Early Carboniferous radiolarians from north-west Thailand: palaeogeographical implications

Moderately well-preserved radiolarian assemblages are described from bedded cherts south of Mae Hong Son, north-west Thailand. Twenty species and subspecies are identified, including one new species ( Archocyrtium sashidai Feng sp. nov.). The assemblages belong to the middle Early Carboniferous Albaillella indensis and Eostylodictya rota zones. The new data suggest that there was a pelagic basin between the Shan-Thai terrane and Gondwana during the Early Carboniferous. This implies, contrary to previous interpretations, that the Shan-Thai terrane had already rifted apart from Gondwana during the Early Carboniferous.     

Some ostracodes from the Gur'yanovka Formation (Upper Ordovician) of northeastern Gorny Altai

Ostracodes from the Gur'yano-ka Formation (Upper Ordo-ician, Sandbian and Katian stages) of Gorny Altai, Russia, are studied for the first time. Some localities with fossil ostracodes of this age are described briefly. Ele-en new species of the genera Ballardina, Eurychilina, Laccochilina, Bolbina, Retiprimites, Pseudozygobolbina, Bullaeferum, Soanella, Egoro-ella, and Allertemmysa are described and figured. The pre-iously described species Leperditella aff. par-ipunctata V. Ivanova, 1959, Grammolomatella valdari V. Ivanova et Melnikova 1977, Longidorsa? baltica Meidla, 1996, and Steusloffina cuneata (Steusloff, 1895) and ostracodes in open nomenclature, Bollia sp., Klimphores sp., Rectella sp., Longiscula sp., are only figured.     

New lower Callovian ostracodes from the Kursk Region

Lower Callovian deposits (subpatruus and koenigi ammonite zones) in the Mikhailovskii Mine section (Central Russia, Kursk Region) yielded 13 ostracode species (two of them are new) belonging to ten genera. This ostracode assemblage corresponds to ostracode beds with Praeschuleridea wartae-Pleurocythere kurskensis. The stratigraphic range of these beds corresponds to three ammonite biohorizons: Chamoussetia crobyloides, Kepplerites gowerianus gowerianus, and K. indigestus. Three distinct ostracode assemblages have been defined in the section based on their taxonomy and occurrence pattern. Two new species, Pleurocythere kurskensis sp. nov. and Pseudohutsonia wienholzae sp. nov., are described.     

Olfactory acuity in theropods: palaeobiological and evolutionary implications

This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds.     

Ordovician receptaculitids from California and their significance

Well preserved receptaculitids from the Middle Ordovician in the Grapevine Mountains of Eastern California have been collected and studied. These highly variable specimens are regarded as intrapopulational variants of one species. This variation is due to differences in the microenvironment and to the occurrence of individuals at various stages of growth. These specimens are assigned to Ischadites mammillaris (Walcott 1884).This species differs from the similar species of Ischadites and Receptaculites in the following features: (1) small, numerous outer plates; (2) interlocking rays between the elements; and (3) curved and bifurcated inner shafts. Ischadites mammillaris is described and its morphology is compared to that of sponges and dasycladacean algae. Recent algal interpretations that regard the closed extremity of the receptaculitid as the growing end are believed to be incorrect. It is concluded that Ischadites mammillaris as well as other similar receptaculitids should retain their tentative alignment with the Porifera.     

A molecular palaeobiological hypothesis for the origin of aplacophoran molluscs and their derivation from chiton-like ancestors

Aplacophorans have long been argued to be basal molluscs. We present a molecular phylogeny, including the aplacophorans Neomeniomorpha (Solenogastres) and Chaetodermomorpha (Caudofoveata), which recovered instead the clade Aculifera (Aplacophora + Polyplacophora). Our relaxed Bayesian molecular clock estimates an Early Ordovician appearance of the aculiferan crown group consistent with the presence of chiton-like molluscs with seven or eight dorsal shell plates by the Late Cambrian (approx. 501-490 Ma). Molecular, embryological and palaeontological data indicate that aplacophorans, as well as chitons, evolved from a paraphyletic assemblage of chiton-like ancestors. The recovery of cephalopods as a sister group to aculiferans suggests that the plesiomorphic condition in molluscs might be a morphology similar to that found in monoplacophorans.     

New ostracodes of the families Loxoconchidae and Trachyleberididae from the Barremian-Albian of southwestern Crimea

New species of ostracodes of the families Loxoconchidae Sars, 1925 and Trachyleberididae Sylvester-Bradley, 1948 are described from the Upper Barremian-Albian sediments of southwestern Crimea. Loxoella? macrofoveata sp. nov. and L.? microfoveata sp. nov. belong to the family Loxoconchidae. Exophthal-mocythere posteropilosa sp. nov. belongs to the family Trachyleberididae.     

