Cretaceous Bivalves Research Articles

Early Cretaceous bivalves of the Romualdo Formation, Araripe Basin, northeastern Brazil

The fossil-rich Romualdo Formation (late Aptian/early Albian), Araripe Basin, northeastern Brazil, contains world-renowned Fossillagerstätten characterized by exceptionally preserved fossils. Macroinvertebrates in this formation are primarily represented by mollusks, echinoids, and decapod crustaceans. Mollusk shells are abundant in certain stratigraphic intervals, forming coquinas or shell pavements. Despite recent advances in our understanding of the taxonomy of certain groups, comprehensive taxonomic studies are lacking for almost the entire bivalve fauna. Therefore, a detailed taxonomic analysis is presented here. The described bivalves include four new genera (Araripenomia, Ciceromya, Inversatella, Australoeocallista), and six new species (Araripenomia infirma, Inversatella cearensis, Ciceromya edentulosa, Australoeocallista juazeiroi, Legumen kaririense, and Corbulomima delicata), in addition to Musculus maroimensis, Crassatella maroimensis, “Myrtea” sp. and “Tellina” sp. This bivalve fauna mainly consists of cosmopolitan and endemic brackish/marine genera, with Tethyan affinities. The fauna is not homogeneously distributed in the sedimentary succession of the Romualdo Formation, but is constrained to the third order highstand systems tract. Bivalves recorded from muddy facies are strongly dominated by infaunal and semi-infaunal suspension feeders. Assemblages of the sand-dominated facies, with dense shell accumulations of semi-infaunal to epifaunal byssate and infaunal suspension feeders, were formed under shallow, higher energy conditions. Despite the degree of generic endemicity, the mytilids, anomiids, crassateliids, astartids, tellinids, and corbulids are related to the bivalve fauna of the Early Cretaceous Riachuelo Formation of the Sergipe-Alagoas Basin, as previously demonstrated for the bakevelliids and echinoids. Indeed, the Romualdo bivalve fauna is, in part, a modified and impoverished brackish/marine fauna of the Riachuelo Formation.

Body size evolution of the Late Cretaceous bivalves from Ariyalur, southern India

An organism's body size is one of its most fundamental and observable traits for extant and fossil taxa. In the present study, we document long-term evolutionary trends in body size of Late Cretaceous bivalves from the Ariyalur Sub-basin, southern India. Our data suggest a significant increase in bivalve body size from the Cenomanian to the Maastrichtian. However, this increase is not gradual and does not strictly follow Cope's Rule, the tendency for size to increase over time. Rather, a non-directional trajectory of body size increase is evident across various taxonomic ranks. The similarity between the long-term trends observed at higher (class and order) and lower taxonomic levels (family and genus) suggests congruence of the underlying macroevolutionary and microevolutionary processes. We evaluate these body size trends with respect to decreasing paleolatitudes and cyclic changes in the relative sea-level of the basin. Both of these factors are recognized to have influenced body size variation, but isolating the impacts of individual factors is challenging.

Putative hydroid symbionts recorded by bioclaustrations in fossil molluscan shells: a revision and reinterpretation of the cecidogenus Rodocanalis

AbstractThe fossil record yields a peculiar phenomenon in different kinds of molluscan shells: bioclaustrations formed around (epi)symbionts during growth of the hosts' shell margin. Four morphologies, two of them formerly considered bioerosion traces, are here united in the parataxonomy of bioclaustration structures under the revised cecidogenus Rodocanalis. These are: (1) simple linear grooves (Rodocanalis linearis csp. nov.) formed below the periostracum in Pleistocene to Recent endobenthic bivalves; (2) series of distally ramifying grooves (Rodocanalis runicus) in Silurian orthoconic nautiloids; (3) irregular networks of grooves (Rodocanalis reticulatus) in Jurassic to Cretaceous bivalves and gastropods; and (4) regular reticulate networks (Rodocanalis geometricus csp. nov.) in Jurassic to Cretaceous gastropods. The linear grooves might be associated with commensal worms, while multiple lines of reasoning point towards hydrozoan symbionts in the case of the branched and anastomosing grooves. After the hydrozoan larva settles and the first polyp becomes fixed on the calcareous ostracum at the shell margin, the process of bioclaustration commences when the periostracum surrounds the base of the polyp, which moves towards the external shell surface, while the hydrorhizae develop in the only possible direction: towards the shell growth margin. This enables new polyps to originate at the shell edge by budding, while the bioclaustration of the stolonial hydrorhizae advances. We consider the nature of this symbiotic relationship as mutualism, with the hydrozoan symbiont taking advantage of the host's feeding current or food debris, and the molluscan host profiting from the defensive capability of the hydrozoan's cnidocysts.

