bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early Paleozoic Hyolitha from North America: reexamination of Walcott's and Resser's type specimens
Authors: Malinky John Mark 
Published: August 2016

Concepts of the family Hyolithidae Nicholson fide Fisher and the generaHyolithesEichwald andOrthothecaNovak have been expanded through time to encompass a variety of morphologically dissimilar shells. The Hyolithidae is here considered to include only those hyolithid species which have a rounded (convex) dorsum; slopes on the dorsum are inflated, and the venter may be flat or slightly inflated.Hyolithesencompasses species which possess a low dorsum and a prominent longitudinal sulcus along each edge of the dorsum; the ligula is short and the apertural rim is flared. The emended concept ofOrthothecaincludes only those species of orthothecid hyoliths which have a subtriangular transverse outline and longitudinal lirae covering the shell on both dorsum and venter.Eighteen species ofHyolithesand one species ofOrthothecafrom the Appalachian region and Western Interior were reexamined in light of more modern taxonomic concepts and standards of quality for type material. Reexamination of type specimens ofH. similisWalcott from the Lower Cambrian of Newfoundland,H. whiteiResser from the Lower Cambrian of Nevada,H. billingsiWalcott from the Lower Cambrian of Nevada,H. gallatinensisResser from the Upper Cambrian of Wyoming, andH. partitusResser from the Middle Cambrian of Alabama indicates that none of these species representsHyolithes. Hyolithes similisis here included under the new genusSimilotheca,in the new family Similothecidae.Hyolithes whiteiis designated as the type species of the new genusNevadotheca,to whichH. billingsimay also belong.Hyolithes gallatinensisis referred toBurithesMissarzhevsky with question, andH. partitusmay representJoachimilitesMarek. The type or types ofH. attenuatusWalcott,H. cecropsWalcott,H. comptusHowell,H. cowanensisResser,H. curticeiResser,H. idahoensisResser,H. prolixusResser,H. resseriHowell,H. shaleriWalcott,H. terranovicusWalcott, andH. wanneriResser and Howell lack shells and/or other taxonomically important features such as a complete aperture, rendering the diagnoses of these species incomplete. Their names should only be used for the type specimens until better preserved topotypes become available for study. Morphology of the types ofH.?corrugatusWalcott and “Orthotheca”solaResser does not support placement in the Hyolitha; the affinities of these species are uncertain.
Approaches to systematic and evolutionary studies of perplexing groups: an example using fenestrate Bryozoa
Authors: Hageman Steven J. 
Published: August 2016

Recognition of discrete taxa is an enduring problem in the biological sciences, especially for taxonomists who work with groups that display a great degree of homeomorphy at low taxonomic levels. Selection of the type and number of characters used to make taxonomic distinctions is important because it reflects taxonomic concepts for a group as a whole. Often the validity of characters used to develop classifications is not documented and resulting classifications are therefore suspect. However, classifications can be tested for their objectivity with numerical analysis and characters can be evaluated for their relative value for making taxonomic splits by a variety of statistical techniques. In addition, evaluation of the distribution of character states can lead to insights into evolutionary histories of any group. This study provides such an analysis.Fenestrate cryptostome Bryozoa are abundant and diverse in many upper Paleozoic rocks, and are therefore potentially highly useful for a variety of paleontologic studies. However, study of fenestrates is hampered by necessary complex preparation techniques and problems encountered with homeomorphy. In addition, inconsistent applications of inadequate methodologies have contributed to an unsatisfactory taxonomy. Results from cluster and discriminant analyses demonstrate that fenestrate species can be objectively recognized. Species distinctions are most clear when all available characters are used, although some characters are more diagnostic than others.Results from cluster and discriminant analyses suggest that fenestrate genera represent major evolutionary shifts associated with the development of key character(s) that allowed entry into new adaptive zones. Key characters allow for an oligothetic classification of genera, which is not merely an artifact created to simplify taxonomic analysis. Diversification of species within adaptive zones resulted in a natural hierarchy of genus-level and species-level characters. Iterative evolution at the species level within separate adaptive zones resulted in a great deal of homeomorphy.Morphometric analysis provides insights into several aspects of the paleobiology of this traditionally problematic group. Similar comprehensive studies may prove equally productive for other groups.
Paleoecologic and taxonomic implications of Sphenothallus and Sphenothallus-like specimens from Ohio and areas adjacent to Ohio
Authors: Neal Maxwell Lewis , Hannibal Joseph T. 
Published: August 2016

