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

2017 ◽  
Author(s):  
Anne Hildenbrand ◽  
◽  
Gregor Austermann ◽  
Peter Bengtson
Keyword(s):  
Middle Cambrian ◽  
Small Shelly Fossils ◽  
Conception Bay

Affinities of the alleged earliest Cambrian gastropod Aldanella

2013 ◽  
Vol 91 (12) ◽  
pp. 914-923 ◽  
Author(s):  
Jerzy Dzik ◽  
Dawid Mazurek
Keyword(s):  
Shell Morphology ◽  
Skewed Distribution ◽  
Phylogenetic Position ◽  
Soft Body ◽  
Middle Cambrian ◽  
Small Shelly Fossils ◽  
Embryonic Shell ◽  
Mode Of Life ◽  
Early Palaeozoic ◽  
Mature Size

Unlike true Palaeozoic gastropods, but similar to some coeval hyoliths, the cup-like hemispherical embryonic shell of Aldanella attleborensis (Shaler and Foerste, 1888) from the earliest Cambrian (early Tommotian) Erkeket Formation of northern Siberia bears a mucro. Also, the pattern of mortality, with right-skewed distribution and a peak at about 1.0 mm diameter, is not similar to that of early Palaeozoic gastropods; there is no evidence of metamorphosis that would end the pelagic larval stage of ontogeny. Specimens of larger size are rare in samples of phosphatized “small shelly fossils” but are known in related species of the genus, of up to 3–5 mm diameter. A phosphatized soft body is preserved in a few specimens of A. attleborensis, one bearing possible chaetae of about 5 μm diameter. Such bunches of chaetae arming locomotory organs were earlier identified in the genus Pelagiella Matthew, 1895, a more derived member of the same lineage. It shares with the genus Aldanella Vostokova, 1962 also the mucronate embryonic shell and acicular aragonitic shell wall microstructure. The presence of chaetae-bearing organs suggests pelagic mode of life of pelagiellids at maturity. Middle Cambrian Pelagiella shells reached 7 mm in diameter, suggesting evolutionary increase in mature size. Embryonic shell morphology, wall microstructure, and the presence of locomotory organs with a fan of chaetae contradicts gastropod, and even conchiferan affinity of the pelagiellids, but together with the pattern of ontogeny conforms to the enigmatic Palaeozoic hyoliths. They differ in having opercula closing the shell apertures and in lacking evidence of chaetae. The helens, paired apertural appendages of possible locomotory function occurring in apertures of some of them, do not reveal any similarity to chaetae in their development. We propose classifying the order Pelagiellida in the class Hyolitha rather than in the class Gastropoda, until its phylogenetic position is clarified. Such understood hyoliths may represent the earliest stage in evolution of molluscs, immediately following initial diversification of the spiralians (lophotrochozoans) into phyla.

scholarly journals Cambrian microfossils from the Tethyan Himalaya

2016 ◽  
Vol 90 (1) ◽  
pp. 10-30 ◽  
Author(s):  
Ian R. Gilbert ◽  
Nigel C. Hughes ◽  
Paul M. Myrow
Keyword(s):  
Indian Subcontinent ◽  
Age Determination ◽  
Acid Digestion ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
Small Shelly Fossils ◽  
Stage 4 ◽  
Stratigraphic Ranges ◽  
A New Species ◽  
Tethyan Himalaya

AbstractCambrian biostratigraphy of the Indian subcontinent is best documented from the Parahio Formation of the Tethyan Himalaya. Recently established trilobite biostratigraphy shows that the formation encompasses the latest part of unnamed Stage 4 and much of unnamed Stage 5. A variety of small shelly fossils have been recovered via acid digestion of carbonate beds and include tetract and pentact hexactinellid sponge spicules, chancelloriid spicules belonging to Chancelloria sp. and a new species, Archiasterella dhiraji, shells of an helcionelloid comparable to Igorella maidipingensis, a meraspid ptychopariid trilobite, the tubular Cupitheca sp., a poorly preserved hyolith, and an assortment of spinose microfossils of uncertain affinity. These newly recovered microfossils are consistent with the trilobite-based lower and middle Cambrian age determination and do not support a late Cambrian age for the top of the Parahio Formation advocated in some recent literature. The microfossils reported herein significantly expand the known diversity of such fossils from Cambrian strata in the Himalayan region, and allow for comparison of this fauna with others from Gondwanaland and elsewhere. Integration with trilobite data indicate that the stratigraphic ranges of many small shelly fossils described in this study are greater than previously recognized.

