Assessing the biodiversity of Ordovician ostracods from the Argentine Precordillera

2007 ◽  
Vol 81 (6) ◽  
pp. 1442-1453 ◽  
Author(s):  
María José Salas

Ostracod faunas from the Lower to Middle Ordovician rocks of the Argentine Precordillera Basin (Gualcamayo and Las Aguaditas Formations) are studied. A new family, Garcianidae, is erected. One new genus,Jeanvannieria, and six species are recognized, two of which are new (Jachalipisthia bicornataandJeanvannieria bulbosa). The diversity and composition of the Precordilleran ostracods is evaluated on the basis of previous taxonomic analysis and the fauna studied here. The diversity is moderate, with a peak of 50 species during the early Caradoc. The composition of the fauna is characterized by the dominance of podocopes with a high percentage of binodicopes and a lack of palaeocopes, which is in agreement with a deep shelf environment. The carbonate slope setting of the Las Aguaditas Formation is the deepest environment yet found with Ordovician ostracods and records a relatively diverse fauna. The presence ofEctoprimitioidessuggests biogeographic affinities between the Precordillera and Laurentia. The rest of the fauna contains a high percentage of endemic genera and a mixture of genera with several affinities, Baltic, peri-Gondwanan, and Australian.

2007 ◽  
Vol 44 (10) ◽  
pp. 1479-1501 ◽  
Author(s):  
John Pojeta Jr. ◽  
Christopher A Stott

The new Ordovician palaeotaxodont family Nucularcidae and the new genus Nucularca are described. Included in Nucularca are four previously described species that have taxodont dentition: N. cingulata (Ulrich) (the type species), N. pectunculoides (Hall), N. lorrainensis (Foerste), and N. gorensis (Foerste). All four species are of Late Ordovician (Cincinnatian Katian) age and occur in eastern Canada and the northeastern USA. Ctenodonta borealis Foerste is regarded as a subjective synonym of Nucularca lorrainensis. No new species names are proposed. The Nucularcidae includes the genera Nucularca and Sthenodonta Pojeta and Gilbert-Tomlinson (1977). Sthenodonta occurs in central Australia in rocks of Middle Ordovician (Darriwilian) age. The 12 family group names previously proposed for Ordovician palaeotaxodonts having taxodont dentition are reviewed and evaluated in the Appendix.


2017 ◽  
Vol 91 (3) ◽  
pp. 493-511 ◽  
Author(s):  
Huaibao P. Liu ◽  
Stig M. Bergström ◽  
Brian J. Witzke ◽  
Derek E. G. Briggs ◽  
Robert M. McKay ◽  
...  

AbstractConsiderable numbers of exceptionally preserved conodont apparatuses with hyaline elements are present in the middle-upper Darriwilian (Middle Ordovician, Whiterockian) Winneshiek Konservat-Lagerstätte in northeastern Iowa. These fossils, which are associated with a restricted biota including other conodonts, occur in fine-grained clastic sediments deposited in a meteorite impact crater. Among these conodont apparatuses, the common ones are identified asArcheognathus primusCullison, 1938 andIowagnathus grandisnew genus new species. The 6-element apparatus ofA.primuscomprises two pairs of archeognathiform (P) and one pair of coleodiform (S) elements. The 15-element apparatus ofI.grandisn. gen. n. sp. is somewhat reminiscent of the prioniodinid type and contains ramiform elements of alate (one element) and digyrate, bipennate, or tertiopedate types (7 pairs). Both conodont taxa are characterized by giant elements and the preservation of both crowns and basal bodies, the latter not previously reported in Ordovician conodont apparatuses. Comparison of the apparatus size in the Winneshiek specimens with that of the Scottish Carboniferous soft-part-preserved conodont animals suggests that the Iowa animals were significantly larger than the latter. The apparatus ofA.primusdiffers conspicuously from the apparatuses of the prioniodontidPromissumfrom the Upper Ordovician Soom Shale of South Africa although the apparatus architecture ofI.grandisn. gen. n. sp. shows some similarity to it. Based on the Winneshiek collections, a new family Iowagnathidae in Conodonta is proposed.


1988 ◽  
Vol 66 (10) ◽  
pp. 2243-2252 ◽  
Author(s):  
R. O. Brinkhurst

A combination of classical and computer-aided methods suggests that the Haplotaxidae can now be divided into several genera. Alphadrilus nov.gen. is monotypic for Alphadrilus smithii n.comb. Delaya nov.gen. contains D. bureschi, D. leruthi, D. corbarensis, D. cantabronensis, and D. navarrensis, all n.comb. Adenodrilus is retained for A. denticulatus, Heterochaetella for H. glandularis, and Villiersia for V. guanivora. The new genus Hologynus nov.gen. is erected for H. ornamentus and H. hologynus and its probable synonyms. Haplotaxis is retained for the gordioides-like species with specialized pharynx and chaetae associated with a predaceous habit. Pelodrilus is retained for P. violaceus and perhaps P. ignatovi and P. africanus (incertae sedis) and its probable synonyms. Tiguassu is elevated to the status of the type of a new family, Tiguassidae. Metataxis sensu Omodeo is placed incertae sedis in the order Lumbricina.