Sphenothallus and fossils similar to Sphenothallus are found in Ordovician, Devonian, and Mississippian rock units in Ohio and adjacent states and provinces. Although the Ordovician of Québec, Ontario, and Indiana has yielded parts of tubes, Ordovician specimens from southwest Ohio and nearby areas consist almost entirely of holdfasts on hardgrounds and shelly fossils. Sphenothallus is abundant in the Chagrin Shale (Famennian) of northeast Ohio where it is found in about four percent of concretions that contain identifiable fossils. The Chagrin specimens, usually parts of tubes, are occasionally preserved three-dimensionally. The rate of distal expansion of Chagrin Sphenothallus tubes varies intraspecifically; thus, this rate cannot be used to distinguish species. Some Chagrin specimens are attached to larger, conspecific specimens and to articulate brachiopods. Brachiopods have also been found attached to Chagrin Sphenothallus. Bedford-Berea sequence (Famennian) specimens from northern Kentucky and Meadville Member (Kinderhookian or Osagian) specimens from the Cuyahoga Formation of northeast Ohio are usually preserved as flattened tubes. In both occurrences tubes are similar in width, indicating that individuals in each assemblage are probably the same age. Meadville tubes possess characteristics diagnostic of Sphenothallus, but Bedford-Berea specimens, which lack longitudinal thickenings and exhibit little tube tapering, cannot be assigned to Sphenothallus sensu strictu.Sphenothallus was a gregarious, opportunistic species, tolerant of dysaerobic conditions and able to colonize environments ranging from hardgrounds to soft, muddy sea bottoms. No distinct branching was observed among the Chagrin, Bedford-Berea, or Meadville specimens, suggesting that larval dispersal was the primary mode of reproduction for the genus.
Cupulocrinid crinoids from the Middle Ordovician (Galena Group, Dunleith Formation) of northern Iowa and southern Minnesota
Authors: Brower James C. 
Published: August 2016

Two cupulocrinids,Cupulocrinus crossmanin. sp. andPraecupulocrinus conjugans(Billings) n. gen., are known from the Middle Ordovician (Galena Group, Dunleith Formation) of northern Iowa and southern Minnesota. Various morphologic and ontogenetic features demonstrate thatPraecupulocrinusis more primitive thanCupulocrinus. The two species commonly occur together. In addition, both taxa coexisted at similar levels with stem lengths ranging from about 1.5 cm in juveniles to 15 cm in adults. Relatively complete growth sequences illustrate growth and variation and show how two related crinoids subdivided feeding niches. The crown volume provides a satisfactory surrogate variable for the size of the animal. The food-gathering system of the cupulocrinids is mainly augmented by the addition of new plates at the ends of the arms. The number of plates in the arms and the arm length exhibit positive allometry relative to crown volume, largely due to development of new branches at the arm tips. The food-gathering capacity equals the number of food-catching tube-feet multiplied by the average width of the food grooves. Food-gathering capacity is also positively allometric with respect to crown volume and the amount of tissue that must be supplied with food. Consequently, the ratio of food-gathering capacity:crown volume is either constant or declines slightly with increasing size and age. The food groove width increases throughout ontogeny so adult crinoids ate larger food particles than juveniles.Praecupulocrinus conjugans(Billings) n. gen. has more narrow food grooves thanCupulocrinus crossmanin. sp. of comparable size and age, which suggests niche differentiation based on food-particle size. The arm and tube-foot geometry indicates that both cupulocrinids utilized the same type of suspension feeding.The morphology of the anal sac and the lack of “patelloid” processes in the arms indicate thatCupulocrinus sepulchrumRamsbottom from the Upper Ordovician of Scotland belongs toDendrocrinus.
Posterolateral markings on dinosaur tracks, Cameron Dinosaur Tracksite, Lower Jurassic Moenave Formation, northeastern Arizona
Authors: Irby Grace V. 
Published: August 2016