Upper Cretaceous bivalves from Northeastern Algeria: Description and paleobiogeography

The systematic study of bivalves collected from the Cenomanian-Turonian succession of the Bellezma-Batna Mountains (northeastern Algeria) led identification of nine species belonging to eight genera, three of which, Nicaisolopha nicaisei (Coquand), Pterotrigonia (Scabrotrigonia) scabra (Lamarck), and Agelasina plenodonta Riedel, were recorded for the first time from the study area. Particular attention was paid to the rudist fauna, including Vaccinites praegiganteus (Toucas), Vaccinites rousseli (Douvillé), and Sauvagesia nicaisei (Coquand), occurring in very large numbers within composite biostromes (5 to 10 m-thick) composed of both hippuritids and radiolitids. A distribution map of Cenomanian-Turonian bivalves is established based on data from Algeria and other localities.The map shows that the most bivalve genera are widely distributed and some of them are probably cosmopolitan. They are present in northern Africa, Middle East, south and northern Europe, western Africa, and South America, with some taxa are also known from the south-eastern coast of Africa (Madagascar and South Africa) and India.

Case study of the convergent evolution in the color patterns in the freshwater bivalves

The class Bivalvia (phylum Mollusca) is one of the most successful at survival groups of animals with diverse color patterns on their shells, and they are occasionally preserved in the fossil record as residual color patterns. However, the fossil record of the residual color patterns in freshwater bivalves could be traced only to the Miocene, greatly limiting color pattern evolution knowledge. We present the color patterns of the Cretaceous freshwater bivalves belonging to three extinct families of the order Trigoniida (hereinafter the Kitadani Freshwater Bivalves) from Japan, which is the oldest and the second fossil record of freshwater molluscan color patterns. The Kitadani Freshwater Bivalves consists of two types of color patterns: stripes along the growth lines and radial rays tapered toward the umbo, which resemble that of the colored bands of extant freshwater bivalves. This resemblance of the color patterns between the Kitadani Freshwater Bivalves and the extant species indicates that the color patterns of the freshwater bivalves represent the convergent evolution between Trigoniida and Unionida. To explain this convergent evolution, we advocate three conceivable factors: the phylogenetic constraints, monotonous habitats typical of freshwater ecosystems, and the predation pressure by visual predators in freshwater sediments.

Faunal change in Cretaceous endemic shallow-marine bivalve genera/subgenera of the northeast Pacific

Endemic shallow-marine Cretaceous bivalves in the northeast Pacific region (NEP), extending from southwestern Alaska to the northern part of Baja California Sur, Mexico, are tabulated and discussed in detail for the first time. Twenty-three genera/subgenera are recognized. Their first appearance was in the Valanginian, and their biodiversity continued to be very low during the rest of the Early Cretaceous. The bivalves of the middle Albian Alisitos Formation in northern Baja California are excluded because they did not live in the NEP. The highest number (13) of NEP endemic bivalve genera/subgenera occurred during the Turonian, which was the warmest time of the Cretaceous. At the Turonian/Coniacian boundary, when cooler waters migrated southward, there was a moderate dropoff in endemics that persisted until an origination event near the beginning of the early Maastrichtian, when 11 were present. Five of the 11 were present also during the Turonian, but the others were newcomers. Only three survived the turnover associated with the “Middle Maastrichtian Event” (MME), and none survived the K/Pg boundary mass-extinction event.

田代正之著「化石図鑑」日本の中生代白亜紀二枚貝

田代正之著「化石図鑑」日本の中生代白亜紀二枚貝

日本の中生代汽水生二枚貝化石群に関する研究の現状 : 天草地域の白亜系から産出する二枚貝の生息域とジュラ紀〜白亜紀マガキ類の古生態について( 干潟の自然,その過去と現在)

日本の中生代汽水生二枚貝化石群に関する研究の現状 : 天草地域の白亜系から産出する二枚貝の生息域とジュラ紀〜白亜紀マガキ類の古生態について( 干潟の自然,その過去と現在)

