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Gastropod egg capsules preserved on an Early Cretaceous ammonite from Daghestan, Russia
Abstract
Tiny, circular objects preserved in the form of rims have been detected on an Early Cretaceous (early Aptian) ammonite from Daghestan, Russia. They are preserved on the body chamber portion of the mould, where they occur either as isolated rims or, more commonly, as structures closely neighbouring with each other. Comparisons with similar Recent and fossil structures indicate that they are remnants of gastropod egg capsules preserved as attachment bases, and most probably were produced by neritimorph gastropods. The egg capsules were deposited within an empty ammonite body chamber where the gastropods found a site sheltered against potential scavengers and predators. The occurrence of only attachment bases indicates, that the egg capsules may have hatched. Although they are preserved in the form of iron oxides, during fossilization the originally organic egg capsules underwent pyritization followed by later weathering. This is the first record of this kind from the Lower Cretaceous.
... These three-dimensionally preserved capsules are definitely the best preserved fossils of this kind, enabling the observation of both their exterior and interior parts. Zatoń and Mironenko (2015b) also reported neritimorph-like egg capsule remnants preserved on a Lower Cretaceous (early Aptian) ammonite mould from Daghestan in Russia. Possible gastropod egg capsules preserved as carbonaceous compressions on non-marine bivalve moulds are also known from the Miocene of Czech Republic (Mikuláš and Dvořák, 2001). ...
... This indicates that they were attached to the inner side of the empty shell wall. Such a mode of occurrence of these structures is known in other ammonite body chambers from the Lower Jurassic (Kaiser and Voigt, 1983), Upper Jurassic (Zatoń and Mironenko, 2015a) and Lower Cretaceous deposits (Zatoń and Mironenko, 2015b). One may suggest that being preserved in the ammonites, the observed hemispherical objects may represent the fossilized ammonite eggs. ...
... Although relatively rarely reported from the fossil record, the structures interpreted as gastropod egg capsules are preserved in a wide array of preservational modes, being dolomitized (probably secondarily, Kaiser and Voigt, 1983), pyritized (Riegraf and Schubert, 1991;Schubert et al., 2008;Zatoń and Mironenko, 2015b), phosphatized (Zatoń and Mironenko, 2015a), preserved by bioimmuration (Zatoń et al., 2013) or as carbonaceous compressions (Mikuláš and Dvořák, 2001;Zatoń et al., 2009), and even as calcitized capsules as in the present case. This suggests that such structures, although still rarely reported, may in fact be fossilized in various diagenetic conditions, and thus should be more common in the fossil record. ...
Small-sized (0.8–1.6 mm in diameter), circular to oval, three-dimensionally preserved calcitized structures have been found embedded within ammonite body chamber moulds from the Lower Aptian (Lower Cretaceous) of Russia. The characteristic morphology, consisting of a flat attachment base and convex upper hemisphere possessing an apical, tiny, circular opening indicate that these structures represent gastropod (possibly Caenogastropoda) egg capsules. Originally, the egg capsules were attached to the empty shells of the ammonites Deshayesites and Sinzovia which later were embedded within carbonate concretions. The preservation of the egg capsules resulted from both their deposition within a suitable, cryptic habitat provided by the empty ammonite shells, and the quick cementation of the infilling sediment which not only sufficiently protected the capsules from external environment, but also created a suitable, closed microenvironment for fossilization. The calcitization of the egg capsules may have occurred under low pH conditions in an environment characterized by a very low concentration of phosphorous ions essential for phosphatization. So far, such structures are known from a few examples derived from different stratigraphic horizons and geographic locations. Those which are known have been reported in the form of pyritized, phosphatized, carbonaceous and even bioimmured fossils. The calcitized gastropod egg capsules presented here indicate, that such structures may in fact be preserved by a wide array of fossilization modes in different paleoenvironments/microenvironments. Thus, such fossils seem to be much more common in the fossil record than previously considered.
... Morphologically most similar to the present finds are supposed fossil gastropod egg clusters, especially with regards to the ring like impressions of egg capsule bases (e.g., Zatoń et al. 2009;Klug et al. 2019). Despite the supposedly low preservation potential of gastropod egg clutches, these have a fairly remarkable fossil record and putative examples were described from various substrates including Tertiary bivalve shells (Mikuláš & Dvořák 2001), Cretaceous gastropod (Zatoń et al. 2013) and ammonite shells (Zatoń & Mironenko 2015;Zatoń et al. 2017), Jurassic wood (Riegraf & Schubert 1991;Schubert et al. 2008), carbonatic concretions (Keupp et al. 2016), ammonites and belemnites (Kaiser & Voigt 1983;Scharfenberg et al. 2022) and bivalve shells (Kaiser & Voigt 1977;Zatoń et al. 2009), as well as Pennsylvanian pteridosperm foliage (Lucas et al. 2021) and bivalve shells (Emrich et al. 2017). The hitherto oldest supposed gastropod egg clusters were described from Late Devonian ammonite shells (Klug et al. 2019). ...
Subcircular structures on the carapaces of the giant clam shrimp Palaeolimnadiopsis obenaueri from the early Permian Meisenheim Formation of the Saar-Nahe Basin are figured and described. These are interpreted as gastropod egg clutches. This is a rare occurrence of Palaeozoic gastropod egg deposition and the first case where this behaviour is reported in connection with clam shrimp carapaces.
... Autochthonous non-vertebrate eggs from the Amaltheenton Facies of Buttenheim Keupp et al. (2016b) described for the first time pyritized remnants of a presumed molluscan spawn (pyritized fixation bases and flattened egg capsules) from the Late Pliensbachian sediments of the Buttenheim clay pit. They discussed Hayamia reticulata, a gastropod found in the same outcrop, as the originator, owing to comparisons with similar findings of the Lower Jurassic of Poland and the Early Cretaceous of Daghestan (Zatoń et al. 2009;Zatoń and Mironenko 2015a) as well as modern spawns of neritimorph gastropods. The loosely arranged cluster of about 40 egg capsules is attached to the surface of a calcareous nodule (75 × 32 mm) of EPH and occupies an area of about 300 mm 2 ( Fig. 2A, B). ...
Our paper shows several clusters of circular fossil egg capsules from the Franconian Amaltheenton Facies (Lower Jurassic, Upper Pliensbachian), mostly found in the clay pit south of Buttenheim. The egg capsules are scatteredly and irregularly arranged on various substrates like calcareous nodules, mollusk shells, or sunken driftwoods. Marine gastropods have been presumed as their producers spawning their eggs autochthonous. Only one specimen exhibits a regular honeycomb-like pattern of small pyritized eggs deposited seemingly within driftwood but originally lead in a small deadwood break. We interpret it as representing a possible allochthonous insect spawn drifted off from the about 70 km removed coastal region.
