Role of predation and parasitism in the extinction of the inoceramid bivalves: an evaluation

The inoceramid bivalves were dominant constituents of marine, epifaunal communities throughout the Late Mesozoic. They experienced a rapid decline in the Early Maastrichtian and virtually all taxa disappeared 1.5 Myr prior to the Cretaceous-Tertiary (K-T) boundary. The ultimate cause for their demise is still controversial. This study evaluates the role predation, parasitism and/or disease played in the evolution and extinction of Early Maastrichtian inoceramids from the Western Interior Seaway of North America (WIS). Escalation - the 'evolutionary arms race' between predators and prey - is said to be one of the most influential selective agents in evolution. Evidence of predation, parasitism, and disease in inoceramids is virtually undocumented prior to the Turonian. However, populations of inoceramids from the Late Cretaceous Pierre Shale show a marked increase in the number of individuals in which evidence for attempted predation and/or parasitism is preserved. The percentage of predation and/or parasitism steadily increases between the Baculites baculus and the B. grandis ammonite biozones (uppermost Campanian through Lower Maastrichtian) from 2.6% to values as high as 44.6%. The dramatic increase in shell deformities among inoceramids corresponds to a rapid radiation of shell-crushing brachyuran crabs and may be related to their activity. The introduction of new, efficient predators, such as brachyuran crabs, combined with parasitism and disease could have stressed inoceramid populations. Thus, they may have been more susceptible to environmental perturbations than under normal 'background' conditions. The disappearance of the inoceramids, at least from the WIS, may be one of the few cases where virtually an entire family lost the 'evolutionary arms race'.     

Shell mineralogical trends in epifaunal Mesozoic bivalves and their relationship to seawater chemistry and atmospheric carbon dioxide concentration

The Late Triassic-Early Jurassic change from aragonite- to calcite-facilitating conditions in the oceans, which was caused by a decrease of the Mg²⁺/Ca²⁺ ratio of seawater in combination with an increase of the partial pressure of carbon dioxide, also affected the shell mineralogy of epifaunal bivalves. In the “calcite sea” of the Jurassic and Cretaceous, the most diverse and abundant families of epifaunal bivalves had largely calcitic shells. Some of them, such as the Inoceramidae, acquired this shell mineralogy earlier in Earth's history but did not significantly diversify until the onset of “calcite sea” conditions. Others, however, replaced aragonite by calcite in their shell at the beginning of the Jurassic, as shown for the Ostreidae, Gryphaeidae, Pectinidae, Plicatulidae, and Buchiidae. In these families, replacement of aragonite by calcite took place in the middle and inner layer of the shell and was not associated with changes in morphology and life habit. It is therefore proposed that lower metabolic costs rather than higher resistance against dissolution or advantageous physical properties triggered the calcite expansion in their shells. This explanation fits well the observation that clades of thin-shelled bivalves were less affected by the change of seawater chemistry. Thick-shelled clades, by contrast, may suffer a severe decline in diversity until they adapt their shell mineralogy, as demonstrated by the Hippuritoida: The diversity of the Megalodontoidea, which failed to adapt their shell mineralogy to “calcite sea” conditions, dramatically decreased at the end of the Triassic, whereas their descendents became dominant carbonate producers during the Late Mesozoic after they acquired a calcitic outer shell layer in the Late Jurassic. These examples indicate that changes in the seawater chemistry and in the partial pressure of carbon dioxide are factors that influence the diversity of carbonate-secreting animals, and, as in the case of the decline of the Megalodontoidea, may contribute to mass extinctions.     