O-13 山中地溝帯東域から産出した白亜紀二枚貝化石とその意義

O-13 山中地溝帯東域から産出した白亜紀二枚貝化石とその意義

O-42 ロシア沿海州ジュラブレフカ帯から産出したテチス北方型前期白亜紀二枚貝化石(6. 環日本海-東アジアの地殻構造とテクトニクス,口頭発表,一般発表)

O-42 ロシア沿海州ジュラブレフカ帯から産出したテチス北方型前期白亜紀二枚貝化石(6. 環日本海-東アジアの地殻構造とテクトニクス,口頭発表,一般発表)

Early Aptian (Early Cretaceous) freshwater bivalves from the Australian–Antarctic rift, southeast Victoria

Australian Mesozoic freshwater and estuarine bivalves belonging to the Hyriidae, Glauconomidae and Sphaeriidae have been described from only a few localities in Queensland, New South Wales and South Australia, revealing a low-diversity fauna. The hyriids Megalovirgus flemingi McMichael, 1956, and Megalovirgus stirlingi sp. nov. are among the first Cretaceous freshwater bivalves to be described from Victoria and were recovered from upper Strezlecki Group (lower Aptian) strata, ca 4 km southwest of Inverloch, Gippsland Basin. These strata represent major fluvial flood deposits that accumulated in the Australia–Antarctica rift during the Early Cretaceous breakup of eastern Gondwana. The distribution of Megalovirgus flemingi in the Cretaceous of both New Zealand and Victoria indicates close links in the freshwater faunas between Zealandia and southeastern Australia during the Early Cretaceous.

Historical distribution patterns of trigonioidids (non-marine Cretaceous bivalves) in Asia and their palaeogeographic significance

The non-marine trigonioidid bivalves show five phases of radiation in the Cretaceous of Pal-Asia: pre-Aptian (?Valanginian/Hauterivian-Barremian), Aptian, Albian, Cenomanian and Turonian-Maastrichtian. Their distribution patterns show two distinct palaeo-river systems feeding trigonioidids. Before the Cenomanian, the river system occupied the southwestern-southern-southeastern Pal-Asian continental margin areas. During the Turonian-Maastrichtian, it extended along the line of southcentral China-eastern China-northeastern China-northern China and Mongolia-northwestern China-eastern Fergana Basin of Kyrgyzstan-western Tajikistan Basin of Tajikistan-Tashkent area of Kazakhstan-central Kyzylkum of northern Uzbekistan-Aral Sea area of Kazakhstan. Furthermore, the general trigonioidid distribution pattern demonstrates that Japan was probably attached to part of eastern China and/or Korea during the ?Valanginian/Hauterivian-Cenomanian stages.

Resolution and limitations of faunal similarity indices of biogeographic data for testing predicted paleogeographic reconstructions and estimating intercontinental distances: A test case of modern and Cretaceous bivalves

Faunas in biogeographic regions have been compared with descriptive indices such as the Jaccard, Simpson, and the probabilistic Raup–Crick coefficients. The question is which approach is the best for testing paleogeographic reconstructions. Based on modern geography and the location of predicted biogeographic boundaries, such as deep ocean basins, convergence of cold and warm water currents, and land barriers, I have plotted eleven faunal realms. Biogeographic data composed of presence or absence information on 996 species of modern bivalves within these realms were compiled and analyzed with the above listed indices. Land barriers and biogeographic regions separated by 6000 km. of deep ocean or widely spaced latitudinally produced statistically significantly different faunas. Convergence of cold and warm currents did not produce significantly different faunas. This may be due to seasonal movement of the convergence zone. A natural logarithmic transformation of the Jaccard's coefficient was found to show the best correlation between the bivalve fauna data and distance between biogeographic regions within an ocean basin. This may be because the Jaccard coefficient incorporates both faunal compositional and diversity differences in its measure. The best fit of the faunal data and distance by the least squares method is given by the equation: Distance = − [ln(JC) + 0.75209] / 0.00036. When applied to a Late Cretaceous bivalve fossil dataset, the distance obtained by the above equation gave a paleolongitudinal separation for North America and Europe similar to that based on magnetic anomaly sea floor data.

