Jurassic Bivalves Research Articles

Late Jurassic (Kimmeridgian) bivalves from northwestern Algeria (Daïa and Nador mountains): Systematics and palaeobiogeography

The bivalve fauna of the Upper Jurassic (Kimmeridgian) successions belonging to the Daïa and Nador mountains (NW Algeria) is taxonomically described and figured. For the first time, sixteen bivalve taxa were identified, partly in open nomenclature because of their poor state of preservation. Most taxa are represented by internal casts. The fauna was collected from two different formations of the same age: the Dolomies de Tlemcen Formation in the Daïa Mountains and the Faïdja Formation in the Nador Mountains. The lithologic characteristics of these formations, together with their fossil content and taphonomic features, confirm that these localities are characterized by marine conditions. The north-western Algerian bivalve assemblage holds the largest portion of cosmopolitan species.

Drilling predation on Early Jurassic bivalves and behavioral patterns of the presumed gastropod predator—evidence from Pliensbachian soft-bottom deposits of northern Germany

AbstractDrilling predation is a common reason for mortality of benthic mollusks but did not become common until the late Mesozoic. The scarcity of drill holes in the early Mesozoic fossil record limits our understanding of the evolution of drilling behavior and its role on shaping early Mesozoic marine communities. Here, we use drilling traces on several bivalve taxa from the Lower Jurassic (Pliensbachian) marine soft-bottom deposits in northern Germany to explore behavioral patterns of the predator (e.g., site selectivity, change in site-selective behavior with age). Although none of the known drilling gastropod groups existed in the Pliensbachian, including the studied localities, the drill-hole morphology suggests that the predator was probably a gastropod. The ecology and identity of the target prey changes from a diverse array of epifaunal to infaunal taxa in older deposits to focus on a single, large, deep infaunal taxon, Gresslya intermedia, in younger deposits, suggesting a potential trend in prey selectivity over time. Spatial point pattern analysis of traces (SPPAT) reveals an aggregated pattern of drill holes on Gresslya, suggesting strong selectivity in drill-hole location. Drilling on a single large infaunal taxon and site selectivity are common patterns also inferred previously from the drilled deep infaunal Eothyasira from the Pliensbachian of southern Germany. In addition to the scarcity of predators, the highly specialized behavior of the early drilling predators, including strong prey selectivity in terms of prey identity and life habit, can partly explain the rarity of the early Mesozoic drill holes.

Jurassic bivalves from the Spiti area of the Himalayas, northern India

The present study describes and illustrates six bivalve taxa from the Early Bathonian to Early Callovian Ferruginous Oolite Formation and 24 taxa from the Callovian to basal-most Cretaceous Spiti Shale Formation of the Spiti and Zanskar areas in the Indian Himalayas. The Spiti Shale Formation contains a low-diversity bivalve fauna that is concentrated in few horizons, particularly in the lower member of the formation. With few exceptions, the bivalves are poorly preserved. Bivalve taxa recorded by earlier studies are revised wherever possible. Several of the taxa, most of which are from mid- to outer shelf environments, are characteristic of the south-eastern margin of the Neotethys, but some are also closely related to forms occurring in Kachchh, a rift basin situated at the western margin of the Indian Craton.

Peculiarities of Stratigraphic Distribution and Paleoecology of Jurassic Bivalve Mollusks of the Pre-Сarpathian Foredeep


 
 
 
 Pre-Carpathian region is one of the oldest oil and gas producing regions of our country, which is attracting more and more attention of scientists. In the Outer zone of the Pre-Carpathian Foredeep, Jurassic deposits occur at considerable depths (up to 3,000 m), so we obtain almost all geological information about them exclusively during the study of core material selected during drilling. A comprehensive and detailed study of the Jurassic deposits of this zone during exploration drilling in the 1950s contributed to the discovery of the Kokhanivske and Sudovovyshnianske oil deposits and Rudkivske gas deposit, as well as a number of oil and gas manifestations. After that, the interest in the conditions of formation and stratification of Jurassic deposits increased. Researchers have begun to treat them as the promising objects for oil and gas exploration. Jurassic deposits in the Pre-Сarpathian Foredeep fill a single depression – the Stryi Jurassic deflection, covered by a thick layer of Cretaceous and Neogene rocks. The study of their geology and stratigraphy has acquired important applied and scientific significance, because stratigraphic research serves as a basis for clarifying the history of geological development of the region, performing tectonic constructions, reconstruction of paleogeographic and paleoecological conditions, comparison of productive horizons and specification of their stratigraphic position, search for new objects promising for hydrocarbons. Extremely rare finds of paleontological remains (which are not always well preserved) do not allow to unambiguously determining the age of the host rocks. It is still not always possible to clearly stratigraphically distinguish and correlate these rocks due to weak paleontological study and partial uncertainty in the interpretation of the geological structure of these strata. Despite the significant amount of research we have done, there are some debatable issues regarding the completeness of the section of these rocks and the presence of separate stratigraphic units in them. For many years, we have studied in detail and comprehensively bivalve mollusks found in the core of wells drilled in the Outer zone of the Pre-Carpathian Foredeep. As a result, the age of the host strata was specified and confirmed, as well as the thickness of individual stratigraphic units.
 