Exceptional preservation of a novel gill grade in large Cretaceous inoceramids: systematic and palaeobiological implications

Organised mineralised structures observed in large inoceramids (valves on a metre scale) from the Late Albian, Toolebuc Formation, Australia (Inoceramus sutherlandi McCoy, 1865), and the Santonian, Niobrara Formation, USA (Platyceramus sp.), were investigated using variable pressure scanning electron microscope (SEM) with energy‐dispersive X‐ray spectroscopy (EDX), X‐ray microcomputed tomography (micro‐CT) and X‐ray diffraction (XRD) analyses. These indicate that the structures comprised a phosphate framework of aligned tubes and shallow troughs overlain perpendicularly by evenly spaced structures. In the Toolebuc Inoceramus, these are U‐shaped cross‐structures, whilst in the Niobrara Platyceramus, they comprise bundled fibre elements. Comparison with modern bivalves indicates that the observed phosphatised structures represent soft‐tissue preservation of the gills, as suggested in earlier publications. The tubes and troughs are remnants of a filamental support framework comprising ordinary and primary filaments, whilst the U‐shaped cross‐structures (I. sutherlandi) and fibrous bands (Platyceramus) represent preserved longitudinal gill musculature. Internal perforate and strand‐like fabric observed on the internal surface of some Platyceramus tubular structures suggests that the framework comprised collagen. The presence of primary and ordinary filaments in numerous unusually large plicae, in at least two lamellae, indicates that the gill structures were heterorhabdic. Each plica has at least 40 ordinary filaments, an exceptional number when compared with the maximum of 20 present in modern heterorhabdic gills. The absence of incontrovertible interfilament junctions makes it difficult to say whether inoceramids were filibranch, pseudolamellibranch or eulamellibranch. However, structures that are best attributed to intraplical junctions between filaments suggest the Inoceramidae had gills akin to those of pseudolamellibranch bivalves, although their unusually large number of filaments per plica is more reminiscent of homorhabdic eulamellibranch gills. The general form of the gill is similar to that described in some other pteriomorphs, most specifically Pteria. However, it has more complex junctions and interconnections, although these are not as intricate or pervasive as those observed in the pseudolamellibranch Ostreidae. The connections and well‐developed filament framework allowed the gill to reach its unusually large size, supporting the large size of these inoceramid species. The unusually large size of the gill and its components indicate that the organism fed on the larger suspended organic particles in the water column. It would also have been capable of processing large volumes of water quickly, leading to greater potential for food accumulation and with likely implications for respiratory efficiency. This may help explain the common association of inoceramids with oxygen‐deficient palaeoenvironments, particularly as the general structure of the inoceramid gill is very different to that observed in the commonest extant chemosymbiotic bivalves.     

Tithonian-Berriasian foraminiferal faunas from the Torinosu-type calcareous blocks of the southern Kanto Mountains, Japan: their implications for post-accretionary tectonics of Jurassic to Cretaceous terranes

The Torinosu-type limestones, having many lithologic characters showing their original deposition on shallow shelves, are widely distributed in the Jurassic to Cretaceous terranes of Japan. The foraminiferal faunas from the Jurassic to the lowermost Cretaceous of Japan were first revealed in the calcareous blocks of the southern Kanto Mountains. Distinguished microfaunas consist of 39 species including many marker species of the Upper Jurassic to Lower Cretaceous in Europe, West Asia, and North Africa such as Melathrokerion spirialis, Charentia evoluta, Freixialina planispiralis, Nautiloculina oolithica, Everticyclammina cf. virguliana, Haplophragmium lutzei and Pseudocyclammina lituus. These faunas suggest a Tithonian to Berriasian age of Torinosu-type limestones. They are contained in four tectonostratigraphic units (Kamiyozawa, Hikawa and Gozenyama Formations; Ogouchi Group) continuously accreted from Middle Jurassic to Late Cretaceous. The younger deposition age of Torinosu-type limestones than the accretion age (Bajocian to Bathonian) in the Kamiyozawa Formation and their older age than the accretion age of the Ogouchi Group (late Albian to middle Maastrichtian) are important to date the post-accretionary tectonics of Jurassic to Cretaceous terranes of Japan and to explain the emplacement process of Torinosu-type limestones.     

