bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple planar coincidences with N-fold symmetry
Authors: Baake Michael , Grimm Uwe
Published: July 2006

Planar coincidence site lattices and modules with N-fold symmetry are well understood in a formulation based on cyclotomic fields, in particular for the class number one case, where they appear as certain principal ideals in the corresponding ring of integers. We extend this approach to multiple coincidences, which apply to triple or multiple junctions. In particular, we give explicit results for spectral, combinatorial and asymptotic properties in terms of Dirichlet series generating functions.
Decagon covering model and equivalent HBS-tiling model
Authors: Gummelt Petra
Published: July 2006

For decagonal Al—Co—Ni quasicrystals, coverings based on a single decagonally shaped columnar 20 Å-cluster as well as tilings of so-called hexagon-, boat- and star-tiles are used to model the atomic structure. We introduce geometrically defined local transformation rules which enable us to replace a covering of overlapping congruent decagons by an equivalent HBS-tiling at the same scale and vice versa. Starting from an obvious one-to-one correspondence in case of idealized, perfect Penrose order, we show that there is a very similar relation also for random decagon coverings with slightly relaxed structure. The proofs given here complete our statements announced in previous work.
A series of sheet-structured alkali metal uranyl oxalate hydrates: structures and IR spectra
Authors: Giesting Paul Arthur , Porter Nathan J. , Burns Peter Carman
Published: July 2006

The novel compounds K[(UO2)2(C2O4)2OH] · 2 H2O (KUrOx), Rb[(UO2)2(C2O4)2OH] · 2 H2O (RbUrOx), and Cs[(UO2)2(C2O4)2OH] · H2O (CsUrOx) have been synthesized by mild hydrothermal methods. Single crystal diffraction data collected at 125 K using MoK
α radiation and a CCD-based area detector were used to solve and refine the crystal structures by full-matrix least-squares techniques to agreement indices (KUrOx, RbUrOx, CsUrOx) wR
2 = 0.045, 0.062, 0.042 for all data, and R1 = 0.023, 0.030, 0.022 calculated for 1834, 1863, 1821 unique reflections respectively. The compounds KUrOx, RbUrOx, and CsUrOx are all monoclinic, space group P21/m, Z = 2. The unit cell of KUrOx has the dimensions a = 5.6427(4), b = 13.7123(9), c = 9.2669(6) Å, β = 98.7490(10)°, V = 708.68(8) Å3. The unit cell of RbUrOx has the dimensions a = 5.6225(4), b = 13.8339(9), c = 9.3308(6) Å, β = 98.1590(10)°, V = 718.41(8) Å3. The unit cell of CsUrOx has the dimensions a = 5.4688(3), b = 13.5710(8), c = 9.5408(5) Å, β = 97.5830(10)°, V = 701.90(7) Å3. The structures consist of chains of uranyl pentagonal bipyramids connected by oxalate groups and hydroxyl groups, and are isotypic with the compound NH4[(UO2)2(C2O4)2OH] · 2 H2O studied by Artem’eva et al. (2003); all four of these compounds are structurally composed of sheets made by polymerizing the chains of UO2C2O4(H2O) · 2 H2O (Jayadevan and Chackraburtty, 1972; Mikhailov et al., (1999), this being achieved by removing a H atom from an H2O group in the coordination sphere of the uranyl ion to form a hydroxyl vertex that is shared by two uranyl ions. Compensating positive charges are provided by the inclusion of large monovalent cations in channels that run through the sheets; these channels also contain hydrogen-bound H2O groups. The positions of the cations and H2O groups change in relation to the uranyl oxalate sheets and to each other through the series. The infrared spectra of these materials collected at room temperature are also presented and compared with previous work.
Fluorescence Resonance Energy Transfer Between Polyphenolic Compounds and Riboflavin Indicates a Possible Accessory Photoreceptor Function for Some Polyphenolic Compounds
Authors: Chandrakuntal Kumar , Thomas Neena Mary , Kumar Pradeep G. , Laloraya Malini , Laloraya Manmohan M.
Published: July 2006

The photoreceptive extreme tip of the wheat coleoptile exhibits intense green‐yellow fluorescence under UV light, suggesting the presence of UV‐absorbing materials. Fluorescence spectra of the intact coleoptile tip and tip homogenate showed the presence of the known photoreceptor pigments flavin and carotene, and a preponderance of phenolic compounds. Absorption spectra and fluorescence spectra of various phenolic compounds showed close overlap with the absorption and fluorescence spectra of the wheat coleoptile tip homogenate. Fluorescence spectra of several phenolic compounds showed close overlap with the absorption bands of flavin, carotene and pterine, suggesting possible energy transduction from phenols to these photoreceptors. Excitation of gentisic acid and ferulic acid with 340 nm light in the presence of flavin showed enhancement of flavin fluorescence in a concentration‐ and viscosity‐dependent fashion, indicating fluorescence resonance energy transfer between them and riboflavin. Furthermore, several phenolic compounds tested generated superoxide anion on excitation at 340 nm, suggesting that superoxide‐dependent signal cascades could operate in a polyphenol‐mediated pathway. Phenolic compounds thus may act as accessory photoreceptors bringing about excitation energy transfer to the reactive photoreceptor molecules, or they may take over the function of the normal photoreceptor in genetic mutations lacking the system, or both processes may occur. The responses of plants to UV‐B and UV‐A light in mutants may be explained in terms of various phenolics acting as energy transducers in photoreceptor functioning.
For Gloria Anzaldúa: Collecting America, Performing Friendship
Authors: Schweitzer Ivy
Published: July 2006

