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A new abyssal cyclostome bryozoan genus and species, Vasopora ceramica n. gen., n. sp., is described from the eastern Russian exploration area of the Clarion–Clipperton Fracture Zone based on newly collected material from Yuzhmorgeologiya GLD4–19 station 421 (13.23408° N, 134.22180° W, 4809 m depth). Generic characters include an erect pedunculate colony with a distinct boundary between column and flared capitulum, short autozooidal peristomes in a single whorl, numerous alveoli, a central unidirectional sac-like gonozooid covered by a surficial network of crossed ridges continuous with adjacent rims of alveoli, a laterally opening ooeciopore, and the entire capitulum surface being minutely densely granular to subspinulate. Whereas the skeletal microstructure of the capitulum surface comprises irregular imbricated crystallites, the column has a planar-spherulitic fabric of acicular crystallites in fan-like arrays, and there are no pseudopores. The sharp boundary between capitulum and column, with their different microstructure separates Vasopora n. gen. from the two existing genera of Alyonushkidae that are found in the same environment. Vasopora n. gen. has a stalk formed of calcified exterior wall, whereas it is interior-walled in Alyonushka and Calyssopora.

In a one-year study, a new record of the freshwater thiarid snail, Tarebia granifera, was collected in huge amounts from the River Nile in Qena province, Upper Egypt. Tarebia granifera is a highly invasive species that has spread throughout the tropical world and can displace native gastropods as well as cause damage to water systems by clogging pipes and machinery. The shell is extremely variable in size, shape, and sculpture: obtusely to elongate conical, elevated spire up to 8 – 13 whorls, the ultimate whorl large; coarsely sculptured by elevated ridges in a vertical and spiral direction, causing a pattern of strong and blunt nodules. It was noticed that the apex is always eroded and the umbilicus is closed. Aperture is almost vertical, oval, pointed above, and rounded below. The operculum is corneous, opaque, dark reddish-brown. The type of operculum of the investigated snail is paucispiral with the nucleus placed in the far bottom right corner. Growth lines are coarse and irregular. The soft parts show the typical parts of the gastropod body, which are; the head, foot, and visceral mass. The head and foot of the active snail can be seen protruding out of the shell. The pallial organs are typically like thiarid in both form and position. The mantle is the most important and specialized organ of the Gastropoda, for it not only bears the glands that secrete the shell but it also serves as a base to which the ctenidium, ospharadium, and several excretory and reproductive outlets are attached. The mantle of the present species is a thin, fleshy, cone-shaped cap and hangs over the body. It is appressed closely to the interior of the last half of the last whorl and thus creates an open cavity into which water may enter freely to bathe the gills. The anterior border bears a series of 4– 5 large, projecting, fleshy papillae; the farthest to the left being the largest. The four papillae, the farthest to the left, are bulbous at their basal attachment to the mantle and are pointed at their distal ends, which may be seen projecting well beyond the edge of the shell. While, to the right, there are 6 to 8 progressively smaller papillae that are not bulbous at their base and act as the accessory respiratory systems and as chemoreceptors.

The terrestrial snail genus Stemmatopsis is mainly distributed in northern Vietnam and northern Laos. In total five species of Stemmatopsis are discovered, including two described herein. Stemmatopsis arcuatolabris sp. nov. has a small distorted-ovate shell with last whorl protruded quite strongly from ventral side. It has a thickened, expanded peristome with bended palatal side having a bow-like shape. Stemmatopsis dolium sp. nov., has a small, oblique-ovate shell, an approximately quadrangular aperture, and a wave-like shape at the palatal side of peristome.

A new genus and species of Cepolidae are described from the Island of Cuba: Plagiosimilis gibarensis gen. et sp. nov. It is classified in Cepolidae based on the following diagnostic characteristics of the family: dart apparatus consisting of a dart sac with a pedunculated gland on its apical side, both covered by a sheath; at the base of the dart apparatus there are two accessory glands; absence of a diverticulum. The specimens from the new genus come from the northern part of the Holguin province in the vicinity of the town of Gibara and live in special habitat dominated by Tillandsia plants. Shell with the rounded last whorl last very globular round, circular umbilicus and strongly reflected lip distinguish conchologically the new genus. The reproductive system and the shell differ from the other genera, although it have a certain similarity with the genera Plagioptycha and Hemitrochus.

A biometric comparison is carried out on selected tests of the foraminiferal species Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermudez, 1935). The Rosalina douvillei specimens were recovered from the marginal marine Oligocene/Miocene site of Russingen (Mainz Basin, Germany), the lacustrine beds of the lower Miocene site of Bunol (Valencian Community, Spain) and the middle/ upper Miocene site of Fuendetodos (Aragon, Spain). The Trichohyalus aguayoi tests were collected in the current coastal lagoon of Torreblanca and recovered from Holocene cores sampled in the Peniscola marsh and in the coastal lagoon of l’Albufera de Valencia, all them in the Valencian Community (Spain). In addition, the chronostratigraphic and geographical distribution of both species is also summarized. Trichohyalus aguayoi and Rosalina douvillei share many morphological characteristics but the measured specimens of Trichohyalus aguayoi are characterized by generally larger sizes, narrower and more elongate chambers and a higher number of chambers in the outer whorl. The Rosalina douvillei specimens from Fuendetodos are as large as Trichohyalus aguayoi and show particularly high chamber size increase rates but also few and less elongate chambers in the last whorl. The number and shape of chambers in the last whorl seem thus to be controlled at least in part by hereditary factors. The morphological affinity between the two species probably constitute an example of convergence derived from similar environmental conditions but further research is required to discard phylogenetic proximity.

Author(s): Powell, II, Charles L.; Houart, Roland | Abstract: Califrapana n. gen., is proposed for California late Oligocene to early Miocene muricids attributed previously to the possibly Paleocene to modern western Pacific and Indian oceans genus Rapana. Four fossil species have been assigned to Rapana in the eastern Pacific. One of these species, R. perrini Clark and Arnold (1923), should be placed in another genus, the other species Purpura vaquerosensis Arnold (1907), R. imperialis Hertlein and Jordan (1927), and R. serrai Wiedey (1928) are synonymized here with the morphologically variable species Califrapana vaquerosensis n. comb. We confirm C. vaquerosensis is an index fossil for the lower and middle “Vaqueros” California provincial molluscan stage of late Oligocene to early Miocene age in southern California and Baja California, Mexico, although the lack of numerical dating and the misuse of lithostratigraphic and biostratigraphic names had made that difficult to determine. Califrapana is distinguishable from similar genera by 1) its heavier shell, 2) an aperture that is pointed at its anterior and posterior ends, 3) more numerous fine to coarse spiral cords on the ultimate whorl, 4) less numerous nodes at the top of the ultimate whorl, which are commonly larger and more pronounced, and 5) the siphonal fasciole, which is large and broad, with a large, open channel.

The aspidoceratid ammonites have been traditionally included in the superfamily Perisphinctoidea. However, the basis of this is unclear for they bear unique combinations of characters unknown in typical perisphinctoids: (1) the distinct laevaptychus, (2) stout shells with high growth rate of the whorl section area, (3) prominent ornamentation with tubercles, spines and strong growth lines running in parallel over strong ribs, (4) lack of constrictions, (5) short to very short bodychamber, and (6) sexual dimorphism characterized by miniaturized microconchs and small-sized macroconchs besides the larger ones, including changes of sex during ontogeny in many cases. Considering the uniqueness of these characters we propose herein to raise the family Aspidoceratidae to the rank of a superfamily Aspidoceratoidea, ranging from the earliest Late Callovian to the Early Berriasian Jacobi Zone. The new superfamily includes two families, Aspidoceratidae (Aspidoceratinae, Euaspidoceratinae, Epipeltoceratinae and Hybonoticeratinae), and Peltoceratidae (Peltoceratinae and Gregoryceratinae nov. subfam.). The highly differentiated features of the aspidoceratoids indicate that their life-histories were very different from those of the perisphinctoids; these ammonites show great promise for studies of developmental and evolutionary patterns and processes, and can be used for bio­stratigraphic-chronostratigraphic purposes and interprovincial correlations.