 
 

Taxonomy and palaeoecology of the Early Jurassic (Pliensbachian) bivalves from Buttenheim, Franconia (Southern Germany)

Taxonomy and palaeoecology of the Early Jurassic (Pliensbachian) bivalves from Buttenheim, Franconia (Southern Germany)

The Early Jurassic Bivalvia from the Hettangian and Lower Sinemurian of south-west Britain

Part 3 continues the descriptions of early Jurassic bivalves from the Hettangian and Lower Sinemurian stages of south-west Britain. Nine species are assigned to the subclass Anomalodesmata, including the genera Pholadomya (Pholadomya), Homomya, Goniomya (Goniomya), Pleuromya, Platymyoidea (including P. morrisi sp. nov.), Gresslya, Pteromya and Mactromya. The genus Mactromya is reassigned from the Lucinoidea to the Edmondioidea based on hinge and musculature features.

The Early Jurassic Bivalvia from the Hettangian and Lower Sinemurian of South-West Britain Part 2

ABSTRACTPart 2 continues the descriptions of early Jurassic bivalves from the Hettangian and Lower Sinemurian stages of south-west Britain. Seven species are assigned to the subclass Heteroconchia, including the genera Neocrassina (Neocrassina), Cardinia, Tutcheria, Tancredia (Tancredia) and Protocardia (Protocardia). Two species are assigned to the subclass Lucinata, including the genera Mesomiltha and Luciniola.

Evolutionary and ecological patterns in body size, shape, and ornamentation in the Jurassic bivalve Chlamys (Chlamys) textoria (Schlotheim, 1820)

Changes in body size have been the subject of numerous palaeontological and neontological studies, but despite several general postulated "rules", the underlying processes controlling them are still incompletely understood, and their broad applicability is debated. Here we utilise morphological and ecological data from the Jurassic marine bivalve Chlamys textoria (Schlotheim, 1820) to analyse spatial and temporal trends in body size and ornamentation. We find: (1) fluctuations in body size during the Jurassic and no support for Cope's rule (the tendency to increase body size over geological time within an individual lineage); (2) a gradual increase in the average height to length ratio of the valves during the Jurassic. In the absence of any obvious adaptive advantage we suggest genetic drift as the causal mechanism; (3) a significantly larger mean body size in mid-palaeolatitudes than in the Jurassic tropics, providing evidence for the validity of Bergmann's rule (the assertion that body mass increases with latitude); and (4) a complex relationship between the number of plicae and the environment, which we explain as an improvement towards camouflaging the shell. doi:10.1002/mmng.201200002

Record of intense predatory drilling from Upper Jurassic bivalves of Kutch, India: Implications for the history of biotic interaction

The study of past biotic interactions is important not only to understand the paleoecological history of a community, but also to test the evolutionary role of such interactions. Drill holes in invertebrate exoskeletons provide one of the very few scenarios where biotic interaction could be studied directly and the related hypotheses could be tested with statistical rigor. Hence, the documentation and interpretation of the spatio-temporal patterns of drill hole frequencies has been the subject of extensive paleontological research. The two main gastropod groups responsible for the drilling predation in modern marine environment arose in Cretaceous as supported by their body fossil. However, the drill holes have been reported from the fossils of as far back as Precambrian age. The trend shows an overall low but variable intensity in Paleozoic and Mesozoic and a significant increase in Cenozoic. There are few reported cases of drilled bivalves from the Mesozoic, although in those instances, frequencies are fairly low. Most of the previous records of drilling predation during Paleozoic and Mesozoic come from North America and Western Europe. Here we report 148 drilled bivalve specimens of a single species from the Upper Jurassic horizon in western India. This is highest in number for any taxon ever recorded since Precambrian to Cretaceous. The frequency of drilling constitutes 30% of shells of the same species examined. This drilling frequency is highest when compared to all the reported Mesozoic drilling frequencies in Bivalves. The shapes of the drill holes are indicative of gastropod predation. The drilling gastropods responsible for these lethal attacks are also similar to their modern counterparts in terms of their highly selective prey choice and site-specificity. These results suggest that (1) Mesozoic bivalves were preyed upon by drilling gastropods, often with high intensities, and (2) the specialized characters of modern drilling predators were also present in Mesozoic. This largely unexplored record of bivalve drill holes from the Middle Mesozoic contradicts the general trend of “Mesozoic quiescence” as claimed by most researchers.