Burgess Shale-type preservation of both non-mineralizing and ‘shelly’ Cambrian organisms from the Mackenzie Mountains, northwestern Canada

1996 ◽  
Vol 70 (6) ◽  
pp. 893-899 ◽  
Author(s):  
N. J. Butterfield ◽  
C. J. Nicholas
Keyword(s):  
Granular Material ◽  
Surface Texture ◽  
Hydrofluoric Acid ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Small Shelly Fossils ◽  
Polygonal Surface ◽  
Acid Processing ◽  
Mackenzie Mountains ◽  
Type Preservation

Lower to Middle Cambrian shales of the Mount Cap Formation in the Mackenzie Mountains, northwestern Canada, host a variety of Burgess Shale-type macrofossils, including anomalocarid claws, several taxa of bivalved arthropod, articulated hyolithids, and articulated chancelloriids. Hydrofluoric acid processing has also yielded a broad range of organic-walled fossils, most of which are derived from forms more typically known as shelly fossils; e.g., trilobites, inarticulate brachiopods, small shelly fossils (SSF), hyolithids, and chancelloriids. Organic-walled hyolithids include conchs, opercula and helens; the proximal articulation of the helens is erosive, suggesting that they were formed “instantaneously” and periodically replaced. Organic-walled chancelloriid sclerites exhibit a polygonal surface texture and an inner “pith” of dark granular material with distally oriented conoidal divisions; such a pattern is similar to that seen in the fibers of some modern horny sponges and points to a poriferan relationship for the chancelloriids. The robust nature but minimal relief of most of these fossils suggests that primary biomineralization was minimal.

Small shelly fossils from the basal Emigrant Formation (Cambrian, uppermost Dyeran Stage) of Split Mountain, Nevada

2006 ◽  
Vol 43 (4) ◽  
pp. 487-496 ◽  
Author(s):  
Christian B Skovsted
Keyword(s):  
New Taxa ◽  
Great Basin ◽  
Global Distribution ◽  
Early Cambrian ◽  
Specific Level ◽  
Middle Cambrian ◽  
Small Shelly Fossils

A latest Early Cambrian fauna of helcionelloid molluscs and small shelly fossils from the basal Emigrant Formation of Nevada is described. The fauna is the first of its kind to be described from trilobite-bearing strata in the Great Basin and is well preserved, but of limited diversity. At the specific level the assemblage is largely endemic, but it contains several genera with global distribution in the Lower and Middle Cambrian. Costipelagiella nevadense n.sp. in the fauna is the oldest representative of the widespread, but little known genus Costipelagiella Horný, 1964. Two additional new taxa are described: Anabarella chelata n.sp. and Parkula esmeraldina n.sp.

A new mobergellan (small shelly fossils) from the early middle cambrian of morocco and its significance

PalZ ◽  
2006 ◽  
Vol 80 (3) ◽  
pp. 209-220 ◽  
Author(s):  
Michael Streng ◽  
Christian B. Skovsted
Keyword(s):  
Middle Cambrian ◽  
Small Shelly Fossils

Shelly fossils from the Early Cambrian (Toyonian) Wirrealpa, Aroona Creek, and Ramsay Limestones of South Australia

1993 ◽  
Vol 67 (5) ◽  
pp. 758-787 ◽  
Author(s):  
Glenn A. Brock ◽  
Barry J. Cooper
Keyword(s):  
Sequence Stratigraphy ◽  
Siberian Platform ◽  
South Australia ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Marine Transgression ◽  
Small Shelly Fossils ◽  
Flinders Ranges ◽  
Yorke Peninsula

Small shelly fossils from the Wirrealpa and Aroona Creek Limestones, Flinders Ranges, and the temporally equivalent Ramsay Limestone, Yorke Peninsula, South Australia, are described and assessed. These formations, deposited during a widespread marine transgression, have traditionally been assigned an early Middle Cambrian age based on lateral facies relationships, lithostratigraphic interpretation, and age diagnostic trilobites. However, new data from regional sequence stratigraphy and mounting paleontological evidence suggest that a late Early Cambrian age (equivalent to the Toyonian Stage from the Siberian Platform) is more appropriate for these units. Twenty-four taxa, including a number of problematica, poriferans, coeloscleritophorans, palaeoscolecidans, “conodontomorphs,” hyolithelminthes, hyoliths, mollusks, and inarticulate brachiopods, are reported herein; many of these have not previously been reported from the Cambrian of South Australia. The enigmatic Chalasiocranos exquisitum n. gen. and sp., known from disarticulated tuberculate cone-shaped phosphatic sclerites, and Protomelission gatehousei n. gen. and sp., a problematic, perhaps colonial organism, known from phosphatic plates, are especially notable. The genus Kaimenella is formally included in the Palaeoscolecida, and two species (including K. dailyi n. sp.) are recognized.