... Comparable observations were led on ammonite body chambers hosting other crustaceans like lobsters (Glypheidea and Erymidae) that are thought to have used dead ammonite remains as food source and shelter (Posidonia Shales of Dotternhausen for the Toarcian; Portland Limestones for the Tithonian; Fraaye and Jäger 1995). From the Tithonian, it has also been inferred that caenogastropods used ammonite body chambers to deposit their egg capsules (Zatoń and Mironenko 2015). ...
Because it is biased compared to the reality of ancient life, the fossil record requires specific terminology when dealing with possible ancient biological associations of organisms. Among the range of interactions between ancient organisms, paleosymbioses are noticeable representatives of paleoecological diversities and key elements to understand the evolution of lineages over time. They may provide evidence for unsuspected associations because they involve extinct organisms or simply because they are not maintained anymore among modern representatives. They may allow one to constrain the evolution of organisms by dating the ancestry of large lineage pairings over time and are often a favorable material to discover ancient minute-sized phyla. When sufficiently expressed over time and lineages, paleosymbioses can inform directly on large biological questions (e.g. selection toward life cycle diversity), but also on ecological issues (e.g. the general processes that lead to the internalization of a symbiont). Consequently, paleosymbioses are highly worthwhile components of the paleontological record.
Sphenothallus is a problematic fossil with possible cnidarian affinities. Two species of Sphenothallus, S. aff. longissimus and S. kukersianus, occur in the normal marine sediments of the Late Ordovician of Estonia. S. longissimus is more common than S. kukersianus and has a range from early Sandbian to middle Katian. Sphenothallus had a wide paleobiogeographic distribution in the Late Ordovician. The tubes of Sphenothallus are composed of lamellae with a homogeneous microstructure. The homogeneous microstructure could represent a diagenetic fabric, based on the similarity to diagenetic structures in Torellella (Cnidaria?, Hyolithelminthes). Tubes of Sphenothallus have an apatitic composition, but one tube contains lamellae of diagenetic calcite within the apatitic structure. Sphenothallus presumably had originally biomineralized apatitic tubes. Different lattice parameters of the apatite indicate that biomineralization systems of phosphatic cnidarians Sphenothallus and Conularia sp. may have been different.
A monoplacophoran species and about 100 species of gastropods are recorded from hydrothermal vents and various kinds of seeps from the Atlantic and Pacific Oceans. Previously described species are supplemented with new information on distribution, ecology, morphology, and systematics. The zoogeography of these faunas is discussed and it is noticed that there is a good resemblance in generic composition between the vent and seep localities, while the species usually occur in only one of the two environments. More than 95% of the species found in vents have not been found outside this environment, and the endemic species make up more than 99.5% of the individuals. The fauna of the seeps is less well demarcated. Two species of Provanna (Caenogastropoda, Provannidae) are recorded from sunken drift wood in the NE Pacific. The genus was previously thought to be endemic to vent and seep environments. The fauna of the recently investigated vent system at the East Pacific Rise, 17°S is very similar to that of the more northern (9-21°N) localities; 14 species out of 16 are shared. Available evidence for a hypothesized relict character of the gastropod fauna is evaluated and failed to support the hypothesis. Spermatophores were found in Melanodrymia sp., the first known case in Neomphalina. A possible case of imposex is reported from the conid genus Phymorhynchus. The first monoplacophoran from hydrothermal vents is described, Rokopella segonzaci, sp. nov. (Family Neopilinidae), from the Mid-Atlantic Ridge at about 38°N. The following new gastropod taxa are described. Patellogastropoda. Family Neolepetopsidae: Paralepetopsis ferrugivora, sp. nov., from the Mid-Atlantic Ridge, 37°N; P. lepichoni, sp. nov., from the Nankai Trough off south-eastern Honshu, Japan. Vetigastropoda. Family uncertain: Adeuomphalus trochanter, sp. nov., from the Juan de Fuca Ridge; Sahlingia xandaros, gen. et sp. nov., from the Aleutian Trench. Family Lepetodrilidae: Lepetodrilus atlanticus, sp. nov., from the Mid Atlantic Ridge, 23-38°N. Family Sutilizonidae: Sutilizona pterodon, sp. nov., from the Mid-Atlantic Ridge, 23°N; S. tunnicliffae, sp. nov., from the Juan de Fuca Ridge. Skeneidae: Bruceiella athlia, sp. nov., from seeps in the Aleutian Trench. Trochidae: Falsimargarita nauduri, sp. nov., from vents at the East Pacific Rise at 17°S; Fucaria mystax, sp. nov., from vents off eastern New Guinea. Uncertain position. Family Neomphalidae: Melanodrymia galeronae, sp. nov., from the East Pacific Rise at 13°N; Retiskenea diploura, gen. et sp. nov., from the Aleutian Trench; Lacunoides vitreus, sp. nov., from the Juan de Fuca Ridge. Family Peltospiridae: Lirapex costellata, sp. nov., from the Mid-Atlantic Ridge at 37°N; Nodopelta rigneae, sp. nov., from the East Pacific Rise at 13°N; Peltospira smaragdina, sp. nov., from the Mid-Atlantic Ridge, 15-38°N. Depressigyra? statura Goedert & Benham, 1999, from Eocene seep deposits in the state of Washington is transferred to Retiskenea. Neritimorpha. Family Phenacolepadidae: Shinkailepas briandi, sp. nov., from the Mid-Atlantic Ridge, 15-38°N. Caenogastropoda. Family Cerithiopsidae: Speculator cariosus, gen. et sp. nov. from the Juan de Fuca Ridge. Family Vitrinellidae: Neusas, gen. nov., marshalli (Sykes, 1925), from the bathyal Northeast Atlantic. Family Elachisinidae: Laeviphitus desbruyeresi, sp. nov., from the Mid-Atlantic Ridge, 37°N. Buccinidae: Bayerius peruvianus, sp. nov., from seeps off Peru; Eosipho auzendei, sp. nov., from vents at the East Pacific Rise at 17°S. Conidae: Bathybela papyracea, sp. nov., from Gulf of California, off Jalisco; Phymorhynchus major, sp. nov., from the East Pacific Rise at 13°N; P. carinatus, sp. nov., from the Mid-Atlantic Ridge, 15-23°N; P. ovatus, sp. nov., from the Mid-Atlantic Ridge, 15-37°N. Heterobranchia. Family Hyalogyrinidae: Hyalogyrina globularis, sp. nov., from the Juan de Fuca Ridge; H. umbellifera, sp. nov., from seeps in the Aleutian Trench. Family Orbitestellidae: Lurifax vitreus, gen. et sp. nov., from the Mid-Atlantic Ridge, 37-38°N. Family Xylodisculidae: Xylodiscula analoga, sp. nov., from the Mid-Atlantic Ridge, 37°N.
