The cycloids represent an enigmatic arthropod group of probably crustacean affinity, occurring mostly in the younger Paleozoic, from the early Carboniferous up to the Late Triassic (Schram et al., 1997). Superficially, cycloids strikingly resemble crabs and were thought to have had a similar lifestyle, becoming extinct when crabs started to radiate. Recently, the existence of a Late Cretaceous cycloid, Maastrichtiocaris rostratus Fraaije et al., 2003, from the Maastrichtian of the Netherlands, proved that cycloids did not go extinct at the end of the Triassic as believed for a long time, but survived much longer, co-occurring with crabs. Due to obvious collecting bias and the incompleteness of the fossil record of arthropods with relatively delicate carapaces in general, neither Jurassic nor Early Cretaceous representatives have been reported hitherto. However, from the Lower Jurassic Posidonienschiefer (‘Posidonia Shale’) of southwestern Germany—famous for its excellent fossil preservation, not only of marine vertebrates and large crinoids living on driftwood, but also many other invertebrate groups (Riegraf et al., 1984; Urlichs et al., 1994)—now a single specimen of a cycloid is recorded and described herein. Although this record helps link the bias between the Triassic and the Late Cretaceous occurrences, the characters of the specimen differ strongly from those of other cycloids, thus requiring the erection of a new genus and species.

Corynexochid trilobites of the Cambrian of Morocco are described and the subfamily Acontheinae is revised. With Kootenia beethoveni n. sp., Kootenia spp. indet., Strettonia sp. A, Clavigellus annulus n. gen. and sp., and gen. et sp. incert., the Moroccan Corynexochida comprise only a few forms that are almost exclusively restricted to the High Atlas Mountains. Biogeographical relationships are weak; strong relationships may exist with the faunas of the Shropshire area as already exemplified by some eodiscid and ellipsocephalid taxa.

The new genus and species, Gondekia hastula, are described from the Middle Devonian (Givetian) Hungry Hollow Formation of southwestern Ontario. Astraeospongium lancifer Reimann, 1945, is also included in the new genus and A. acicularis is considered a synonym of that species. Gondekia has a flat saucer-like form and a felted, but thin, skeleton composed of at least three orders of regularly spaced and oriented simple sexiradiates. Gondekia is placed in the Eiffeliidae but is convergent toward the Astraeospongiidae in having a somewhat thickened wall.

The discovery of domatial dimorphism in the leperditellid ostracode Loculocavata n. gen. and the monotiopleurid Primitiella minima (Harris), and the possibility that Leperditella Ulrich exhibits domatial dimorphism, requires a revision of the concept and/or diagnosis of the Platycopina. Domatial dimorphism is manifested by a special domiciliar space for egg/brood care in females. Domatia are represented by a loculate domiciliar wall or by a more generalized space bounded anteriorly by an interior partition caused by thickening or folding (sulcation) of the shell wall. Domatial dimorphism occurs in morphologically diverse ostracodes as shown by the podocopine Mesocyprideis, kloedenellids, cytherellids, monotiopleurids, the leperditellid Loculocavata n. gen., and by its possible occurrence in Hypotetragona and Leperditella. Changes in the present concept and/or diagnosis of the Platycopina are required to account for the above. Possible classifications range from restricting the Platycopina to holosolenic ostracodes with R/L overlap and domatial dimorphism to including within the Platycopina all groups that exhibit domatial dimorphism. The position of adductor muscle attachment in Loculocavata n. gen. and Primitiella minima (Harris) suggests that L2 may be the external expression of the position of adductor muscle attachment in some ostracodes.

The placoderm Titanichthys from the Late Devonian (Famennian) is based on incomplete and fragmentary specimens that have hindered understanding of its overall anatomy and phylogenetic relationships. A new, nearly complete, articulated specimen from the Upper Devonian Cleveland Shale provides new information about the previously undescribed rostral, postmarginal, postsuborbital, submarginal, posterior superognathal plates, and the nasal capsule. A revised diagnosis is provided for the genus. Three new diagnostic characters are identified, including a transversely elliptical rostral plate that does not contact adjacent plates, a reduced posterior superognathal, and a median dorsal plate that inserts into the posterior dorsal lateral plate. The first comprehensive phylogenetic analysis of Titanichthys indicates that the genus is a basal aspinothoracid arthrodire closely related to the enigmatic taxa Bungartius and Tafilalichthys.