scholarly journals Small shelly fossils in the cambrian basement of the West Siberian geosyneclise

2019 ◽  
Vol 27 (1) ◽  
pp. 3-11
Author(s):  
N. V. Novozhilova ◽  
I. V. Korovnikov
Keyword(s):  
Lower Cambrian ◽  
Skeletal Remains ◽  
The West ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
Small Shelly Fossils ◽  
Tomsk Region ◽  
First Time

This paper describes for the first time the entire Cambrian skeletal problematics from the parametric well Vostok-1 (Tomsk region, 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.

scholarly journals First Report of Small Shelly Fossils from the Cambrian Miaolingian Limestones (Zhangxia and Hsuzhuang Formations) in Yiyang County, Henan Province of North China

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1104
Author(s):  
Yazhou Hu ◽  
Lars E. Holmer ◽  
Yue Liang ◽  
Xiaolin Duan ◽  
Zhifei Zhang
Keyword(s):  
North China ◽  
South Australia ◽  
Lamellar Microstructure ◽  
Henan Province ◽  
North China Platform ◽  
Middle Cambrian ◽  
First Report ◽  
Primary Layer ◽  
Small Shelly Fossils ◽  
First Time

Small Shelly Fossils (SSFs) from the Cambrian are widely distributed and well known across different paleocontinents of the world. However, middle Cambrian SSFs from North China Platform have only rarely been documented until now. In this paper, we presented the first report on SSFs from bioclastic and oolitic limestones of the Zhangxia and Hsuzhuang formations of Henan province, North China. The carbonate-hosted fauna includes brachiopods (Micromitra sp., M. modesta, Eoobolus sp., and Schizopholis sp.), helcionellids (Oelandiella accordionata and O. aliciae), hyolithids, Hyolithellus sp., Chancelloria eros, sponge spicules, echinoderm ossicles, and chancelloriid sclerites. In terms of preservation, the brachiopod shell valves of M. modesta appeared to be homogeneous, consisting of tightly packed phosphate grains. Eoobolus sp. is composed of primary layer and secondary baculate, both of which consist of tightly compacted phosphate grains. Schizopholis sp. has multiple-lamellar phosphatized microstructures that distinctly differ from the other brachiopods recovered from the Longwanggou section. A similar multiple-lamellar microstructure was also revealed in conchs of Hyolithellus, with tightly compacted phosphate grains. The argillaceous shell of Oelandiella accordionata and O. aliciae, and the calcitic inner molds of hyolith did not preserve any shell structure. The helcionellids O. accordionata and O. aliciae and the brachiopod M. modesta were reported for the first time from North China. The fauna is most similar to the middle Cambrian faunas of South Australia, in the brachiopod and mollusk components; it is also similar in composition of brachiopods and mollusks to coeval faunas from South China. The new fauna of SSFs in the Yiyang Longwanggou Section indicated that the Hsuzhuang and Zhangxia formations are late Drumian to middle Guzhuangian in age, most likely correlating with the Murrawong Creek Formation of South Australia.

scholarly journals Paleomagnetic insights into the Cambrian biogeographic conundrum: Did the North China craton link Laurentia and East Gondwana?

Geology ◽  
2020 ◽  
Author(s):  
Hanqing Zhao ◽  
Shihong Zhang ◽  
Maoyan Zhu ◽  
Jikai Ding ◽  
Haiyan Li ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Tilt Test ◽  
Strong Ties ◽  
Middle Cambrian ◽  
The North ◽  
Late Cambrian ◽  
Small Shelly Fossils ◽  
Paleomagnetic Pole

Redlichiid trilobite and small shelly fossils indicate strong ties of the North China craton (NCC) to Gondwana during the early Cambrian, while recent discoveries of the characteristic fossils of Laurentia in Wuliuan shales in the eastern NCC imply its possible connection with Laurentia during the middle Cambrian. Here we report a new paleomagnetic pole at 31.8°S, 140.4°E (radius of 95% confidence cone of paleomagnetic pole, A95, = 5.3°), obtained from the Wuliuan (ca. 505 Ma) Hsuchuang Formation, by averaging our new data and existing virtual geomagnetic poles acquired from different parts of the NCC. A positive regional tilt test and the presence of geomagnetic reversals demonstrate that the remanence was primary. The paleomagnetic data permit placing the NCC near 20°N between Laurentia and Australia at ca. 505 Ma, suggesting that the NCC may have played the role of biogeographic link between East Gondwana and Laurentia in the middle Cambrian. Low-latitudinal westward ocean currents may have facilitated faunal migrations from Laurentia to East Gondwanan blocks via the NCC as well as the newly formed tectono-paleogeographic archipelago, which likely further enhanced biological exchange in the late Cambrian.

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