Fossil gastropod egg capsules have rarely been reported from the fossil record. This paper describes gastropod egg capsules preserved exclusively on cardiniid bivalves from Lower Jurassic (Hettangian) deltaic deposits of the Holy Cross Mountains area, central Poland. In most instances, only the bases of the egg capsules are preserved as dark outer rings with hollow cavities inside. Some specimens, however, are preserved as dark circular spots or even shallow depressions on the bivalve molds. The general occurrence, morphology, size and composition of the egg capsules as revealed by Energy Dispersive Spectroscopy (EDS) analyses and elemental mapping point to neritimorphs as the most probable producers. The egg capsules are composed primarily of organic matter with some calcium. Recent neritid gastropods possess aragonitic spherules within the egg capsule wails composed of conchiolin or chitin, which strengthen them and increase their chance of fossilization compared to egg capsules of other gastropods. Recent neritids lay their egg capsules on mollusk shells as well. The occurrence of Early Jurassic egg capsules only on redeposited cardiniid bivalve shells may suggest that the shells were the best medium for egg-capsule deposition. The occurrence of egg capsule bases together with dark circular spots, interpreted as compressed unhatched capsules, suggests that these egg capsules either hatched or were deposited at different times in the same place. The Early Jurassic egg capsules were preserved due to the strengthening role of the carbonate phase within the wall and rapid burial coupled with limited bioturbation in deltaic settings. The prodelta-delta front depositional environment, with high rates of sedimentation by rivers and sediment redistribution by wave and current action, was favorable for preserving these fossils.
The egg capsules of neritid snails (Gastropoda: Neritimorpha) are made of a tough inner organic layer and an outer calcareous layer for further reinforcement. Such hard capsules are less susceptible to mechanical damage compared with soft or thin capsules of other gastropods, and there have been only a few reports of predation on neritid eggs. Here, we describe drilling predation on the reinforced egg capsule of Nerita japonica by Reishia clavigera (Caenogastropoda: Muricidae) on a high intertidal rocky shore in central Japan. The muricid makes a small, elliptical drill hole in the capsule lid by the use of both an accessory boring organ (ABO) and a radula, as it does in mollusc and barnacle shells. The etching around the hole by the acid secretion from the ABO, which can be observed under a dis-secting microscope and by scanning electron microscopy, should provide an effective way to identify muricid predation on neritid eggs, probably not only by R. clavigera but also by other species in the warm temperate to tropical regions all over the world. Reishia clavigera made drill holes in c. 14% of the capsules, making it possibly the main cause of mortality for neritid eggs at the study site. However, this mortality rate is lower than those previously reported for caenogastropod eggs with softer capsules. All penetrated capsules of N. japonica were white (rather than brownish) and newly laid, suggesting that their acid-resistant organic layer had yet to harden at the time of radular rasping. The thick organic layer and calcareous coating are an effective armour, not only against the usual type of grazing but also against more sophisticated predation involving the chemical and mechanical boring of Muricidae.
ABSTRACT We describe a small crab inside the phragmocone of a heteromorph cephalopod Baculites sp. smooth from the Gammon Ferruginous member (lower Campanian) of the pierre Shale in Butte County, South Dakota. The crab Ferricorda kimberlyae (Bishop, 1987) is well preserved with its carapace and pereiopods parallel to and between two septa of the phragmocone. Because of its superb preservation, the specimen is unlikely to have been washed into the phragmocone. The crab probably retreated into the phragmocone chamber to avoid predation or to molt and was subsequently buried by an influx of rapid sedimentation. This is the first instance of inquilinism by a crab in a heteromorph ammonite. Despite the rarity of such fossils, the occurrence of crabs inside ammonite shells was probably not uncommon on sea floors during the mesozoic. mor-phological details of the specimen reveal that Ferricorda is a dynomenid crab. INtRoDUCtIoN
Stratigraphically important ammonites Deshayesites ex gr. deshayesi (d’Orbigny, 1840), Deshayesites sp. juv., and Paradeshayesites aff. callidiscus [Casey, 1961] from lower Aptian pelagic sediments at the Verkhorech’e Village have been described and depicted. The new finds
and revision of previously found ammonites allow the recognition of ammonite zones Deshayesites volgensis and Deshayesites deshayesi in the Southwestern Crimea.
Gastropod egg masses are often deposited in the intertidal zone, where they are exposed to variable and often stressful environmental conditions that may affect the encapsulated embryonic development and survival of offspring. The present paper reviews data on developmental variation in gastropod egg masses owing to temperature, salinity, ultraviolet radiation (UVR) and oxygen availability. In general, increases in temperature or oxygen availability accelerate development, whereas UVR or extremes of salinity and temperature slow development and/or increase embryonic mortality. The relationships among these factors are discussed, as are their interactions with biotic factors, such as fouling, embryonic position within the egg mass and predation. One purpose of the present review is to raise awareness of these interactions so they become a focus for future research. Protective mechanisms of egg masses against environmental stresses are also reviewed. M R04001 I nt e rt id a l s t re s ses and g ast ro pod egg m a sse s R. P rzes la ws ki Additional keywords: mollusc, oxygen availability, reproduction, salinity, temperature, ultraviolet radiation.
Clusters of gastropod egg capsules, inferred to be of neritoids and attached to the inner shell wall of the ultimate whorl of a large volutid gastropod, are here recorded from the upper Nekum Member (Maastricht Formation; late Maastrichtian) of the ENCI-HeidelbergCement Group quarry, St Pietersberg (Maastricht, southeast Netherlands). Because the aragonitic shell of the volutid has dissolved, the outlines of the egg capsules are now revealed on the steinkern of indurated biocalcarenite, having been subsequently overgrown by cheilostome bryozoan colonies and preserved as mould bioimmurations. This represents the first example of gastropod eggs preserved through bioimmuration, as well as the first record of gastropod eggs from the Cretaceous.
