How to recognize in situ fossil cephalopods: evidence from experiments with modern Nautilus

Field and flume experiments with modern Nautilus pompilius establish two prerequisites to recognize in situ preservation of fossil cephalopod shells (soft parts were within body chamber in situ at the time of fossilization): occurrence of the upper jaw within the body chamber and the position of jaws within the body chamber. Morphology of shells and jaws in modern and fossil nautiloids is so similar that these prerequisites can be applied for fossil nautiloids and provide implications for ammonoids. The upper jaws of Nautilus start to move at a water velocity of > 0.2 m/s, when the shells are reoriented with the aperture downstream; jaws are therefore unlikely to be secondarily deposited near the shell aperture by bottom currents. The lower jaws, moved at the velocity of > 0.1 m/s, can be deposited around the shell aperture by weak current (0.1–0.2 m/s in velocity), but never enter the inside of body chamber. Neither jaw is likely to be separately and selectively displaced from the inside of the body chamber through scavenging of the soft parts by burrowing infaunal animals. An upper jaw preserved inside the body chamber, together with a lower jaw, is thus a reliable indicator of in situ preservation; a sole lower jaw preserved around the shell aperture is likely to be secondarily deposited. Sedimentary structures inferring rapid burial events and jaw size are useful as additional evidence. Smaller jaws were more likely to be displaced from the body chamber by scavenging by infaunal animals after in situ burial, so that smaller jaws preserved within the body chamber suggest less scavenging. These findings are crucial to interpreting the taphonomic history and palaeo-ecology of fossil cephalopods.     

黔北上奥陶统宝塔组头足类多样性初探*

上奥陶统宝塔组(桑比阶–凯迪阶)是华南分布广泛的标志性地层单元, 以发育特殊的网纹状灰岩并产出大量头足类化石为特征。黔北桐梓县尧龙山地区的宝塔组厚度较大, 出露极好, 产出数量丰富、保存精美和特征典型的头足类化石。本文在研究区酒店垭、集镇采坑和天域极地3个宝塔组剖面采集到大量原域埋藏的头足类化石, 共8属11种及少量属种未定类型, 以直形壳或盘形壳、体管很小且适合远洋深水游泳的类型为主, 整体上符合扬子台地深水陆棚Sinoceras–Michelinoceras–Disoceras生物相特征。基于壳体扩大率、壳径与体管直径比、气室高与隔壁颈长比、隔壁下凹度、壳径与气室高比等参数变量的主成分分析表明, 在外部特征不显著的情况下, Sinoceras和Michelinoceras的直观差别是壳体扩大率, 而Michelinoceras属不同种的差异主要体现在气室高与隔壁颈长之比, 其他特征的区分度并不明显。层面上单位面积的化石定量统计显示, 尧龙山地区宝塔组中头足类的多样性较高, 并以Sinoceras和Michelinoceras具有极高的个体丰度为特征。扬子板块在奥陶纪桑比期–凯迪期之交处于高水位的陆表海环境, 栖息环境均一化和生态系统复杂化可能是促进该时期头足类动物的复苏和多样性演化的重要原因。     

A new fossil bird from the Early Cretaceous of Gansu Province,northwestern China

We report on the discovery of an Early Cretaceous bird from northwestern Gansu Province, in northwestern China. Represented by a nearly complete left wing and shoulder girdle the size of a rock dove, the new bird was quarried from laminated yellowish mudstones of the Xiagou Formation (Xinminpu Group) near Changma, in the Jiuquan area. These deposits have previously yielded the only known specimen of Gansus yumenensis, a basal ornithuromorph represented by the distal half of a hind limb with long and slender digits. Several derived characters of the new occurrence supports its allocation within Enantiornithes: (1) a convex lateral margin of the coracoid, (2) a minor metacarpal that projects distally more than the major metacarpal and (3) a proximal phalanx of the major digit longer than the intermediate (second) phalanx. The general proportions of the wing suggest it was a flier comparable to most other known enantiornithine birds. Although, direct comparisons between the new fossil and Gansus are not possible, phylogenetic based inferences supports their placement into two different clades. While the new fossil falls definitively within the enantiornithines, G. Yumenensis falls within the ornithuromorphs. The new occurrence thus adds to the taxonomic diversity of Early Cretaceous birds from Gansu Province in particular and central Asia in general.     