Correlations exist between diversity and colonial growth pattern and variability in Paleozoic stenolaemate bryozoans. Habitats occupied by diverse communities contained colonies whose growth trajectories were different and were more highly constrained than those of low-diversity habitats. Because previous studies have not examined variability during colony growth, it was unclear whether observed variabilities were constant during growth (astogeny) or whether variability changed with age. Astogenetic trajectories and growth variability are here reexamined in populations of colonies of Heterotrypa ulrichi from the same high-diversity and low-diversity communities examined by Pachut (1989).

Growth trajectories of populations differ in both intermonticular and monticular regions of colonies for fundamental stereological characters. Total zooidal surface areas generally decrease during astogeny whereas zooidal densities increase. Surface areas per zooid also decrease with increasing age, but are consistently larger in monticular zooecia and in populations from low-diversity communities irrespective of the colony region sampled. These patterns of declining values are caused by increasing wall thicknesses, larger and more abundant mesozooecia and acanthostyles, and the development of maculae during colony growth. Larger values in low-diversity settings may have provided reproductive and feeding benefits necessary for survival.

Covariances reflect levels of morphological integration and are larger in populations from high-diversity communities in both intermonticular and monticular regions. Values differ more during early stages of growth (1–3) than later in astogeny (stages 4–5), and are consistently higher in intermonitulcar than in monticular zooecia. Lower levels of integration in monticules may be caused by spatial adjustments as the number of monticules increases across the expanding colony surface during growth. In general, stabilizing selection may have been weaker and less effective in establishing character covariance patterns in populations from low-diversity communities, perhaps because of greater environmental stress. These findings suggest that evaluations of astogenetic patterns and age-related changes in levels of morphological integration within a paleoenvironmental context are important in measuring species richness, in determining the direction of character evolution, and in assessing tempo and mode of evolutionary changes.

The Chesterian (Upper Mississippian) Imo Formation in north-central Arkansas contains an abundant, diverse, and well-preserved gastropod fauna, comprising 35 species referrable to 21 genera and subgenera. Bellerophontaceans and pleurotomariaceans show the greatest species diversity. New taxa proposed include: Euphemites chesterensis, E. whirligigi, Retispira yochelsoni, Patellilabia rhombadella, P. sulcata, Straparollus (Euomphalus) konobasis, S. (E.) variabilis, Trepospira (Angyomphalus) desultoria, Glabrocingulum (Glabrocingulum) parasolum, G. (G.) parvanodum, G. (G.) coronulum, Naticopsis (Marmolatella) macgordoni, N. (M.) imoensis, Globozyga mediocris, and Girtyspira microspirula.

Relicts of color patterns are present on four taxa. Repair of broken shells is common. Borings of acrothoracic barnacles and possibly that of a gastropod are present. Coprolites with gastropods attached may indicate a coprophagous habit, only grazing on the algae and bacteria growing on the coprolite, or may just be a circumstance of preservation.

The Careless Creek Quarry (CCQ) is a multitaxic bonebed in the Campanian Judith River Formation of south-central Montana (USA) that produced a diverse assemblage of vertebrates, including several dinosaurian clades. We describe the morphology of the CCQ hadrosaurid material and reevaluate its taxonomic affinities. Our osteological comparative observations, coupled with maximum parsimony phylogenetic analyses, indicate that the majority of the hadrosaurid material is referable to kritosaurin saurolophines. Only an ischium is unambiguously referable to Lambeosaurinae. Most of the kritosaurin specimens likely represent a taxon that forms a polytomy with species of Gryposaurus and Rhinorex condrupus Gates and Sheetz, 2015. This form may represent individuals of either G. latidens Horner, 1992 or G. notabilis Lambe, 1914, or a new species cogeneric or not with Gryposaurus. The juvenile material exemplifies several patterns of mandibular and appendicular osteological variation previously observed in other hadrosaurids. However, it also shows some departures from the common trends, supporting the fact that not all skeletal growth changes can be generalized to all hadrosaurids.