Maria Helena Ribeiro Hessel: Lower Turonian inoceramids from Sergipe, Brazil: systematics, stratigraphy and palaeoecology

Abstract: Lower Turonian inoceramid bivalves are described from the Sergipe Basin in northeastern Brazil, and a palaeoecological analysis of the region is attempted. The principal locality, Retiro 26, comprises a sequence of 35 m of the Cotinguiba Limestone Formation. Various unconformities occur in the sequence. The formation is inferred to have been deposited in an outer shelf environment of a subtropical shallow sea, with oscillating water depth, occasional strong bottom currents and ephemeral reductions of the oxygen level. The inoceramids show some endemism. Two inoceramid associations are recognized: the Mytiloides mytiloides and the Mytiloides hercynicus associations. Four new species of divergently ornamented inoceramids are described and referred to the new genus Rhyssomytiloides . Two new species of Sergipia and some previously known species of Mytiloides and Rhyssomytiloides are also described.     

Modelling various sculptures in the Cretaceous bivalve Inoceramus hobetsensis

The geometry of the external shell sculpture in the Late Cretaceous inoceramid bivalve Inoceramus hobetsensis Nagao & Matsumoto, 1939 was studied both empirically and theoretically. A large sample, collected from the Upper Cretaceous of Hokkaido, Japan, shows remarkably high intraspecific variation in the shell sculptural pattern. Quasi-commarginal ribs, slightly oblique to the external growth increments, occur in some specimens. These sculptures are commonly irregular in strength and spacing, and their features are successfully modelled by computer simulations when the commarginal ribs are superposed with nearly concentric divaricate rib. Computer models indicate that the divergent sculpture element, often found in other inoceramids, was present throughout the evolution of I. hobetsensis and was developing in the evolutionary lineage from I. hobetsensis nonsulcatus to I. hobetsensis hobetsensis, although it was only weakly expressed. The results also suggest that some apparently distinct sculptural patterns of I. hobetsensis are the result of minor changes in the morphogenetic program.     

Mesozoic Radiolaria of Bosnia and Serbia: New data

Jurassic and Cretaceous radiolarian faunas were discovered in bedded chert of the Dinaric and Vardar tectonic zones of Bosnia and Herzegovina. Only Triassic radiolarians have previously been described in Bosnia and Herzegovina, while the finds of Bajocian, Bathonian-Callovian, Oxfordian-Kimmeridgian, Tithonian-Berriasian, and Campanian are new. Additional localities of Triassic and Jurassic radiolarians were investigated in Serbia. By correlation with radiolarians from the previous studies within Serbia, the Late Aalenian-Bajocian and Bathonian-Callovian Serbian radiolarian beds are newly dated. The first find of Cretaceous radiolarians in Serbia is reported. The oldest Mesozoic Radiolaria-bearing formations outcropping in the Western Belt of the Vardar Zone are dated Mid-Upper Triassic. The youngest radiolarians come from the Upper Cretaceous (Campanian) of the northern part of this belt of the Vardar Zone, where they co-occur with planktonic foraminifers. The distribution of 70 radiolarian samples within sections is shown. The taxonomic composition of 39 samples is analyzed. Radiolarian species extracted from 13 samples are described and figured. The list of 72 taxa and 3 plates of Jurassic radiolarians of Bosnia and Herzegovina, 3 plates of Triassic, 1 plate of Middle Jurassic, and 1 plate of Upper Cretaceous radiolarians of Serbia are presented.     