Multicellular-like compartmentalization of cytoplast in fossil larger foraminifera

Foraminifera are usually between 0.1 and 1 mm in size, thus falling within the range of the largest eukaryotic cells. However, some fossil and extant foraminiferal species reach diameters of more than 100 mm. One hypothesis of how these gigantic sizes could have been attained by these unicellular organisms is the temporary compartmentalization of cytoplasm into smaller volumes of effective metabolism, as reported for several recent species. Evidence of this phenomenon is shown in fossil genera of larger foraminifera belonging to five families of Cretaceous to Oligocene age. Alternative interpretations are discussed.     

Pollen morphology and fossil record of the feathery mistletoe family Misodendraceae

Misodendraceae is a small family of mistletoes in the order Santalales. Its distribution is restricted to the southern South American temperate forests. The family comprises the sole genus Misodendrum with eight species of hemiparasitic shrubs, mainly parasitising the southern beech Nothofagus. This contribution presents palynological evidence from seven species, using light microscopy and scanning electron microscopy. Pollen grains are consistently small, periporate and echinate, although differences in the length of echini and number and size of pores were noted. Pollen features can be used to distinguish groups of species and, in some cases, individual species. Cluster analysis of pollen characters differentiates two main groups: one includes M. brachystachyum, M. oblongifolium and M. quadriflorum; and the other includes M. gayanum, M. linearifolium, M. punctulatum and M. angulatum. Palynological results are compared with previous systematic studies of the family. The South American fossil pollen record is summarised and characters of the fossil pollen are analysed using UPGMA to test the relationships between extant and fossil species. Miocene pollen resulted similar to species of subgenus Angelopogon while Eocene pollen is disimilar to extant species of Misodendraceae.     

Bichordites monastiriensis from the Pleistocene of southeast Jamaica

Bichordites monastiriensis Plaziat and Mahmoudi 1988, produced by burrowing spatangoid echinoids, is figured and described from shallow marine siliciclastic strata of the Pleistocene Old Pera Beds (Coastal Group) of southeast Jamaica. Its occurrence there represents only the second formal recording of this monospecific ichno‐taxon and extends its geographic range from the Mediterranean region to the Caribbean. The spatangoid species that produced this trace fossil is unknown, but, unlike examples from other areas, it is unlikely to be Echinocardium.     

Pelagic cephalopods from eastern Australia: species composition, horizontal and vertical distribution determined from the diets of pelagic fishes

The distribution and relative biomass of cephalopods from pelagic waters off eastern Australia was examined between 1997 and 2004 from stomach contents of swordfish, yellowfin tuna and dolphinfish taken in the domestic longline fishery. A total of 38 taxa from 19 families were identified. Comparison of the species composition of the three predators indicated pronounced differences in cephalopod species composition. In swordfish, species of the family Ommastrephidae, particularly Ommastrephes bartramii (Lesueur 1821) and Nototodarus gouldi (McCoy 1888) dominated, whereas a more diverse mix of species was identified from yellowfin-sampled cephalopods. Todaropsis eblanae (Ball 1841) was the main cephalopod sampled from the surface-dwelling dolphinfish. For swordfish-sampled cephalopods, significant relationships were found between biomass and season, fluorescence and year. In yellowfin tuna, cephalopod biomass was significantly correlated with season, area and sea surface temperature. Significant factors differed between predator-sampler, possibly reflecting the limits of the predator, but could also give insights into individual cephalopod species distributions. However, the increase in cephalopod biomass over summer in both swordfish and yellowfin tuna suggested cephalopod biomass was higher over summer in the region.     

Bryozoans as substratum of fossil fistulose Foraminifera (Fam. Polymorphinidae)

In the Upper Cretaceous-Lower Tertiary sections exposed in the Curfs quarries at Berg (munic. Berg en Terblijt - also known as Geulhem, southern Netherlands) and some other localities, numerous foraminifers of the family Polymorphinidae with complete fistulose apertures have been found. These apertures, which are equipped with circular openings and auxiliary apertural chambers, branching and numerous narrow projecting tubes or stolons, have been widely reported, but their role has been the subject of controversy. The Dutch material shows the foraminifers attached with the apertural tubes to fragments of bryozoan colonies or molluscan shells, suggesting that the tubes could perhaps act as holdfast organs. Most specimens were found in calcarenites of the nearshore facies. The foraminifers cannot be treated as symbiotic organisms nor parasites but as epifauna in search of protection from mechanical destruction by waves and current action. The present case may be best explained as an adaptation of sessile foraminifers with fragile hyaline tests to live in highly disadvantageous, high-energy conditions.     