This paper describes a new genus Liaous, with L. shaiwensis He and Chen n. gen. n. sp. as the type species, from the Xinyuan Formation of Anisian age in Ziyun, southern Guizhou, China. The phylogenetic tree revealed by the parsimony analysis shows that Liaous is closely allied to both Mentzelia Quenstedt, 1871 and Paramentzelia Xu, 1978 of the subfamily Mentzeliinae. A new classification scheme for the Spiriferinoidea is also proposed based on a phylogenetic tree of the superfamily indicated by parsimony analysis. The Spiriferinoidea includes three families and nine subfamilies. Three new subfamilies—Madoinae He and Chen, new subfam., Qinghaispiriferininae He and Chen, new subfam., and Triadispirinae He and Chen, new subfam. are proposed. Liaous shaiwensis He and Chen n. gen. n. sp. is found in the Posidonia wengensis-Liaous shaiwensis (P-L) paleocommunity, which is dominated by r-strategists (i.e., organisms defined by a fauna with a high dominance and small body sizes) and has a low diversity and high dominance. The P-L paleocommunity therefore has little similarity to its coeval communities from the Anisian Stage of South China and instead it appears more similar to the Lower Triassic shelly faunas in community structures. This paleocommunity is interpreted to have inhabited a relatively deep, low-energy, dysaerobic offshore basin/slope setting with the influence of episodic storms.

Proconchidium brodeurensis n. sp. occurs 212 m above the base of member B of the Baillarge Formation on Brodeur Peninsula, Baffin Island, 8 m below the Ordovician–Silurian boundary. Study of Proconchidium shows that it can be easily distinguished from Eoconchidium but possesses many characters that are similar to those in Tcherskidium. Analysis of internal structures suggests that the three genera can be distinguished from each other and belong to Virgianidae. Tcherskidiidae is a synonym of Virgianidae and should be abandoned.

This represents the first recorded occurrence of Proconchidium in North America. Although this genus and its related genera Tcherskidium Sapelnikov, 1972, and Eoconchidium Rozman, 1967, are common in Ashgill strata of Eurasia, they have not been recorded or illustrated from North America. This led to the suggestion that distinct brachiopod biogeographic provinces may have existed during the Ashgill. The occurrence of these genera probably indicates that they may have lived in mostly tropical and subtropical zones.

Three new species of freshwater gastropods are described from the lower Eocene Adjuntas Formation. Five more species are reported from the same fauna. This is the first report of Tertiary freshwater Mollusca of the Campanian–lower Eocene Difunta Group. The three new species (Hemisinus (Longiverena) reticulosus, Hemisinus (Longiverena) adjuntaensis, and Melanatria ypresiana) belong to the family Thiaridae, which today is a worldwide distributed group of freshwater gastropods of medical importance. Paleoenvironmental interpretation for red, green, and yellow beds of Adjuntas Formation suggests delta-plain deposits. Gastropods here described lived in swamps and marshes of this portion of the ancestral Gulf of Mexico.

The heliolitid fauna of the Upper Silurian West Point Formation of southern Gaspé, Québec, Canada, consists of Propora tubulata (Lonsdale), Heliolites decipiens (McCoy), H. daintreei Nicholson and Etheridge, and Heliolites sp. cf. H. bohemicus Wentzel. All of these species are common in Europe, but are rare in North America. Heliolites sp. cf. H. bohemicus and H. daintreei are newly reported for North America. Very restricted facies occurrences, and presumed environmental preferences, of species such as P. tubulata and H. daintreei suggest that facies occurrences may be useful, along with conventional morphological criteria, in distinguishing species of heliolitid corals.