Ecophenotypic Plasticity Versus Evolutionary Trends—Morphological Variability in Upper Jurassic Bivalve Shells from Portugal

Upper Jurassic marginal marine strata of the Lusitanian Basin (central Portugal) yield a rich benthic macro fauna from which three bivalve target taxa, i.e., Arcomytilus, Isognomon, and Eomiodon, were chosen for morphometric studies, because of their abundance both in space and time and their variability in shell shape. The shells have been analysed with regard to outline shape (Fourier shape analysis), dimensions, ornamentation (Arcumytilus) and ligament arrangement (Isognomon). Additionally, data on co-occurring fauna and palaeotemperatures calculated from δ18O values have been recorded. The results of the morphometric analyses have been interpreted with regard to phytogeny and palaeoecology. In all target taxa, a distinct, rapid size increase at around the Early/Late Kimmeridgian boundary is evident. Potential causes for this process are discussed, and an increase in food availability is regarded the most likely scenario. In Isognomon rugosus, a distinct change in resilifer arrangement co-occurs with s...

The effects of taxonomic standardization on sampling-standardized estimates of historical diversity.

Occurrence-based databases such as the Palaeobiology database (PBDB) provide means of accommodating the heterogeneities of the fossil record when evaluating historical diversity patterns. Although palaeontologists have given ample attention to the effects of taxonomic practice on diversity patterns derived from synoptic databases (those using first and last appearances of taxa), workers have not examined the effects of taxonomic error on occurrence-based diversity studies. Here, we contrast diversity patterns and diversity dynamics between raw data and taxonomically vetted data in the PBDB to evaluate the effects of taxonomic errors. We examine three groups: Palaeozoic gastropods, Jurassic bivalves and Cenozoic bivalves. We contrast genus-level diversity patterns based on: (i) all occurrences assigned to a genus (i.e. both species records and records identifying only the genus), (ii) only occurrences for which a species is identified, and (iii) only occurrences for which a species is identified, but after vetting the genus to which the species is assigned. Extensive generic reassignments elevate origination and extinction rates within Palaeozoic gastropods and origination rates within Cenozoic bivalves. However, vetting increases generic richness markedly only for Cenozoic bivalves, and even then the increase is less than 10%. Moreover, the patterns of standing generic richness are highly similar under all three data treatments. Unless our results are unusual, taxonomic standardization can elevate diversity dynamics in some cases, but it will not greatly change inferred richness over time.

Faunal affinity of Toarcian-Aalenian (Early Jurassic) bivalves from Mae Sot and Umphang (Tak Province), Northwestern Thailand

In the Mae Sot and Umphang areas (NW Thailand), Jurassic strata seal the Permian and Triassic substratum of the Shan-Thai terrane with a brecciated conglomerate. Pliensbachian to Early Bajocian shallow marine strata are intercalated within the partly terrestrial Jurassic sequence. Thirty-five Toarcian-Aalenian bivalve species from Mae Sot and Umphang were identified. Among these,Eomiodon chumphonensis Hayami is known only from Thailand, whereasParvamussium donaiense (Mansuy),Myophoriella saurini Hayami,Thracia loducensis Hayami,Pholadomya (Bucardiomya) fontainei Hayami,Thracia loducensis Hayami andModiolus sestiniae Hayami were originally described in Vietnam.M. sestiniae also occurs in Iran. The greater part of the fauna, however, shows varying degrees of affinity with Myanmar (6 species), Cutch (10 species), Japan (13 species) and Europe (9 species), Levant (2 species). In view of these, it appears that these highly endemic Toarcian-Aalenian bivalves from Thailand characterize the Southeastern Asian Province of Tethys.