Field sampling bias, museum collections and completeness of the fossil record

Museum specimens, particularly old collections, typically lack comprehensive field data and determination of substrate, sampling biases, etc., is problematic. Diversity at the generic level of all identifiable latest Cretaceous (Campanian–Maastrichtian) echinoderm remains in major museum collections from the Mons (southern Belgium) and Danish (Jylland (Jutland) and Sjælland (Zealand)) basins were compared to those of the Liège-Limburg Basin. The last-named has been studied in detail, including microscopical analysis of ossicles picked from bulk samples. Echinoids of the Mons Basin show similarities to those of the Liège-Limburg Basin, but crinoids, asteroids and ophiuroids remain poorly known from the former. Echinoderms of the Danish Basin resemble those of similar chalk lithofacies in the Liège-Limburg Basin, despite significant geographical separation. These disparities can be explained, at least in part, by collector bias in sampling methodology, although differences in substrate presumably also had an influence.     

A new fossil flower from the Turonian of New Jersey: Dressiantha bicarpellata gen. et sp. nov. (Capparales)

Recent discoveries of fossil reproductive structures from deposits of the Raritan Formation in New Jersey (Turonian, Upper Cretaceous, ~90 million years BP) include a previously undescribed representative of the Order Capparales. The fossils are usually charcoalified with three-dimensional structure and excellent anatomical details. In the present contribution, we introduce a taxon represented by fossil flowers that have a combination of characters now found in the families of the Order Capparales sensu Cronquist. The fossil species is characterized by an unique suite of characters, such as the presence of a gynophore, arrangement of the sepals, unequal petal size, monothecal anthers, and a bicarpellate gynoecium, that are found in extant families of the Order Capparales. This new taxon constitutes an important addition to our understanding of Cretaceous angiosperm diversity and represents the oldest known fossil record for the Capparales. Heretofore, the oldest known capparalean was from the Late Tertiary sediments of North America.     

Brood chambers constructed from spines in fossil and Recent cheilostome bryozoans

Most cheilostome bryozoans brood their larvae in skeletal structures called ovicells which, in evolutionary terms, were derived from spines. Ovicells in the great majority of fossil and Recent cheilostomes, however, have lost all or most traces of their spinose origin. Here we review the occurrence of spinose (including costate) brood chambers in cheilostomes, investigating in detail 32 species belonging to ten genera among five families (Calloporidae, Monoporellidae, Macroporidae, Cribrilinidae and Tendridae). Spinose ovicells are moderately common in the Upper Cretaceous, where they are recorded in 28 species, and also occur in one Palaeocene, seven Eocene‐Miocene and 11 Recent species. The most primitive cheilostome ovicells occur in mid‐Cretaceous calloporids in which a group of mural spines belonging to the distal zooid were apparently bent towards the maternal zooid to form a cage‐like structure for reception of the embryo. The bases of these spines were initially aligned in a distally concave row that later became straight, distally convex and finally horseshoe‐shaped, affording progressively better protection for the developing embryo. We suggest that primitive monoporellids inherited from calloporid ancestors a distally concave arrangement of ovicell spine bases, while cribrilinids inherited a horseshoe‐shaped arrangement. Important trends that can be recognized in early ovicell evolution include: (1) loss of basal spine articulation; (2) spine flattening; (3) closure of the gaps between spines; (4) reduction in spine number (through loss or fusion), and (5) development of a concave ovicell floor. The conventional ‘unipartite’ ovicells found in the majority of cheilostomes may have originated either by spine fusion, as seems likely in some cribrilinids, or through a progressive loss of spines via an intermediate stage, seen in some calloporids and in two monoporellids, where the ovicell comprises a large pair of flattened spines. The spinose ovicells of some monoporellids and macroporids subsequently evolved investments of hypostegal coelom that allowed secretion of a surface layer of cryptocystal calcification. Acanthostegous brood chambers characteristic of Tendridae apparently provide an example of independent evolution of spinose brooding structures. © 2005 The Natural History Museum, London, Zoological Journal of the Linnean Society, 2005, 144 , 317?361.     