Raised shell projections on the inner shell walls that form pits on the internal moulds of Devonian ammonoids have been known for several decades. New specimens from Morocco reveal novel details of these structures; most, if not all, of which consist of a capsule of ammonoid shell that covers tiny tubes attached to the outer (= lateral or ventral) shell wall from the inside. In accordance with comparable Recent occurrences of similar structures in molluscs, we use the term "pearls" for these structures and the pits they form on the internal moulds. The nature of these encapsulated tubes is de− scribed and discussed. Because of the presence of these tubes inside the pearls, pearl arrangement, and their similarity to Recent mollusc occurrences, the tubes are interpreted as traces of parasitoses. The pearls and pits were grouped into five types based on differences in morphology, size, and arrangement. Then, having used these traits to perform a simple cladistic analysis, the resulting cladogram was compared to the phylogeny of ammonoids. Based on this comparison, it appears likely that the parasites underwent a co−evolution with the ammonoids, which lasted 10 to 15 Ma. Patterns of evo− lutionary events include co−speciation, "drowning on arrival" (end of parasite lineage near base of a new host clade), and "missing the boat" (parasite lineage does not adapt to a new host clade, thus not evolving a new parasite clade). Because of the lack of fossilised soft tissue, only speculations can be made about the systematic affiliation of the parasites, their life−cycle, infection strategy, and ecological framework. Some co−occurring bivalves also have pits reminiscent to struc− tures caused by trematodes in Recent forms. Based on the available information, the tubes are interpreted as artefacts of trematode infestations, which, if correct, would extend the fossil record of parasitic trematodes into the Early Devonian.
Data on embryonic, larval, and postlarval morphology of the gastropod conchs from the Mid Jurassic to Early Cretaceous black clays from Poland are used to improve their taxonomy. The phylogenetic relationships of the fossil gastropod taxa to their Recent relatives are traced. The results show that most of the Recent groups were already present in the Mid Jurassic. The vetigastropods are apparently conservative and shells of some groups have not changed significantly for at least 160 Ma. The most primitive extant caenogastropods (e.g., Cerithioidea and Ampullospiridae) most probably have originated from the branches which diverged already in the Late Paleozoic. The other caenogastropods have undergone significant radiation in the Triassic. Then the Caenogastropoda had a period of relative stagnation. The significant exception is emergence and rapid radiation of Neogastropoda during the Cretaceous. The most diversified Mesozoic family of Heterostropha, the Mathildidae, had its acme from the Late Triassic to the Early Cretaceous. Later the family gradually declines and nowadays it is a relic group. The oldest cephalaspidean opisthobranchians are known since the Early Triassic but the significant radiation has taken place in the Mid Jurassic. The siphonariids, the marine pulmonates, are recognized from the Early Cretaceous. 135 species (54 of them new) and two new genera (Dzikella and Gnaszynium) are described.
Direct animal behavior can be inferred from the fossil record only in exceptional circumstances. The exceptional mode of preservation of ammonoid shells in the Posidonia Shale (Lower Jurassic, lower Toarcian) of Dotternhausen in southern Germany, with only the organic periostracum preserved, provides an excellent opportunity to observe the contents of the ammonoid body chamber because this periostracum is translucent. Here, we report upon three delicate lobsters preserved within a compressed ammonoid specimen of Harpoceras falciferum. We attempt to explain this gregarious behavior. The three lobsters were studied using standard microscopy under low angle light. The lobsters belong to the extinct family of the Eryonidae; further identification was not possible. The organic material of the three small lobsters is preserved more than halfway into the ammonoid body chamber. The lobsters are closely spaced and are positioned with their tails oriented toward each other. The specimens are interpreted to represent corpses rather than molts. The lobsters probably sought shelter in preparation for molting or against predators such as fish that were present in Dotternhausen. Alternatively, the soft tissue of the ammonoid may have been a source of food that attracted the lobsters, or it may have served as a long-term residency for the lobsters (inquilinism). The lobsters represent the oldest known example of gregariousness amongst lobsters and decapods in the fossil record. Gregarious behavior in lobsters, also known for extant lobsters, thus developed earlier in earth's history than previously known. Moreover, this is one of the oldest known examples of decapod crustaceans preserved within cephalopod shells.
Among the diverse patterns of energy allocation to the offspring of gastropods, the presence of egg capsules to protect embryos is common. Females of the edible snail
Zidona dufresnei attach egg capsules to hard substrates in shallow Argentine Patagonian waters (40�450S, 64�560W) during spring-summer. Embryonic development takes about 30 days at 22�C. In this study, three likely capsule
predator species and the marks left by each on egg capsule
walls were identified in laboratory experiments in February
2010. Abundances of predators and egg capsules with evidence of predation were assessed in the field in the summers of 2010 and 2011. Under laboratory conditions (N = 10 replicates per treatment and control), the predation rate by the chiton Chaetopleura isabellei was the highest (up to 90%), followed by the gastropod Tegula patagonica and the crab Neohelice granulata (*20% each). Nearly 60% of 41 capsules found in the field showed signs of predation.
According to the marks identified in the laboratory, C. isabellei was responsible for 79% of this predation, and T. patagonica for the rest. Predation appears to be important during the encapsulated early life and could be an agent for selecting for resistant capsule walls and a relatively shorter development time.
Odontocymbiola magellanica is the only known South American volutid gastropod that deposits calcareous egg capsules. The spawn is moulded and fixed
to flat or convex surfaces by the female's ventral pedal gland, during an hours-long process in which the female adopts a
stereotyped posture and appears nonreactive to most external stimuli. Microscopically, the different cells of the ventral
pedal gland show features suggesting their participation in the secretion of both the organic matrix and the calcium component
of the calcareous layer. The latter consists mainly of numerous spherspherulites that are packed together around cylindrical,
septated spaces which traverse the spherspherulitic layer and attach to the membranous layers surrounding the capsule cavity.
These septated spaces should ensure permeability of the capsule wall, which is necessary for gas exchange and excretion by
the embryo. The calcareous layer is made of high-magnesium calcite, a calcium carbonate polymorph in which Ca is partially
substituted by Mg in the calcite lattice. Mg substitution is thought to confer a greater crack resistance to the mineral;
it is found in many invertebrates, but apparently has not been reported before in molluscs. Odontocymbiola magellanica is a long-lived species, investing heavily in its egg capsules.
The encapsulation of eggs within benthic egg capsules or gelatinous egg masses is a common phenomenon among many marine invertebrate groups, yet the functional significance of many aspects of these egg coverings remains unexplored. In this paper I review what is known about the effectiveness of neogastropod egg capsules in protecting embryos from physical stresses associated with the marine intertidal environment. Egg capsules spawned by intertidal neogastropod molluscs can provide embryos with significant protection from desiccation, osmotic stress, and ultraviolet (UV) radiation, relative to embryos devoid of such coverings. Despite this, capsules desiccate rapidly in air, are highly permeable to small solute molecules, and are not impervious to incident UV radiation. Egg capsules of intertidal gastropods are also substantially more permeable to water molecules than the well studied egg cases and egg shells of insects and terrestrial vertebrates and may be no more effective in protecting embryos from such physical stresses than the capsules of exclusively subtidal gastropods. Hence, capsular cases appear to be poorly adapted to protecting embryos from environmental stresses associated with periodic exposure to air. The degree to which the encapsulated embryos of intertidal neogastropods are protected from environmental stresses thus may be more reflective of adult spawning site selection and tolerances of encapsulated embryos to these stresses, than properties of the capsular case, per se. Clearly, however, there is much still to be learned about the protective nature of capsule walls and the tremendous diversity of egg coverings that exists within the Gastropoda.