Posterolateral markings, appearing as short, rectilinear grooves projecting from the posterior margins of digit IV, occur on tracks in five of 34 trackways at the Cameron Dinosaur Tracksite in the Dinosaur Canyon Member of the Lower Jurassic Moenave Formation, northeastern Arizona. A new ichnospecies, Grallator (Anchisauripus) madseni, is described from these five trackways made by bipedal, tridactyl dinosaurs. The size and morphology of the tracks suggest that they may represent trackmakers similar to Coelophysis and Syntarsus, two dinosaurs described from Triassic and Jurassic deposits in northeastern Arizona and northwestern New Mexico.Among the working hypotheses cited as possible causes of the posterolateral markings are: 1) they were made by the dragging of digit III or of the metatarsus; 2) they are marks produced by a feature similar to a horny excrescence or cornified ridge on digitometatarsal pad IV; and 3) they are related to a peculiarity that may have resulted from sexual dimorphism.
Modified legs (clasping appendages?) of Carboniferous euphoberiid millipeds (Diplopoda: Euphoberiida)
Authors: Hannibal Joseph T. 
Published: August 2016

Six specimens belonging to several euphoberiid diplopod species have a pair of modified legs located along the midbody. These appendages are robust, much stouter than normal walking legs, and are attached to a sternite that is longer than those preceding and following. Euphoberiid modified legs differ in position from those of modern diplopods, being located neither near the anterior end as are gonopods nor at the anterior or posterior ends, as are clasping appendages of various modern forms. The presence of such appendages supports ordinal status for the euphoberiids.The prominent spines of euphoberiids would have precluded intertwining types of mating behavior observed in many types of elongate modern diplopods. Judged by their robust nature and location, the modified legs may have been clasping appendages used during the mating process. “Intromittent organs” described on various taxa of fossil Diplopoda by the early paleomyriapodologists Scudder and Fritsch are suspect.
Taxonomy and distribution of the buccinid gastropod Brachysphingus from uppermost Cretaceous and Lower Cenozoic marine strata of the Pacific Slope of North America
Authors: Squires Richard L. 
Published: August 2016

Brachysphingus is a low-spired bucciniform neogastropod known only from the fossil record of California and northern Baja California. The earliest species, Brachysphingus gibbosus Nelson, 1925, ranges in age from latest Cretaceous or possibly earliest Paleocene to the late Paleocene. During the early Paleocene, the smoothish B. gibbosus evolved into the axially ribbed B. sinuatus Gabb, 1869, which is the senior primary synonym of B. gabbi Stewart, 1927. During the late Paleocene, B. sinuatus evolved into B. mammilatus Clark and Woodford, 1927, which is the youngest species of Brachysphingus and which lasted into the early Eocene.All three species of Brachysphingus were shallow-marine dwellers subject to transport into deeper waters via turbidity currents.
Hystricurid trilobite larvae from the Garden City Formation (Lower Ordovician) of Idaho and their phylogenetic implications
Authors: Lee Dong-Chan , Chatterton Brian D. E. 
Published: August 2016

Hystricurids are considered to constitute the earliest (early Ibexian or Tremadocian) family of Proetida, based on comparisons of hystricurid larvae with younger proetide and Cambrian ptychopariide larvae. The hystricurid larvae share a fusiform glabella falling short of the anterior margin with other proetide larvae, which were derived from Cambrian ptychopariide larvae with a forward-expanding glabella. Two discrete morphotypes of hystricurid larvae are recognized. The first type is characterized by the development of a pattern of regularly distributed tubercles on the shield and the presence of a preglabellar field. The second is characterized by the presence of glabellar furrows (discontinuous or transglabellar), an indented posterior margin, and a lack of tuberculation. Each of these hystricurid lineages represented by a distinct larval morphotype is considered ancestral (or sistergroup) to a different group of younger proetides. The second larval morphotype is considered a phylogenetic intermediate between the first type and ptychopariide larvae. Several larval features of these primitive proetides are considered to have originated by early onset of post-larval features of the ptychopariides (peramorphic pattern).Newly described hystricurid species areHystricurusn. sp. A,Hystricurus? sp. A,Hystricurus? sp. B, ‘Paraplethopeltis’ n. sp. A, ‘Paraplethopeltis’ sp. B, andHyperbolochiluscf.marginauctum.
Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?
Authors: Bailey Jack Bowman 
Published: August 2016