It has long been considered that all monograptids have theca 1 originating from a primary porus in the sicula (i.e., sinus and lacuna stages; Bulman, 1970). The major basis for this assumption has been studies of Late Silurian monograptid species such as Saetograptus chimaera (Barrande), Pristiograptus bohemicus (Barrande), and Pristiograptus dubius (Suess) (e.g., Eisenack, 1942; Walker, 1953; Urbanek, 1958). That all monograptids possessed this type of development was not questioned due to the lack of well-preserved, early monograptid specimens clearly showing the sicula–theca 1 relationship. Hutt et al. (1970) described Monograptus gregarius Lapworth, from the gregarius Zone, as having theca 1 originating through a primary porus (Hutt et al., 1970; Rickards and Hutt, 1970, referred to this as a “primary notch” although, according to Bulman, 1970, p. V11, the notch corresponds only to the sinus stage). Their figures of these specimens, however, do not unequivocally confirm its presence (Hutt et al., 1970, p. 14, Pl. 3, figs. 65, 67). Rickards and Hutt (1970) alluded to the possible presence of a primary porus in Atavograptus ceryx (Rickards and Hutt) from the persculptus Zone, but could not determine its existence with certainty. Mitchell (1987) was the first to question the presence of this mode of development of theca 1 in relation to the origin of the monograptids. He proposed, however, that the development of the fully uniserial rhabdosome was coincident with a change in both the sicular structure (the sinus and lacuna stages) and the early ontogeny of theca 1. He suggested that the sinus and lacuna stages represented a homologue of the hooded foramen seen in the th 11 protheca of some Pattern H species, from which th 12 emerges and that, in the uniserial monograptids, this feature is accelerated in the astogenetic sequence, appearing in the metasicular ontogeny rather than that of the first theca. He pointed out that this hypothesis could only be tested once suitable, isolated specimens of earliest monograptids could be studied to see if the sinus and lacuna stages were, indeed, coincident with the achievement of a fully uniserial rhabdosome. New evidence from isolated, early monograptid material allows us to test Mitchell's theory on monograptid origin.

Non-spicular sponges constitute >8% of the extant sponge biodiversity at the species level, yet their evolutionary history is poorly known due to a sparse fossil record. The genus Vauxia, previously only known from middle Cambrian (Miaolingian, Wuliuan) Lagerstätten, was regarded as the earliest fossil record of non-spicular demosponges. Here we describe the first vauxiid sponge, Vauxia leioia new species, from the early Cambrian Chengjiang Biota (Series 2, Stage 3). This sponge exhibits a double-layered fibrous skeleton: the mesh and fiber thickness of the endosomal layer are irregular while the dermal layer, which directly connects with the endosomal skeleton without intermediate supporting fibers, is regular in both aspects. Measurements using scanning electron microscope and Raman spectroscopy revealed that the endosomal fibers are composed of carbonaceous material, but are tomographically indiscernible from the host rock, while the dermal fibers are preserved as impressions without obvious accumulation of carbonaceous material. Although the original composition of the dermal skeleton is now hard to establish, we cannot rule out that it was siliceous. The morphological characters of V. leioia n. sp. represent an intermediate state between other Vauxia species and the recently established vauxiid genus Angulosuspongia. However, more data are required to reconstruct the phylogenetic relationship among these taxa.

UUID: http://zoobank.org/0ebb91b8-5dad-420f-bb2c-dc203d37bebd

Exceptionally preserved specimens of the Cambrian stem-group brachiopod Mickwitzia occidens Walcott, 1908 are described in detail from the Indian Springs Lagerstätte in Nevada, USA. Shell structure and preserved mantle setae from these specimens reveal a variable diagenetic (taphonomic) history and provide insight into the phylogenetic position of mickwitziids. Morphologic and morphometric comparison to M. monilifera (Linnarsson, 1869) from Sweden and M. muralensis Walcott, 1913 from British Columbia, Canada reveals clear species-level distinctions. Scanning electron microscopic analysis allows revision of the generic diagnosis. The Mickwitzia shell is characterized by the presence of inwardly pointing phosphatic cones and tangential setae-bearing tubes. The inwardly pointing cone structures are not consistent with setal bearing structures as previously thought, but rather represent endopunctae-like structures. Acrotretid-like shell structures and shell-penetrating setae in M. occidens strengthen the previously proposed close relationship between stem-group brachiopods and tommotiids, a group of small shelly fossils.