2019 ◽  
Vol 94 (2) ◽  
pp. 273-278
Author(s):  
Björn Kröger ◽  
Juan Carlos Gutiérrez-Marco

AbstractThe order Intejocerida is an enigmatic, short-lived cephalopod taxon known previously only from Early–Middle Ordovician beds of Siberia and the United States. Here we report a new genus, Cabaneroceras, and a new species, C. aznari, from Middle Ordovician strata of central Spain. This finding widens the paleogeographic range of the order toward high-paleolatitudinal areas of peri-Gondwana. A curved conch, characteristic for the new genus, was previously unknown from members of the Intejocerida.UUID: http://zoobank.org/21f0a09c-5265-4d29-824b-6b105d36b791


1988 ◽  
Vol 62 (2) ◽  
pp. 218-233 ◽  
Author(s):  
John Mark Malinky

Concepts of the family Hyolithidae Nicholson fide Fisher and the genera Hyolithes Eichwald and Orthotheca Novak 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. Hyolithes encompasses 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 of Orthotheca includes 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 of Hyolithes and one species of Orthotheca from 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 of H. similis Walcott from the Lower Cambrian of Newfoundland, H. whitei Resser from the Lower Cambrian of Nevada, H. billingsi Walcott from the Lower Cambrian of Nevada, H. gallatinensis Resser from the Upper Cambrian of Wyoming, and H. partitus Resser from the Middle Cambrian of Alabama indicates that none of these species represents Hyolithes. Hyolithes similis is here included under the new genus Similotheca, in the new family Similothecidae. Hyolithes whitei is designated as the type species of the new genus Nevadotheca, to which H. billingsi may also belong. Hyolithes gallatinensis is referred to Burithes Missarzhevsky with question, and H. partitus may represent Joachimilites Marek. The type or types of H. attenuatus Walcott, H. cecrops Walcott, H. comptus Howell, H. cowanensis Resser, H. curticei Resser, H. idahoensis Resser, H. prolixus Resser, H. resseri Howell, H. shaleri Walcott, H. terranovicus Walcott, and H. wanneri Resser 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 of H.? corrugatus Walcott and “Orthotheca” sola Resser does not support placement in the Hyolitha; the affinities of these species are uncertain.


1974 ◽  
Vol 52 (4) ◽  
pp. 701-705 ◽  
Author(s):  
William Campbell Steere ◽  
Zennoske Iwatsuki

The name Pseudoditrichum mirabile Steere et Iwatsuki is proposed for a minute moss with leafy stem 1-3 mm high and seta 6 mm long; it was collected on calcareous silt near the Sloan River, Great Bear Lake, Northwest Territories, only a few miles south of the Arctic Circle. The gametophytic characters agree well with those of the Ditrichaceae, a relatively primitive family, but the peristome is clearly double, with the inner and outer teeth opposite, which thereby indicates a much more advanced phylogenetic position, perhaps at the evolutionary level of the Funariaceae. As the combination of gametophytic and sporophytic characteristics exhibited by this moss does not occur in any existing family of mosses, it is therefore deemed necessary to create the new family Pseudoditrichaceae for the new genus and species described here.


1992 ◽  
Vol 70 (8) ◽  
pp. 1617-1658 ◽  
Author(s):  
R. A. Shoemaker ◽  
C. E. Babcock
Keyword(s):  

Six genera of the order Pleosporales are revised taxonomically. Although five genera have unusual applanate ascospores, they are members of three different families. Clathrospora (10 species, 2 new), Comoclathris (21 species, 7 new), and Macrospora (3 species) are placed in a new family Diademaceae in which the ascoma opening is a characteristic flat circular lid. Diademosa, a new genus with one species with terete ascospores is placed in Diademaceae. Graphyllium (3 species) is placed in the family Hysteriaceae characterized by hysterothecia with a slit-like opening. Platysporoides n.gen. (11 species, 1 new) is maintained in the Pleosporaceae because of the terete pored beak of the ascomata. Key words: Pleosporales, applanate ascospores, Clathrospora, Comoclathris, Macrospora, Diademosa, Graphyllium, Platysporoides.


Zootaxa ◽  
2005 ◽  
Vol 1085 (1) ◽  
pp. 21 ◽  
Author(s):  
JEAN JUST

A new genus and species of janiroidean Asellota, Xenosella coxospinosa, is described from the mid-bathyal slope off the coast of south-eastern Australia. Following a comparison of the new species to several families of broadly similar body shape, with emphasis on monotypic Pleurocopidae, a new family, Xenosellidae, is proposed for the new species. In the course of comparing relevant taxa, the current placements of Prethura Kensley in the Santiidae and Salvatiella Müller in the Munnidae are rejected. The two genera are considered to be incertae sedis within the Asellota superfamily Janiroidea pending further studies.


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