Minute "strings" composed of spherical to oval bodies were found attached to shells of the Miocene bivalve Pseudoanodonta sp. Some strings are interrupted, and neighbouring bodies may be either broadly connected or almost separated. The same surfaces of bivalve shells show less frequently also clusters of larger circular bodies. These are densely spaced but usually not touching the neighbouring ones. Interpretation of the described structures as plant fossils (e.g., algae) is unlike; their similarity to eggs of various recent invertebrates, fish or amphibians is evident. The small size of the spherical or circular bodies makes improbable their explanation as frog eggs; the location of the bodies on external surface of bivalve shells is unlike for insects. Therefore, only the explanation of the described structures as gastropod or fish eggs seems to be realistic.
The encapsulation of eggs within benthic egg capsules or gelatinous egg masses is a common phenomenon among many marine invertebrate groups, yet the functional significance of many aspects of these egg coverings remains unexplored. In this paper I review what is known about the effectiveness of neogastropod egg capsules in protecting embryos from physical stresses associated with the marine intertidal environment. Egg capsules spawned by intcrtidal neogastropod molluscs can provide embryos with significant protection from desiccation, osmotic stress, and ultraviolet (UV) radiation, relative to embryos devoid of such coverings. Despite this, capsules desiccate rapidly in air, are highly permeable to small solute molecules, and are not impervious to incident UV radiation. Egg capsules of intertidal gastropods are also substantially more permeable to water molecules than the well studied egg cases and egg shells of insects and terrestrial vertebrates and may be no more effective in protecting embryos from such physical stresses than the capsules of exclusively subtidal gastropods. Hence, capsular cases appear to be poorly adapted to protecting embryos from environmental stresses associated with periodic exposure to air. The degree to which the encapsulated embryos of intertidal neogastropods are protected from environmental stresses thus may be more reflective of adult spawning site selection and tolerances of encapsulated embryos to these stresses, than properties of the capsular case, per se. Clearly, however, there is much still to be learned about the protective nature of capsule walls and the tremendous diversity of egg coverings that exists within the Gastropoda.
The idea that monomorph Deshayesitaceae descended from heteromorph Heteroceratidae is confirmed. This transition from Heteroceras and further to Turkmeniceras is based upon a similar type of suture line morphogenesis and sculpture in late Colchidites and early Turkmeniceras. A zonal subdivision of Lower Aptian in areas of the eastern and also partially of the western hemispheres is suggested mainly in accordance with the development of the Deshayesitaceae. The Lower Aptian ammonite zones of the Middle Volga region, of the Northern Caucasus and of Turkmenistan are characterized. Biozones of Barremian and Aptian boundary deposits from the Mediterranean and Boreal realms are compared. Seven genera of the superfamily Deshayesitaceae (family Deshayesitidae) are described: Turkmeniceras TOVBINA, 1962; Deshayesites KAZANSKY, 1914; Paradeshayesites KEMPER, 1967; Obsoleticeras BOGDANOVA & MIKHAILOVA, 1999; Dufrenoyia KILIAN & REBOUL, 1915; Burckhardtites HUMPHREY, 1949, Neodeshayesites CASEY, 1964; diagnoses of known species are given and three new species are erected: Turkmeniceras tovbinae sp. nov., Deshayesites caseyi sp. nov. and D. kemperi sp. nov.
This chapter presents an overview and analysis of the phylogeny and evolution of the molluscan class Gastropoda. It explains that Gastropoda is the largest molluscan class and it contains the greatest diversity of described marine species. Estimates of the numbers of extant gastropod species range from a minimum of 40,000 to a maximum of almost 150,000. It describes the gastropod morphology and their significance to humans and provides a summary of the key features of major groups of gastropods.
A review of the processes required for exceptional preservation of soft-bodied fossils demonstrates that anoxia does not significantly inhibit decay and emphasizes the importance of early diagenetic mineralization. Early diagenesis is the principal factor amongst the complex processes leading to soft-part preservation. The development of a particular preservational mineral is controlled by rate of burial, amount of organic detritus, and salinity. A new causative classification of soft-bodied fossil biotas is presented based upon fossil mineralogy and mineral paragenesis. -Author
Egg capsules of Neritina, a prosobranch gastropod common in the marginal lagoons and estuaries of southwestern Nigeria, resemble described species of the foraminifer Hemisphaerammina Loeblich and Tappan, 1957, in shape, size, morphology and test composition. The attention of paleontologists is drawn to this resemblance, and it is suggested that described Recent species of Hemisphaerammina be re-examined, as they might possibly be gastropod capsules.
Clusters of gastropod egg capsules, inferred to be of neritoids and attached to the inner shell wall of the ultimate whorl of a large volutid gastropod, are here recorded from the upper Nekum Member (Maastricht Formation; late Maastrichtian) of the ENCI−Heidelberg Cement Group quarry, St Pieters− berg (Maastricht, southeast Netherlands). Because the arago− nitic shell of the volutid has dissolved, the outlines of the egg capsules are now revealed on the steinkern of indurated bio− calcarenite, having been subsequently overgrown by cheilo− stome bryozoan colonies and preserved as mould bioimmura− tions. This represents the first example of gastropod eggs pre− served through bioimmuration, as well as the first record of gastropod eggs from the Cretaceous.
Chitin occurs in a variety of invertebrates, especially in arthropod cuticles, but is rarely reported in the fossil record. Although it has been detected in fossils as old as Middle Cambrian and Silurian, the majority of records come from much younger, Cenozoic deposits. In this paper, we report the preservation of chitin in Early Jurassic neritimorph gastropod egg capsules deposited in bivalve shells from prodelta-deltafront and nearshore paleoenvironments of the Holy Cross Mountains, Poland. We used a number of analytical methods to confirm the presence of chitin preserved in these ancient fossils. This is the first record of chitin preservation in Mesozoic deposits that, interestingly, do not follow the conventional Konservat-Lagerstatten manner of preserving soft-bodied and non-biomineralized organisms. We believe that deltaic settings characterized by episodic, high input of fluvial deposits, oligohaline conditions, and oxygen-poor microenvironment within the sediment-as well as early cementation of sediment infilling the shells-were crucial for chitin preservation. The preservation of chitin in such recalcitrant structures as egg capsules and deposits that formed outside conventional Konservat-Lagerstatten conditions renders it likely similar deposits may yield promise for discoveries of similar biological macromolecules.
