraphic importance. Comparison between the stratigraphic occurrences of microfossils reported here and skeletal animal fossils published by others suggests that animals and phytoplankton radiated in tandem during the Cambrian explosion.
The discovery of new specimens and restudy of known collections resulted in revision of some members of the cladid crinoid family Cupressocrinitidae. “Cupressocrinites gracilis” is generically separated from Cupressocrinites whereby “Procupressocrinus” is resurrected from synonomy and assigned to the Cupressocrinitidae with C. gracilisGoldfuss, 1831 as the type species. Studies of the Sandberger collection presuppose the revision of “Abbreviatocrinites abbreviatus altus” (=A. altus n. comb.) and A. nodosus. Furthermore, the hitherto undetermined cupressocrinitids are described as Cupressocrinites ahuettensis n. sp. and Robustocrinites cataphractus n. sp. The event-controlled distribution of Robustocrinites is discussed and shows similarities to other crinoid genera within the Eifel region. Observed arm-regeneration in Robustocrinites, as well as the postmortem incurred ossicular-boring of an indeterminable organism and the skeletal-colonization by a trepostome bryozoan, are further observations of other pre- and postmortem ossicular modifications in cupressocrinitid skeletons.
Gordonaster brassfieldensis is a new genus and species of Asteroidea (Echinodermata) described from the Lower Silurian Brassfield Formation of east-central Kentucky. Tentatively assigned to the poorly understood Palaeasteridae, Gordonaster shares much with Ordovician asteroids, yet it also exhibits apparent homoplasies that presage the post-Paleozoic crown group. Available specimens also indicate that the ontogenetic pattern of ossicular addition seen in the crown group was established during the Paleozoic.
Protosalvinia first occur in association with conodonts of the Upper trachytera Zone and below the Three Lick Bed in the Ohio Shale and the Ellicott Shale of the central and northern Appalachian Basin, as well as in the Clegg Creek Member of the New Albany Shale of the Illinois Basin. In the Chattanooga Shale of the southern Appalachian Basin, Protosalvinia are found no lower than the Upper marginifera Zone or associated with obviously reworked conodonts in the Middle expansa Zone. Regionally Protosalvinia are associated with a disconformity and may be found with conodonts of the Lower expansa Zone.
The genus Prolagus is very common in the Neogene and Quaternary of Europe, western Asia and northern Africa. However, the complexity of its systematics, mainly based on p3 characters that show great inter- and intraspecific variability, led to an under-utilization of Prolagus in biochronology and palaeogeography studies. A re-analysis of the species of Prolagus recorded in the Escobosa de Calatañazor karst fissure fillings (Duero Basin, northern Spain, MN7/8, late Middle Miocene) includes the introduction of new maxillary and mandibular morphological characters (position, shape and size of premolar and mandibular foramina) and new dental measurements (hypoflexus depth, distal hypercone length, and partial width of upper premolars; relative length of trigonid of lower molariform teeth) to be used for species discrimination within the genus Prolagus. The new morphological characters and measurements introduced in this paper allow for a more accurate taxonomic assignment of Prolagus species, thus improving the estimation of faunal palaeodiversity, detection of sympatric species and taphonomic mixing, and contributing to more reliable biochronological, palaeogeographical, and phylogenetic inferences based on Prolagus.
The Actinoceramus sulcatus lineage (Parkinson, 1819) (Bivalvia: Inoceramidae) is a very distinctive and abundant component of late Albian (Early Cretaceous) molluscan assemblages that is found throughout Europe, Central Asia, Japan and the Far East of Russia, southern and western North America, South Africa, and possibly India, in a range of shallow- to deep-marine facies. The lineage encompasses a wide and continuous range of morphologies that provide evidence of phyletic evolution at varying rates combined with large ecophenotypic plasticity within populations. The evolution of A. sulcatus marks the oldest appearance of well-developed radial folds and sulci within the Inoceramidae. The range of morphological variation makes formal taxonomic subdivision of the group problematic. Here we use a combination of formal successional subspecies and informal morphotypes to subdivide the lineage into the following taxa: A. sulcatus forma sulcatus, A. sulcatus forma subsulcatus (Wiltshire, 1869), A. sulcatus forma munsoni (Cragin, 1894), and A. sulcatus biometricus Crampton, 1996. Within these taxa and morphotypes, we synonymise a large number of earlier names that have been applied to variants within the lineage. Each of the forms recognized has biostratigraphic utility and we describe four new lineage biozones, in ascending order: A. concentricus parabolicus, A. sulcatus, A. sulcatus forma munsoni, and A. sulcatus biometricus biozones. The lowest occurrence of A. sulcatus is approximately coincident with the base of the upper Albian as currently defined, at least throughout most of Europe, and this datum provides a valuable tool in correlation. The nature of radial folds within the A. sulcatus lineage poses interesting but still unanswered questions regarding shell morphogenesis in bivalves and the functional significance (if any) of radial folds in the Inoceramidae.
Abundant tubular macrofossils occur in finely laminated siltstones and shales of the 548–542 Ma Schwarzrand Subgroup, Nama Group, Namibia. The Nama tubes occur in both the Vingerbreek and Feldschuhhorn members commonly in dense populations and always in fine-grained, lower shore-face lithologies deposited below fair-weather wave base. The tubes are preserved mostly as compressed casts and molds that range in width from 0.6 to 2.1 mm; apparently incomplete specimens reach lengths up to 10 cm. All specimens show sinuous bending and occasional brittle fracture, indicating an original construction of strong but flexible organic matter. Feldschuhhorn specimens preserve fine longitudinal pleats or folds that record pliant organic walls, but the older Vingerbreek populations do not. Similarly, some specimens in the Feldschuhhorn Member display branching, while Vingerbreek tubes do not. The abundant Feldschuhhorn tubes are assigned to the widespread Ediacaran problematicum Vendotaenia antiqua; however, the distinctive Vingerbreek population remains in open nomenclature. The most abundant fossils in Nama rocks, these tubes resemble populations in Ediacaran successions from Russia, China, Spain, and elsewhere. Beyond their local importance, then, such tubes may turn out to be the most abundant record of Ediacaran life.