It was an unexpectedly chilly day in May 2004 when the news flashed across various electronic mailing lists that Gloria Anzaldúa had died from complications related to diabetes. I was in the midst of teaching a course on contemporary issues in feminism to a formidable group of undergraduate women and men, in which we were reading “How to Tame a Wild Tongue” and “La Conciencia de la Mestiza: Towards a New Consciousness.” These are my favorite essays from Anzaldúa's Borderlands / La Frontera: The New Mestiza, a text published in 1987 and still crucial to any understanding of identity and politics in feminism today. The announcement, made by Anzaldúa's coeditor and compañera, Cherrie Moraga, requested that we construct homemade shrines to honor Anzaldúa's presence and aid her passing. My classroom was in Dartmouth Hall, a venerable eighteenth-century building only a stone's throw from Baker Library, whose tower sports a weathervane with the image of Dartmouth's founder, Reverend Eleazar Wheelock, teaching a crosslegged, befeathered, and pipe-smoking Indian, Samson Occom, his most famous student, beneath the symbolic lone pine. Into the graywalled room, I brought objects that seemed out of place there and incendiary: candles, flowers, incense, and books—an armful of wellthumbed volumes containing the nearly talismanic words, her own and those of others, that Anzaldúa struggled to bring into print.
Anzaldúa and Transnational American Studies
Authors: Castillo Debra A.
Published: July 2006

For several years now, at least since the 2000 census, the United States has in one way or another told itself that it needs to come to terms with what it means to live in a country of over forty million Latinos/as. Latina actors grace the covers of People magazine, Latin beats percolate through the earbuds of iPods, and McDonald's serves up breakfast burritos alongside its McMuffins. In the academic world, the increasing consciousness of the Latino/a presence in the United States means that it is now unthinkable for any major university not to have a program of studies focusing on the histories and cultures of this ill-defined population; it means border theory is increasingly present on our syllabi; and it means that we all nod our heads wisely when the name “Gloria Anzaldúa” is mentioned. For years before her untimely death, Anzaldúa complained bitterly about being “repeatedly tokeni[zed]” (“Haciendo Caras” xvi), as one of the same half dozen women continually called on as a resource for academic collaboration. Being a token meant that she saw clearly how she was both overhyped and treated less than seriously; worse, she felt drained of the energy that would allow her to continue her literary and political work.
When clocks (and communities) collide: Estimating divergence time from
molecules and the fossil record
Authors: Brochu Christopher A. , Sumrall Colin D. , Theodor Jessica M.
Published: July 2006

Traditionally, deep time was the domain of paleontology. Origination
time could be assessed only through reference to first appearance data in
the rock record. This changed almost from the beginnings of modern molecular
biology, when it was realized that molecules could be used to calculate
divergence times between living species. Early studies relied on
immunological distance information, and the underlying rationale was simple:
because evolution involves changes to the genetic code, and because these
changes accumulate over time, we should expect the number of accumulated
changes (the molecular distance) between living taxa to increase as their
time of divergence becomes older (Zuckerkandl and Pauling, 1962). By
inferring a rate of evolution of the genetic code, we can place absolute
time estimates on divergence points.
Patterns of calibration age sensitivity with quartet dating
methods
Authors: Brochu Christopher A.
Published: July 2006

Because more than one calibration is used, quartet dating (a molecular
dating method) is thought to reduce error that might arise from a single
calibration point. Within crocodylians, there is a strong correlation
between calibration age and divergence estimate for five mitochondrial genes
and one nuclear gene—estimates based on two Neogene calibrations are all
younger than those based on two Paleogene calibrations, and estimates based
on one Neogene and one Paleogene calibration are of intermediate age.
Confidence limits on the youngest estimates exclude the oldest estimates,
and in several cases they exclude known minimum divergences from fossil
occurrences. Addition of time to the calibrations improves among-quartet and
stratigraphic consistency, but not all kinds of modifications have the same
impact; addition of uniform blocks of time to all calibrations efficiently
increases among-quartet consistency, but with range extensions that more
than double some of the Neogene calibrations. Modest increases in
calibration age disproportionately impact divergence estimates based on
later calibrations. Some among-quartet disparity might reflect calibration
error, especially among caimans, but some range extensions necessary to
improve consistency are unreasonably long. Quartet dating appears to
systematically undercompensate branch length error with late calibrations
and overcompensate it with early calibrations, but in all cases very
reasonable results—alligatorid-crocodylid divergence in the Late Cretaceous
and Alligator-caiman divergence at or near the
Cretaceous-Tertiary boundary—are obtained when both a Neogene and a
Paleogene calibration is used. This suggests that, given current likelihood
models, the use of calibrations sampling different parts of a clade's
history is the best strategy when using quartet dating.
Simulations of evolutionary radiations and their application to
understanding the probability of a Cambrian explosion
Authors: Levinton Jeffrey , Dubb Lindsey , Wray Gregory A.
Published: July 2006

