small shelly fossils
219510322
Small shelly fossils and carbon isotopes from the early Cambrian (Stages 3 4) Mural Formation of western Laurentia
The extraordinary window of phosphatized and phosphatic small shelly fossils (SSF) during the early and middle Cambrian is an important testament to the radiation of biomineralizing metazoans. While SSF are well known from most Cambrian palaeocontinents during this time interval, western Laurentia has relatively few SSF faunas. Here we describe a diverse SSF fauna from the early Cambrian (Stages 3 4) Mural Formation at three localities in Alberta and British Columbia, Canada, complemented by carbon isotope measurements to aid in a potential future bio chemostratigraphic framework. The fauna expands the recorded SSF assemblage diversity in western Laurentia and includes several brachiopods, four bradoriids, three chancelloriids, two hyoliths, a tommotiid and a helcionellid mollusc as well as echinoderm ossicles and specimens of Microdictyon, Volborthella and Hyolithellus. New taxa include the tommotiid genus Canadiella gen. nov. the new bradoriid species Hipponicharion perforata sp. nov. and Pseudobeyrichona taurata sp. nov. Compared with contemporaneous faunas from western Laurentia, the fauna is relatively diverse, particularly in taxa with originally phosphatic shells, which appear to be associated with archaeocyathid build ups. This suggests that the generally low faunal diversity in western Laurentia may be at least partly a consequence of poor sampling of suitable archaeocyathan reef environments. In addition, the tommotiid Canadiella filigrana appears to be of biostratigraphical significance in Cambrian Stage 3 strata of western Laurentia, and the unexpected high diversity of bradoriid arthropods in the fauna also suggests that this group may prove useful for biostratigraphical resolution in
Christian B Skovsted Uwe Balthasar Jakob Vinther Erik A Sperling
195240220
Small Shelly Fossils in the Cambrian Basement of the West Siberian Geosyneclise
This paper describes for the first time the entire Cambrian skeletal problematics from the parametric well Vostok 1 (Tomsk oblast, eastern part of the West Siberian Plate) found in the Lower Cambrian Churbiga Formation, Middle Cambrian Pudzhelga Formation, and Upper Cambrian Kondes and Shedelga formations. The investigation has made it possible to detail the biostratigraphic division of the Lower Cambrian in the studied well using the small shelly fossils and to reveal confinement of the main findings of problematic skeletal remains to the shallow carbonate shelf settings.
Stratigraphy and Geological Correlation
N V Novozhilova Igor' V Korovnikov
199100840
Early Cambrian Small Shelly Fossils from northwest Mexico: Biostratigraphic implications for Laurentia
Lea Devaere Sebastien Clausen Jesus Porfirio Sosa-Leon Juan Jose Palafox-Reyes Blanca Estela Buitron-Sanchez Daniel Vachard
91292529
Distribution of Atdabanian (Early Cambrian) Trilobites, Archaeocyaths, and Small Shelly Fossils in the Altai Sayan Folded Area
The distribution of the main faunal groups of the Atdabanian Age of Early Cambrian in the Altai Sayan folded area (ASFA) are analyzed. It is shown that Late Atdabanian assemblages of small shelly fossils of the Kuznetsk Alatau and Altai Mountains include in general the same taxa. At that time, these territories were probably situated rather close to each other and connected with the Siberian Platform. A similar result was obtained analyzing the distribution of trilobite assemblages. It is shown that the Western and Eastern Sayan Mountains have more similar forms with Mongolian assemblages. It is also shown that, in the Atdabanian, the greatest taxonomic diversity of trilobites was confined to the areas of the paleobasin where there was accumulation of organogenic carbonate sediments. It is shown that archaeocyaths from ASFA are older than the taxa characteristic of the assemblage from the Nochoroicyathus mariiskii Zone. At the boundary of the Kiya and Kameshki horizons, archaeocyaths sharply increase in abundance and many taxa with the ring and complex internal walls appeared. This boundary is traced throughout the territory of ASFA.