木兰科的化石记录

通过整理和分析木兰科植物的化石记录发现：不论是植物大化石还是花粉,迄今为止在白垩纪以前地层中尚无可靠的记录,自白垩纪以来,木兰科的许多种广泛发生于北半球,如亚洲,欧洲及北美等地,但非洲和大洋洲至今尚未发现木兰科的化石记录。该科最早的化石记录为中国东北延吉地区早白垩世大拉子组的喙柱始木兰Archimagnolia rostrato-stylose Tao et Zhang. 根据现有化石记录,并结合木兰科现代植物的地理分布,推测：1）木兰科的起源时间不迟于早白垩世Aptian-Albian期;2）木兰科起源地点可能是东亚,后来经过欧洲进入北美,再从北美迁移到达南美洲;3）在地质历史时期,木兰属的出现比鹅掌楸属早,从而支持根据形态学与分子系统学研究得出的木兰属较鹅掌楸属原始的结论。     

Upper jurassic to lower cretaceous carbonate facies of african affinities in a Peri-European area: Chalkidiki Peninsula, Greece

Summary The Epanomi-New Iraklia area (West coast of the Chalkidiki peninsula) is considered to belong to the Prepeonias subzone (or Gevgeli unit), with a palaeogeographic position near the European margin, represented by the Serbo-Macedonian massif, and at a considerable distance from the fragmented African plate, the marginal block of which is here the Pelagonian Domain. In some boreholes in the area an Upper Jurassic to Lowei Cretaceous limestone sequence has been observed, ending with an unconformity and followed by an Upper Middle-Lower Upper Eocene transgressive bioclastic limestone, an Upper Eocene to Lower Oligocene clastic series and Neogene deposits. This Upper Jurassic to Lower Cretaceous carbonate platform sequence and probably the Upper Jurassic limestones with bauxites of the nearby Mt. Katsika, show African affinities, viz: the presence of the essentially Aptian algal speciesSalpingoporella dinarica, an African plate marker; the chlorozoan type association and the bauxite formation during the Late Jurassic indicating tropical conditions; finally, the chloralgal type association and the sporadic presence of radial-fibrous ooids during the Early Cretaceous indicating peritropical conditions. Lower Cretaceous limestones are apparently missing in the innermost Hellenides. In the Pelagonian Domain s.l., on the other hand, Upper Jurassic to Lower Cretaceous limestones are found in some places, with same characteristics as in the Epanomi-New Iraklia boreholes. On the contrary, the Upper Eocene to Lower Oligocene clastic series of the boreholes can be correlated with the Axios (=Vardar) molassic basin, inline with its present situation. During the Mesozoic, the Epanomi area therefore belonged to a micro-block, next to the NE margin of the Pelagonian Domain, in contrast to earlier interpretations. Its present time position results from Early Cenozoic tectonic phases.     

Lizards of the family Hodzhakuliidae (Scincomorpha) from the lower Cretaceous of Mongolia

The lizard family Hodzhakuliidae (Scincomorpha) endemic to the Early Cretaceous of Central Asia is characterized in the light of finds from the Khoobur (Höövör) locality in Mongolia. Available material includes Hodzhakulia magna Nessov, 1985 described from the Upper Albian of Uzbekistan and three new genera and species. It is proposed that Hodzhakuliidae occupied the adaptive zone of small carnivorous predators before the appearance of Platynota.     

The oldest species of the genus <Emphasis Type="Italic">Glaphyrus</Emphasis> Latr. (Coleoptera: Scarabaeoidea: Glaphyridae) from the Mesozoic of China

Glaphyrus ancestralis sp. nov. is described from the Yixian Formation (Upper Jurassic or Lower Cretaceous). The species is not only one of the earliest records of the family Glaphyridae but also the oldest representative of an extant genus of the family.     

J. Deprat,l’Eubée (Grèce) et les fossiles introuvables

In Evia (Greece), limestones attributed to the lower Cretaceous by J. Deprat are in fact of Triassic to Upper Jurassic age. These erroneous attributions are based on the allegedly presence of Barremian and Albian fossils and on the supposed progressive passage of these limestones to the Cenomanian ones. Generally, except for the upper Cretaceous rich in Rudists and known since older works, a big part of the stratigraphical attributions of J. Deprat in Median Evia are erroneous.     