A molecular survey of animal phylogeny (Wray et al., 1996) recovered the
presumed correct temporal order of the phylogenetic splits
Protostomata-Deuterostomata, Echinodermata-Chordata, and
Agnatha-Gnathostomata in studies of six of seven gene sequences. This result
raised the question of how this order could be recovered if all of the phyla
had appeared in a Cambrian “explosion” of less than 10 m.y., given the
expected erratic nature of the molecular “clock.” We simulated trees, and
molecular sequence evolution along the trees, under different evolutionary
radiation scenarios, with different periods of radiation, relative to times
of subsequent evolution. Simulations and phylogenetic analyses of sequences
derived from a simulated “Cambrian explosion” of 10–35 million years did not
allow the successful recovery of the correct tree, using neighbor-joining,
maximum likelihood, or parsimony methods. Success in recovering phylogenies
under a Cambrian divergence scenario (520 million years ago) did not exceed
80 percent without an extended divergence time interval of at least 100 m.y.
An increased substitution rate during the initial radiation improved the
ability to recover correct phylogenies, especially when the rate was 8–10
times the rate following the radiation. Our results militate against the
likelihood of an Early Cambrian or slightly longer explosion of the animal
phyla, as apparently supported by the fossil record. Some limitations to
these conclusions are discussed.
The effect of external and internal fossil calibrations on the avian
evolutionary timescale
Authors: van Tuinen Marcel , Hedges S. Blair
Published: July 2006

Molecular clocks can provide insights into the evolutionary timescale of
groups with unusually biased or fragmentary fossil records, such as birds.
In those cases, it is advantageous to establish internal anchor
points—molecular time estimates—using the best external fossil calibrations.
In turn, those anchor points can be used as calibrations for more detailed
time estimation within the group under study. This method also avoids the
inherent problems in drawing conclusions about the evolution of a group
based on data tied to the poor fossil record of that same group. The
galliform-anseriform divergence (∼90 million years ago) is an example of
such an ideal anchor point for molecular clock analyses in birds.
Reductio ad absurdum: Testing the evolutionary relationships of Ediacaran and Paleozoic problematic fossils using molecular divergence dates
Authors: Waggoner Ben , Collins Allen G.
Published: July 2006

Many of the late Neoproterozoic “Ediacaran fossils” have been referred to the Cnidaria, often on the basis of vague or poorly known features. However, representatives of the living Chondrophorina (=Porpitidae, Hydrozoa), Pennatulacea (Anthozoa), and Coronatae and/or Stauromedusae (Scyphozoa) have all been identified in Ediacaran biotas, based on specific morphological features preserved in a number of specimens. These three cnidarian groups have plausible Paleozoic representatives as well, but many of their Paleozoic fossils are also somewhat problematic. We test these systematic hypotheses by using them to calibrate divergence dates across the Cnidaria, based on an extensive molecular phylogeny of extant cnidarians. In thisreductio ad absurdumapproach, if a calibration based on one interpretation of a problematic fossil yields a glaringly inconsistent age for a better-known clade, that interpretation is likely to be mistaken. We find that assuming the existence of Pennatulacea and Scyphozoa in the “Ediacara biota” places the root of the Cnidaria between 800 and 1,000 Ma, a figure which is, at least, not out of line with other molecular clock estimates. However, assuming the existence of the Chondrophorina in the Neoproterozoic, or anywhere in the Paleozoic, pushes the root of the Cnidaria back to between 1,500 and 2,000 Ga, which is considerably older than the oldest previous estimates for the origin of the Cnidaria. We suggest that the likeliest explanation is that chondrophorines were not present in the late Precambrian or Paleozoic. The Ediacaran and Paleozoic fossils previously interpreted as chondrophorines probably represent other taxa.
Sponges from the Park City Formation (Permian) of Wyoming
Authors: Rigby J. Keith , Boyd Donald W.
Published: July 2006

A new small twiglike anthaspidellid sponge, Virgaspongiella
ramosa new genus and species, and an incrusting lithistid
sponge have been recovered from silicified residues of etched limestone
blocks from the Middle Permian Franson Member of the Park City Formation in
western Wyoming. Virgaspongiella n. gen. has a
skeleton of upwardly and outwardly divergent trabs formed of merged tips of
runglike dendroclone spicules in ladderlike series. One to a few oxeas
function as coring spicules in the trabs and project as fine spines from the
dermal surface, and other monaxial spicules project from pores of the
canals.

The incrusting sponge, Incrustatospongia
superficiala new genus and species, forms a distinct,
thin, uniform lithistid skeletal layer, composed largely of X-shaped
dendroclones, incrusted on both the inner and outer surfaces of productoid
brachiopod valves. Separated monaxial spicules locally protrude from the
sponge's dermal surface apparently as spinose defensive elements.
Paleoecological and phylogenetic implications of asexual reproduction in the Permian scleractiniamorphNumidiaphyllum
Authors: Ezaki Yoichi
Published: July 2006

