摘要:

Fariña, R.A. 1995 11 30 Limb bone strength and habits in large glyptodonts.The masses of some large Pleistocene species of the fossil family Glyptodontidae (Mammalia; Xenarthra) were estimated from the volumes of models. Their centres of mass were also estimated. Dimensions of limb bones and limb muscles were used to assess the athleticism of these species, using an approach previously applied to dinosaurs. The femora show higher athletic indicators (even when supporting the whole weight of the animal) than humeri in the quadrupedal stance. It is therefore proposed that performing strenuous locomotor activities bipedally was not only possible but even advantageous for minimizing risk of bone failure. The muscular dimensions analysed are consistent with this conclusion. The possible biological meaning of these mechanical results is considered. Since the smaller and older (early Miocene) glyptodontPropalaehoplophorusdoes not share this condition, it is suggested that it was developed later in the history of the group, perhaps as a feature related to the acquisition of large size.Glyptodonts, fossil, Xenarthra, biomechanics, locomotion, extinct megafauna, palaeobiology, evolution

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01422.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Martinez, J.‐N.&Sudre, 1. 1995 11 30 The astragalus of Paleogene artiodactyls: comparative morphology, variability and prediction of body mass.Lethaia, Vol. 28, pp. 197–209. Oslo. ISSN 0024–1164.The morphology of the astragalus is analysed in nineteen Paleogene artiodactyls (suborders Palaeodonta, Suina, Ancodonta and Ruminantia). This morphology is related to the functional adaptations of the appendicular skeleton, but some diagnostic characters can be seen at the family level. For the populations examined, the proportions of this bone show a low intraspecific variability, which does not allow detection of any dimorphism. An allometric relationship between the dimensions of the astragalus and the body mass has been established for extant species, allowing estimates for the fossil species. In most cases, the interval between the two extreme estimations using the astragalus includes the estimated body mass using M/1 area. The limits of this method are discussed, and it is suggested that the dimensions of the astragalus give a better estimation of the body mass than the dental area. □Artiodactyls, astragalus, comparative morphology, body mass, allometry, Pa

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01423.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Kanazawa, K. 1995 11 30 How spatangoids produce their traces: relationship between burrowing mechanism and trace structure.Two spatangoid echinoids,Echinocardium cordatumandLovenia elongata, were allowed to produce their traces in poorly and well‐sorted sediments in aquaria. In poorly sorted sediments they formed distinct traces, comparable to fossil traces. Sorting of sediment occurred during transportation by the lateroventral spines and brought about characteristic patterns in grain size at the bottoms of the burrows and in redeposited sediment, which made the traces visible. Differences in the burrowing mechanism betweenE. cordatumandL. elongataare reflected in their trace structures.E. cordatumformed a laminated backlill structure which resulted from periodic accumulation of excavated sediment behind it, whileL. elongatasimply pushed excavated sediment by compression to the posterior sides of the test, so that their traces lack a distinct laminated structure and the width of the trace becomes larger than that of the animal. In well‐sorted sediment, the echinoids burrowed in the same way as in poorly sorted sediment, but no visible trace was produced other than a drain tube. These observations reasonably explain some characteristic modes of occurrence of fossil spatangoid traces. Their different morphological expressions depend on sediment texture and the uneven lithification of traces.Spatangoids, trace, burrowing mechan

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01424.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Baumiller, T. K.&Hagdorn, H. 1995 1130: Taphonomy as a guide to functional morphology ofHoloainus, the first post‐Paleozoic crinoid.A taphonomic approach, in which patterns of fragmentation are used to infer the organization of soft tissue and function in crinoid stalks, was applied to pluricolumnals of the first post‐Paleozoic crinoid,Holocrinus. The observed patterns are analogous to those for isocrinid crinoids, suggesting thatHoloctinusand isocrinid stalks are functionally similar in having specialized sites for autotomy. Stalk autotomy inHolocrinuscould not have been predicted based on morphological criteria alone: the stalk ofHolocrinuslacks synostosial articulations, which among the isocrinids are the sites of autotomy. This implies that taphonomic data can supplement and sometimes supersede morphological data as a basis for functional reconstructions. Stalk autotomy inHolocrinusindicates that this trait was not derived independently by the isocrinids and comatulids, but rather that it was primitively shared by them. If pentacrinitids could not autotomize their stalks, as is likely, this would represent a loss of this ability through paedomorphosis. □Holocrinus, articulates, arinoids, taphonomy, autotomy, heteroc