The genus Helicorbitoides MacGillavry represents an evolutionary stage in the transition of rotaloidean with primary spiral chambers to the forms displaying an orbitoidal-type growth pattern in the Campanian. Unlike the widespread distribution of its possible ancestor Pseudosiderolites (Douville) and its descendant Lepidorbitoides Silvestri, Helicorbitoides was reported from only a few localities in Europe and Turkey (Western Tethys). The genus has been previously subdivided into two evolutionary stages, H. voigti van Gorsel and H. longispiralis (Papp and Kupper) based on quantitative and qualitative test parameters. We here introduce a primitive developmental stage of Helicorbitoides by studying a new population from a calciturbidite bed of the Campanian Tonya Formation in NW Turkey. This provides the first biometric data of the genus from this part of the Tethys. The Helicorbitoides specimens, with thick robust lenticular tests, possess a low trochospiral to planispiral primary spiral of chambers that reach up to the periphery of the test, and 'orbitoidal-type' chamberlets (secondary chamberlets) between the whorls and on the wall of the last whorl. The secondary chamberlets, however, never form complete cycles. In axial sections, the lateral chambers are dense and occupy both the axial and the lateral sides of the whorls. The number of primary spiral chambers with a single stolon varies between 8 and 12 (with an average of 9.63). According to previously proposed species limits, our population is assigned to an advanced developmental stage of H. voigti, and represents a transitional developmental stage between two successive species (H. voigti-longispiralis). The associated orbitoidids belong to Orbitoides medius, with an embryo size (Li + li) ranging from 370 to 800 pm (with an average of 525.4 mu m). The number of epi-embryonic chambers (E) varies between 4 and 6 (with an average of 4.5). Pseudosiderolites vidali is the only siderolitid genus in the studied sample. The age of the turbidite bed is considered as early late Campanian (referable to the Radotruncana calcarata Zone) or slightly older ('Inoceramus' tenuilineatus Zone) based on the previous records of planktonic foraminifera and inoceramids from the same section and the occurrence of Pseudosiderolites vidali. (C) 2019 Elsevier Ltd. All rights reserved.

Tambareauella new genus with its type species Operculina (Nummulitoides) azilensis Tambareau (1966) is described and photographed from an outcrop of the Late Ypresian of Le Mas-d'Azil, southwestern France. Tambareauella is characterized by a small to medium test, involute coiling in the early ontogenetic stage (1st whorl) to complanate evolute in the last two whorls, lax spire outwards, flattened discoidal test with inflated polar region and rounded periphery, concentrated granules at the center of the test in the form of a boss, straight septa becoming curved at the top and of anastomosing nature, raised spiral suture, rhomboid chambers two or three times higher than long especially in the last two whorls and rather thick marginal cord. Tambareauella new genus belongs to the family Nummulitidae, and this new genus compares well with its allied taxa. The new taxon is found associated with forms of the Nummulites/Alveolina levis zone of Late Ypresian age (SBZ 9- SBZ 10 of Serra-Kiel et al., 1998). Another species Tambareauella russeiesensis n. sp. is recorded from the Late Ypresian Esna Shale, Wadi Naoz stratigraphic section, Gebel Umm Russeies, El Galala El Bahariya, Eastern Desert, Egypt.

Tima nigroannulata sp. nov. is described from medusae collected in shallow waters of four prefectures on the Pacific coast of Japan (Miyagi, Fukushima, Kanagawa, and Miyazaki), as well as from cultures maintained at two aquaria (Enoshima Aquarium, Kanagawa Prefecture; Tsuruoka City Kamo Aquarium, Yamagata Prefecture). Adult medusae differ from those of other known species of the genus Tima Eschscholtz, 1829 in the following combination of characters: (1) umbrella usually hemispherical or higher, (2) marginal tentacles up to 50 or more in number; and (3) black pigment granules form a ring around the umbrella rim, and sometimes extend onto the tentacles and radial canals. Their hydroids, from aquarium cultures, have stolonal colonies with pedicels of varied length, vestigial hydrothecae, slender and vase- to club-shaped hydranths, and a whorl of about 20 filiform tentacles with an intertentacular web basally. Medusa buds develop singly within gonothecae that arise from the hydrothecal pedicels. The cnidomes of both hydroid and medusa stages comprise heteronemes, provisionally identified as microbasic mastigophores. Medusae of T. nigroannulata are confirmed as a unique, cohesive lineage by comparing mtDNA COI sequence fragments with those from two congeners, resulting in three well-supported reciprocally monophyletic clades, one representing each species. Records of the western Atlantic medusa Tima formosa L. Agassiz, 1862 from Japan overlap those of T. nigroannulata, and are believed to have been based on the new species described herein.

In this study, a new late Campanian (Late Cretaceous) heteromorph ammonoid, Didymoceras morozumii Misaki and Tsujino sp. nov., from the Hiketa Formation, Izumi Group, southwestern Japan, is described. It is characterized by a loose helical post-embryonic early whorl and relatively tight helical middle whorls, followed by a retroversal hook with a highly elevated apertural end, and two rows of irregular tubercles. Didymoceras morozumii sp. nov. occurs in the upper part of the Didymoceras sp. Zone, which is overlain by the Didymoceras awajiense Zone. Didymoceras awajiense-bearing beds of the Hiketa Formation in the study area is correlated to the lower part of that of the Toyajo Formation in the Kii Peninsula on the basis of the shell forms of D. awajiense. Didymoceras morozumii sp. nov. and D. awajiense have similar characteristics, and it is thought that D. awajiense evolved from D. morozumii sp. nov. As indicated in the descendants, some specimens of D. morozumii sp. nov. are also encrusted by anomiid bivalves.

Background Expression of sexual dimorphism is recognised in various fossil groups of molluscs such as the Ammonoidea, an extinct group of shelled cephalopods. During the Mesozoic, the best-documented sexual dimorphic examples are seen in the Jurassic superfamily Perisphinctoidea. It is usually expressed by distinct adult size and apertural modifications between the antidimorphs. Putative males (otherwise referred to as microconch) are small in size and develop lappets at the end of the shell while the females (macroconch) are larger and bear a simple peristome. Dubious cases are, however, known in that superfamily, which often relate to taxonomic biases or lack of diagnostic characters, and some others expose ontogenetic anomalies illustrated by ‘sex reversals’ in the shell morphology and ornamentation. Results The discovery of two specimens of the Callovian Aspidoceratidae Peltoceras athleta (Phillips), having both female and male features, questions the significance and causes of ‘sex reversals’ in the Ammonoidea. The two specimens have started with the macroconch ontogeny of Peltoceras athleta and show an apparent change toward maleness in the adult, as illustrated by their rounded whorl section, ribs retroversion, fading of the tubercles and lappets typical of the microconchs. Few other cases of female-to-male, as well as male-to-female ‘sex reversal’, are known in the fossil record, all belonging to the Jurassic Perisphinctoidea (families Perisphinctidae or Aspidoceratidae). Since all Jurassic Perisphinctoidea are strictly gonochoristic, these ‘sex reversals’ are pathological in nature and are herein referred to as a new forma-type pathology: namely “forma hermaphrodita”. Conclusions In the absence of any clear evidence of injury or parasitism, we hypothesize that such “forma hermaphrodita” individuals illustrate pathologic cases of intersexuality. Little is known about the ammonoid soft parts, and it is not possible to determine which internal sexual organs occur in specimens having both male and female external shell features. Abnormal feminisation and/or masculinisation also occur in modern cephalopods, the latter also grouping only gonochoric species. This phenomenon is similarly illustrated by a change in the adult body size and a mixing of both female and male structures. In that case, intersexuality is either advantageous in the population or caused sterility. The causes of intersexuality are not clearly established but environmental pollutants are evoked in modern cephalopods because they act as endocrine disrupters. ‘Sex reversals’ and/or non-functional reproductive abnormalities have also been caused by endocrine disrupters in various gonochoric gastropods species, but infestation, genetic abnormalities, temperature fluctuations or viruses are multiple causes, which can stimulate or inhibit neural-endocrinal activity by direct gonadal influence, and ultimately lead to feminisation or masculinisation in fishes, isopods, crustaceans, and gastropods as well. Regardless of whether “forma hermaphrodita” is due to an exogenic or endogenic cause, the record of intersex Perisphinctoidea in the Jurassic can be explained by the ready recognition of dimorphic pairs, and the easy collection of large and sufficiently preserved fossil palaeopopulations in which intersex specimens have statistically more chance to be found.