Numidiaphyllumis one of the Paleozoic scleractiniamorphs. The genus is characterized by a poorly integrated, uniserial fasciculate form with an epithecate wall and simple morphological traits. Parent corallites are divided into several daughter corallites using one mode of division among several theoretically possible alternatives. Bipartite increase is most common, followed by hexapartite and then tripartite increase. Daughter corallites possess relatively large diameters from the beginning, along with a robust colonial pattern. This parricidal increase caused the morphologies of both parent and daughter corallites to be greatly altered and to show high morphological variability. For ecological and structural reasons, co-occurring daughter corallites generally are equal or subequal in size. Daughter corallites initially show a bilateral symmetry in both outline and septal arrangement during the course of hystero-ontogeny. However, this symmetry results only from structural necessity and is transitory. It is not homologous with the bilaterality of body plans characteristic of anthozoan groups. The morphological simplicity, related parricidal reproduction, and resulting poorly integrated growth form as seen inNumidiaphyllum, all suggest conservative features that could have resulted from phylogenetic antiquity within the scleractiniamorph body plan. Those generalized features are not themselves related to immediate phylogenetic relationships with any simply constructed rugosan group, nor would they have been due to surrounding, stressful ecologic conditions. They may have been phylogenetic-specific.
The Devonian of the Hodh area (Islamic Republic of Mauritania): Paleontology and stratigraphy
Authors: Racheboeuf Patrick R. , Gourvennec Rémy , Deynoux Max , Brice Denise
Published: July 2006

Paleontological study of 16 samples from four sections through the Silurian-Devonian marine deposits of the Hodh region establishes the development of the Middle Devonìan and adds to our knowledge of the Paleozoic sequence in the West African platform. Above Silurian deposits locally dated by graptolites from the Llandovery, Devonian shales yield an abundant although low diversity benthic fauna, which is assigned to a Givetian age. The brachiopod fauna shows strong affinity with the NE Americas Realm. Two new species are described,Arcuaminetes deynouxiandEleutherokomma monodi.The revision of the Devonian fauna of the Hodh area supports: 1) the apparent lack of Lower Devonian deposits; 2) the Givetian age of the Devonian succession; and 3) the strong eastern Americas Realm affinity of the fauna, as previously established for the Mauritanian Adrar area.
New Emsian (late Early Devonian) gastropods from Limestone Mountain, Medfra B-4 quadrangle, west-central Alaska (Farewell Terrane), and their paleobiogeographic affinities and evolutionary significance
Authors: Frýda Jiří , Blodgett Robert B.
Published: July 2006

A significant number of small-sized gastropods are described from Emsian (late Early Devonian) strata on the south flank of Limestone Mountain, Medfra B-4 quadrangle, west-central Alaska, providing the first detailed taxonomic inventory of Emsian gastropods from the Farewell terrane of southwestern and west-central Alaska. The fauna is distinctly of Old World Realm character, and contains not a single species in common with Emsian faunas of nearby nonaccreted rocks of western Canada and east-central Alaska (“Western Canada Province” of Blodgett et al., 2001a). The generaBalbinipleuraBandel and Frýda, 1996 andNanochilinaFrýda, 1998, as well as the subgenusPalaeozygopleura (Rhenozyga)Frýda, 2000, are reported for the first time in the Devonian of the Western Hemisphere. The gastropod fauna includes members of three (i.e., Archaeogastropoda, Caenogastropoda, and Heterobranchia) of the five modern gastropod subclasses, illustrating that these gastropod lineages were separated from each other since the Early Devonian. New taxa include the new generaArctozone, Farewellia, andMedfrazyga, represented by the new speciesArctozone cooki, Farewellia heidelbergerae, andMedfrazyga clauticae.Further new species includeQuadricarina (Quadricarina?) noklebergi, Balbinipleura krawczynskii, Decorospira lepaini, Decorospira? minutula, Palaeozygopleura (Rhenozyga) reifenstuhli, andNanochilina gubanovi.In addition, the following previously described gastropods are also discussed and illustrated:Alaskiella medfraensisFrýda and Blodgett, 1998;Alaskacirrus bandeliFrýda and Blodgett, 1998; andKuskokwimia mooreiFrýda and Blodgett, 2001a.
Homolidae de Haan, 1839 and Homolodromiidae Alcock, 1900 (Crustacea: Decapoda: Brachyura) from the Pacific Northwest of North America and a reassessment of their fossil records
Authors: Schweitzer Carrie E. , Nyborg Torrey G. , Feldmann R. M. , Ross Richard L. M.
Published: July 2006