Several dinosaurs, notablyOuranosaurusandSpinosaurus,have vertebral columns marked by prominent arrays of elongated neural spines. Using pelycosaurian sailbacks likeDimetrodonas analogies, popular orthodoxy holds that the tall spines served as supporting struts for dorsal sails of purported thermoregulatory function, especially heat dissipation in tropical climates. It is argued here that the neural spines ofOuranosaurus, Spinosaurus,and several other long-spined dinosaurs favor bison-like humps rather than sails: 1) in functional morphology and relative elongation they are dissimilar to pelycosaur spines but homoplastically converge on the spines of high-withered ungulates; 2) the usefulness of a sail in thermoregulation has been exaggerated—in large tetrapods it would have been fairly efficient as a thermal amplifier but ineffective as a radiator; hence large sail-bearing dinosaurs in open tropical climates are improbable; 3) the insulation properties of humps favor gigantothermy, the most likely thermobiological model for large dinosaurs.Dinosaur humps are probable adaptations for: 1) energy storage, maintenance of gigantothermy, and heat-shielding in unshaded habitats; 2) long-distance migration from feeding to nesting grounds across terrains of variable productivity; and 3) lipid conservation for production of large clutches of eggs at the nesting site. Because sacral, caudal, or dorsal humps were relatively common traits among certain groups, the fashionably anorexic image of many large dinosaurs must be emended.
Inozoan calcareous Porifera from the Permian reefs in South China
Authors: Rigby J. Keith , Jiasong Fan , Wei Zhang 
Published: August 2016

Inozoans are described from patch reefs on the carbonate platform of eastern Sichuan, from the uppermost Permian Laolongdong reefs in the Changxing Formation (Kazanian–Tatarian) at Beipei, northwest of Chongqing, and from Middle and Upper Permian reefs from the Maokou (Kungurian), Wujiaping (Ufimian), and Changxing Formations at Xiangbo, Longlin County, in northwestern Guangxi. Classification of inozoans, particularly late Paleozoic ones, is still in a state of flux, but genera recognized to date can be keyed using the general nature of the spongocoel, canals, and growth form.New genera described areIntratubospongia, Grossotubenella, Cavusonella, andRadicanalospongia. The new species described areStellispongia radiata, S. minor, Peronidella beipeiensis, P. regulara, P. parva, Intratubospongia typica, I. tenuiperforata, I. multisi-phonata, I. minima, Grossotubenella parallela, Cavusonella caverna, andRadicanalospongia normala. ACorynellathat is not identifiable to species and a sphinctozoan-like inozoan(?) sp. A that has a fibrous-appearing internal skeleton but is poorly preserved are also described. Inozoans and other sponges are major frame-builders in the Permian reefs of South China and our fauna is one of the most diverse late Paleozoic assemblages described to date.
Lower Cambrian pediculate lingulids from Yunnan, China
Authors: Yugan Jin , Xianguang Hou , Huayu Wang 
Published: August 2016

The vermiform pedicle is one of the most distinctive organs of modern lingulids, but it is rarely preserved. Only two fossil specimens of lingulids with pedicle casts have been reported, one from the Ordovician and the other from the Devonian. No record of fossil pedicles ofLingulellaandLingulepis, the dominant Cambrian and Early Ordovician lingulids, is known. Fossil lingulids from the Lower Cambrian of Chengjiang County, Yunnan, suggest that the structure and function of the pedicle of the lingulids has not changed significantly from its first appearance. A comparison of fossil pedicle of lingulids from the Lower Cambrian, Chengjiang County (China), the Burgess Shale, Middle Cambrian, British Columbia (Canada), the Trenton Formation, Middle Ordovician, New York (U.S.A.), and the Devonian, Devonshire (England, U.K.) shows that the delthyrial area to which the pedicle muscles are attached was reduced in length through time until these muscles were completely embraced by the two valves.Two species,Lingulella chengjiangensisn. sp. andLingulepis malongensisRong, are described.
Lower Cambrian demosponges and hexactinellid sponges from Yunnan, China
Authors: Rigby J. Keith , Xian-Guang Hou 
Published: August 2016

The assemblage of demosponge and hexactinellid sponges described here was collected from the Lower Cambrian, Atdabanian, Yu'anshan Member of the Chiungchussu Formation, at the Maotianshan and Xiaolantian sections in Chengjiang County, Yunnan Province, 70 km southeast of Kunming. The sponges occur in relatively massive to weakly graded-bedded, grayish-yellow mudstone and silty mudstone. They are associated with other soft-bodied and skeletonized fossils. The new demosponge species and generaChoiaella radiata, Allantospongia mica, and the questionable spongeParvulonoda dubiaare described, along with new specimens ofLeptomitus teretiusculusChen, Hou, and Lu, 1989, the hexactinellid sponge,Triticispongia diagonataMehl and Reitner, 1993 and the probable hexactinellid sponge,Saetaspongia densaMehl and Reitner, 1993.The sponges occur in what may be distal turbidite deposits, and they may have been buried essentially in situ by these argillaceous accumulations.
Patterns of crystallographic axis orientation in blastoid skeletal elements
Authors: Bodenbender Brian E. 
Published: August 2016