Globuligerina glinskikhae nov. sp. Gradstein & Waskowska and Globuligerina waskowskae nov. sp. Gradstein are new species of Jurassic planktonic foraminifera from the Middle Jurassic of Dagestan and Poland. G. glinskikhae nov. sp. with its remarkable ‘protoglobigerine’ test may be an early evolutionary offshoot of Globuligerina oxfordiana (Grigelis). It may be an index taxon for upper Bajocian through Bathonian strata in Eastern Europe and Southwest Asia, and might be recognizable also in thin sections. We consider G. waskowskae nov. sp. to be a possible forerunner of Conoglobigerina helvetojurassica (Haeusler), the first planktonic foraminiferal species with a reticulate wall texture. Currently, is only known from Poland. In some localities, specimens of G. oxfordiana and of G. glinskikhae nov. sp. posses an additional apertural opening, often lacking a rim; its function is enigmatic. The postulated lineage from Jurassic Globuligerina balakhmatovae (Morozova) to Cretaceous Clavihedbergella eocretacea Neagu is refined with the description of Petaloglobigerina simmonsi nov. gen., nov. sp. Gradstein from the Kimmeridgian of Portugal. The evolutionary transition from G. balakhmatovae to P. simmonsi occurs by means of the ontogenic development of a petaloid test, with a pronounced flattening of the whorl with ovate chambers, the last ones often offset and twisted. Jurassic planktonic foraminifera, now known to consist of three genera and 12+ species underwent long periods of stasis, interrupted by late Bajocian, mid-Oxfordian and early Kimmeridgian evolution. The three ‘stasis and root’ taxa G. oxfordiana, G. bathoniana and G. balakhmatovae are geographically widespread in lower to mid palaeo-latitudes, and stratigraphically long ranging within the Middle and Late Jurassic. Modern digital microscopes, with co-axial and side LED lighting and excellent image stacking software are important tools in the study of Jurassic planktonic foraminifera, and fast and cost-effective communication tools in modern micropalaeontology.

International audience; Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non‐planispiral coiling. Such aberrant forms appeared convergently four times within this extinct group of cephalopods. Since Wiedmann's seminal paper in this journal, the palaeobiology of heteromorphs has advanced substantially. Combining direct evidence from their fossil record, indirect insights from phylogenetic bracketing, and physical as well as virtual models, we reach an improved understanding of heteromorph ammonoid palaeobiology. Their anatomy, buoyancy, locomotion, predators, diet, palaeoecology, and extinction are discussed. Based on phylogenetic bracketing with nautiloids and coleoids, heteromorphs like other ammonoids had 10 arms, a well‐developed brain, lens eyes, a buccal mass with a radula and a smaller upper as well as a larger lower jaw, and ammonia in their soft tissue. Heteromorphs likely lacked arm suckers, hooks, tentacles, a hood, and an ink sac. All Cretaceous heteromorphs share an aptychus‐type lower jaw with a lamellar calcitic covering. Differences in radular tooth morphology and size in heteromorphs suggest a microphagous diet. Stomach contents of heteromorphs comprise planktic crustaceans, gastropods, and crinoids, suggesting a zooplanktic diet. Forms with a U‐shaped body chamber (ancylocone) are regarded as suspension feeders, whereas orthoconic forms additionally might have consumed benthic prey. Heteromorphs could achieve near‐neutral buoyancy regardless of conch shape or ontogeny. Orthoconic heteromorphs likely had a vertical orientation, whereas ancylocone heteromorphs had a near‐horizontal aperture pointing upwards. Heteromorphs with a U‐shaped body chamber are more stable hydrodynamically than modern Nautilus and were unable substantially to modify their orientation by active locomotion, i.e. they had no or limited access to benthic prey at adulthood. Pathologies reported for heteromorphs were likely inflicted by crustaceans, fish, marine reptiles, and other cephalopods. Pathologies on Ptychoceras corroborates an external shell and rejects the endocochleate hypothesis. Devonian, Triassic, and Jurassic heteromorphs had a preference for deep‐subtidal to offshore facies but are rare in shallow‐subtidal, slope, and bathyal facies. Early Cretaceous heteromorphs preferred deep‐subtidal to bathyal facies. Late Cretaceous heteromorphs are common in shallow‐subtidal to offshore facies. Oxygen isotope data suggest rapid growth and a demersal habitat for adult Discoscaphites and Baculites. A benthic embryonic stage, planktic hatchlings, and a habitat change after one whorl is proposed for Hoploscaphites. Carbon isotope data indicate that some Baculites lived throughout their lives at cold seeps. Adaptation to a planktic life habit potentially drove selection towards smaller hatchlings, implying high fecundity and an ecological role of the hatchlings as micro‐ and mesoplankton. The Chicxulub impact at the Cretaceous/Paleogene (K/Pg) boundary 66 million years ago is the likely trigger for the extinction of ammonoids. Ammonoids likely persisted after this event for 40–500 thousand years and are exclusively represented by heteromorphs. The ammonoid extinction is linked to their small hatchling sizes, planktotrophic diets, and higher metabolic rates than in nautilids, which survived the K/Pg mass extinction event.

Ocean acidification is expected to impact the high latitude oceans first, as CO2 dissolves more easily in colder waters. At the current rate of anthropogenic CO2 emissions, the sub-Antarctic Zone will start to experience undersaturated conditions with respect to aragonite within the next few decades, which will affect marine calcifying organisms. Shelled pteropods, a group of calcifying zooplankton, are considered to be especially sensitive to changes in carbonate chemistry because of their thin aragonite shells. Limacina retroversa is the most abundant pteropod in sub-Antarctic waters, and plays an important role in the carbonate pump. However, not much is known about its response to ocean acidification. In this study, we investigated differences in calcification between L. retroversa individuals exposed to ocean carbonate chemistry conditions of the past (pH 8.19; mid-1880s), present (pH 8.06), and near-future (pH 7.93; predicted for 2050) in the sub-Antarctic. After 3 days of exposure, calcification responses were quantified by calcein staining, shell weighing, and Micro-CT scanning. In pteropods exposed to past conditions, calcification occurred over the entire shell and the leading edge of the last whorl, whilst individuals incubated under present and near-future conditions mostly invested in extending their shells, rather than calcifying over their entire shell. Moreover, individuals exposed to past conditions formed larger shell volumes compared to present and future conditions, suggesting that calcification is already decreased in today’s sub-Antarctic waters. Shells of individuals incubated under near-future conditions did not increase in shell weight during the incubation, and had a lower density compared to past and present conditions, suggesting that calcification will be further compromised in the future. This demonstrates the high sensitivity of L. retroversa to relatively small and short-term changes in carbonate chemistry. A reduction in calcification of L. retroversa in the rapidly acidifying waters of the sub-Antarctic will have a major impact on aragonite-CaCO3 export from oceanic surface waters to the deep sea.