Heteromorph ammonites from the Tata Limestone Formation (Aptian–Lower Albian), Hungary

An important new ammonite fauna was collected by Fülöp in 1953 and 1960 from basal lenses between a Tithonian hardground and the overlying Tata Limestone Formation containing many heteromorph ammonites. This assemblage of ammonites has been determined as being of Early Albian ( tardefurcata Zone) age. Among the heteromorphs are species of Tonohamites and Ptychoceras , which are familiar components of Late Aptian or Early Albian ammonite faunas. The genera Ephamulina , Hamites and Protanisoceras are also recorded, the earliest species of which had previously come from sediments of late Early Albian ( mammillatum Zone) age. While Hamites and Protanisoceras are common in Europe, Ephamulina had previously only been known from Madagascar. The discovery of Ephamulina , Hamites and Protanisoceras supports the view that these phylogenetically significant ammonites had radiated close to the Aptian/Albian boundary. Four new species of Hamites ( H. czaszari , H. fazekasensis , H. fueloepi and H. kalvariensis ) and one new species of Tonohamites ( T. boldii ) are described.     

Insect-damaged fossil leaves record food web response to ancient climate change and extinction

Plants and herbivorous insects have dominated terrestrial ecosystems for over 300 million years. Uniquely in the fossil record, foliage with well-preserved insect damage offers abundant and diverse information both about producers and about ecological and sometimes taxonomic groups of consumers. These data are ideally suited to investigate food web response to environmental perturbations, and they represent an invaluable deep-time complement to neoecological studies of global change. Correlations between feeding diversity and temperature, between herbivory and leaf traits that are modulated by climate, and between insect diversity and plant diversity can all be investigated in deep time. To illustrate, I emphasize recent work on the time interval from the latest Cretaceous through the middle Eocene (67-47 million years ago (Ma)), including two significant events that affected life: the end-Cretaceous mass extinction (65.5 Ma) and its ensuing recovery; and globally warming temperatures across the Paleocene-Eocene boundary (55.8 Ma). Climatic effects predicted from neoecology generally hold true in these deep-time settings. Rising temperature is associated with increased herbivory in multiple studies, a result with major predictive importance for current global warming. Diverse floras are usually associated with diverse insect damage; however, recovery from the end-Cretaceous extinction reveals uncorrelated plant and insect diversity as food webs rebuilt chaotically from a drastically simplified state. Calibration studies from living forests are needed to improve interpretation of the fossil data.     

Phylogeny and systematic revision of Eocene Cricetidae (Rodentia,Mammalia) from Central and East Asia: on the origin of cricetid rodents

The origin of the Cricetidae and the relationships among earliest species from Central and East Asia are still disputed. The taxonomic status of some Eocene cricetid taxa is also doubtful. A parsimony analysis based on 65 cranial and dental characters and including 22 early Myomorpha was performed to elucidate these issues. As a result, the North American Elymys, known as the first Myodonta, belongs to dipodoid rodents, although it shares a suite of characters with the first cricetids. This implies that the split between dipodoids and muroids occurred in North America during the early middle Eocene, as previously supposed. The disputed Simimys and Nonomys could constitute an early dipodoid radiation. It appears that the earliest offshoot of the cricetid clade is the Asian genus Palasiomys. This taxon has a more advanced cricetid plan than contemporaneous dipodoids. The genus Raricricetodon no longer exists here because it is polyphyletic; the species are included in Palasiomys (P. minor, P. trapezius) and Pappocricetodon (P. zhongtiaensis). The genus Pappocricetodon displays a complete cricetid plan associated with both the loss of P⁴ and the development of an anterocone on M¹. The disputed genera Eocricetodon and Oxynocricetodon characterize the beginning of the Oligocene radiations of Eucricetodontinae throughout the Holarctic continents.     

A New Marine Reptile (Sauropterygia) from New Zealand: Further Evidence for A Late Cretaceous Austral Radiation of Cryptoclidid Plesiosaurs

Kaiwhekea katiki gen. et sp. nov. represents the first described cryptoclidid plesiosaurian from New Zealand. It is one of the largest cryptoclidids known, at a length of over 6.5 m, and represents the third reported genus of austral Late Cretaceous cryptoclidids. Kaiwhekea katiki is from siltstones of the Katiki Formation, upper Haumurian Stage (Cenomanian–Maastrichtian; c. 69–70 Ma) of coastal Otago, South Island, New Zealand. In the Late Cretaceous, the locality lay close to the polar circle. The holotype and only known specimen is an articulated skeleton with skull, preserved mostly as natural molds, but which lacks the forelimbs and pectoral girdle. The skull is relatively large and possesses several distinct characters, including a substantial, deep, jugal. There are about 43 upper and 42 lower teeth in each jaw quadrant; all are homodont, slim, and slightly recurved, lacking prominent ornament. Kaiwhekea probably took single soft-bodied prey. Based on cranial structure, it clearly belongs with the Cryptoclididae, but is not certainly close to the southern Late Cretaceous cryptoclidids Morturneria (Seymour Island, Antarctica) and Aristonectes (Chile, Argentina).     