Taxonomic diversity dynamics of the Jurassic bivalves in the Caucasus: Regional trends and recognition of global patterns

Jurassic bivalves were quite diverse in the Caucasus—a region located on the northern margin of the Tethys Ocean. Stratigraphic ranges of 513 species were compiled. Total species number, already low, declined during the Early Jurassic, reaching its minimum in the Toarcian (27 species). Although this coincided with the Pliensbachian–Toarcian global mass extinction, the latter is not evident for the Caucasian bivalves. Diversity rises occurred in the Aalenian and then in the Bajocian, when 77 species existed. In the Bathonian species number did not change. A diversity explosion took place in the Callovian, when favourable palaeoenvironmental conditions were established. 163 species are known from deposits of this age. This event is recognized globally as generic diversity significantly rose at this time all over the world. When a rimmed shelf was developed in the Late Callovian–Oxfordian, total species number reached its maximum (166 species). But a regional salinity crisis in the Kimmeridgian–Tithonian led to a final diversity drop, when 86 species existed in the Tithonian. Bivalves could not recover at the end-Jurassic, along with other representatives of shelly benthos. Comparison with the other well-known salinity crisis, which occurred in the Messinian in the Mediterranean, suggests that the Late Jurassic event in the Caucasus was much stronger and stressed bivalve assemblages for a longer time. The influence of the end-Jurassic mass extinction has not been fully documented. Throughout the Jurassic benthic assemblages within the Caucasus changed rapidly. This regional diversity dynamics corresponds quite well to the global trends. Both sea-level and marine palaeotemperature changes may have had an indirect influence on regional bivalve diversity, as they fluctuated strongly during the Jurassic.

Early Jurassic shallow-marine bivalves from Xiaping, southern Hunan, China

Early Jurassic shallow-marine bivalves from Xiaping, southern Hunan, China

Middle‐Late Jurassic bivalves of the superfamily Veneroidea from New Zealand and New Caledonia

Bivalves of the families Arcticidae, Isocyprinidae n. fam., and Veneridae are described from the Middle‐Late Jurassic of New Zealand and New Caledonia. Morphology of shells from several genera in Arcticidae, Isocyprinidae, Veniellidae n. fam., and Veneridae is analysed in detail. These families are shown to be closely related in terms of morphological shell characters, especially ontogenetic and evolutionary hinge development. This is highlighted by identical ranges in commissural outline and shell form together with similar strength and form of ornamentation, and the fact that hinge plate development is an uninterrupted evolutionary process between Arcticidae and Isocyprinidae to Veneridae. These converging lineages show that Veneridae is at least diphyletic. This same evolutionary process is also shown to be an ontogenetic function of shells, with the final state of hinge development limited by maximum shell size. The family Corbiculidae is considered to be a major offshoot from one of the two lineages defined by Arcticidae‐Veneridae or Isocyprinidae‐Veneridae. These factors justify the superfamilies Arcticoidea and Corbiculoidea being synonymised with Veneroidea. In New Zealand, Isocyprinidae is represented by Austrocyprina n. gen. (one species). Veneridae is present in the form of Eocallista (one new species), and Austrocardilanx n. gen. (two new species). Arcticidae has been recorded from New Zealand and New Caledonia, and is represented by Antarctica n. gen. (one species).

Presence of a posterodorsal ridge in Jurassic to Recent larval shells of arcoidean bivalves

A posterodorsal notch is known from the larval shells (PII) of extant Ostreidae and Gryphaeidae. 1‐3 It results from a postanal ciliary tuft that deforms the shell edge and leaves a ridge-like growth track on the prodissoconch. 3 In fossil Ostreoidea this feature has been traced back into the Middle Jurassic, and was considered a probable autapomorphic character of the Ostreoidea. 4,5 The aim of this research note is, however, to document a posterodorsal ridge in some larval shells of Jurassic, Cretaceous, Eocene and Recent arcoid bivalves. All studied specimens were juveniles (� 3 mm in length), making determination of their taxonomic position below superfamily level beyond the scope of this study. The Recent material was collected in the lagoon and reef area of Foulpointe (also known as Mahavelona), 58 km north of Tamatave in northeastern Madagascar, from depths not greater than 5 m. The Eocene material was collected near Damery in the Paris Basin, France, and is of Lutetian age. 6 The Cretaceous material was collected in the vicinity of Ambatolafia in the Mahajanga Basin in northwestern Madagascar, and is of lower Albian age. 7 The Jurassic material was collected 3 km south of Zakaraha in southwestern Madagascar, and is of Bajocian age. 8 In all cases, sediment samples were taken and fractionated by sieving with mesh-sizes of 2.0, 1.0 and 0.5 mm. The Cretaceous and Jurassic samples were treated with a 5‐10% H2O2 solution using standard procedures prior to sieving. Specimens were mounted on stubs, sputter-coated with gold, and photos were taken with a Leo 1455VP scanning electron microscope. In all, 28 specimens belonging to seven species were examined (Table 1); in species E and G only right valves were available for study. The material is deposited in the palaeontological collection of the Museum fur Naturkunde in Berlin, Germany.