Sixteen species of Latrunculiidae Topsent, 1922, belonging to the genera Latrunculia du Bocage, 1869, Strongylodesma Lévi, 1969, Cyclacanthia Samaai & Kelly, 2004, Samaai & Kelly, 2002, are currently known from the temperate waters of South Africa. Extensive new sponge collections from the Amathole region of South Africa revealed the existence of three new species of Tsitsikamma, T. amatholensis sp. nov., T. madiba sp. nov., and T. beukesi sp. nov., and a new species of the endemic South African genus Cyclacanthia, C. rethahofmeyri sp. nov. With the recent addition of two new species of Tsitsikamma from Algoa Bay and Tsitsikamma National Park (T. michaeli Parker-Nance, 2019; T. nguni Parker-Nance, 2019) the total number of known South African Latrunculiidae is now 20 species in four genera. Here we propose two new subgenera of Tsitsikamma, Tsitsikamma Samaai & Kelly, 2002 and Clavicaulis subgen. nov., based on the morphological groups “favus” and “pedunculata” hypothesized by Parker-Nance et al. (2019). Species in the nominotypical subgenus Tsitsikamma, containing the type species, are thick encrusting to hemispherical with a rigid honeycombed choanosome, while species in the new subgenus Clavicaulis subgen. nov. have a purse or sac-like morphology with little choanosomal structure. Despite the obvious species-level differences in morphology, multivariate analysis based on spicule measurements (anisostyle length, discorhabd length, shaft and whorl length) was not able to distinguish between the proposed Tsitsikamma species, but separated known species T. favus Samaai & Kelly, 2002, T. pedunculata Samaai & Kelly, 2003, and T. scurra Samaai & Kelly, 2003, from each other. Similarly, DNA barcoding of the mitochondrial COI and the nuclear ITS of Tsitsikamma specimens failed to clearly differentiate between species, but was able to differentiate sister taxon relationships within the Latrunculiidae.

The age of the primitive ichthyopterygian Thaisaurus is more accurately defined due to the discovery of a new species of the ammonoid genus Marcouxia from beds about 2.4 m below the horizon from which the holotype of Thaisaurus chonglakmanii was collected in the Phukhaothong Dolomite Member of the Chaiburi Formation in the Phatthalung area, southern Thailand. The shell of Marcouxia chaiburiensis sp. nov. is characterized by a quadrate whorl section, an arched venter with a sub-acute keel-like elevation, and spiny tubercles on the ventrolateral shoulders as well as numerous regularly spaced, radial or slightly prorsiradiate ribs. Because the range of Marcouxia is limited to the Columbites parisianus Subzone of the lower Spathian (upper Olenekian, Lower Triassic) in the western USA, the age of Thaisaurus is likely constrained to the early Spathian, thus suggesting it is one of the oldest known ichthyopterygians.

Odontella rapoporti sp. nov., from Tierra del Fuego is described, as the third species of the Odontella lobata group, which has a subantarctic distribution. The new species is similar to O. lobata and O. setosa, but can be distinguished from them by the number of chaetae on the dens (6 or 7 chaetae in O. setosa vs. 5 chaetae in the other species) and the number of chaetae in the distal whorl of the tibiotarsus (9 chaetae in O. lobata vs. 11 in the other species). The closely related monotypic genus Afrodontella Deharveng, 1981, and its type species (A. septemlobata) are described.

Littorina Férussac, 1822 is an abundant genus of small gastropods found in the upper littoral zone of rocky seashores worldwide. Although ecologically important, shell-based species identification in this genus is challenging due to phenotypic variation in shell morphology and lack of diagnostic characters among morphologically similar species. In this study, we revised the taxonomy of Korean Littorina species using morphological characters (shell and radula) and cox1 mitochondrial DNA sequences for three Korean species: L. brevicula, L. sitkana, and L. horikawai. Results suggest that L. sitkana was erroneously reported as L. kasatka in a previous study. A new record for Littorina horikawai (Matsubayashi & Habe in Habe, 1979), previously unknown from Korea, is described, which can be distinguished from L. sitkana by the presence of alternating white and brown spiral ribs on each whorl. Comparison of the mtDNA cox1 gene sequences shows very low intraspecific variation even between geographically distant populations. A phylogenetic tree supports a close relationship between L. horikawai and L. sitkana, consistent with earlier phylogenetic studies.

Ammonites have disparate adult morphologies indicative of diverse ecological niches, but ammonite hatchlings are small (~1 mm diameter), which raises questions about the similarity of egg incubation and hatchling life mode in ammonites. ModernNautilusis sometimes used as a model organism for understanding ammonites, but despite their outward similarities, the groups are only distantly related. Trends in ammonite diversity and extinction vulnerability in the fossil record contrast starkly with those of nautilids, and embryonic shells from Late Cretaceous ammonites are two orders of magnitude smaller than nautilid embryonic shells. To investigate possible environmental changes experienced by ammonite hatchlings, we used secondary ion mass spectrometry to analyze the oxygen and carbon isotope composition of the embryonic shells and early postembryonic whorls of five juveniles ofHoploscaphites comprimusobtained from a single concretion in the Fox Hills Formation of South Dakota. Co-occurring bivalves and diagenetic calcite were also analyzed to provide a benthic baseline for comparison. The oxygen isotope ratios of embryonic shells are more like those of benthic bivalves, suggesting that ammonite eggs were laid on the bottom. Ammonite shell immediately after hatching has more negative δ18O, suggesting movement to more shallow water that is potentially warmer and/or fresher. After approximately one whorl of postembryonic growth, the values of δ18O become more positive in three of the five individuals, suggesting that these animals transitioned to a more demersal mode of life. Two other individuals transition to even lower δ18O values that could suggest movement to nearshore brackish water. These data suggest that ammonites, like many modern coleoids, may have spawned at different times of the year. Because scaphites were one of the short-term Cretaceous–Paleogene extinction survivors, it is possible that this characteristic allowed them to develop a broader geographic range and, consequently, a greater resistance to extinction.

The beginning of the Cambrian explosion is characterized by the onset of infaunalization and the appearance of systematic patterns of burrowing. The trace fossil Gyrolithes is common in the Ediacaran-Cambrian Global Stratotype Section and Point, where it shows a higher diversity and burrow depth than previously reported from any Cambrian spiral vertical burrows. Two ichnospecies are present: G. scintillus isp. nov. exhibits a small burrow radius to whorl radius ratio, whereas G. gyratus (Hofmann) exhibits an exceptionally large ratio that formerly led to its identification as an aberrant ichnospecies of Skolithos. The helical morphology of these Cambrian Gyrolithes is interpreted as having served two purposes: as an anchor in a relatively high-energy environment, and as an optimal shape for maximizing surface area for bacterial gardening. These shallow-marine gardening burrows share a similar feeding strategy as graphoglyptids, suggesting that shallow early Cambrian sediments may have been relatively poor in organics and thus further supporting the model for onshore-offshore migration of gardening burrows.