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01425.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

McKinney, F.K, Delvolve, 7.‐J.&Sobieraj, J. 1995 11 30:Conulariasp. from the Pyrénées: further support for scyphozoan affinities of the Conularida.Several specimens ofConulariafrom the mid‐Carboniferous Culm Formation of the Pyrénées occur as clusters with a large central specimen and several smaller divergent individuals that may be buds from the larger central specimen. Other individual and clustered specimens exhibit complex polygonal cross‐sections that are inferred to have resulted from longitudinal fission of a precursor pyramid into two or more descendant individuals. Apparent budding and transverse fission (strobilation) of conulariids have been reported previously, but we have found no earlier record of longitudinal fission. The existence of this additional mode of asexual increase in conulariids further supports their affinities with the scyphozoan Cnidaria.Conularida, Scypho‐zoa, fission, Carboniferou

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01426.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Mitchell, L., Curry, G.B.&Fallick, A.E. 1995 11 30: Stable‐isotope and amino acid profiles of the New Zealand giant Pliocene oysterCrassostrea ingens.Oxygen and carbon stable‐isotope profiles and intracrystalline amino acid profiles (free and total) were determined for the New Zealand giant Pliocene oysterCrassostrea ingensby sampling annual growth increments along a sagittal section. These profiles reflect both ontogenetic and environmental change over the life‐time of the oyster (approximately 20 years). There is a gradual increase in δ18O from the umbo towards the shell margin and a subsequent levelling‐off about halfway along the shell. This pattern probably reflects a decrease in the growth rate of the oyster rather than a temperature effect. The δ13C profile initially increases sharply at the umbo and then gradually decreases towards the shell margin. This may be due to kinetic or metabolic effects associated with the development of a fast‐growing juvenile into a slower‐growing, sexually mature adult, or it may be due to the influence of13C‐depleted carbon derived from the oxidation of organic matter in the surrounding sediment. The amino acid profile reveals a gradual decrease in abundance from the umbo to the shell margin, indicative of a progressive increase in the relative amounts of inorganic carbonate to protein over the life of the oyster, that may also be a consequence of decreasing growth rate. Glycine and alanine are the two most common amino acids in both the free and total amino acid profiles: free (i.e. naturally hydrolysed) amino acids account for about three quarters of the total amino acids present. □Biogeochemistiy, stable isotopes, amino acids, envi

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01427.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Popov, L.&Holmer, L.E. 1994 Cambrian‐Ordovician lingulate brachio‐pods from Scandinavia, Kazakhstan, and South Ural Mountains.Fossils and Strata, No. 35,156 pp. and 115 figu

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01428.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Batt, R.J. 1995 11 30 A test of a new technique illustrating faunal dominance trends: Application to the ‘Trilobite Beds’ interval of the Middle Devonian Wanakah Shale in western New York.Lethaia, Vol. 28, pp. 245–258. Oslo. ISSN 0024–1164.A new graphic technique illustrating species relative abundance trends through stratigraphic sections facilitates recognition of subtle temporal and geographic changes in environment. This technique is illustrated by application to three closely spaced sections through the ‘Trilobite Beds’ interval of the Wanakah Shale of western New York. Graphic representation of faunal data from bed‐by‐bed sampling of these sections allows recognition of water depth changes that may be related to small‐scale cyclic eustatic sealevel fluctuations. Comparison of graphs for neighboring sections, aided by excellent chronostratigraphic control, allows delineation of seafloor topography. During deposition of the study interval, the seafloor was consistently shallowest at the western section and deepest at the middle site. □Wanakah Shale, Hamilton Group, Devonian, Darien Center Submember, ‘Trilobite Beds