New material collected from Cretaceous and Tertiary rocks of the Pacific Northwest of North America has prompted a reevaluation of the fossil record of the Homolidae de Haan, 1839 and the Homolodromiidae Alcock, 1900. The fossil records of the homolid generaHomolaLeach, 1815;HomolopsisBell, 1863; andHoplitocarcinusBeurlen, 1928 are restricted, andLatheticocarcinusBishop, 1988, which is synonymous withEohomolaCollins and Rasmussen, 1992 andMetahomolaCollins and Rasmussen, 1992, is reinstated as a distinctive genus. Thirteen new combinations resulted from reinstatement ofLatheticocarcinus: L. adelphinus(Collins and Rasmussen, 1992),L. affinis(Jakobsen and Collins, 1997),L. atlanticus(Roberts, 1962),L. brevis(Collins, Kanie, and Karasawa, 1992),L brightoni(Wright and Collins, 1972),L. centurialis(Bishop, 1992),L. declinata(Collins, Fraaye, and Jagt, 1995),L. dispar(Roberts, 1962),L. pikeae(Bishop and Brannen, 1992),L. punctatus(Rathbun, 1917),L. schlueteri(Beurlen, 1928),L. shapiroiBishop, 1988,L. spiniga(Jakobsen and Collins, 1997), andL. transiens(Segerberg, 1900). A new species,Latheticocarcinus ludvigseni, is described from Cretaceous rocks of British Columbia. The first fossil occurrence of the extant homolid genusParomolopsis, P. piersoninew species, is recorded from Miocene rocks of Oregon.Paromola pritchardiJenkins, 1977 is formally transferred toDagnaudusGuinot and Richer de Forges (1995) as suggested by Guinot and Richer de Forges (1995). The extinct family Prosopidae von Meyer, 1860 is referred to the Homolodromioidea Alcock, 1900, following previous work.Palehomola gorrelliRathbun, 1926 is transferred from the Homolidae to the Homolodromiidae, and the new genusRhinodromiais erected to containHomolopsis richardsoniWoodward, 1896, from Cretaceous rocks of British Columbia. A new terminology is suggested for describing the rostral area in homolodromiids, in an attempt to alleviate considerable confusion over that issue. The morphologic similarity of fossil and extant members in both the Homolidae and the Homolodromiidae suggest that these two brachyuran families are evolutionarily conservative, much as the lobsters are. In addition, the similar paleobiogeographic and evolutionary patterns seen in the two families suggests that either they are closely related or that brachyuran families exhibited similar evolutionary and dispersal trends early in their history.
Shark-bitten protostegid turtles from the Upper Cretaceous Mooreville
Chalk, Alabama
Authors: Shimada Kenshu , Hooks G. E.
Published: July 2006

Protostegids are Cretaceous marine turtles. Fossil materials assignable
to the family Protostegidae range from early Albian to Late Campanian in age
and have been described from all continents except Antarctica (Hirayama,
1995). The group includes two gigantic forms,
Archelon Wieland and
Protostega Cope, that reached maximum
carapace lengths in excess of 2 m and rank among the largest turtles that
ever lived.

In this paper, we describe two specimens of Protostega
gigas Cope housed in the Field Museum of Natural History
(FMNH), Chicago, Illinois: FMNH P27452 and FMNH PR58. Both are from the
Mooreville Chalk (Upper Santonian to Lower Campanian: Mancini et al., 1995)
in Greene County, Alabama, and are noteworthy because they show tooth marks
from at least one large shark. One of the specimens also exhibits five
embedded teeth of the Late Cretaceous cretoxyrhinid shark
Cretoxyrhina mantelli (Agassiz). This note
constitutes the first report of protostegid turtles bitten by
C. mantelli.
Matoniaceous ferns (Gleicheniales) from the Middle Triassic of Antarctica
Authors: Klavins Sharon D. , Taylor Thomas N. , Taylor Edith L.
Published: July 2006

The Matoniaceae is one of the most ancient lineages of extant ferns, with a fossil record that extends from the early Mesozoic. Currently they are considered to be a systematically isolated group that occupies a basal position in the phylogeny of leptosporangiate ferns. Although the extant taxa of Matoniaceae are today restricted to the Malaysian archipelago, a diverse assemblage of matoniaceous ferns occurred on every continent, including Antarctica, during the Mesozoic. Here we describe anatomically preserved, detached fern sori and sporangia from the Fremouw Formation with a combination of characters that affiliates them with the Matoniaceae. Sori are peltate with more than 25 crowded sporangia that display simple maturation. The indusium is multiseriate and centrally attached to a massive, vascularized receptacle. Sporangia are globose to ovoid with vertical, meandering, incomplete annuli, and are helically attached to the receptacle in three to four gyres. This report places this fern as the earliest known occurrence of the Matoniaceae in the fossil record. Characters observed in the sori offer insights regarding organizational patterns of reproductive structures in the family. Additionally, the presence of a peltate indusium in the earliest known representative of the family contradicts the hypothesized evolutionary sequence in development of this structure in the family.
Life association of shell and operculum of Ceratopea Ulrich, 1911
(Ordovician; Gastropoda)
Authors: Rohr David M. , Fix Michael F. , Darrough Guy
Published: July 2006

Ceratopea Ulrich, 1911, from the Lower
Ordovician of North America, Greenland, and Scotland, is one of a few
gastropod genera that was established on the calcareous operculum and not
the shell. The operculum is commonly found disassociated, and for many years
the nature of the shell itself was unknown (Yochelson, 1975). Yochelson and
Bridge (1957, pl. 38, figs. 8–9) illustrated an artificial association of
C. unguis with its presumed shell made years
earlier by Ulrich and Bridge (Yochelson, written commun.). However, the
basal part of the shell is not present. Only one life association of the
shell and operculum has been previously documented (Yochelson and Wise,
1972), and that shell is incompletely preserved.
A new species of the diplopod Amynilyspes (Oniscomorpha) from the
Stephanian Lagerstätte of Montceau-les-Mines, France
Authors: Racheboeuf Patrick R. , Hannibal Joseph T. , Vannier Jean
Published: July 2006