Inquilinism is that association in which one organism lives within another, using the host as a place of refuge. Four specimens are described from the Jurassic of England and Germany which illustrates ammonite inquilinism by decapods. The inquiline use of ammonite shells in the geological record, and its ecological and taphonomical implications are discussed.
The Late Cretaceous bryozoan fauna of North America has been severely neglected in the past. In this preliminary study based on museum material and a limited amount of fieldwork, we describe a total of 128 Campanian-Maastrichtian bryozoan species from Delaware, New Jersey, North Carolina, South Carolina, Tennessee, Georgia, Alabama, Mississippi, Louisiana and Arkansas. Eighty-two of these species are new, as are five (Basslerinella, Pseudoallantopora, Kristerina, Turnerella and Peedeesella) of the 77 genera. One new family, Peedeesellidae, is proposed. Cheilostomes, with 94 species (73 per cent of the total), outnumber cyclostomes, with 34 species (27 percent), a pattern matching that seen elsewhere in the world in coeval deposits. There appear to be very few species (4) in common with the better known bryozoan faunas of the same age from Europe. Although both local and regional diversities are moderately high, most of the Atlantic and Gulf Coastal Plain bryozoans are encrusters; erect species are uncommon and are never present in suffi cient density to form bryozoan limestones, in contrast to some Maastrichtian deposits from other regions.
Abstract An internal impression of the right valve of Pseudopecten aequivalvis (Sow.) from the Domerium layer (= Lias δ) at a discontinued
iron-ore surface mine, Haverlahwiese near Salzgitter, contains bowl-shaped structures which may be interpreted as gastropod
spawn. These are compared with similarly formed half-spheres of recent gastropod eggs which are laid on the inner side of
a pecten shell.
Neritid snails (Gastropoda: Neritimorpha) protect their eggs in a hard capsule, of tough conchiolin, reinforced by mineral particles derived from the faeces and stored in a special sac near the anus and oviduct opening. Predation on this arguably hardest of molluscan egg capsule is described and illustrated here; neritids of the freshwater to brackish-water genera Clithon and Vittina, generally classified as herbivores, feed facultatively on the eggs of various confamilial species after breaking the reinforced capsule lid by means of prolonged radular rasping. Intensive predation pressure by these common inhabitants in Indo-West Pacific coastal streams may have given rise to the remarkable egg-laying behaviour of Neritina on the shells of other living snails. Our laboratory examination showed that Neritina species deposited clusters of egg capsules more frequently on the living shell than on other substrates, and that the predation rate was significantly lower on this moving 'nursery'. Predation rate was even lower on the small egg capsules of Clithon and Vittina themselves, which were deposited one by one in the depressions on the rough surfaces of stones.
The structure, permeability to water and salts, and internal osmotic concentration of the egg capsules of the marine gastropod Ocenebra erinacea (L.) have been examined at various stages between deposition and hatching. The egg capsule of this species is composed of protein fibres arranged in four laminae, enclosing a protein-gel matrix containing developing embryos. Radio-tracer studies of intact capsules show them to be freely permeable to water and salts at all stages of embryonic development; thus, transfer to media of differing osmotic concentrations is quickly reflected in changes in the intracapsular osmotic concentration and by transitory weight changes. The lack of protection exposes embryos to the risk of osmotic shock or desiccation and embryonic mortalities can occur. Encapsulated embryos are shown to contain increasing amounts of proteolytic substances as hatching approaches. At hatching, these substances are apparently secreted into the gel matrix causing structural and osmotic changes in the capsule. These result in the expulsion of the mucus plug sealing the top of the capsule, thereby allowing the embryos to escape.
A diverse sclerozoan assemblages consisting of both encrusting and boring biota are described from the large limid bivalves Ctenostreon from the Callovian hardground setting of Zalas in southern Poland. At least 27 encrusting and seven bioerosion taxa are reported here, which makes this assemblage not only one of the most diverse in the Middle Jurassic, but the richest in encrusting taxa from the Callovian. The encrusters consist of cryptic biota of which sedentary polychaetes and cyclostome bryozoans dominate with respect to both species number and abundance. The bioerosion traces are dominated by tiny pits referred to the ichnogenus Oichnus, probably made by some soft-bodied biota in the present case, followed by the borings of acrothoracican barnacles (Rogerella). The first colonizers of the bivalve shells probably were borers as they only occur in the host shells. The encrusting pioneers presumably were oysters and oyster-like bivalves, followed by opportunistic serpulid/sabellid polychaetes and cyclostome bryozoans. The last colonizers were calcisponges and thecideide brachiopods. In comparison to the only known Late Callovian shallow and reef-associated, tropical sclerozoans of Israel, the assemblage from the open-marine, deeper setting of Poland is much richer in encrusting taxa. Such a surprising high encruster diversity in the marine northern paleo-latitude may have resulted from the deeper and calmer environment with a both reduced sedimentation rate and algal cover, and without any significant salinity changes, the factors that are thought to have impacted the tropical and shallow-marine sclerozoans from Israel.
The free-swimming young of the Rissoidse are particularly important in the plankton for there is always one or more species present in any month and they usually occur in great abundance. The various species live between tide-marks, in the laminarian and coralline zones and in deeper water in several fathoms depth; wherever tow-nettings are taken they usually contain some species of this family. The inshore waters, however, are the richest in rissoids. Even in winter certain species are common round the Plymouth coasts. Some years ago it was found that very young herring just before losing the yolk-sac and about a fortnight old had been eating small rissoids, evidently almost newly hatched (Plate I, Fig. 1). The herring up to a length of about 12 mm. and just after the yolk-sac had disappeared altogether continued to eat them but usually after this size they ate only small Crustacea. From 1917 to 1921 it was found that out of 140 young herring examined, 91 had fed on these small gastropods. In later years they were also found feeding on them (Lebour, 1921, 1924). Other minute planktonic organisms were eaten, including algæ, tintinnids, copepod and cirripede nauplii and very small adult copepods; also a minute bivalve larva but no other gastropod, although other veligers were present in the plankton, Patella being specially common. The young herrings hatch out from December to February, therefore these little gastropods must also hatch at this time and this proves to be the case for in the plankton there are large numbers of these very young veligers (Plate I, Figs. 7–8). Later on, in spring, older stages of the same mollusc abound and are quite the commonest veligers in the plankton near the coast (Plate I, Figs. 17–19). In the summer they have almost entirely disappeared.