Comments are provided on a published paper on Middle Jurassic Laevaptychus from central Mexico [C.Esquivel-Macias, P.Zell, J.A.Moreno-Bedmar and K.Flores-Castro, Giant Middle Jurassic (Bathonian) cf. Laevaptychus sp. of the Aztlan section, Hidalgo State, central Mexico, Journal of South American Earth Sciences, 110, 103302]. This article describes an interesting finding of large-sized ammonite lower jaws (aptychi referred to Laevaptychus paragenus), claimed as the largest Jurassic aptychi ever known. However, the age of these specimens was erroneously defined due to misidentification of an associated ammonite specimen as Bathonian Procerites. Although poorly preserved, this ammonite shows typical features of the Kimmeridgian genus Idoceras. The Kimmeridgian age of these occurrences is in agreement with findings of Laevaptychus, as this is one of few aptychi formal genera, which belongs to a single ammonite family (Aspidoceratidae). Aspidoceratids appeared in the late Callovian and during the evolution of this lineage maximum sizes of adult specimens and the relative whorl height gradually increased up to Kimmeridgian - Tithonian; only prior to their extinction in early Berriasian, aspidoceratids became uncommon and smaller in size. Laevaptychi are thick-valved aptychi, which have high preservation potential while compared with other aptychi of Jurassic ammonites and their host shells. Giant laevaptychi reported in previous publications (the largest of which reaches 35 cm in length) are briefly reviewed. In adult aspidoceratids the maximum length of aptychi is slightly less than the maximum whorl height. Thus, taking into account the size of the largest aspidoceratid ammonites (up to 85 cm in diameter), the estimated length of the largest laevaptychi can be expected to be ~35–40 cm, which is close to their known record.

The type material of Cylindroporella sugdeni Elliott, 1957, is revised. The total lack of sterile laterals and consequently the absence of the diagnostic feature of the genus Cylindroporella, i.e., the alternation of sterile and fertile laterals within the same whorl, leads to its exclusion from the genus Cylindroporella Johnson, 1954, and to its ascription to the genus Holosporella Pia, 1930. Recent stratigraphic investigations suggest that the stratum typicum originally reported as Early Cretaceous in age is more precisely Hauterivian or possibly Early Barremian in age.

The nautilid Eutrephoceras dekayi (Morton 1834) is relatively abundant in the lower Maastrichtian (Upper Cretaceous) Pierre Shale of east-central Montana. We analysed the morphology, size frequency distribution, and isotope composition of a large collection of 220 well-preserved specimens including hatchlings, juveniles and adults. The newly hatched shell is approximately 14 mm in diameter with a body chamber one-third whorl in angular length terminating in the nepionic constriction. Internally, the embryonic shell contains five septa. Juveniles are abundant and comprise two-thirds of the sample whereas sub-adults, defined by the incipient flattening of the venter, are rare. Adults comprise approximately one-third of the sample and average 100 mm in diameter. The co-occurrence of newly hatched shells, small juveniles and adults suggests that the eggs were laid in the same area in which the hatchlings developed. Based on the excellent preservation of the juveniles, we conclude that they did not float into the area after death, but lived in the region, implying that this area served as a nursery for young animals. The calculated temperatures of the embryonic shells are similar to those of the post-embryonic shells and generally range from 16 to 18 °C. Upon hatching, the nautilids probably followed a demersal mode of life and lived in well-oxygenated water ≤50 m deep. An examination of lethal injuries (puncture holes) suggests that all ontogenetic stages were equally vulnerable to predation. The proximity of the site to the Sheridan Delta suggests that the specimens were smothered by sudden pulses of sediment transported into the area by major storms.

The veliconcha larva of the predatory gastropod Conus spurius Gmelin, 1791 is described and for the first time illustrated based on material from Sanibel Island, Florida. Hatchling veliconchas were 1470–1570 μm (mean = 1530) long, with first protoconch whorl maximum diameter 670–740 μm (mean = 710), and estimated egg diameter 570 μm. Veliconchas can swim for a few minutes to a few hours before settling. They have well-developed paired velar lobes each 600–700 μm in length, an extensible foot with a distinct metapodium separated from the remainder of the foot by a transverse fold, and operculum. Several early life history traits of C. spurius, particularly hatching as large veliconcha larvae with predominantly lecithotrophic, nearly non-planktonic development, closely resemble those of a well-defined clade of Conus Linnaeus, 1758 species that prey on other gastropods. They contrast with the majority of species in this hyperdiverse genus, which hatch as much smaller planktonic, obligatory planktotrophic veliger larvae. As adults they comprise a vermivorous feeding guild, preying exclusively or nearly so on polychaete annelids. Limited data suggest that C. spurius may share this trait with them but it may also prey on molluscs. Recent molecular phylogenetic trees suggest that the characters “pelagic development” and “non-pelagic development” (or nearly so

A species of the genus Ammonicera Vayssiere, 1893 collected from coralline algae communities in Jeju Island, South Korea, is described as a new species, A. aurea, for science. Its morphological characters are described and illustrated by SEM micrographs. This new species can be clearly distinguished from other Ammonicera species from the Pacific Ocean by the presence of a spiral cord and about 25 slightly-elevated axial ribs, resulting in about 25 nodules at intersecting points of the cord and ribs on the last whorl of the teleoconch.

In this study, we describe as the earliest representatives of involutinids a new population comprising one new genus (Praetriadodiscus) and two new species (P. zaninettiae and P. tappanae) from the Great Bank of Guizhou in the Nanpanjiang Basin of south China. This new population appears to have diverged from an undetermined pseudoammodiscid ancestor in the late Smithian, during the second phase of foraminiferal recovery from the end-Permian mass extinction. The new genus exhibits a two-layered wall, inner microgranular and outer hyaline, fibrous and aragonitic, and a planispirally coiled, lenticular test with one lamella for one complete whorl of the deuteroloculus. The genus Triadodiscus, which may represent the last common ancestor of the Order Involutinida, is potentially the direct descendant of this new population characterized by a two-layered wall.

The Late Visean (Early Carboniferous) ammonoid species Goniatites sphaericus (Sowerby, 1814) is revised with the use of the type material. With respect to conch morphology, suture line and particularly shell ornament, it is regarded as a senior synonym of the species Goniatites fimbriatus (Foord and Crick, 1897) and must therefore be re-established as an important index fossil for the ammonoid stratigraphy of the Rhenohercynian and Subvariscan shelves. The Goniatites fimbriatus Zone has been re-named Goniatites sphaericus Zone on this basis. The study of ontogenetic changes in the conch parameters shows that intraspecific variation occurs within a wide range. In the whorl profile, variation is very high in small juveniles, while in the coiling rate, intermediate growth stages are more strongly affected.

The Devonian marine strata of southwestern Ontario, Canada, have been well documented geologically, but their vertebrate fossils are poorly studied. Here we report a new onychodontiform (Osteichthyes, Sarcopterygii) Onychodus eriensis n. sp. from the Dundee Formation (Eifelian–Givetian boundary, 390–387 Ma) of southwestern Ontario represented by two well-preserved onychodontiform lower jaws. The most complete specimen consists of a large (28 cm), well-preserved right jaw with most of the dentition present. The dentary has 50 teeth, not including the parasymphysial tusk whorl, which is poorly preserved but consists of at least three tusks. The anteriormost teeth of the dentary are also not complete, but the second dentary tooth is notably procurved. The posterior teeth are conical and approximately equal in size for much of the length of the tooth row. Onychodus eriensis n. sp. differs from the closely related contemporary species Onychodus sigmoides and all other onychodonts in that it has a strong dorsal curvature of the anterior dentary ramus and marked anterior expansion of the dentary. An expanded phylogenetic analysis of Devonian onychodontiforms suggests that O. eriensis is closely related to Onychodus jandamarrai. The new material indicates that Onychodontiformes is more diverse than previously recognized, and that further analysis of vertebrate remains from southwestern Ontario will lead to additional insights into the diversity of Devonian sarcopterygians.