Spinous oniscomorph millipedes are rare faunal components of the upper
Palaeozoic (Shear, 1997). Amynilyspes (type
species A. wortheni Scudder, 1882; OD) is an
Upper Carboniferous spinous oniscomorph (pill millipede) which was first
described from the Middle Pennsylvanian (Westphalian D equivalent)
Fossil-Lagerstätte of Mazon Creek. Later Fritsch (1899) described two
species (A. typicus and A.
crescens) from the Wesphalian D Gaskohle of Nýřany in
Bohemia. More recently A. typicus was recorded
from the Stephanian B of the Saarland (Förster, 1973), then from the
Stephanian B of the Blanzy-Montceau-les-Mines Basin (Langiaux and Sotty,
1977; Poplin, 1994). Although myriapods were already known to occur in the
Montceau-les-Mines Lagerstätte (Langiaux and Sotty, 1976; Rolfe et al.,
1982; Poplin and Heyler, 1994) the presence of
Amynilyspes at Montceau-les-Mines was first
published in a regional publication (“La Physiophile” Langiaux and Sotty,
1976, 1977), and it has passed almost unnoticed.
A new meristid brachiopod genus from the Lower Carboniferous of Guizhou, China
Authors: Sun Yuanlin , Ma Xueping , Baliński Andrzej , Zhang Yubo
Published: July 2006

The rowleyellinae is a small subfamily of meristelloid athyridid brachiopods, previously with only one genus,RowleyellaWeller, 1911 (Alvarez and Brunton, 1995; Alvarez et al., 1998; Alvarez and Rong, 2002). In this paper we report a new meristelloid athyridid brachiopod genusMuhuathyrisfrom a newly discovered, very diverse Tournaisian brachiopod fauna in South China. It is noteworthy that this newly discovered fauna is slightly older than that reported earlier from the same outcrop (Balinski, 1999). A full discussion of the newly discovered fauna is currently in preparation. Morphological features ofMuhuathyrisn. gen. suggest that it is probably an evolutionary intermediate betweenCamarophorellaHall and Clarke, 1893 andRowleyellaWeller, 1911. The new genus differs fromCamarophorellaandRowleyellaonly in the nature of the structures beneath the septalium in the dorsal valve. InCamarophorellaa shoe lifter is present in front of or beneath the septalium. InRowleyellaa cruralium rests on the dorsal median septum under the septalium and extends to the front of septalium. Lateral to the dorsal median septum, two thin and short plates, asymmetrically disposed, are present posteriorly under the cruralium, which were considered by Carter (1991) as a very posteriorly placed shoe lifter. In the new genus a structure consisting of two plates lateral to the dorsal median septum is attached to the dorsal surface of septalium near the crural bases. This structure extends from the dorsal beak to the posterior of the adductor muscle fields. It may be developed as two vertical plates lateral to the median septum, or, when the plates converge medially, as a sessile or median septum-supported cruraliumlike platform. The structure primarily acts as support to the crural bases and septalium rather than a dorsal adductor muscle platform, but may also serve as part of dorsal adductor muscle attachments in some individuals. It seems probable that this structure might be homologous to the cruralium inRowleyella.For this reason we put the new genus within the subfamily Rowleyellinae.
Beyond competition
Authors: Gould Stephen Jay
Published: July 2006

In a rare lapse of judgment, T. H. Huxley defined science as “organized common sense.” Huxley's motivation cannot be faulted, for he wished, by this definition, to stress the accessibility of science to any well-educated person. In the first paragraph of his most famous work on popular science (The Crayfish: An Introduction to the Study of Zoology, 1880), Huxley stated the fallacy that he wished to dispel with this definition:

Many persons seem to believe that what is termed Science is of a widely different nature from ordinary knowledge, and that the methods by which scientific truths are ascertained involve mental operations of a recondite and mysterious nature, comprehensible only by the initiated, and as distinct in their character as in their subject matter, from the processes by which we discriminate between fact and fancy in ordinary life.
Competitive displacement among post-Paleozoic cyclostome and cheilostome bryozoans
Authors: Sepkoski J. John , McKinney Frank K. , Lidgard Scott
Published: July 2006

Encrusting bryozoans provide one of the few systems in the fossil record in which ecological competition can be observed directly at local scales. The macroevolutionary history of diversity of cyclostome and cheilostome bryozoans is consistent with a coupled-logistic model of clade displacement predicated on species within clades interacting competitively. The model matches observed diversity history if the model is perturbed by a mass extinction with a position and magnitude analogous to the Cretaceous / Tertiary boundary event. Although it is difficult to measure all parameters in the model from fossil data, critical factors are intrinsic rates of extinction, which can be measured. Cyclostomes maintained a rather low rate of extinction the model solutions predict that they would lose diversity only slowly as competitively superior species of cheilostomes diversified into their environment. Thus, the microecological record of preserved competitive interactions between cyclostome and cheilostome bryozoans and the macroevolutionary record of global diversity are consistent in regard to competition as a significant influence on diversity histories of post-Paleozoic bryozoans.
The muricid gastropod subfamily Rapaninae: phylogeny and ecological history
Authors: Vermeij Geerat J. , Carlson Sandra J.
Published: July 2006

Members of the neogastropod muricid subfamily Rapaninae are abundant, shallow-water predators whose phylogeny was previously investigated by Kool (1993b), who used mainly anatomical characters. In order to deepen understanding of the evolution of this important clade and to incorporate functional, ecological fossil evidence, we performed a phylogenetic analysis based on 34 shell characters in 45 genus-level taxa, including five muricid outgroups. Cladograms based on shell characters alone differed from those founded on anatomical features these analyses differed from the phylogenetic reconstruction combining all available morphological evidence. The preferred cladogram incorporates all evidence and reveals a “Thaisgroup” and an “Ergalataxclade” that both emerge from the derived portion of a more primitive, paraphyletic group of other rapanines. The Ocenebrinae, the other four outgroup taxa three ergalataxine taxa all lie outside the rapanine clade that includes the remaining ergalataxines as a derived subclade.