Early Cretaceous bivalves of the Neuquén Basin, west‐central Argentina: notes on taxonomy, palaeobiogeography and palaeoecology

AbstractThis paper provides an updated taxonomic inventory of the bivalve fauna collected in the Pilmatué Member of the Agrio Formation of the Neuquén Basin, west‐central Argentina, places the fauna in its palaeobiogeographic setting, and addresses its palaeoecological significance. Thirty‐one Late Valanginian to Early Hauterivian bivalve species within 24 genera were identified. A large part (32%) of the identified bivalve species occur over a wide geographical area: from the Pacific coast of South America to Europe, North Africa, Central Asia and East and South Africa; some are also recorded in Japan. A relatively high degree of endemism (26%) is shown, suggesting that some of the bivalve species had barriers to their dispersal; larval strategy and length of larval development were probably important. A significant number (42%) of the bivalve taxa are left in open nomenclature as they are probably new species. Bivalve guilds are described to interpret palaeoecology, in particular the ecospace utilization. Guilds are based on tiering, life habit, and feeding category. Eight guilds are recognized: free‐lying epifaunal, cemented epifaunal, epibyssate, boring, endobyssate, shallow burrowing, deep burrowing and deep burrowing with symbiotic bacteria. The fauna is composed only of suspension‐feeders indicating that food resources were dominantly in suspension, in agreement with the predominantly shallow‐water aspect of the study deposits. The ecospace utilization in the shoreface is broader than in the offshore shelf, suggesting more favourable living conditions and/or a wider range of different habitat types represented. Copyright © 2007 John Wiley & Sons, Ltd.

Middle Cretaceous (Cenomanian) bivalves from the Karai Formation, Uttattur Group, of the Cauvery Basin, south India

– Sixty species of Bivalvia, representing 28 families and 41 genera, are recorded from three outcrops of the Karai Formation (Uttattur Group, Cauvery Basin) near Odiyam village, Tiruchirapalli district, south India. Both Kunnam and Odiyam Members of the Formation are represented in the study material.

PALEOECOLOGY OF GIANT INOCERAMIDAE (PLATYCERAMUS) ON A SANTONIAN (CRETACEOUS) SEAFLOOR IN COLORADO

Giant Middle Coniacian to Lower Campanian Platyceramus Seitz is among the largest Cretaceous bivalves, commonly reaching an axial length of over 1 m, and occasionally over 2–3 m in size. The genus is characterized by its large size, very low convexity, normal inflation limited mostly to the umbonal area, and flattened flanks. It is especially common in moderately deep calcareous shale facies, as well as in chalks and limestones of the Niobrara Formation and equivalents. Preferred facies contain abundant pyrite, elevated total organic carbon (TOC), and very low biotic diversity. The genus maintains its giant size in these facies, and becomes more abundant. It clearly prefers dysoxic facies. As such, it probably is chemosymbiotic; photosymbiosis is almost ruled out because of inferred water depths of 200–350 m. It is also found more sparsely, and of smaller size, in oxygenated facies, including shoreface sandstone. The study area contains over 81 giant-sized Platyceramus platinus (Logan, 1898) on a single bedding plane; there are very few small ones. This allows spacing, orientation, and size analysis to be performed on an adult population.

Radiolarians, bivalves and the J/K boundary in the Birafu Formation, southern Kurosegawa Belt, Central Shikoku, SW Japan

The Oxfordian-Berriasian Birafu Formation in the southern Kurosegawa Belt (Permian accretion terrane), Central Shikoku, SW Japan, yields micro- and mega-faunas that contribute to the biostratigraphy across the Jurassic-Cretaceous boundary. The type section consists of turbiditic sandstone and mudstone with an upward-fining tendency in the lower members (A1–A3). The middle members (B1–B2) are coarse sandstone and mudstone with muddy limestone intercalations, whereas the upper member C is characterized by a fine-grained turbiditic succession. Radiolarians define the assemblage zones (AZ):Kilinora spiralis AZ (Oxfordian) in member A2,Loopus primitivus AZ (Tithonian) in the upper part of member A3, andPseudodictyomitra carpatica AZ (Berriasian—lower Valanginian) in members B2 and C. These give at least an Oxfordian—Berriasian total time-range to the Birafu Formation. The mixed marine and brackish bivalve assemblage of members B1 and B2 (lower part) comprisesGrammatodon takiensis Tamura,Pterotrigonia toyamai (Yehara) andCtenoides tosanus Kimura, the range of which is Late Jurassic to Earliest Cretaceous, andAguilerella nagatoensis (Ohta),Miltha japonica Tashiro andIsocyprina japonica Tashiro and Kozai, having an Early Cretaceous range. The concurrent range of Jurassic to Cretaceous bivalves and exclusively Cretaceous species is significant for the clarification of bivalve evolution across the Jurassic—Cretaceous boundary. The Berriasian appearance of Cretaceous marine and non-marine bivalves takes place while Late Jurassic marine bivalves still survived. We consider Member B1 as Berriasian with the J/K boundary situated at its base.