Maastrichtian island in the central European Basin—new data inferred from palynofacies analysis and inoceramid stratigraphy

The palynological study and palynofacies analysis supported by size analysis of opaque phytoclasts and diversity indexes for particulate organic matter in stratigraphically well-constrained (inoceramid biostratigraphy) sections is applied in monotonous Upper Cretaceous carbonate-siliciclastic sediments of southern Poland. Integrated data allow for the estimation of the proximity of an uplifted area from the studied sections. For the first time in palynofacies analysis, both Simpson’s Index of Diversity (1 ? D) and Shannon’s index are used for organic matter distribution providing a comprehensive understanding of a proximal–distal trend in a sedimentary basin. Cluster analysis allowed grouping the samples within proximal to distal shelf zones. The size analysis of opaque woody phytoclasts is used to extrapolate the distance from the source area. Palynofacies analysis indicates the existence of an uplifted area (probably connected with “Kukernitz Island”) in the Holy Cross part of the Danish-Polish Trough during the Maastrichtian. The presented results improve contemporary paleogeographical interpretations for this part of the Late Cretaceous central European Basin. The youngest Maastrichtian deposits of the Miechów Synclinorium are described, based on inoceramids which are of early Late Maastrichtian age.     

A NEW LATE CRETACEOUS MACROSEMIID FISH (NEOPTERYGII, HALECOSTOMI) FROM MOROCCO, WITH TEMPORAL AND GEOGRAPHICAL RANGE EXTENSIONS FOR THE FAMILY

Abstract:  A recent collection of actinopterygian fossil fishes from a previously unreported locality in the Cenomanian or Turonian of southeastern Morocco includes a single specimen of a macrosemiid fish. Macrosemiids are more common in Jurassic and Early Cretaceous deposits, with the previously known range of the family being Late Triassic through Aptian or Albian. This discovery therefore extends the temporal range of the family into the Late Cretaceous. Moreover, macrosemiids had not previously been reported from northern Africa or the Moroccan area of the Tethys basin; therefore, this fossil also increases the geographical range of the family. The Moroccan macrosemiid is described in a new genus and species, Agoultichthys chattertoni . A phylogenetic analysis places it basal to all other genera of the family with the exception of Notagogus . Diagnostic characters of the new species include the high number of scales laterally along the body and the greater number of dorsal fin rays than in other members of the family.     

Echinochara triplicata sp. nov. (Clavatoraceae,fossil Charophyta) from the Lower Albian of Tunisia

Echinochara Peck, 1957 is a poorly known charophyte genus from the Upper Jurassic and Lower Cretaceous of the United States and Europe. Its fossil record is currently limited to two species, Echinochara spinosa Peck, 1957 and Echinochara peckii (Mädler, 1952) nov. comb. Grambast, 1956 emend. Schudack, 1993, which have obscure phylogenetic relationships. A third species of this genus, Echinochara triplicata nov. sp., is described here from the Lower Albian of Jebel Koumine (Central Tunisia) and is hypothesized to derive from the Barremian-Aptian morphotypes of Echinochara peckii. The new species represents the first record of the genus in Africa and its more recent record worldwide. It occurs along with the clavatoraceans: Clavator harrisii zavialensis and Atopochara trivolvis trivolvis and provides an additional tool for the biostratigraphic characterization of non-marine Albian of Europe and North Africa.     

Armored dinosaurs(Ornithischia: Ankylosauria)) from the Middle and Upper Jurassic of England

Hitherto the earliest positive record of ankylosaurs(armored dinosaurs) has been from beds well up in the Lower Cretaceous; in fact, however, specimens referable to the ankylosaurian family Nodosauridae are present in the Middle and Upper Jurassic of England: from the Middle Callovian [partial mandible Sarcolestes leedsiLydekker]], the Upper Oxfordian [femur Cryptodraco eumerus (Seeley)), maxilla Priodontognathus phillipsii (Seeley))], and the Upper Tithonian [caudal vertebra, tooth]. The Tithonian tooth and those of Priodontognathus are large and similar to those of the nodosaurids Priconodon and Sauropelta (Lower Cretaceous, U.S.A.). The incomplete mandible of Sarcolestes is similar to that of Sauropelta with a dermal scute fused to the lateral surface, and a tooth row extending to the anterior end of the jaw; an unusual feature is the caniniform first tooth. The quadrupedal ankylosaurs and stegosaurs probably represent separate evolutionary lines that extend back at least into the Lower Jurassic, and both lines probably evolved from ornithopod dinosaurs that were bipedal. Nodosaurid ankylosaurs occur in Europe from the Middle Jurassic to Late Cretaceous and probably reached North America via a filter route in the early Cretaceous.     