Se describe un nuevo género y dos nuevas especies de gastrópodos continentales del nivel superior de la Formación Irene (probablemente Huayqueriense–Montehermosense, Plioceno temprano), que aparece expuesta en la cuenca del río Quequén Salado (provincia de Buenos Aires, Argentina). El nuevo género y especie corresponde a un gastrópodo de agua dulce (Argentisioliella pardignasi, Cochliopidae), morfológicamente similar a aquellos descriptos para la Formación Pebas de edad pliocena. Los ejemplares presentan forma bulloide, abertura larga y estrecha, peristoma acanalado y dos pliegues en la pared columelar. Ésta es la primera descripción de formas similares de las Formaciones Irene y Pebas. Se describe una nueva especie de Bulimulidae (Bocourtia (Kuschelenia?) bonariensis), siendo el registro más antiguo del género, encontrado muy distante de su actual distribución (noroeste de Argentina). El ejemplar es un molde interno, con algo más de tres vueltas convexas y abertura grande, su distribución podría coincidir con los momentos finales del cambio climático de edad mio–pliocena, cuando numerosos gastrópodos terrestres patagónicos y pampeanos desaparecieron. Un espécimen del Strophocheilidae terrestre Austroborus fue encontrado en buen estado de conservación, presentando conchilla casi completa, con más de 4.5 vueltas convexas, y última vuelta y abertura grandes. El género está presente en el Pleistoceno y el Holoceno del área estudiada; viviendo en zonas restringidas de Argentina y Uruguay, con una distribución disyunta y relictual. A new genus and two new fossil species of continental gastropods from the upper part of the Irene Formation - which is probably Huayquerian-Montehermosian (early Pliocene) and is exposed in the Quequén Salado River (Buenos Aires Province, Argentina) - are described: the new genus and species of freshwater gastropod Argentisioliella pardignasi (Cochliopidae) and a new species of landsnail of the family Bulimulidae (Bocourtia (Kuschelenia?) bonariensis). Argentisioliella pardignasi is morphologically related to those described for the Pebas Formation of Pliocene age. The specimens have bulloid morphology, long and narrow aperture, with a channeled peristome and two folds in the columellar wall. This is the first description of similar snails of the Pebas and Irene formations. Bocourtia (Kuschelenia?) bonariensis is the most ancient record for the genus, being recorded far away from the area of its current distribution (northwest Argentina). The specimen is an internal cast, with more than three convex whorls and a large aperture. Its distribution would coincide with the final phase of the Mio-Pliocene climatic change, when numerous terrestrial gastropods of Patagonian and Pampean provenance disappeared. A well-conserved specimen of the terrestrial snail Austroborus (Strophocheilidae Pilsbry), showing an almost complete shell, with more than 4.5 convex whorls, last whorl and large aperture, was also recorded. In the study area, this genus was present during the Pleistocene and Holocene, living in restricted areas of Argentina and Uruguay, with a disjunctive and relictual distribution. Fil: Miquel, Sergio Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina

A new species of Euthema of mid-Cretaceous age (Cenomanian, ca. 99–98 Ma), E. annae sp. nov., is described on the basis of two shells in Burmese amber (northern Myanmar). It differs by the presence of a parietal inclusion in the aperture and by the weakly convex whorls with dense, diagonally aligned ribs on the last whorl. The genus Euthema is redescribed, and a new synonym recognised, Paleodiplommatina. A list of all currently described molluscan species from Burmese amber is provided. Lagocheilus electrospira is reassigned to the genus Eotrichophorus. The taxonomic diversity and abundance of molluscs in Burmese amber are discussed on the basis of 198 observed snail inclusions from amber trading exchange and published data. Apparently, molluscs are much more common in Burmese amber than in any other deposit of amber, with a notable predominance of Cyclophoroidea. There are no specimens that could indicate the presence of Stylommatophora, Ellobioidea or other “pulmonates”.

Megalospheric specimens of Heterostegina from four localities in Western and Central Cuba were morphometrically investigated using test characters, which are described by 15 growth-independent and growth-invariant attributes that enable complete test reconstruction in equatorial sections. The species Heterostegina cubana, H. ocalana , and Heterostegina sp. indet. were classified by nonmetric multidimensional scaling and cluster analysis. Discriminant analysis yielded significant separators between species such as the perimeter ratio of the first chamberlets, the decrease in chamberlet length from the previous spiral to the marginal side, the chamber height at the spiral side of the previous whorl, and the proloculus size. Based on a further discriminant analysis, specimens of H. ocalana from different localities, including specimens from Panama, are strongly separated by the number of operculinid chambers, the extension grade of the marginal spiral and the backward bend of chambers, documenting paleogeographic differences and apparent evolutionary trends such as the reduction of the number of operculinid chambers. In Cuba, Heterostegina is represented by H. cubana and Heterostegina sp. indet. in the Bartonian to lower Priabonian (calcareous nannofossil Zones NP 16-NP 17), while Heterostegina ocalana ranges from Priabonian (nannofossil Zones NP 17 to NP 19-20/CP 15) to probably lower Oligocene (Rupelian) in the lower and middle part of the planktic foraminiferal Zone O 1 (P 18) and in the middle part of the calcareous nannofossil Zone NP 21 (CP 16).

The mantle tissue is essential for understanding the diverse ecology and shell morphology of ammonoid cephalopods. Here, we report on irregular calcareous sheets in a well-preserved shell of a Late Cretaceous phylloceratid ammonoid Hypophylloceras subramosum from Hokkaido, Japan, and their significance for repairing the conch through the mantle inside the body chamber. The sheets are composed of nacreous layers arranged parallel to the irregularly distorted outer whorl surface. The nacreous sheets formed earlier are unevenly distributed and attached to the outer shell wall locally, whereas the last formed sheet covers a wide area of the outer shell wall. The absence of any interruption of ribbing around the irregular area suggests that these sheets were secreted inside the body chamber from the inner mantle. Gross morphological and X-ray computed tomography observations revealed that the spacing of septal formation was not affected by this event. The complex structure of the irregular sheets suggests a highly flexible mantle inside the body chamber.

Archachatina marginata (Swainson), Achatina achatina (Linnaeus) and Achatina fulica Bowdich were examined for their shell whorl morphometrics (20 snails per species) and the calcium, iron and phosphorus content in the shell whorls (10 snails per species). The species differed in the degree of shell mineralization (the highest in the medium-sized A. achatina, intermediate in the smallest-sized A. fulica and the smallest in the largest-sized A. marginata) which was not ageor environment-dependent, since all the experimental snails were 12 months old adults of 6 whorls, originating from the same snail farm. In all three species the degree of shell mineralization decreased from the apical (oldest) to the body (youngest) whorl, thus depending entirely on the whorl’s age. The inter-specific differences in calcium content should be considered when using shells for medical or agricultural purposes.

Three genera of gastropods described from the Lower Devonian Rockhouse Formation of Hardin County, Tennessee, currently are considered to be junior subjective synonyms ofPlatyceras(Visitator) Perner, 1911. Evaluation of the type specimens of these genera as well as types of two other gastropods from the same formation reveals the following:Platyostoma quadrangulare(Dunbar, 1920) is the only platyceratid gastropod among them;Saffordella tennessensisDunbar, 1920 has a selenizone above midwhorl so it is an eotomarioidean belonging to the Gosseletinidae;Aulopea nelsoniDunbar, 1920 and the lectotype ofDistemnostoma princepsDunbar, 1920 each has a broad subsutural sinus on the upper whorl surface similar to the Omphalotrochidae, as well as a basal sinus similar to certain primitive caenogastropods, so their systematic position is uncertain; I considerHolopea planidorsataDunbar, 1920 to be a juvenile specimen ofD. princeps; the fragmentary paralectotype ofD. princepspossibly represents a gerontic form ofDistemnostoma curtumDunbar, 1920, which possesses a well-developed selenizone on an upwardly projecting shoulder at the edge of the upper whorl surface. BecauseD. curtumappears to be unrelated toD. princeps, the genotype ofDistemnostoma, I propose the new generic nameOmocordellaforD. curtum. The new family Micromphalidae is erected to include OrdovicianSlehoferiaRohr and Fryda, 2001, lower CarboniferousMicromphalusKnight, 1945, andOmocordellan. gen.