Three kinds of gastropod eggs are described from the Middle Liassic (Pliensbachian) of northern Germany. Circular, netlike or honeycomb patterns on the innerside of the living chambers of the ammonite Pleuroceras spinatum (Brugière) and two Lytoceratids are compared with spat of Recent Gastropoda (Neritaceac and Columbellidae [?]). Other interpretations, such as ooids, conelles, faecal pellets, or eggs of ammonites are excluded. The striking likeness between spat of Recent Columbellidae and incrusting cheilostomatous membranimorph bryozoans (Conopeum) is pointed out. On the muddy sea floor, open lamellibranch shells and living chambers of ammonites offered a suitable hard and sheltered substrate for gastropod spawn.Gastropoda, Neritacea, eggs, ammonite living chambers, Cheilustomata, faecal pellets, Jurassic, Pliensbachian, NW Germany.
Aus dem norddeutschcn Lias γ-δ (Pliensbachium) werden drei Katcgorien von Gastropodenlaich be-schrieben. Es handelt sich teils um isolierte kreisrunde oder wabenbis hetzartige Strukturen auf der Innenwand von Ammonitenwohnkammern, bcsonders von Pleuroceras spinatum (Brugière) und zwei Lytoceratiden. Die Deutung als Gastropodenlaich gründet sich auf den Vergleich mil rezenten Eiablagen von Gastropoden (Neriten und Columbellidae [?]). Andere Deutungsmöglichkeiten (Ooide, Conellcn, Kotpillcn, Ammoniteneier) werden ausgeschlossen. Auf die verblüffende Áhnlichkeit zwischen rezentem Columbellidae-Laich und inkrustierenden cheilostomcn membranimorphen Bryozoen (Conopeum) wird hingewiesen. Die Innenráume von Molluskenschalen (Ammonitenwohnkammern, klaffende Schalen von Lamellibranchiaten) boten auf schlammigen Weichböden Substratlaichern unter den Gastropoden offcnbar günsttge Laichgelegenheiten.
A partially disarticulated actinopterygian fish preserved in a large three-dimensional ammonite body chamber is described from the Kimmeridgian of western France. Taphonomic observations on the degree of preservation of the fish and the development of epibiont organisms on the inner wall of the shell indicate a rather long time interval before sediment totally filled the body chamber. The fish, referred to an indeterminate Macrosemiidae, probably used this empty ammonite (Rasenioides, Aulacostephanidae) shell as a refuge, or possibly for spawning and/or brooding. It can be assumed that ammonite shells may have constituted common shelters for demersal fishes living in an open-marine shelf environment, near to a muddy bottom devoid of rocks.
An Early Cretaceous (Hauterivian) hermit crab perfectly preserved within an ammonite is described. Palaeontologists have focused too much on the wrong class of molluscs in their attempt to analyse the evolution of the pagurids. The shift of mollusc habitation during the Cretaceous, from ammonites to gastropods, affected the morphology of the aperture–blocking hermit–crab claws.
Van Iten, H., Cox, R. S. & Mapes, R. H. 1992 04 15: New data on the morphology of Sphenothallus Hall: implications for its affinities. Lethaia, Vol. 25, pp. 135–144. Oslo. ISSN 0024–1164.
Recent speculation on the phylogenetic relationships of Sphenothallus Hall, 1847 has focused on two alternatives: (1) affinity with hydrozoan or scyphozoan cnidarians, or (2) affinity with annelids or other ‘worms’. We have found that some species of Sphenothallus formed branching clonal colonies, and that others produced a thin transverse wall, similar to the conulariid schott. Sphenothallus tests are composed of carbonate apatite and are built of numerous, extremely thin lamellae (< 1 μm) that parallel the surface of the test. The holdfast, long interpreted as consisting of a pair of nested cups, actually consists of a single closed, broadly conical expansion floored by a thin basal membrane. Many thecate hydrozoan and scyphozoan polyps form branching clonal colonies and produce a thin transverse wall, similar to that produced by Sphenothallus. Further, thecae of coronatid scyphozoans are built of submicron-thick lamellae that parallel the outer surface of the theca, and coronatid thecae possess a closed, broadly conical apical expansion that serves as a holdfast. No such combination of characteristics exists among annelids or other non-cnidarian taxa. The recent discovery of paired tentacles in Sphenofhallus from the Early Devonian Hunsrück Slate by Fauchald et al., thought to indicate that Sphenorhallus was wormlike, does not militate against a hypothesis of affinity with cnidarians. We therefore favour the hypothesis of a cnidarian affinity for Sphenothallus. * Sphenothallus, vermiform problematica, phylogenetic inference, coloniality, Cnidoria, Hydrozoa, Scyphozoa, Annelida, conulariids, byroniids, Bear Gulch Limestone.
Die Arbeit behandelt die frühontogenetische Mollusken-Entwicklung der Schale und der diese bildenden Epithelien. Speziell werden Archaeogastropoden, Ammoniten und Neritaceen behandelt und mit einigen ausgewählten höheren Gastropoden verglichen, Archaeogastropoden, Neritaceen und höhere Gastropoden sind paläontologisch gut trennbare Gruppen, wenn die Bildung und Morphologie der frühontogenetischen Schalen verglichen werden. Eine Verbindung zwischen Archaeogastropoden und Ammoniten zeigt sich in der Art der Mineralisierung der organischen Primärschälchen. Cephalopoden sind generell eine ziemlich einheitliche Gruppe der Mollusken, deren Vorfahren den Vorfahren der Archaeogastropoden nahe verwandt waren. Neritaceen und höhere Schnecken verbindet die innere Befruchtung sowie der Besitz einer echten Larve, die den Archaeogastropoden wie auch den Cephalopoden fehlt. Die Ergebnisse werden in einem Schema des Entwicklungsablaufes in der Ontogenese dargestellt und zur Phylogenese des Molluskenstammes in Bezug gebracht. Hierzu werden auch einige Entwicklungsabläufe bei Käferschnecken, Muscheln und Scaphopoden miteinbezogen. Es erweist sich, daß einige in der Systematik bisher noch bewertete Eigenschaften und Merkmale nur sehr mit Vorsicht genutzt werden dürfen, während andere bisher wenig beachtete Kriterien mehr Aussagekraft besitzen als bisher vermutet. Die Bildung der Schalendrüse erweist sich als die zentrale Erfindung der Mollusken, die vermutlich während des oberen Kambriums die Conchifera entstehen ließ. Mit vielen Beispielen wird belegt, daß innerhalb aller behandelten Molluskengruppen eine Ausdeutung fossiler Schalenreste nur dann zu sinnvollen Ergebnissen führt, wenn die Bildungsweise der Schale bei rezenten Verwandten gut untersucht ist. Umgekehrt zeigt es sich, daß Modelle der Evolution der Mollusken, die nur auf Rezentbefunden basieren, in der Regel wenig Ähnlichkeit mit dem tatsächlichen Ablauf der Geschehnisse aufweisen.