We used the phylogenetic results to probe aspects of the ecological history of the Rapaninae. Our data imply that antipredatory shell defenses (elongated aperture, denticles on the inner side of the outer lip robust external spines and tubercles) evolved multiple times, mainly in post–early Miocene clades in the Indo–West Pacific region. These results support earlier nonphylogenetic inferences.

We compared known prey types and methods of predation of living rapanines with their distribution on our phylogenetic tree. The plesiomorphic mode of feeding in the Rapaninae is drilling of hard-shelled prey. Feeding by other means and on such soft-bodied prey as sipunculan and polychaete worms evolved several times independently among post–early Miocene rapanines in the Indo–West Pacific. Methods of predation on hard-shelled prey that involve edge-drilling or attack by way of the aperture also evolved independently several times, but did so throughout the geographical range of the subfamily.

Specialization for life on the upper shore occurred in at least eight lineages, all but two of which are confined to the Indo–West Pacific. Ecological diversification of the Rapaninae was therefore most common in the tropical Indo–West Pacific during and after early Miocene time. This diversification occurred in a setting of already high biological diversity and intense competition and predation.
Modern mucociliary creeping trails and the bodyplans of Neoproterozoic trace-makers
Authors: Collins Allen G. , Lipps Jere H. , Valentine James W.
Published: July 2006

The bulk of Neoproterozoic trace fossils can be interpreted as horizontal creeping trails produced by minute vermiform organisms moving on or just beneath the seafloor or under algal mats. We have investigated the formation of trails by living cnidarians and platyhelminths that creep by cilia on mucus ribbons. These relatively simple metazoans produce trails that are similar in size and morphology to some Neoproterozoic traces, owing to the entrainment of sediment within their mucus trails. Thus a mucociliary locomotory system provides sufficient means to form some types of Neoproterozoic traces. It follows that the body architectures of the Neoproterozoic trace-makers may have been quite simple, though complex bodyplans are, of course, not ruled out. Thus, the use of Neoproterozoic trace fossils to constrain the time of origin of bilaterians or of any crown-group bilaterian taxon remains questionable.
Contrasting evolutionary flexibility in sister groups: disparity and diversity in Mesozoic atelostomate echinoids
Authors: Eble Gunther J.
Published: July 2006

Temporal asymmetries in clade histories have often been studied in lower Paleozoic radiations. Post-Paleozoic patterns, however, are less well understood. In this paper, disparity and diversity changes in Mesozoic heart urchins were analyzed at the ordinal level, with contrasts among the sister groups Holasteroida and Spatangoida, their paraphyletic stem group Disasteroida the more inclusive clade, the superorder Atelostomata. A 38-dimensional landmark-based morphospace representing test architecture was used to describe morphological evolution in terms of total variance and total range. Discordances between disparity and diversity were evident and were expressed both as deceleration in morphological diversification in all groups and as disproportionately higher disparity early in the histories of the Atelostomata, Holasteroida Spatangoida. The finding that the early atelostomate disparity peak coincides with the origin of the orders Holasteroida and Spatangoida lends support to the perception of orders as semi-independent entities in the biological hierarchy and as meaningful proxies for morphological distinctness.

A comparison of holasteroid and spatangoid responses to the end-Cretaceous mass extinction revealed morphological selectivity. Paleocene spatangoid survivors showed no change in disparity relative to the Campanian-Maastrichtian sample, suggesting nonselectivity. Holasteroids suffered a pronounced loss in disparity (despite a rather high Late Cretaceous level of disparity), indicating morphological selectivity of extinction.

Partitioning of disparity into plastral and nonplastral components, reflecting different degrees of developmental entrenchment and functionality, suggests that the origin of holasteroids and spatangoids is more consistent with an exploration of the developmental flexibility of nonplastral constructions than with uniform ecospace occupation. Within groups, several patterns were also most consistent with intrinsic controls. For plastral landmarks, there is an apparent increase in developmental modularity and decrease in developmental constraint from disasteroids to holasteroids and spatangoids. For nonplastral landmarks, no substantial change in disparity was observed from disasteroids to holasteroids and spatangoids, suggesting the maintenance of a developmental constraint despite the passage of time and ecological differentiation. More generally, this study suggests that certain topologies of disparity and evolutionary mechanisms potentially characteristic of the lower Paleozoic radiations of higher taxa (e.g., developmental flexibility) need not be confined to any given time period or hierarchical level.
Bivalve taphonomy in tropical mixed siliciclastic-carbonate settings. II. Effect of bivalve life habits and shell types
Authors: Best Mairi M. R. , Kidwell Susan M.
Published: July 2006