民和盆地早白垩世晚期的孢粉组合

民和盆地的甘肃兰州柴家台地区,下白垩统河口组上亚组含有较丰富的孢粉化石。上亚组上部是以Ｓｃｈｉｚａｅｏｉｓｐｏｒｉｔｅｓ－Ｃｉｃａｔｒｉｃｏｓｉｓｐｏｒｉｔｅｓ为代表的孢粉组合,并可划分出上下两个亚组合,分别以Ｃｌａｓｓｏｐｏｌｌｉｓ－Ｓｃｈｉｚａｅｏｉｓｐｏｒｉｔｅｓ和Ｐｉｃｅａｐｏｌｌｅｎｉｔｅｓ－Ｃｉｃａｔｒｉｃｏｓｉｓｐｏｒｉｔｅｓ来表示。通过对主要孢粉属种地史分布规律的分析和与国内外各地同时代孢粉组合的对比,认为其地质时代是早白垩世晚期的Ａｐｔｉａｎ－Ａｌｂｉａｎ 期,上部的第二亚组合可能更晚,为Ａｌｂｉａｎ 期;孢粉化石产出的这段地层是迄今民和盆地所发现的下白垩统最高的层位     

Ephedroid fossil pollen from the Lower Cretaceous (Upper Albian) of Hokkaido,Japan

This paper presents eight ephedroid palynomorphs from the Lower Cretaceous (Upper Albian) of Hokkaido, Japan. The ephedroid palynomorphs are ellipsoid and polyplicate pollen grains that show a wide range of variation in pollen size, shape, and plication. These ephedroid palynomorphs suggest a wide range of diversity in Gnetales at mid- or high-paleolatitude in the eastern side of Lauresia during the Upper Albian.     

Biostratigraphy of Lower Cretaceous microfossils from the Araripe basin, northeastern Brazil

A biostratigraphic study was carried out in the Lower Cretaceous Araripe basin, northeastern Brazil, allowing the recognition of several chronostratigraphic units: the Dom João (Jurassic?-Lower Cretaceous?), the Rio da Serra (Neocomian) and the Alagoas (Aptian/Albian) local stages. For the first time a large hiatus between the Rio da Serra and Alagoas local stages is carefully documented. The palynomorphs and the ostracode associations throughout the Jurassic?-Aptian/Albian sequence allow the interpretation of the paleoenvironmental evolution of the Araripe basin which otherwise confirms that a polycyclical sedimentation occurred in the basin, being one of the controlling factors on the distribution of ostracodes and palynomorphes.     

Larval shell morphology of <Emphasis Type="Italic">Inoceramus pictus</Emphasis>: all suspicions confirmed

Inoceramids were eurytopic bivalves and have a wide application as biostratigraphic index fossils in the Upper Cretaceous. Their paleoecology, however, is far from being understood. Here the prodissoconch of Inoceramus pictus is described. It was found in an upper Cenomanian shallow water methane-seep deposit in the Tropic Shale, southern Utah, USA. The larval shell consists of a small prodissoconch-1 and a large prodissoconch-2. The shell morphology indicates a planktotrophic larval phase with wide dispersal potential, and which confirms previous hypotheses of inoceramid larval ecology. Comparison with other inoceramid prodissoconchs shows that larval shell morphology cannot generally explain dispersal, and that more factors must have played a role in the distribution of species.