Phaeodarian Radiolaria from the Upper Cretaceous beds of central Japan

Upper Cretaceous Phaeodarea (Radiolaria) were recovered from the Shoya Formation, which crops out 100 km northwest of Tokyo, central Japan. The Shoya Formation consists of about 600 m-thick marine sedimentary rocks, represented by alternating beds of sandstone and mudstone, which are overlain by about 10 m of Phaeodarian-bearing siliceous mudstone. The latter is assigned to the Upper Cretaceous (late Campanian to early Maastrichtian) based on the associated Polycystine Radiolarian fossils. In spite of the poor general preservation of nearly all Phaeodarian specimens as recrystallized quartz infillings, three new Phaeodarian species, Challengeranium cretaceum, Challengeron paleotriangulum, and Medusetta fossilis, were identified on the basis of their shape and ornamentation. Our finding, together with two other very recent reports of fossil Phaeodarians clearly document that the origin of Phaeodarian Radiolarians can be extended back to at least the Upper Cretaceous.     

Studies on fossil Metasequoia from north-east China and their taxonomic implications

Specimens of Metasequoia from the Late Cretaceous or Early Tertiary collected from the Wuyun Formation, Jiayin County, Heilongjiang Province, north-east China, include shoots, female and male cones. Vegetative and reproductive features as well as details of leaf cuticle are described. Comparative studies on fossil and living specimens of the genus suggest a new approach to the classification of species of Metasequoia. Our investigations indicate that extant M. glyptostroboides is distinct from all of the recognized fossil species. The specimens described here, in addition to those previously regarded as M. disticha, M. japonica, M. chinensis, M. cuneata, M. papillapollenites, M. miocenica, M. kimurae, M. onukii, M. europaea, M. asiatica and M. nathorstii , are now considered to belong to a single species, namely M. occidentalis. A further valid species is M. milleri , which can be distinguished from M. occidentalis by the morphology of the male cones and the vegetative organs.     

Taphonomy and ichnology of cephalopod shells in a Maastrichtian chalk from Western Australia

The post-mortem history of a prolific Maastrichtian ammonite and nautiloid fauna preserved as phosphatic steinkerns in chalk of the upper Miria Formation of Western Australia is described. Sediment infilling of phragmocones, required for their fossilisation, was accomplished by means of perforations in the shell wall induced by the activity of abundant endoliths. These include borings ascribed to clionid sponges (Entobia), thallophytes, polychaete worms (including Caulostrepis and probable Maeandropolydora), phoronids (Talpina and Gnathichnus) and others of conjectural origin. Sediment infilling by this mechanism is considered to be more applicable to the taphonomy of phragmocones in general than sediment entry through the siphuncle and to be indicative of low sedimentation rates for the hosting strata. Nonheteromorph ammonites, and the nautiloid Cimomia, are preserved almost exclusively as phragmocones in the upper Miria Formation, and are numerically subordinate to the heteromorph Eubaculites which, together with Glyptoxoceras, is preserved predominantly as body chambers. This phragmocone/body chamber preservational contrast is attributed to the influence of shell shape on pre-burial mechanical abrasion. The apparent dominance of Eubaculites is considered to be largely a preservational artifact and ascribed to the ease with which body chambers were infilled, and thereby favoured for steinkern formation, relative to phragmocones. Phragmocones, or parts thereof. not filled with sediment were eliminated from the fossil record by diagenetic aragonite dissolution. Many ammonites with open umbilici have the early whorls missing. This we attribute to the trapping of sediment in the umbilicus prior to burial, preventing endolith attack whereby the early whorls avoided a sediment infilling. However, the protected inner whorls of involute ammonites and Cimomia, which have closed umbilici, and the inner whorls of evolute ammonites where a cemented umbilical plug supported the mouldic cavity left by shell dissolution, were preserved and were commonly infilled with calcite spar later in diagenesis. The dearth of cephalopod fossils in chalk underlying the upper Miria Formation is ascribed to diagenesis in which aragonite dissolution was not preceded by cementation.