The ability of the egg capsules of three intertidal gastropod species to protect embryos against low-salinity stress was examined. Encapsulated embryos of Ilyanassa obsoleta (Say), Nucella lamellosa (Gmelin), and N. lima (Gmelin) were far more tolerant of transfer to water of reduced salinity than were embryos which had been prematurely removed from egg capsules and transferred to low-salinity sea water directly. However, the walls of N. lamellosa and N. lima capsules were found to be permeable to salts and at least to small carbohydrate molecules (glucose). Correspondingly, indirect evidence for all three species and direct evidence for N. lamellosa indicates that the osmotic concentration of intracapsular fluid declines to near ambient after transfer of egg capsules to dilute medium. Experiments conducted using embryos of N. lamellosa suggest that the egg capsules may protect embryos by reducing the rate at which the osmotic concentration of intracapsular fluid decreases rather than by reducing the magnitude of the decrease.
A well-supported phylogeny of the Neritopsina, a gastropod superorder archaic in origin, radiated ecologically and diverse in morphology, is reconstructed based on partial 28S rRNA sequences. The result (Neritopsidae (Hydrocenidae (Helicinidae + Neritiliidae) (Neritidae + Phenacolepadidae))) is highly congruent with the fossil records and the character distribution of reproductive tracts in extant taxa. We suggest that the Neritopsina originated in subtidal shallow waters, invaded the land and became fully terrestrial at least three times in different clades, by the extinct Dawsonellidae in the Late Palaeozoic and by the Helicinidae and Hydrocenidae in the Mesozoic. Invasion of fresh- and brackish waters is prevalent among the Neritopsina as the Jurassic and freshwater ancestory is most probable for helicinids. The Phenacolepadidae, a group exclusively inhabiting dysoxic environments, colonized deep-sea hydrothermal vents and seeps in the Late Cretaceous or Early Cenozoic. Submarine caves have served as refuges for the archaic Neritopsidae since the Early to Middle Cenozoic, and the marine neritopsine slug Titiscania represents a highly specialized but relatively recent offshoot of this family. The Neritiliidae is another clade to be found utilizing submarine caves as shelter by the Oligocene; once adapted to the completely dark environment, but some neritiliids have immigrated to surface freshwater habitats.
Preservation Recent neritimorph gastropods (especially those of the family Neritidae and Neritiliidae) are known to produce the hardest egg capsules of all molluscs EDS spectra of the egg capsule rim and central matrix. Fig. 5. Plot of measurements of fossil and Recent neritimorph egg capsules
- M N Zato
- A A Mironenko
- Fukumori
M. Zato n, A.A. Mironenko / Cretaceous Research 55 (2015) 285e291 4.3. Preservation Recent neritimorph gastropods (especially those of the family Neritidae and Neritiliidae) are known to produce the hardest egg capsules of all molluscs (Kano and Fukumori 2010; Fukumori et al., Fig. 4. EDS spectra of the egg capsule rim and central matrix. Fig. 5. Plot of measurements of fossil and Recent neritimorph egg capsules (data from Kano and Fukumori 2010; Zato n et al., 2009; 2013, and present study).
Cretaceous Bryozoa from the Campanian and Maastrichtian of the Atlantic and Gulf Coastal Plains, United States New data on the morphology of Spheno-thallus Hall: implications for its affinities
- P D Taylor
- F K Mckinney
Taylor, P.D., McKinney, F.K., 2006. Cretaceous Bryozoa from the Campanian and Maastrichtian of the Atlantic and Gulf Coastal Plains, United States. Scripta Geologica 132, 1e346. Van Iten, H., Cox, R.S., Mapes, R.H., 1992. New data on the morphology of Spheno-thallus Hall: implications for its affinities. Lethaia 25, 135e144.
An ammoniteefish association from the Kimmeridgian (Upper Jurassic) of La Rochelle, western France Gastropoda and Monoplacophora from hydrothermal vents and seeps; new taxa and records
- R Vullo
- L Cavin
- V Clochard
Vullo, R., Cavin, L., Clochard, V., 2009. An ammoniteefish association from the Kimmeridgian (Upper Jurassic) of La Rochelle, western France. Lethaia 42, 462e468. War en, A., Bouchet, P., 2001. Gastropoda and Monoplacophora from hydrothermal vents and seeps; new taxa and records. The Veliger.
Some Early Aptian Deshayesitidae from Central Daghestan
- T N Bogdanova
- I V Kvantaliani
- M Z Sharikadze
Bogdanova, T.N., Kvantaliani, I.V., Sharikadze, M.Z., 1979. Some Early Aptian
Deshayesitidae from Central Daghestan. Geologica Balcanica 9, 3e12 [in
Russian].
Molluscs: prosobranch and pyramidellid gastropods Published for the Linnean Society of London and The Estuarine and Brackish-Water Sciences Association by
- A Graham
Graham, A., 1988. Molluscs: prosobranch and pyramidellid gastropods. In:
Kermack, D.M., Barnes, R.S.K. (Eds.), Synopses of the British Fauna (New Series)
No. 2 (Second Edition). Published for the Linnean Society of London and The
Estuarine and Brackish-Water Sciences Association by E.J. Brill/Dr. W. Backhuys,
Leiden, 662 pp.
Preliminary investigations into the development of Neritina fluviatilis L. in brackish and fresh water. Videnskabelige Meddelelser fra dansk naturhistorisk Forening 104
- P Bondesen
Bondesen, P., 1941. Preliminary investigations into the development of Neritina
fluviatilis L. in brackish and fresh water. Videnskabelige Meddelelser fra dansk
naturhistorisk Forening 104, 283e317.
Published for the Linnean Society of London and The Estuarine and Brackish-Water Sciences Association by
- A Graham
Graham, A., 1988. Molluscs: prosobranch and pyramidellid gastropods. In:
Kermack, D.M., Barnes, R.S.K. (Eds.), Synopses of the British Fauna (New Series)
No. 2 (Second Edition). Published for the Linnean Society of London and The
Estuarine and Brackish-Water Sciences Association by E.J. Brill/Dr. W. Backhuys,
Leiden, 662 pp.