Diversity changes in Cretaceous inoceramid bivalves of Japan

ABSTRACT Temporal species-diversity changes in Japanese Cretaceous inoceramid bivalves were analyzed from an extensive literature survey and statistical analysis, with the following results: (1) Species diversity increased gradually from the Upper Albian to Lower Campanian, and then dropped suddenly across the Lower/Upper Campanian (LCa/UCa) boundary; (2) There is no statistical correlation between ammonoid and inoceramid diversity changes in Japan, which must reflect the different ecologies of both groups; (3) Relatively high extinction ratios occurred at boundaries near Oceanic Anoxic Events (OAEs). The extinction events at the Albian/Cenomanian, Cenomanian/Turonian, and Turonian/Coniacian boundaries were potentially caused by OAE1d, 2 and the onset of OAE3, respectively. The drastic diversity decrease at the LCa/UCa boundary probably resulted from an abrupt and large-scale relative sea-level fall in the Yezo forearc basin; and (4) The pattern of diversity changes is similar to that of long-term (2nd-or...

Cretaceous bivalves from Ecuador and northern Peru

New collections of bivalves from Cretaceous sections (Albian-Maastrichtian) in the central Andean Basin, a forearc basin in northern Peru/Ecuador, and the Paita Basins illustrate how paleobiogeographical affinities changed through geological time. During the middle Albian (at Chinimbini), the taxa are cosmopolitan. Upper Albian and Cenomanian faunas (Chinimbini, along Rio Misahualli in Ecuador, and at Pongo de Rentema in Peru) contain mainly Tethyan faunas (known from northern Africa, Texas, and southern Europe). The early Turonian faunas (mainly inoceramids) are Tethyan and have very wide extension. The Coniacian-Santonian faunas (Celendin Formation) are comparable to those from northwest and west Africa, but oysters have a somewhat younger age in Africa than in Ecuador and Peru. Most important, toward the Campanian-Maastrichtian, the faunas from the Paita Basins became largely endemic. For a few taxa of stratigraphical or systematic importance, a more detailed taxonomy is provided.

The influence of antipredatory morphology on survivorship of the Owl Creek Formation molluscan fauna through the end-Cretaceous extinction

The Hypothesis of Escalation states that organisms have changed throughout the Phanerozoic Eon by adapting to increased biotic hazards, such as predation or competition, by developing either physical or behavioral adaptations. One type of physical antipredatory adaptation among molluscs is the development of a thicker, more ornamented (escalated) shell. Although well-escalated organisms may have an advantage during intervals between mass extinctions, their thicker and/or more ornamented shells may provide a problem during extinction intervals when nutrients become scarce. Therefore, we propose that taxa with antipredatory adaptations are more prone to extinction during times of reduced productivity or nutrient availability. To test this hypothesis, upper Cretaceous bivalves and gastropods were collected from the Owl Creek Formation of Mississippi. Taxa were coded for the presence or absence of antipredatory characteristics, such as an overlapping margin and crenulated margin, among bivalve taxa, and apertural teeth, thickened lip and a narrow aperture, among gastropod taxa. The presence or absence of an umbilicus within gastropod taxa was also coded because it may increase a taxon's vulnerability to predation. A value between one and four was assigned to each taxon based on the degree of surface ornamentation and the thickness to height ratio was determined. The measured characteristics were analyzed statistically using the Fisher exact test, χ 2 test and Mann–Whitney U-test to determine whether their presence affected survivorship during the end-Cretaceous extinction. Survivorship was examined at the generic, subgeneric and specific levels. Two of the 36 tests revealed statistically significant results at the 0.05 level: the presence of a crenulated margin among bivalve genera ( p-value=0.031) and ornamentation among bivalve subgenera ( p-value=0.026). The statistical test for a crenulated margin suggests that bivalve genera with this adaptation were more likely to survive, contrary to our hypothesis, and the test for survivorship among bivalve subgenera with respect to ornamentation was significant in favor of our hypothesis. However, most of the statistical tests do not support the prediction that escalated molluscan taxa were more prone to extinction when compared to non-escalated taxa. Survivorship may not be predictable by analyzing only one aspect of an organism. Instead, it may be necessary to analyze statistically a combination of potential survivor strategies, such as morphology and trophic level or habitat.