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At least 73 records · Page 4Linked to original sources
USGS1998

The ichnogenus Curvolithus revisited

The ichnogenus Curvolithus Fritsch, 1908, originally described from the Ordovician of the Prague Basin, typically comprises ribbonlike or tonguelike, flattened, endostratal traces with three rounded lobes on the upper surface. However, considerable confusion persists regarding the ichnotaxonomic status and diagnostic features of its ichnospecies. The type specimens of this ichnotaxon, overlooked in most subsequent reports, are redescribed herein. Curvolithus multiplex Fritsch, 1908, the type species, is retained for specimens with a trilobate upper surface and a quadralobate lower surface, in contrast to the criteria adopted by subsequent authors. The other ichnospecies originally proposed from the type locality, C. gregarius Fritsch, 1908, actually consists of a series of grouped parallel scratch marks forming ridges and should be removed from Curvolithus. Subsequently, four ichnospecies were defined: C.? davidis Webby 1970; C. annulatus Badve and Ghare 1978; C. aequus Walter et al. 1989; and C. manitouensis Maples and Suttner 1990. Curvolithus? davidis shows the typical trilobation of Curvolithus apparently in its lower surface, but the morphology of the upper surface is uncertain. Accordingly, it does not warrant ichnospecific assessment, and is regarded as a nomen dubium. The nature of the annulations on the trilobate upper surface of C. annulatus is unclear, and this ichnospecies is also best considered as a nomen dubium. Curvolithus aequus has a bilobate lower surface and probably represents washed out specimens of Didymaulichnus. Finally, C. manitouensis comprises specimens with a smooth, trilobate upper surface and a smooth, quadralobate lower surface, and is best regarded as a junior synonym of C. multiplex. Curvolithus multiplex has been used incorrectly for Curvolithus with a trilobate upper surface and a trilobate to unilobate lower surface. The new ichnospecies, Curvolithus simplex, is proposed herein for such traces. Curvolithus is interpreted as a locomotion trace (Repichnia) of endostratal carnivores, possibly gastropods, flatworms, or nemerteans. Curvolithus is a component of the Cruziana ichnofacies in shallow-marine facies, either of normal salinity or slightly brackish, in the latter case typically associated with fan deltas.

Journal of Paleontology↗
USGS1998

Trilobites from Lower Mississippian starved basin facies of the southern United States

A distinctive trilobite fauna occurs within condensed stratigraphic sections of the Lower Mississippian (Tournaisian) Chappel Limestone of the Llano region of Texas, the Welden Limestone of Oklahoma, and the Chouteau Limestone of Union County, Illinois. The seven species comprising this fauna are interpreted to have inhabited sediment-starved basinal environments. The starved-basin facies existed in the south-central United States throughout the Tournaisian (Kinderhookian to Osagean). Two species from this fauna, Australosutura llanoensis, and Carbonocoryphe planucauda, are new. The remaining five species, Griffithidella doris (Hall), Griffithidella alternata (Girty), Carbonocoryphe depressa (Girty), Thigiffides roundyi (Girty), and Pudoproetus chappelensis (Hessler), are restricted to starved-basin facies.

Journal of Paleontology↗
USGS1999

The rise and fall of late Paleozoic trilobites of the United States

Based on range data and generic composition, four stages of evolution are recognized for late Paleozoic trilobites of the contiguous United States. Stage 1 occurs in the Lower Mississippian (Kinderhookian-Osagean) and is characterized by a generically diverse association of short-ranging, stenotopic species that are strongly provincial. Stage 2 species are present in the Upper Mississippian and consist of a single, eurytopic, pandemic genus, Paladin. Species of Stage 2 are much longer-ranging than those of Stage 1, and some species may have persisted for as long as 12 m.y. Stage 3 is present within Pennsylvanian and Lower Permian strata and consists initially of the eurytopic, endemic genera Sevillia and Ameura as well as the pandemic genus Ditomopyge. During the middle Pennsylvanian the very long-ranging species Ameura missouriensis and Ditomopyge scitula survived for more than 20 m.y. During the late Pennsylvanian and early Permian, a number of pandemic genera appear to have immigrated into what is now North America. Stage 4 is restricted to the Upper Permian (late Leonardian-Guadalupian) strata and is characterized by short-ranging, stenotopic, provincial genera. The main causal factor controlling the four-stage evolution of late Paleozoic trilobites of the United States is interpreted to be eustacy. Whereas Stage 1 represents an adaptive radiation developed during the Lower Mississippian inundation of North America by the Kaskaskia Sequence, Stage 2 is present in strata deposited during the regression of the Kaskaskia sea. Stage 3 was formed during the transgression and stillstand of the Absaroka Sequence and, although initially endemic, Stage 3 faunas are strongly pandemic in the end when oceanic circulation patterns were at a maximum. A mid-Leonardian sea-level drop caused the extinction of Stage 3 fauna. Sea-level rise near the end of the Leonardian and into the Guadalupian created an adaptive radiation of stentopic species of Stage 4 that quickly became extinct with the latest Permian regression.

Journal of Paleontology↗
USGS1999

Stasis and extinction of Silurian (Llandovery-Wenlock) trilobite associations related to oceanic cyclicity

Silurian trilobites of the central United States belong to a series of temporally-successive associations which appeared abruptly, maintained taxonomic stasis for a time, and then disappeared abruptly. Their disappearance resulted from global perturbations of short-term duration and moderate magnitude, which caused substantial taxonomic replacement but no reorganization of major ecosystems. The most significant extinction and replacement in Silurian trilobite associations in the study area occurs near the Llandovery-Wenlock boundary. This turnover in trilobite associations appears to correspond to Jeppsson's Ireviken Event in his model of oceanic and climatic cyclicity. Major sea-level changes earlier in the Llandovery did not have a similar impact on trilobite associations.

Journal of Paleontology↗
USGS1982

The occurrence of the Complexiopollis-Atlantopollis zone (Palynomorphs) in the Eagle Ford Group (Upper Cretaceous) of Texas

The Lower and lower Upper Cretaceous palynological zones defined in the Atlantic Coastal Plain Province and which occur in the eastern Gulf Coastal Plain Province are characterized by a paucity of marine invertebrate fossils. As a result, correlation of these zones with European and provincial stages, as well as with other microfossil and megafossil zones is tenuous. However, an examination of a complete section of the Eagle Ford Group and adjacent strata in Texas reveals that: 1) the upper part of the Woodbine Formation and the Tarrant Formation of the overlying Eagle Ford Group represent a biostratigraphic interval that is absent in the Atlantic and eastern Gulf Coastal Plain Provinces; 2) the Complexiopollis-Atlantopollis Zone (zone IV of some authors) occurs within the Britton Formation (Eagle Ford Group), and is equivalent to the upper part of the Rotalipora cushmani-greenhornensis Subzone (planktic foraminifers) and possibly to the Sciponoceras gracile Zone (ammonites); 3) the Arcadia Park Formation (Eagle Ford Group) contains a mixed assemblage of palynomorphs that includes guides to both the Complexiopollis-Atlantopollis and the overlying Complexiopollis exigua-Santalacites minor Zones, suggesting that biostratigraphic equivalents of the Arcadia Park Formation are not represented in the Atlantic and eastern Gulf Coastal Plain Provinces; and 4) in the basal part of the Austin Chalk of Texas, only one guide palynomorph to the Complexiopollis-Atlantopollis Zone was recognized, but guides to the Complexiopollis exigua-Santalacites minor Zone are present. The Tuscaloosa Group of the eastern Gulf Coastal Plain appears to be biostratigraphically equivalent to the Complexiopollis-Atlantopollis Zone, and therefore correlative with the middle to upper part of the Britton Formation of the Eagle Ford Group.