First selenosteid placoderms from the eastern Anti‐Atlas of Morocco; osteology,phylogeny and palaeogeographical implications

Abstract: A new placoderm assemblage is reported from the Kellwasser facies of the eastern Anti‐Atlas, Morocco. This is the first record of an abundant Frasnian placoderm assemblage from Africa. The following new selenosteid taxa are described: Draconichthys elegans gen. et sp. nov., Enseosteus marocanensis sp. nov. and Walterosteus lelievrei sp. nov. In addition, material of Rhinosteus cf. parvulus is figured and described for the first time from Gondwana. The genera Enseosteus, Rhinosteus and Walterosteus are reviewed. ‘Wildungenichthys’ is regarded as a junior subjective synonym of Walterosteus. The new material and a revision of the taxa from Bad Wildungen, Germany, are the basis for a new phylogenetic analysis of the selenosteid arthrodires. The monophyly of the selenosteids is confirmed. The North American selenosteids are a sister group of Moroccan and European selenosteids, excluding Pachyosteus. The Moroccan vertebrate assemblage resembles that of Bad Wildungen. This supports the close palaeogeographical positions of Gondwana and Laurussia during the Late Devonian and indicates that biogeographical barriers for placoderms that could have separated the two assemblages were absent.     

The anatomy of Odobenocetops (Delphinoidea, Mammalia), the walrus-like dolphin from the Pliocene of Peru and its palaeobiological implications

The Pliocene Beds of the Pisco Formation on the southern coast of Peru have yielded three new skulls of the walrus-like odontocete, Odobenocetops (Delphinoidea, Cetacea). Two of the skulls are from a slightly younger horizon than the holotype of O. peruvianus and belong to a different species, O. leptodon . The holotype of O. leptodon bears a 135 cm long needle-like right tusk and a small 25 cm long left tusk, the apex of which was erupted. The third skull, referred to a female of O. peruvianus , bears two small tusks similar in size to the small left tusk of the holotype. The new specimens include periotic, tympanic and ear ossicles, which confirm referral to the Order Cetacea and the morphology of the humerus reinforces affinities of odobenocetopsids to monodontids. Because the anterodorsal edge of its orbit is slightly concave O. leptodon had reduced anterodorsal binocular vision, a condition compensated for by the probable presence of a small melon (and inferred echolocation). The head was bent ventrally when swimming in such a way that the long tusk was approximately parallel to the axis of the body. The extremely salient occipital condyles of Odobenocetops are indicative of great mobility of the neck, probably related to bottom-feeding. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society , 2002, 134 , 423–452.     

New brachiopods from the Ordovician of northeastern Russia

New brachiopod taxa, Starnikoviella gen. nov., with the type species S. settedabanica sp. nov. (family Clitambonitidae), and Avdeevella gen. nov., with the type species A. mica sp. nov. (subfamily Glyptomeninae), from the Middle–Upper Ordovician boundary deposits of northeastern Russia are described.     

New species of Amanita from the eastern Himalaya and adjacent regions

Four new species of Amanita, Amanita-ceae (Agaricales) are described from the eastern Himalaya and adjacent regions of southwestern China. Amanita altipes and A. parvipantherina are members of section Amanita, while A. orientifulva and A. liquii are representatives of section Vaginatae. They are compared with similar species and illustrated with line drawings.     

Cambrian–Ordovician trilobite family Missisquoiidae Hupé, 1955: Systematic revision and palaeogeographical considerations based on cladistic analysis

The missisquoiids are among the most important trilobites in the Cambrian–Ordovician boundary interval of Laurentia and Gondwana. This study deals with a systematic review of the family Missisquoiidae based on a cladistic analysis and explores their palaeobiogeographical history. A total of 22 missisquoiid species were selected for cladistic analysis. The cladistic results demonstrate that the family Missisquoiidae includes Parakoldinioidia, Pseudokoldinioidia, Tangshanaspis, and Tasmanocephalus; Lunacrania and Hardyia are included with reservation. The well-known genus Missisquoia is treated as a junior synonym of Parakoldinioidia. Based on the distribution of the missisquoiids, six palaeogeographical areas are recognised: Sino-Korea, Yangtze, Australia, southern Laurentia, northwestern Laurentia, and northeastern Laurentia. Palaeogeographical analyses show that the missisquoiids originated in Gondwana and continued to expand their geographical range within the continent and eventually expanded into the Laurentia. Optimisation results of geographical area transitions demonstrate that there were transitions between the two continents, and evolution of the Laurentian missisquoiids appears to have been strongly influenced by the Gondwanan counterparts. We suggest that dispersal of non-fossilised egg stage probably transported by oceanic currents may have been responsible for these inter-continental transitions.     

Estimation of hearing capabilities of Early Miocene sloths (Mammalia,Xenarthra, Folivora) and palaeobiological implications

The Miocene Santacrucian sloths are a very important assemblage because they represent the first major radiation among sloths and, therefore, they could provide many insights about sloth evolution and diversity. Based on other studies, the hearing capabilities of Pleistocene sloths were identified. For a deeper understanding of these capabilities from an evolutionary point of view, in this article we study the hearing capabilities of Santacrucian sloths. We estimate the frequency range and the best frequency of hearing of six species of stem-megatherines and one species of mylodont. In most cases, the best frequency of hearing is much lower than the expected value for the estimated body mass of the species. This general shift towards low values of frequency is different than the pattern observed in mammals where sound localisation is improved by an increased sensitivity to high frequencies. In this article, we also propose some palaeobiological inferences of the low-frequency shift of hearing range in Miocene Santacrucian sloths.     

New data on late Santonian and early Maastrichtian ostracodes of the Saratov Region

The article presents a paleoenvironmental analysis of ostracode assemblages from Mezino-Lapshinovka (Upper Santonian) and Lokh (Lower Maastrichtian) Formations of the Vishnevoe section (Saratov Region). Two new species Cytherelloidea vishneviensis sp. nov. and Mauritsina mandelstami sp. nov. are described.     

Covered and naked barleys from the Himalaya

Summary Covered and naked barleys from the Himalaya differ significantly from each other in a multivariate way (Murphy and Witcombe 1986). Two hypotheses which could account for this phenomenon are (1) that the caryopsis covering gene (or a gene closely linked with it) exerts a wide-ranging pleiotropic effect, and (2) that the covered and naked types have evolved to differ with respect to the alleles fixed at many loci. Experimental evidence is presented which supports the latter, an explanation which has implications for our understanding of barley phylogeny and evolution.     

Modern distribution of ostracodes and other limnological indicators in southern Lake Malawi: implications for paleocological studies

This modern distribution study from the southwest arm of Lake Malawi quantitatively relates variables of the lake environment to surficial assemblages of ostracodes and other paleoenvironmental indicators (molluscs, Botryococcus, fish, and charcoal) from 102 sites, across a gradient of littoral to shallow profundal conditions. The goal of this research is to use the resultant relationships to help quantify paleoecological interpretations of the fossil record from sediment cores. Site locations varied by depth (1–60 m) and adjacent shoreline environment. Thirty-three ostracode species are identified from 54 sites including four new, undescribed species of Cypridopsinae (2) and Limnocythere (2). Ostracodes are extremely abundant between 1 and 25 m water depth, but are rare to absent between 30 and 60 m. This disappearance is probably taphonomically controlled, with carbonate dissolution in the death assemblage since abundant live ostracodes have been found in the lake at greater than 30 m depth, where bottom sediments lack calcium carbonate. Constrained correspondence analysis (CCA) of ostracode species abundance suggests depth and dissolved oxygen (DO) content to be the primary environmental variables affecting their distribution. Additional CCA models using all biological indicators suggest limnologic variables correlated with depth (e.g., bottom water temperature and DO) and adjacent shoreline environment were most significant.     

New species of stromatoporoidea from the Upper Ordovician and Silurian of the Subpolar Urals

Stromatoporoidea are widespread in the Upper Ordovician and Silurian beds of the Kozhim River (western slope of the Subpolar Urals). Five new species Cystostroma prodigiosum sp. nov., Stylostroma flabellatum sp. nov., Labechiina arguta sp. nov., Ecclimadictyon faveolatum sp. nov., and Araneosustroma astroplexum sp. nov. are described.     

Ginkgoalean woods from the Jurassic of Argentina: Taxonomic considerations and palaeogeographical distribution

A specimen of Baieroxylon rocablanquense nov. sp. from the Roca Blanca Formation (Early Jurassic), and a specimen of Ginkgomyeloxylon tanzanii Giraud and Hankel from the La Matilde Formation (Middle Jurassic), both located in the Santa Cruz province, Argentina, are described in detail. Identification of the morphogenus Baieroxylon is based upon secondary xylem characteristics (cross-field tracheid pitting, cross-fields and ray characters), while identification of Ginkgomyeloxylon is based upon pith, primary xylem and secondary xylem features. A synthesis of Ginkgoalean woods is presented, which combines diagnostic anatomical evidence with data related to stratigraphic and paleogeographical distributions. Based on the results of this analysis, a key for genus-level identification is provided and a new genus, Ginkgopitys, is proposed. These results are used to elucidate global patterns of historical distribution over the course of geological time. In Gondwana, a great diversity of “mixed-type” woods was present during the Mesozoic, especially during the Late Triassic. In contrast, in Laurasia a lower diversity of the mixed-type is recorded for the Paleozoic and Mesozoic, with increases in “abietinoid-type” wood – similar to extant Ginkgo – taking place at the beginning of the Cretaceous. During the Jurassic and Early Cretaceous in both Laurasia and Gondwana, mixed-type and abietinoid-type woods co-existed, illustrating that important evolutionary changes in wood anatomy occurred during the Mesozoic (Jurassic-Cretaceous).