Bivalve death assemblages from subtidal environments within the tropical Bocas del Toro embayment of Caribbean Panama permit a test of the extent to which levels of damage are determined by the intrinsic nature of shell supply (proportion of epifaunal species, thick shells, calcitic shells, low-organic microstructures), as opposed to the extrinsic postmortem environment that shells experience. Only damage to interior surfaces of shells was used, to ensure that damage was unambiguously postmortem in origin. We find that facies-level differences in patterns of damage (the rank order importance of postmortem encrustation, boring, edge-rounding, fine-scale surface degradation) are overwhelmingly controlled by environmental conditions: in each environment, all subsets of the death assemblage present the same damage profile. The composition of shell supply affects only the intensity of the taphonomic signature (i.e., percentage of shells affected) only in environments containing hard substrata (patch reefs, Halimeda gravelly sand, mud among patch reefs). In these environments, epifauna, whether aragonitic or calcitic and whether thin or thick, exhibit significantly higher damage than co-occurring infauna, probably due to the initial period of seafloor exposure they typically experience after death. Thick shells (>0.5 mm), regardless of life habit or mineralogy, are damaged more frequently than thin shells, probably because of selective colonization by fouling organisms. Calcitic shells show no consistently greater frequency of damage than aragonitic shells high-organic microstructures yield mixed patterns. Taphofacies surveys in such depositional systems could thus be confidently based on any subset of the fauna, including diagenetically residual assemblages of calcitic shells and thick-shelled molds. Further tests are needed to determine whether the higher levels of damage observed on some subsets of shells are a consequence of greater time-averaging (thus lower temporal resolution), greater exposure time, preferential attack (potential bias in relative abundance), or some combination of these. Paleobiologically, however, the implication is that ecological subsets of bivalve assemblages are not isotaphonomic, either in tangible damage or in probable bias, within hard-substrate environments, although they may be within soft-sediment environments. In actualistic studies, targeting broad classes of taxa for comparison across environments maximizes our ability to extrapolate taphonomic guidelines into the fossil record, where life habits, skeletal types shallow subtidal habitats have dramatically different patterns of abundance and deployment.
Fenestrate theoretical morphology: geometric constraints on lophophore shape and arrangement in extinct Bryozoa
Authors: Starcher Robert W. , McGhee George R.
Published: July 2006

A geometric analysis of fenestrate bryozoan lophophore shape and arrangement is conducted by creating a theoretical morphospace of apertural positioning within the colonial meshwork. Working from the assumption that fenestrate bryozoans needed to form a continuous filtering surface with contact between adjacent lophophores, we show that within the morphospace three regions exist for optimum close-packing of lophophores with circular projections; all other close-packing configurations in the morphospace require the existence of noncircular lophophores.

Examination of the actual distribution of 251 fenestrate colonies within the morphospace reveals that the morphospace regions occupied by fenestellids and polyporids are displaced and have little overlap, but that they are very similar in size and shape that the colonies scale similarly. With increasing size, fenestrate meshworks expand laterally faster than the branches widen and the proximodistal spacing of the apertures increases, apparently because the larger zooids require disproportionately more room for their lophophores.

Two of the optimum close-packing regions of the morphospace are occupied by fenestrates. The positioning of the fenestellid region within the morphospace suggests that these biserial bryozoans followed a proximodistal-row placement of the lophophores that the lophophores were generally equitentacular, with circular projections. The positioning of the polyporid region within the morphospace suggests that these polyserial bryozoans followed a diagonal-row placement of the lophophores that the lophophores were heteromorphic, with medial lophophores on the branch being more equitentacular whereas the laterally placed lophophores were obliquely truncate. The third optimum close-packing region in the morphospace, corresponding to a hypothetical lateral-row placement of the lophophores within the colony, is unoccupied. We suggest that hypothetical fenestrate morphologies in the vacant region of morphospace have branches that would be too narrow to support normally shaped zooids that the lateral-row placement of the lophophores would have required the branches of the colony to have been perfectly aligned throughout growth.
Taxonomy and temporal diversity patterns
Authors: Robeck Heidi E. , Maley Carlo C. , Donoghue Michael J.
Published: July 2006

Temporal diversity patterns have traditionally been analyzed by counting the number of families or genera present over a series of time periods. This approach has been criticized on the grounds that paraphyletic taxa might introduce artifacts. Sepkoski and Kendrick (1993) simulated phylogenetic trees and different classifications of those trees and concluded that paraphyletic taxa need not be rejected. We have reimplemented their model, extended it, and carried out statistical analyses under a variety of experimental conditions. Our results show that the focus on monophyly vs. paraphyly is misplaced. Instead, it appears that the number of groups in the classification and the distribution of the sizes of those groups have dramatic effects on the recovery of diversity information. Furthermore, the influence of these factors depends on whether the fossil record represents a low- or high-frequency sampling of lineages. When sampling is good, the best results are achieved by classifications with large numbers of small taxa. When sampling is poor, however, the best results are achieved by classifications that include some large and medium-sized groups as well as many smaller groups. This suggests that the best estimates of underlying diversity will be achieved by counting (in the same study) taxa assigned to different ranks, so as to best match the inferred quality of the paleontological sample. In practice this will mean abandoning the commitment to counting taxa at a single rank.