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01429.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Etter, W. 1995 11 30 Benthic diversity patterns in oxygenation gradients: an example from the Middle Jurassic of Switzerland.A high‐resolution study of the lower Opalinum Clay (Aalenian, Middle Jurassic) of northern Switzerland revealed a pattern of macrobenthic diversity and abundance which does not conform with the dysaerobic‐biofacies models currently in use. The upper dysoxic zone contains an association of moderate diversity and moderate abundance which, with increasing oxygen depletion, is replaced by an association dominated by a few peak opportunists (tiny epibenthic bivalves and presumably small annelids) at high abundances but very low diversity. In the lower dysoxic zone, abundance drops to very low levels, but diversity rises again to quite high values. The rather high diversity of the lower dysaerobic biofacies is explained in part by the presence of specialized chemosymbiontic species. The pattern documented in the lower Opalinum Clay has been calibrated by sedimentologic, taphonomic, ichnologic, and microfaunal evidence. It contradicts equilibrium models, which postulate gradual or even linear decreases in both abundance and diversity with increasing oxygen‐depletion of the bottom water. The equation of rising diversity with improved oxygenation can be misleading and can yield erroneous results in the reconstruction of ancient bottom‐water oxygenation. □Dysaerobic biofacies, high‐resolution study, diversity, chemosymbionts, equilibrium and non‐equil

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01430.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Moissette, P.&Saint Martin, J:P. 1995 11 30 Bryozoaires des milieux récifaux miocenes du sillon sud‐rifain au Maroc. [Bryozoans from Miocene reef environments in the South‐Rifian corridor of Morocco.In late Miocene coral reefs from the Fes area (Northern Morocco), bryozoans are the best‐represented group. An inventory of the bryozoan fauna (59 species) was taken on two reefs with different organization and palaeogeographical situation in a late Miocene seaway between the Atlantic and the Mediterranean. A study of the bryozoans and their zoarial forms allows an improved reconstruction of reefal environments and available habitats. Membraniporiforrn (encrusting) colonies largely predominate, whereas celleporiforms (nodular colonies) are more rare. Rigid erect (vinculariiform, adeoniform, and reteporiform) and rigid articulated zoarial types (cellariiform and catenicelliform) are fairly well represented. At depths of about 10 m and on the reef front encrusting bryozoans were well developed in cryptic habitats on living coral substrates. Erect species lived in cavities provided by the coral framework, and plants offered flexible substrates for the attachment of epiphytal forms. □Bryozoa, coral reefs, Morocco, Messininn, pulueoecology.Dans les récifs coralliens du Miocène supérieur de la région de Fes (Maroc septentrional), les bryozoaires constituent, parrni les organismes conservés, le groupe le mieux représenté. Un recensement de la fame de bryozoaires (59 espèces) a été effectué dans deux récifs d'organisation et de situation paléogéographique différentes, dans un secteur de communication entre Atlantique et Méditerranée au MiocéFne supérieur. L'étude des bryozoaires et de leurs formes zoariales permet de proposer une meilleure reconstitution de I'environnement récifal et des habitats disponibles. Les colonies membraniporiformes (encrobtantes) predominent largement, alors que les cellepori‐formes (colonies noduleuses) sont beaucoup plus rares. Les types zoariaux érigés rigides (vincula‐riiforme, adéoniforme et rétéporiforme) et érigés articulés (cellariiforme et catenicelliforme) sont assez bien représentés. A des profondeurs denviron 10 m et dans la partie antérieure des constructions récifales, les bryozoaires encroûtants étaient bien développés dans des habitats cryptiques sur substrats coralliens vivants. Des formes dressées vivaient dans les cavités ménagées par le bâti corallien et des supports végétaux permettaient également la fixation de formes épiphytes. □Bry

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1995.tb01431.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY