摘要:

Webb, G.E. 1994 1015: Parallelism, non‐biotic data and phylogeny reconstruction in paleobiology.Many systematists equate parallelism and convergence. However, whereas convergence is relatively uncommon and easily recognized using divergent characters, parallelism is common but more difficult to recognize because divergent characters are less abundant. Cladists, in particular, equate homeomorphy with convergence and reject parallelism as a distinct concept. Unfortunately, cladistic parsimony analysis may not resolve most parallelism. Therefore, criteria for thea priorirecognition and objective evaluation of parallelism are very significant. Non‐biotic data (e.g., stratigraphic and geographic distribution) provide independent criteria for the construction of hypotheses of parallelism in cases where taxa (1) were geographically isolated during homeomorphic character‐state transformations, (2) occurred with endemic faunas, and (3) evolved in similar environmental conditions as suggested by paleoecological data. Australian lithostrotionoid corals were long considered congeneric with European taxa. However, because of their geographic isolation, occurrence with endemic rugose corals and occurrence in similar depositional environments as European forms, they are now considered a homeomorphic clade, resulting from an extended sequence of parallel character‐state transformations. The high degree of parallelism, combined with abundant symplesiomorphic characters, led to erroneous phylogenetic inferences when non‐biotic data were excluded from analysis.Cladistics, homeomorphy, lithostrotionoid corals, parallelism,

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01407.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

von Bitter, P.H.&Norby, R.D. 1994 10 15: Fossil epithelial cell imprints as indicators of conodont biology.Size and growth characteristics of microsculpture polygons on the cup nodes of the bladelike Pa elements of the conodontLochriea commutatasupport the hypothesis that they are epithelial cell imprints. They are ˜2–6 pn wide and ˜4–10 pn long and are the same size throughout growth of the element. The epithelial imprints increased in number with growth, either linearly or periodically; the latter possibility may be important for defining specific growth stages of conodont elements. The imprint location on the top of nodes suggests that the latter were tissue‐covered and that the scissor‐model of function applies to these bladelike Pa elements. The location of the imprints also reflects evolutionary history: a probable ancestor,L. cracoviensis(Belka), also lacks a platform and possesses well‐developed microsculpture polygons on broad cup nodes. Finally, correlation between internal white matter and external microsculpture suggests that internal osteocytes may have supplied the external secreting cells with calcium phosphate from the innerstorage bank. Conodont biology, fossil epithelial imprints, polygonal microsculpture, Carbonferous, Lochrie

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01408.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Valenzuela‐Ríos, 7.1. 1994 10 15 The Lower Devonian conodontPedavis pesavisand thepesavisZone.Records from Europe and Western North America suggest that a diversificationof Pedavisfaunas took place around the base of what has been called thepesavisZone. This level is reviewed in comparison to sequences in Western North America and Spain. Hitherto, two different taxa,Pedavis pesavisS.S. andPedavis striatus(=Icriodus pesavisof Klapper 1969) have been used indiscriminately in defining the base of thepesavisZone. This revision points out that the chronostratigraphic problems derived from an unknown phylogenetic history of bothP. striatusandP. pesavisremain still unsolved, and thii fact challenges the continued use of either taxon as a zonal index for dating and correlating purposes. To improve this situation a new biostratigraphic unit above thedeltaZone is proposed, thepandorabeta ‐gilbertiunit. This unit is unambiguosly defined, and thus it now enables accurate correlation on a global‐scale basis above thedeltaZone.Conodonts, biostratigraphy, Lower Devonian, Pyrenees,