Paleontological Journal
Igor' V Korovnikov N V Novozhilova D A Tokarev
135177034
Small shelly fossils from the Montezuman Delamaran of the Great Basin in Nevada and California
Abstract. The mixed carbonate siliciclastic successions of the Cambrian Series 2 Cambrian Series 3 interval of the Great Basin are well investigated in respect to their trilobite and brachiopod fauna. In contrast, the small shelly fossils have been mostly unreported. Nine sections in eastern California and southern Nevada have produced a small shelly assemblage of low diversity, which likely reflects non phosphatization and loss of originally calcareous remains. From the Montezuman Delamaran stages we report Anabarella chelata Skovsted, 2006a, Costipelagiella nevadense Skovsted, 2006a, Pelagiella aff. P. subangulata (Tate, 1892) Microcornus sp. Parkula sp. Hyolithellus? sp. Allonia sp. Chancelloria sp. Archiasterella cf. A. hirundo Bengtson in Bengtson et al. 1990, Archaeooides cf. A. granulatus Qian, 1977, and undefined echinoderms and helcionelloid molluscs. The lower part of the Montezuman Stage delivered a number of lobopodian sclerites as Microdictyon rhomboidale Bengtson, Matthews, and Missarzhevsky, 1986, Microdictyon montezumaensis n. sp. and Microdictyon cuneum n. sp. The occurrence of P. aff. P. subangulata and species of Microdictyon in the lower Montezuman Stage offers a fundamental potential for correlation with the base of Cambrian Series 2/Stage 3 of South China, Siberia, and Avalonia.
Journal of Paleontology
Thomas Wotte Frederick A Sundberg
134404563
Phosphatized early Cambrian archaeocyaths and small shelly fossils (SSFs) of southwestern Mongolia
Abstract Archaeocyaths are an enigmatic group of calcifying sponges prevalent in early Cambrian (Terreneuvian to Series 2) successions around the world and preserved predominantly in reefal buildups, but also in adjacent reworked deposits. Here we report exceptionally preserved phosphatized archaeocyaths and small shelly fossils from phosphatized reef flank deposits at the top of the Salaagol Formation of southwestern Mongolia. Recent chemostratigraphic age models suggest that these archaeocyaths are among the earliest reported in the Terreneuvian Stage 2 (Tommotian) These fossils provide a window into the mechanisms of archaeocyath phosphatization, a generally rare mode of archaeocyath preservation. To assess the composition and nature of phosphatization, fossil assemblages were examined in insoluble residue and thin section. These archaeocyaths are preserved as phosphatic internal molds in residue, and both phosphatized and unphosphatized archaeocyaths are present in thin section. The occurrence of internal molds and complementary mineralogical data suggest that the decay of organic material within the archaeocyaths created the necessary redox conditions for apatite nucleation. We propose that, shortly after death, this assemblage was transported to a deeper water environment, and that the presence of organic matter in a low oxygen setting led to abundant phosphatization of archaeocyaths.
Sara B Pruss Camille H Dwyer Emily F Smith Francis A Macdonald Nicholas J Tosca
229780083
The Cambrian explosion in Iran: new insights from small shelly fossils of the Ediacaran Cambrian transition in the Soltanieh and Alborz Mountains
Lea Devaere Dieter Korn Abbas Ghaderi Alireza Karimi Bavandpur
187895373
SMALL SHELLY FOSSILS FROM A SECTION OF THE MONTEZUMAN DYERAN (CAMBRIAN STAGES 3 4) POLETA FORMATION, ESMERALDA COUNTY, NEVADA
John L Moore Susannah M Porter Mark Webster
133962151
Cambrian Series 2 (Stages 3 4) Small Shelly Fossils from East Antarctica
An assemblage of Cambrian Series 2, Stages 3 4 small shelly fossils has been recovered from the Shackleton Limestone and Holyoake Formations of East Antarctica. Small shelly fossils from the early
Thomas M Claybourn
134204994
AGNOSTID TRILOBITES AND SMALL SHELLY FOSSILS (SSFS) FROM THE DRUMIAN (MIDDLE CAMBRIAN) MANUELS RIVER FORMATION, CONCEPTION BAY SOUTH, NEWFOUNDLAND, CANADA IMPLICATIONS FOR BIOSTRATIGRAPHY, PALEOBIOGEOGRAPHY AND PALEOGEOGRAPHY
Anne Hildenbrand Gregor Austermann Peter Bengtson