Texas↗
USGS1983

Conodonts of the western Paleozoic and Triassic belt, Klamath Mountains, California and Oregon

Conodonts were extracted from 32 samples of limestone and 5 samples of chert obtained from the Western Paleozoic and Triassic belt of the Klamath Mountains province. Triassic conodonts were found in 17 samples, and late Paleozoic conodonts in 7 samples. Conodonts of the remaining 13 samples cannot be dated more closely than early or middle Paleozoic through Triassic. The late Paleozoic conodonts are restricted to the North Fork and Hayfork terranes. The Hayfork terrane also contains Early, Middle, and Late Triassic conodonts; mostly Neogondolella. Conodonts from samples of the Rattlesnake Creek terrane and the northern undivided part of the belt are all Late Triassic and are generally Epigondolella. The conodont data support the concept that many of the limestone bodies are olistoliths or tectonic blocks in melange. Color alteration of the conodonts indicates that the rocks of the Western Paleozoic and Triassic belt have been heated to temperatures between 300 degrees and 500 degrees C during regional tectonism.

California, Oregon↗
USGS1950

"Lockhartia" cushmani Applin and Jordan and notes on two previously described foraminifera from tertiary rocks in Florida

This paper discusses changes made in the names of three foraminiferal species originally described by the writers, with particular emphasis on "Lockhartia" cushmani Applin and Jordan. The internal characters of this form are fully described and compared with the diagnostic characteristics of the genus Lockhartia Davies and with the geno-lectotype of Rotalia , R. trochidiformis Lamarck, as given by Davies (1932). Comparisons are also made with Lockhartia bermudezi Cole. A plate of illustrations demonstrates the features described. In addition. Elphidium leonensis Applin and Jordan is briefly discussed and the generic placement of Miscellanea nassauensis Applin and Jordan is mentioned.

Florida↗
USGS1968

Structural adaptation in two Permian brachiopod genera, Salt Range, West Pakistan

Silicified shells with spines preserved allow analysis of spine distribution as a specific character in the genus Marginifera Waagen and confirm validity of Waagen's (1884) six species. The animal lived with the ventral valve down, the adult shell partly buried, but many spines grew above the substrate prior to burial. Pseudopunctae are interpreted as seats of ciliate papillae or elongate setal follicles, as adaptation to partial burial in soft substrate. Auricular chambers, marginal ridges, and endospines provided effective protection against ingression of coarse or harmful particles. Productus opuntia Waagen is assigned to Echinauris Muir-Wood & Cooper; its habitat and adaptations are interpreted as similar to those of Marginifera. The stratigraphic position of the bed containing the late Permian guide ammonoid Cyclolobus proves to be lower than hitherto thought, thus extending the ammonoid's range. A Guadalupe age for the Chhidru formation is suggested.

West Pakistan↗
USGS1967

Chemical Composition of Ectoprocta (Bryozoa)