It is well known that echinoderm skeletal elements behave optically as single calcite crystals, but one implication of this observation, that skeletal units have crystallographic axes with characterizable orientations, has received little attention. This paper examines patterns of crystallographic axis orientations in 43 blastoid species and assesses their usefulness to the study of homology among echinoderm skeletal elements, phylogeny both within blastoids and at higher taxonomic levels, and biomineralization processes.Calcite decoration and optical goniometry techniques reveal intraspecific and interspecific patterns of variation in the orientations ofcandacrystallographic axes in the three major sets of blastoid thecal plates. Within species, basal, radial, and deltoidcaxes all show consistent orientations, clustering near the meridional plane that bisects each plate. In contrast,aaxes of most plates have random orientations, although for a few platesaaxes are clustered rather than random. Whilecaxes from different species all fall about the meridional plane bisecting each plate, inclinations within this plane vary, so crystallographic data can provide new characters for phylogenetic analysis.In assessing homologies among deltoid plates, axes of posterior deltoids show little correspondence with those of regular deltoids, possibly suggesting a nonhomologous origin. Superdeltoids and epideltoids have commingledcaxis orientations and may be homologues.Consistentcaxes within species suggest molecular or cellular control of biomineralization during development, but the occurrence of both random and constrainedaaxes, depending on the plate examined, implies heterogeneities in this control affecting different plates on the theca.
Kirkbyoid ostracodes (Upper Carboniferous) from the Cantabrian Mountains (Spain) and Carnic Alps (Austria and Italy)
Authors: De Posada Luis Carlos Sánchez , Fohrer Beate 
Published: August 2016

Silicified kirkbyoid ostracodes from the Cantabrian Mountains (Spain) bear a striking resemblance to those of the Carnic Alps (Austria and Italy). The Spanish ostracodes come from the upper part of the Cuera Limestones (Bashkirian-upper Moscovian), which are exposed along the Playa de la Huelga section (Ponga Nappe) in the coastal area of eastern Asturias, northern Spain. These fossils were collected from upper Moscovian limestones deposited in an outer-platform environment. Most of the material from the Carnic Alps was obtained from the Nassfeld Pass area (eastern Carnic Alps), near the Austrian-Italian border, in limestones of the Kasimovian-Gzhelian Auernig Group and the Lower Permian Rattendorf Group. The several Auernig Group limestones that contain silicified ostracodes were deposited in a shallow-marine environment.Despite the differences in age (according to fusulinids and conodonts), these kirkbyoids are very similar and in some cases identical.Coronakirkbya pramollanew species andKirkbya carniacantabricanew species occur in both areas. Two other pairs of species,Coronakirkbya krejcigrafiBecker, 1978, andCoronakirkbya carinanew species, andAurikirkbyacf.beckeri(Kozur, 1990) andAurikirkbya carinthicanew species, show close affinities, though they are considered to be different species. Most of the species described herein are either very rare or absent in other regions.The close paleobiogeographic relationships between the Cantabrian Mountains and the Carnic Alps, documented previously only by brachiopods, are confirmed.
Silurian (Wenlock) calymenid trilobites from the Cape Phillips Formation, Central Canadian Arctic
Authors: Adrain Jonathan M. , Edgecombe Gregory D. 
Published: August 2016

Calymenid trilobites are common components of diverse Silurian silicified faunas recovered from the Cape Phillips Formation of the Cape Phillips Basin, central Canadian Arctic Archipelago. Calymenids are represented in the Wenlock of the northern Laurentian region by only two genera,DiacalymeneKegel, 1927, andArcticalymenenew genus (type speciesA. viciousinew species). Calymenid diversity in any given fauna is never higher than two species, although these species may be numerically abundant.Arcticalymenebecame extinct during the Homerian, at which point calymenids disappeared forever from the northern Laurentian record.Other new taxa areArcticalymene cookinew species,A. jonesinew species,A. matlockinew species, andA. rotteninew species. Material representing at least two more species of the new genus is reported in open nomenclature.Diacalymene gabrielsiSiveter and Chatterton, 1996, is recorded from the Cape Phillips Basin.