We describe three species of large scaphitid ammonites (Ammonoidea: Ancyloceratina) from the Upper Cretaceous (upper Campanian–lower Maastrichtian) of the Western Interior of North America. Each species occurs as two dimorphs, referred to as macroconch and microconch. All three species share a similar pattern of ornamentation consisting of long, thin, nonbifurcating ribs on the adoral part of the phragmocone, suggesting that they constitute a single monophyletic clade. Macroconchs of Hoploscaphites crassus (Coryell and Salmon, 1934) are characterized by a globose whorl section, with closely spaced ventrolateral tubercles on the body chamber, usually persisting to the aperture. Macroconchs of Hoploscaphites plenus (Meek and Hayden, 1860) differ from those of H. crassus in having a more subquadrate whorl section with flatter flanks, and fewer, larger, and more widely spaced ventrolateral tubercles. Macroconchs of Hoploscaphites peterseni, n. sp., closely resemble those of H. crassus, but differ in being nearly circular in side view with a more compressed whorl section. All three species lived at approximately the same time in the same general area and depositional environment. They are abundant in the Baculites baculus Zone but also occasionally occur in the B. eliasi Zone and possibly lower part of the B. grandis Zone. They are present in the Pierre Shale of east-central Montana and east-central Wyoming, the Lewis Shale of south-central Wyoming, and the Bearpaw Shale of northeast Montana. It is possible that these three species represent subspecies within a single species or a “flock” of very closely related species, similar to the “species flocks” observed in modern cichlid fishes.

The external area-to-volume ratio of the ammonite shell has been held to be related to morphology but never evaluated quantitatively. A dimensionless ratio, the Vogel number, was computed for large samples of Devonian to Cretaceous ammonites with a new method based on the ADA-model. The estimated ratios range from 2.4 to 3.4. The highest values are exhibited by uncoiled serpenticone ammonites, lowering in the sequence serpenticone-oxycone-spherocone. It is shown that the area-to-volume relationships are controlled by the involution (degree of overlapping) and the relative width of whorl section. The typical evolutionary trends serpenticone–spherocone and/or serpenticone–oxycone, broadly documented through the history of the Ammonoidea, could have been driven, at least in part, by the lowering of the area-to-volume ratio.

Fusiform planispiral tests are found in many lineages of larger foraminifera (e.g. fusulinids, lituolids, alveolinids, soritids, amphisteginids) in which a general trend from spherical or discoidal to elongate test shape has often been noted. Geometrical models are used to illustrate an increasing surface area and the shortened spiral lines of communication of such a trend, with whorl and chamber proportions and volume or spiral length held constant. The suggestion that fusiform planispiral growth is a device to shorten lines of communication from the proloculus to the poles is questioned.

Anthropogenic inputs of CO2 are changing ocean chemistry and will likely affect calcifying marine organisms, particularly aragonite producers such as pteropods. This work seeks to set a benchmark analysis of pteropod shell properties and variability using nanoindentation and electron microscopy to measure the structural and mechanical properties of Subantarctic pteropod shells (Limacina helicina antarctica) collected in 1998 and 2007. The 1998 shells were collected by a sediment trap deployed at 2000 m, 47°S, 142°E, and the 2007 shells were collected using nets from mixed-layer waters in the region (44°–54°S, 140°–155°E). Transmission electron microscopy revealed that the shells are composed of a polycrystalline structure, and no obvious porosity was visible. The hardness and modulus of the shells were measured using shell cross-section nanoindentation, across various regions of the shell from the inner to outer whorl. No change in mechanical properties was found with respect to the region of the shell cross-section probed. There was no statistically significant difference in the mean modulus or hardness of the shells between the 1998 and 2007 data sets. No major changes in the mechanical properties of these pteropod shells were detected between the 1998 and 2007 data sets, and we discuss the possible biases in the sampling techniques in complicating our analysis. However, quantifying the mechanical properties and microstructure of calcified may still provide insights into the responses of calcification to environmental changes, such as ocean acidification.

In order to test the hypothesis that complex suture lines in ammonoids reinforced their shell strength, intraspecific variation of sutural complexity and shell morphologies (whorl shape and septal thickness) of the Cretaceous ammonoid Desmoceras latidorsatum (including three forms) from Madagascar were analyzed. The comparison between the sutural complexity and the whorl shape demonstrated that the more compressed or depressed forms have more complex suture lines than intermediate forms. The more compressed or depressed shells are generally expected to be weaker than intermediate ones that have almost circular whorl cross-sections. A comparison between sutural complexity balance (the ratio of the sutural complexities of the ventral and lateral parts) with the whorl shape demonstrated that the suture lines are more complex in the lateral area of the compressed shells and in the ventral area of the depressed shells. These relationships suggest that the suture lines were more complex in relatively more flattened parts of phragmocones, supporting that the complex suture reinforced the phragmocone against hydrostatic pressure.

Truncorotalia crassaformis has been identified in Pliocene–Holocene assemblages globally but there has been little analysis of specimens from its type locality at Lomita Quarry, California. This has led to confusion about some diagnostic criteria, particularly the presence of a peripheral keel. To better understand variation specimens are studied from the type locality (Pleistocene, c. 400–600 ka), supplemented by material from a plankton trap in Cariaco Basin and from ODP 925, Ceara Rise (Pliocene, c. 4.3 Ma). The damaged holotype has a weak topographic ridge (keel) at the periphery of early chambers of the outer whorl. Several well-preserved specimens have a keel on all chambers of the whorl. Encrustation obscures the periphery on some and masks shell shape. Several outliers in a morphometric analysis of axial shape have distinctive discoidal outlines but ventroconical (cone-like) forms are common. Lomita Marl was deposited on a sheltered, shallow shelf in Chron 1. Foraminifera reworked from the unconformably underlying Repetto Siltstone are present. Specimens resembling the holotype are very rare and often damaged. Morphological disparity is high. It is unlikely that an autochthonous population was sampled. The weak peripheral keel present on some living specimens from Cariaco Basin is built incrementally by a thin featureless calcitic veneer deposited between the morphogenesis of each chamber. The process progressively obscures pores in the primary wall. Its earliest stages have been misidentified as a poreless zone. Ventroconical form is weak in the Ceara Rise Pliocene specimens and is distinguishable from the Cariaco sample. There is only a veneer at the periphery. Although the study does not provide a population-based diagnosis of T. crassaformis it indicates that the name should not be applied to early Pliocene forms.

Regeneration of the calcareous rigiclaudent operculum following severe, non-lethal, predatory attacks is described in two specimens of the characteristic Silurian gastropod Oriostoma from the English Midlands. This is the first record of the regeneration of opercula in Palaeozoic gastropods and of opercula conjoined with shells that have been repaired after significant, failed, durophagous attacks. In one specimen, a series of repaired injuries culminates in a repaired aperture closed by the operculum. In the second specimen, new shell growth has failed to recover the full extent of the original broken whorl, and the new aperture and operculum, though well developed, are smaller than the originals. Both opercula are unusually thin centrally when compared to other, strongly domed, Oriostoma opercula.