Brachiopods of the orders Strophomenida, Orthotetida, and Athyridida from the late middle Frasnian–early Famennian interval (hassi to triangularis conodont zones) in the Namur-Dinant Basin (southeastern margin of Laurussia; southern Belgium) are described. Nine genera and subgenera represented by 12 species are recognized here. One new genus, Retrorstrophia, and one new species, Douvillina area, are erected. Crinisarina stainbrooki is proposed to solve the homonymy between C. reticulata (Gosselet, 1877) and Cleiothyridina reticulata Stainbrook, 1947, the type species of Crinisarina Cooper and Dutro, 1982. A lectotype is selected and illustrated for C. reticulata. A new name is also proposed for Athyris reticulata Chen and Xu, 2000, which is assigned here to Crinisarina: C. shashishanensis nom. nov. In southern Belgium, the last representatives of the families Douvillinidae and Leptostrophiidae (Strophomenida) are from the Upper rhenana Zone (late Frasnian). Athyridid brachiopods, especially the representatives of the subfamily Cleiothyridininae constituted a significant part of the early Famennian recovery faunas with spiriferids and rhynchonellids, just after the late Frasnian mass extinction.

The subfamily Hindellinae is an early group of athyride brachiopods, characterized by a simple jugum that connects the laterally directed spiralia, which are disjunct from the crura. Four genera (Hindella, Cryptothyrella, Koigia, and Hyattidina) are reexamined on the basis of their internal structures, such as the crura and their connection to the hinge, the jugum, and spiralia. The internal brachidium and shell of the Aeronian genus Cryptothyrella differ substantially from those of Hindella. Elkanathyris pallula n. gen. n. sp. is recognized as a posteriorly ribbed hindellide of Aeronian age. These genera are transferred from the Meristellinae to the subfamily Hindellinae (family Hindellidae). On Anticosti Island, Hindella is confined to the Hirnantian (latest Ordovician): it became extinct at the end Ordovician during the last of several mass extinction events that also extinguished the Laframboise reefs at the top of the Ellis Bay Formation. Post-extinction recovery of athyrides was pioneered by small-shelled Koigia, which are abundant in the basal Silurian Becscie Formation. Hyattidina, with a simple brachidium, is abundant in the Aeronian and Telychian of Anticosti, but absent earlier. True meristellines, as envisioned here, first appeared in the Aeronian Gun River Formation. The revised taxonomy and stratigraphic ranges of these earliest athyrides shed light on the nature of the Ordovician–Silurian mass extinction and recovery, and help refine the biostratigraphy of the O-S boundary interval.

Chitinozoa have been recovered from three sections within the Garra Limestone in central New South Wales, Australia. A total of 31 species are identified and two new species, Angochitina hypenetes and Bursachitina mawsonae, are described. Three stratigraphically distinct assemblages from the late Lochkovian to the early Pragian are distinguished and compared with faunas of a similar age from Europe and northern Africa.

Stirpulina saulae n. sp. is the first reported clavagellid from the Pacific Province of North America. Specimens of this clavagellid are from the Ladd Formation of the Santa Ana Mountains, Orange County, southern California. The age of these specimens is Late Turonian based upon the presence of the ammonite Subprionocyclus spp. both above and below the clavagellids in the section. These are, therefore, the oldest reported clavagellids from the western hemisphere, and they give positive support to the European Turonian reports of the genus Stirpulina. The deposits indicate an open-shelf habitat of shallow to moderate depth, and the associated fauna suggests a warm temperate to subtropical marine climate. This is consistent with the previously reported Cretaceous distribution for the group.