Published data on the elemental composition of the Ectoprocta (Bryozoa) are supplemented by new chemical analyses of 28 ectoproct samples, distributed among 13 species, for organic matter, CO 2 calcium, magnesium, strontium, barium, phosphorus and iron. The new data, in addition to the 25 fairly complete analyses previously published (distributed among 19 other species) suggest the existence of 3 species groupings that are based on composition and are related to habitat. Group I consists of genera that have more than 50 percent organic matter (dry weight). It includes all species of the entirely freshwater Phylactolaemata and the commonly brackish-water and freshwater Ctenostomata. Group II includes Cheilostomata having from 25 to 50 percent organic matter (dry weight). These genera are bush-like in growth habit and may be anchored to fine-grained sediment bottoms. Genera in Group II contain appreciable amounts of P 2 O 5 (1.0-2.0 percent) and Fe 2 O 3 (0.4-1.0 percent) in the ash. Only calcite has been observed in the mineralized portion of the skeleton of Group II species. Group III includes Cheilostomata and Cyclostomata that have less than 25 percent organic matter. These forms require stable surfaces for colonization. They contain a lesser amount of P 2 O 5 (0.1-0.6 percent) and of Fe 2 O 3 (less than 0.4 percent) than Group II genera. About 15 percent of Group III species have aragonitic skeletons. "Pure" aragonitic hard parts contain about 1.0 percent SrO (1.4 wt. percent SrCO 3 and 0.3 percent MgO (0.6 wt. percent MgCO 3 ) whereas "pure" calcitic skeletons contain less than 0.4 percent SrO (0.6 wt. percent SrCO 3 ) and more than 3.5 percent MgO (7.4 wt. percent MgCO 3 ). Based on the few species analyzed, some additional taxonomic and ecologic generalizations are suggested. Calcitic cheilostomes contain more magnesium than do calcitic cyclostomes. Warm water calcitic species have higher magnesium concentrations than do cold water calcitic species. Specimens from an estuary contain more P 2 O 5 and less strontium than do specimens from areas of normal marine salinity, and specimens from nearshore areas have more iron than do specimens from deeper offshore areas. The order of concentration of elements in ectoprocts relative to the composition of sea water is 10 5 for phosphorus and iron, 10 3 for barium, 10 2 for calcium and strontium, and 10 1 for magnesium. However, the elements that are highly enriched in ectoprocts, especially iron and phosphorus, may be supplied to a considerable extent by sources other than normal sea water, such as food (diatoms in particular), and occluded matter of terrigenous origin. Twenty-eight protein and chitin amino acids were studied in three representative marine ectoproct species: Bugula simplex, a calcitic cheilostome, Parasmittina nitida, an aragonitic cheilostome, and Tubulipora liliacea, a calcitic cyclostome. Similar proportions but widely different amounts (from 0.6 to 11 percent organism dry weight) of amino acids occur in these species. Obvious variations in amino acid proportions relate more directly to degree of calcification and to mineralogy than to species classification. Chitin amino acids recoverable in residues after leaching with acid form less than 2 percent of the total organic content of the organism.

Journal of Paleontology↗
USGS1964

Morphologic studies of the brachiopod genus Composita

The genus Composita consists of smooth-shelled athyroid brachiopods which in North America have a range from Late Devonian or Early Mississippian to Permian. Morphologic variation in the genus has been recognized by earlier workers, but few have tried to show exact relationships among the various forms. The present writers have attempted to trace the development of the genus through geologic time. Only North American species and varieties of Composita are treated in this paper. Forty-two species and varieties are included in a phylogenetic history of the genus. Nine other species are listed as doubtful forms. Eighteen specific and varietal names are rejected by the writers as obsolete. Morphologic intergradation among associated, synchronous forms is studied with the aid of frequency polygons. Lack of clear separation of the associated species within different maxima of the polygons indicates their dominant intergradation. These forms, previously described qualitatively, are regarded as typological species. A statistical method is used to test for differences between collections containing the same typological species. Significant differences in the slopes of reduced major axes are obtained in length-width, length-depth and depth-width plots of two collections containing Composita subtilita and Composita argentea . Significant differences also are obtained when two collections of Composita subtilita , Composita ovata and Composita elongata are compared in the same way. In spite of these results, slight nomenclatural changes are thought to be unnecessary. Use of the triangular graph as a means of distinguishing vertical subspecies is also tested. Four collections are plotted on one graph and five artificially separated groups of Composita subtilita on another. Mixed results are obtained. The method is suspect because the results are found to depend largely on the number of specimens used.

Journal of Paleontology↗
USGS1968

New names for late Pleistocene diatom species

The homonyn Navicula rotunda Andrews is replaced by the name N. rotundella Andrews; the homonym Epithemia irregularis Andrews is replaced by the name E. emarginata Andrews. The diatoms are from Trempealeau Valley, Wisconsin (Andrews, 1966).