A morphometric analysis of the characteristic whorl cross-sections of 1,200 Jurassic ammonoid species from southern Germany enabled us to characterise their morphospace. The successive Jurassic ammonoid faunas of southern Germany show characteristic patterns in morphospace occupation. While Early and Middle Jurassic ammonoids occupy limited areas of the morphospace range, the Late Jurassic ammonoids cover the entire spectrum. The ammonoids are characterised by an overall increase of both taxonomic diversity and morphological disparity in the course of the Jurassic. Strong fluctuations occur until the middle Late Jurassic, followed by a diversity decrease in the early Kimmeridgian and a disparity reduction in the early Tithonian. While diversity and disparity show similar progression during most of the Early Jurassic, they diverge subsequently and show only poor correlation until the end of the Jurassic. Particularly in the Middle Jurassic diversity and sea level changes correlate strongly. Neither temporal patterns in diversity nor disparity support the hypothesis of a mass extinction event in the early Toarcian. Significant changes in diversity and disparity in the early Callovian support a putative migration event of Boreal ammonoids into the Tethyan realm. doi:10.1002/mmng.201000016

Some bryozoan species occur on gastropod shells occupied by hermit crabs, often dominating the shell surface to the exclusion of other encrusters. Symbioses between bryozoans and pagurid crabs are known from a wide latitudinal range, including tropical, warm- and cold-temperate regions. Here we describe Burdwoodipora paguricola gen. et sp. nov., a cheilostome bryozoan associated with pagurized shells occupied by the hermit crab Pagurus comptus White in subantarctic waters of the Southwest Atlantic. The association seems to be obligate, as the bryozoan was always found enlarging the last whorl of its gastropod substrate. The new species, however, is not species specifc with regard to its shell substrate, as it was found to be associated with 31 species of gastropods with helicoidal coiling. Well-developed colonies may project up to 360° from the outer lip of the shell. The chamber built by the bryozoan is usually larger than the whorl that would have been generated by the gastropod. This is one of the few known cases of an obligate association between a bryozoan and a pagurid crab outside the ascophoran family Hippoporidridae and is also the frst bryozoan/hermit crab symbiosis documented in the subantarctic region. The inclusion of Burdwoodipora in the Pacifcincolidae, a family currently represented by just four species from the Northern Hemisphere, is discussed. Fil: López Gappa, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Liuzzi, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Zelaya, Diego Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina

The gastropod fauna of the Lower Cretaceous of the Argentinian Neuquén Basin contains three aporrhaid species. Protohemichenopus neuquensis Camacho, 1953 is the most abundant, longest-lived, and most geographically widespread of the aporrhaids of this basin, and its protoconch and early teleoconch whorls were unknown until now. The new species Dimorphosoma weaveri features convex to subtly angular spire whorls with opisthocyrt collabral ribs that are more prominent towards the mid-whorl, a bicarinate last whorl with small rounded nodes on the adapical carina, a simple, falcate labral wing which is more or less rectangular proximally and tapering and curving towards its distal end, and a short, straight rostrum. Tylostoma jaworskii Weaver, 1931 is now placed in Harpagodes, and other previous, scattered, coeval records of this genus in the basin are now recognized as part of this single species. It is believed that whereas H. jaworskii preferred shallower-water carbonate settings of low to moderate energy, P. neuquensis and D. weaveri favored siliciclastic to mixed clastic-carbonate environments, in deeper waters. In spite of its endemic elements, this aporrhaid association depicts a predominantly Tethyan influence. Fil: Cataldo, Cecilia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos ; Argentina

The recent reexamination of a tooth-whorl fossil of Helicoprion containing intact jaws shows that the symphyseal tooth-whorl occupies the entire length of Meckel's cartilage. Here, we use the morphology of the jaws and tooth-whorl to reconstruct the jaw musculature and develop a biomechanical model of the feeding mechanism in these early Permian predators. The jaw muscles may have generated large bite-forces; however, the mechanics of the jaws and whorl suggest that Helicoprion was better equipped for feeding on soft-bodied prey. Hard shelled prey would tend to slip anteriorly from the closing jaws due to the curvature of the tooth-whorl, lack of cuspate teeth on the palatoquadrate (PQ), and resistance of the prey. When feeding on soft-bodied prey, deformation of the prey traps prey tissue between the two halves of the PQ and the whorl. The curvature of the tooth-whorl and position of the exposed teeth relative to the jaw joint results in multiple tooth functions from anterior to posterior tooth that aid in feeding on soft-bodied prey. Posterior teeth cut and push prey deeper into the oral cavity, while middle teeth pierce and cut, and anterior teeth hook and drag more of the prey into the mouth. Furthermore, the anterior-posterior edges of the teeth facilitate prey cutting with jaw closure and jaw depression. The paths traveled by each tooth during jaw depression are reminiscent of curved pathways used with slashing weaponry such as swords and knifes. Thus, the jaws and tooth-whorl may have formed a multifunctional tool for capturing, processing, and transporting prey by cyclic opening and closing of the lower jaw in a sawing fashion.

Specimens of a new species of Cerithiidae, Cerithium mangrovum n. sp., were collected during two surveys along the coasts of Hainan and Guangdong Province, China. Usually associated with potamidid snails, this species often occurs in large populations between the mid-high tidal zones in a range of habitats, including mangroves, grass beds, silt, mud, and coral reefs. C. mangrovum n. sp. has a slender and tapering shell and the straight-sided whorl bears three aligned beaded spiral cords. The thick outer lip has a wide posterior sinus. It morphologically resembles C. coralium Kiener, 1841. The shell of C. coralium is usually larger and wider and the spiral cords are not as beaded as in C. mangrovum n. sp. Its radula has a rachidian tooth with a shallow, wide, median basal projection while the rachidian tooth of C. mangrovum n. sp. has a moderately long, median basal projection.

The Triassic–Jurassic extinction resulted in the near demise of the ammonoids. Based on a survey of ammonoid expansion rates, coiling geometry and whorl shape, we use the Raup accretionary growth model to outline a universal morphospace for planispiral shell geometry. We explore the occupation of that planispiral morphospace in terms of both breadth and density of occupation in addition to separately reviewing the occurrence of heteromorphs. Four intervals are recognized: pre-extinction (Carnian to Rhaetian); aftermath (Hettangian); post-extinction (Sinemurian to Aalenian) and recovery (Bajocian to Callovian). The pre-extinction and recovery intervals show maximum disparity. The aftermath is marked by the disappearance of heteromorphs and a dramatic reduction in the range of planispiral morphologies to a core area of the morphospace. It is also characterized by an expansion into an evolute, slowly expanding part of the morphospace that was not occupied prior to the extinction and is soon abandoned during the post-extinction interval. Aftermath and post-extinction ammonoid data show a persistent negative correlation whereby rapid expansion rates are associated with narrow umbilical widths and often compressed whorls. The permanently occupied core area of planispiral morphospace represents generalist demersals whose shells were probably optimizing both hydrodynamic efficiency and shell stability. All other parts of the planispiral morphospace, and the pelagic modes of life the shells probably exploited, were gradually reoccupied during the post-extinction interval. Planispiral adaptation was by diffusion away from the morphospace core rather than by radical jumps. Recovery of disparity was not achieved until some 30 Myr after the extinction event.

Anagaudryceras compressum sp. nov., the most slender of this genus, is newly described from the Nostoceras hetonaiense Zone of earliest Maastrichtian age (Late Cretaceous), in the Hobetsu area, Hokkaido, northern Japan. Its shell is fairly small (< 80 mm in diameter) and compressed with a highly arched venter. The last whorl is ornamented with low, broad, gently flexed band-like ribs. Its ornamentation is very similar to A. matsumotoi, thus suggesting a close phylogenetic relationship with this taxon, which is probably its descendant.

New species Nummulites vetustufabianiin. sp. is described from the El Hamra Formation, Gara El Hamra section Bahariya Oasis Western Desert. The biometrical measurements include maximum and minimum diameter of the successive radii and heights of whorls, length/height ratio, number of chambers and the marginal cord thickness of each whorl for the megalospheric generation as well as the diameter of proloculus were elaborated to differentiate between some allied granulated species such as Nummulites depressus, Nummulites decrouezae, Nummulites cuvillieri and N. vetustufabianiin. sp.Nummulites fabianii group has lateral distribution for the entire Tethys basin, hence such biometrical studies are needed to emphasise the polyphyletic nature of the group.