Selective extinction among Early Jurassic bivalves: A consequence of anoxia

Analyses of taxonomically standardized data sets demonstrate several statistically robust extinction patterns in Early Jurassic bivalve species from northwest Europe and the Andean basins of South America. In both regions, extinction intensities were significantly enhanced in late Pliensbachian and early Toarcian time as compared to all other time intervals. The same intervals (except for the early Toarcian of South America) also represent times of unusual extinction selectivity, with infaunal taxa suffering distinctly more than epifaunal forms. As infaunal suspension feeders are extremely rare components of Early Jurassic oxygen-controlled macrofaunas, these results are entirely compatible with sedimentological and geochemical data suggesting that widespread anoxia was a principal cause of the diversity crisis. Although many biotic traits that enhance survivorship during background times seem to be irrelevant during major mass extinctions, patterns of survivorship selectivity may provide more distinct clues to the causes of less severe mass extinctions.

Middle to Late Jurassic bivalves of the genera Neocrassina and Trigonopis from New Zealand

Bivalves of the genera Neocrassina and Trigonopis are described from the Middle‐Late Jurassic of New Zealand. Neocrassina is represented by three new species. The new subfamily Trigonopinae is introduced to accommodate the genus Trigonopis, which was previously classed as a subgenus of Opis. Trigonopis is represented by one previously described species and one new species. Paleobiogeography is analysed in terms of the global distribution of Neocrassina and Trigonopis. Neocrassina was present in most regions of the Boreal and Tethyan realms. In New Zealand, it is first recorded from rocks of Early Temaikan age (Aalenian‐Bajocian). The distribution of Trigonopis shows that this genus was common in European Tethyan regions, but sparsely distributed elsewhere. A comparison of New Zealand species, with forms from other regions, demonstrates that Trigonopis most likely migrated to the Jurassic southern ocean, by way of the temporary seaway connecting the Tethys Sea with the Bay of Antarctica, during the Callovian marine transgression.

The Jurassic Bivalve Genus Placunopsis: New Evidence On Anatomy and Affinities

The Jurassic bivalve genus Placunopsis Morris and Lycett, 1853 is shown to be an anomiid on account of the detailed anatomy of its hitherto unknown right valve and the corresponding musculature in the left valve. Herein the most appropriate choice for type species is considered to be P. inaequalis (Phillips, 1829), which accommodates a number of the larger Late Jurassic nominal species. A species from the English Bathonian previously confused with P. inaequalis is described as P. fuersichi sp. nov. Placunopsis inaequalis is shown to be closely related to Recent Pododesmus, which has previously been interpreted as the most ‘primitive’ of the extant anomiids on the basis of its anatomy. There is thus no need to retain a separate family for the genus, as has been proposed by some workers. The distinct small species P. socialis Morris and Lycett, 1853 can also be assigned to the anomiids on the basis of the differences between the structure of the outer layers in the two valves, and the presence of a byssal foramen. There is some suggestion of calcification of the byssus, but not enough detail is known of its musculature to justify transferring it to the genus Juranomia Fürsich and Werner, 1989 at this stage. The cemented bivalves traditionally referred to Placunopsis that are so common in the European Muschelkalk (Triassic) are not anomiids and thus require systematic revision.

Middle to Late Jurassic bivalves of the subfamily Astartinae from New Zealand and New Caledonia

Bivalves of the family Astartidae are described from the Middle‐Late Jurassic of New Zealand and New Caledonia. The subfamily Astartinae is represented by five genera, namely, Notoastarte n. gen. (five new species), Nicaniella (one new species), Oxyloma n. gen. (six new species), and Hemimenia n. gen. (two new species). The genus Neocrassina is currently under review. An overview of local stratigraphy is provided for astartine type localities. Paleogeography is analysed in terms of paleocurrents, sea‐level changes, faunal comparisons, and faunal distributions. These factors provide evidence for the temporary opening of an epicontinental seaway along the Gondic corridor, linking the Tethys Sea with the Bay of Antarctica, at least twice during the Middle Jurassic. Morphology of astartids is discussed in detail, and a revised hinge formula for the subfamily Astartinae is presented.