Wisconsin↗
USGS1990

New Washakiin primates (Omomyidae) from the Eocene of Wyoming and Colorado, and comments on the evolution of the Washakiini

Two new species of washakiin omomyids occur in deposits of early Bridgerian age. Shoshonius bowni , sp. nov., from the Aycross Formation, Absaroka Range, Wyoming, differs from S. cooperi in having enlarged conules on the upper molars and a second metaconule, features convergent with Washakius insignis. Washakius izetti , sp. nov., from the Green River Formation, Piceance Creek Basin, Colorado, is the most primitive known species of Washakius , showing incipient development of features present in the later W. insignis and W. woodringi. Washakius , cf. W. izetti occurs in the early Bridgerian of the Huerfano Basin. W. izetti is closely related to Utahia kayi , a. washakiin possibly related to Stockia. Hemiacodon , sometimes included in the Washakiini, is probably more closely related to the Omomyini. Stockia is distinct from Omomys and is questionably included in the Washakiini, of which Loveina is the stem taxon. More advanced washakiins form two groups between which there was significant parallel evolution in dental morphology. One group includes Washakius, Dyseolemur, Utahia , and possibly Stockia , and is characterized by development of an open talonid notch before the consistent appearance of metastylids. The other group consists of Shoshonius , where the establishment of metastylids preceded the full opening of the talonid basins.

Journal of Vertebrate Paleontology↗
USGS2019

Fluvial sedimentary history of Arlington Canyon, Channel Islands National Park, California

Arlington Canyon, in the northwest part of Santa Rosa Island, Channel Islands National Park, California, has been the setting for important scientific discoveries over the past half century, including the oldest human remains in North America, several vertebrate fossil sites, and purported evidence of a catastrophic extinction event at the end of the Pleistocene. The canyon is filled with alluvial sediments that date to between 16.4 and 1.1 ka (thousands of calibrated years before present), representing accumulation that occurred primarily in response to rising sea levels during the late Pleistocene and Holocene. The deposits are laterally discontinuous, exhibit a high degree of sedimentary complexity, and contain evidence of past climates and environments, including fossil bones, burned plant macrofossils, and invertebrate microfossils. Here, we show that it is critical to view the observations, data, and conclusions of scientific studies conducted in the canyon within this larger context so that localized facets of the spatially and temporally extensive alluvial deposits are not misinterpreted or misrepresented. By improving the baseline understanding of processes and drivers of sediment accumulation in Arlington Canyon, we hope to offer a solid foundation and better underpinning for future archeological, paleontological, and geochemical studies here and throughout the northern Channel Islands.

California↗
USGS2003

The Sima de los Huesos hominids date to beyond U/Th equilibrium (>350 kyr) and perhaps to 400-500 kyr: New radiometric dates

The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud breccia underlying an accumulation of the Middle Pleistocene cave bear (U. deningeri). Earlier dating estimates of 200 to 320 kyr were based on U-series and ESR methods applied to bones, made inaccurate by unquantifiable uranium cycling. We report here on a new discovery within the Sima de los Huesos of human bones stratigraphically underlying an in situ speleothem. U-series analyses of the speleothem shows the lower part to be at isotopic U/Th equilibrium, translating to a firm lower limit of 350 kyr for the SH hominids. Finite dates on the upper part suggest a speleothem growth rate of c. 1 cm/32 kyr. This rate, along with paleontological constraints, place the likely age of the hominids in the interval of 400 to 600 kyr. ?? 2002 Elsevier Science Ltd. All rights reserved.

Journal of Archaeological Science↗
USGS1976

Revision of Mississippian stratigraphy, eastern Idaho and northeastern Utah

New paleontologic evidence requires a revision of previous interpretations of the stratigraphy of Mississippian sequences in the Cordilleran miogeosyncline of eastern Idaho and northeastern Utah. A postulated unconformity between rocks of early Osagean age and rocks of middle Meramecian age is no longer tenable in the light of new data. The new evidence supports continuous deposition from the Lodgepole Limestone (Kinderhookian and early Osagean age) into the Little Flat Formation (early Osagean to middle Meramecian age) and its equivalents, and the interpretation of a phosphatic siltstone and shale interval in the lower part of the Little Flat Formation as a starved-basin facies.

Idaho, Utah↗