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01409.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Walossek, D. 1993: The Upper CambrianRehbachiellaand the phylogeny of Branchiopoda and Crustacea.Fossils and Strata 32.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01410.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Hageman, S.J. 1994 10 15: Microevolutionary implications of chal variation in the Paleozoic bryozoanStreblotrypa LethaiaIdeally, studies of microevolution, including those of patterns and rates of speciation, need to account for features of geographic and ecophenotypic morphologic variation. These factors can provide primary sources of variation for evolution to act upon. They can also, however, produce variation among characters that are not directly related to speciation events, thus confounding recognition of larger evolutionary patterns. Because of limitations of geologic settings, features of morphologic variation associated with geographic and ecophenotypic variation are difficult to constrain and are often neglected. Consequences of ignoring potential geographic variation in microevolutionary studies are varied. The likelihood of observing stasis or gradation may increase or decrease depending on initial assumptions. A series of tests that place reasonable limits on potential errors, however, can strengthen conclusions from empirical microevolutionary studies. Late Paleozoic cyclothems of the North American Midcontinent provide an excellent opportunity to study patterns of microevolution and concomitant ecophenotypic and geographic variation. Based on multivariate analysis of 28 morphometric characters, specimens of the rhabdomesine bryozoan genusStreblotrypa, collected from eight coeval localities distributed along a 300 km transect, exhibit a morphologic cline associated with thickening of the skeleton from south to north. Additional specimens were collected from five younger localities to test for temporal and ecologic variation. The range of observed morphologic variation from a single horizon was as great as that observed over the entire stratigraphic sequence from varied lithologies. This indicates a pattern of overall morphological stasis through the interval studied.Bryozoa, clines, microevolution, variability, geographic variation, Carboniferous.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01411.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01412.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Wright, A.D. 1994 10 15: Mantle canals on brachiopod interareas and their significance in brachiopod classification.Mantle canals have been located on the internal surface of the interareas in several clitambonitacean brachiopod genera. This indicates that, in contrast to the cardinal areas of Recent terebratulides and rhynchonellides, these surfaces were lined with mantle, with no fusion of the mantle lobes at the lateral ends of the hinge line, and the coelomic cavity confined to a median zone at the posterior of the shell. The discovery provides additional support for the view of Jaanusson (1971;Smiths. Contr. Paleobiol. 3) that the Beecher (1891) classification has considerable merit, and indicates that the calcareous brachiopods may be subdivided into the three subclasses Craniformea, Protremata and Telotremata.Brachiopoda, classification, Clitambonitacea, interareas, mantle canals, Protremata.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01413.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Alexander, R.R. 1994 10 15: Distribution of pedicle boring traces and the life habit of Late Paleozoic leiorhynchid brachiopods from dysoxic habitats.Pedicle boring traces,Podichnusisp., are concentrated on the anterolateral commissure of both valves ofLeiorhynchoidea carboniferumandL. weeksifrom the black ferruginous micrites of the Chainman Formation (Upper Carboniferous; west‐central Utah, USA) and black phosphatic (‘False Cap’) limestone of the Phosphoria Formation (southeastern Idaho, USA), respectively. The absenceof Podichnusisp. from the posterior of shells of both species indicates that the beak of the shell was buried in the mud, inaccessible to colonization by conspecific larvae. The concentration of pedicle boring traces near the anterolateral incurrent regions of leiorhynchid shells with a well‐developed central fold further suggests that settling conspecific larvae behaved rheotaxically. Larvae were induced to metamorphose near the commissure of the host shell, where suspended food was drawn to the incurrents of the host. The piggybacked mode of life on the anterior of conspecific hosts provided a refuge for juveniles above the dysoxic black sediments. In contrast, modem brachiopods that live as epibionts on skeletal substrates display either a random or posteriorly concentrated distribution of pedicle boring traces.Permian, Carboniferous, brachiopods, leiorhynchids, Podichnus, dysoxic, rh

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01414.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Blake, D.B.&Guensburg, T.E. 1994 10 15: Predation by the Ordovician asteroidPromopalaeasteron a pelecypod.An OrdovicianPrornopalaeaster(Echinodermata: Asteroidea) wrapped about aCuneamya?(Mol‐lusca: Pelecypoda) in the extraoral feeding posture characteristic of Jurassic to modern members of the Asteriidae documents an early origin for this behavioral complex. Modern asteriids are convergent onPromopalaeastet;there is no direct phylogenetic linkage between the two. This fossil occurrence, combined with the success of modem Asteriidae, demonstrates that biological evolution and geological change need not outmode complex life habits. The fossil supports the notion of asteroids as Paleozoic‐type predators, and its existence suggests that asteroids were not significant contributors to changing faunal structures in shelf seas during the Phanerozoic.Asteroidea, Pelecypoda, functional morphology, evolutionary ecol

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01415.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Liljedahl, L. 1994: Silurian nuculoid and modiomorphid bivalves from Sweden.Fossils and Strata 33.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1994.tb01416.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY