Paleoecology and distribution of the Early Cambrian rostroconch Watsonella crosbyi Grabau

1989 ◽  
Vol 63 (5) ◽  
pp. 566-573 ◽  
Author(s):  
Ed Landing
Keyword(s):  
Lower Cambrian ◽  
Thin Shell ◽  
Early Cambrian ◽  
Southern France ◽  
Species Ranges ◽  
Senior Synonym ◽  
Stratigraphic Range ◽  
Rule Out ◽  
Calcareous Nodule

Watsonella crosbyi Grabau, 1900, a senior synonym of Heraultipegma varensalense (Cobbold, 1935) and H. yannense He and Yang, 1982, is the oldest known rostroconch. The species ranges through most of the Early Cambrian and has been recovered from temperate siliciclastic (Avalon Platform) and tropical carbonate (south China, Mongolia?, southern France) environments. Watsonella crosbyi occurs through approximately 880 meters of the sub-trilobitic Lower Cambrian of southeastern Newfoundland. Its lowest occurrence corresponds to the first appearance of relatively diverse small shelly faunas of the pre-Tommotian Watsonella crosbyi Zone (new).The general form of Watsonella crosbyi conchs (laterally compressed, prosogyrate, elongate posterior, subdued comarginal growth lines, very thin shell with anterior and posterior gapes) is similar to that in a number of larger burrowing pelecypods, but this does not rule out other benthic habits. However, recovery of locally common in situ conchs (plane of commissure vertical, long axis subhorizontal) in the lower and upper parts of its stratigraphic range in southeastern Newfoundland corroborates an infaunal life habit for the species. The animal is a prominent element in faunas from offshore, cohesive, siliciclastic mudstones but also occurs in calcareous nodule-rich mudstones, shell hash limestones, and, infrequently, in peritidal algalaminate limestones. A phylogenetic sequence from laterally compressed monoplacophorans to early ribeiroid rostroconchs and leading to the oldest pelecypods was completed by the middle Early Cambrian and involved infaunal mollusks.

Early Cambrian priapulid worms buried with their lined burrows

2006 ◽  
Vol 143 (5) ◽  
pp. 743-748 ◽  
Author(s):  
XI-GUANG ZHANG ◽  
XIAN-GUANG HOU ◽  
JAN BERGSTRÖM
Keyword(s):  
Lower Cambrian ◽  
Southern China ◽  
Early Cambrian ◽  
Exceptional Preservation ◽  
Sediment Layers

Five specimens of the priapulid Maotianshania cylindrica preserved inside their lined burrows were described from the Lower Cambrian Chengjiang deposits near Kunming, southern China. The exceptional preservation suggests that this worm made a dwelling tube by lining within the uppermost sediment layers. This seems to be unique among priapulids in comparison with the Cambrian Selkirkia and Paraselkirkia, as well as some modern priapulid larvae and loriciferans. Taphonomic evidence indicates that the burrow-and-worm specimens are not buried in situ but were moved by storm, tsunami, or turbidity generated currents that are thought to have brought sedimentary material intermittently.

Faunas and Cambrian volcanism on the Avalonian marginal platform, southern New Brunswick

2008 ◽  
Vol 82 (5) ◽  
pp. 884-905 ◽  
Author(s):  
Ed Landing ◽  
Susan C. Johnson ◽  
Gerd Geyer
Keyword(s):  
New Brunswick ◽  
Sea Level ◽  
Lower Cambrian ◽  
Volcanic Edifice ◽  
Early Cambrian ◽  
Early Paleozoic ◽  
Middle Cambrian ◽  
Cool Water ◽  
Senior Synonym ◽  
Lane Formation

The Cambrian inlier at Beaver Harbour, southern New Brunswick, is now confidently referred to the marginal platform of the late Proterozoic–Early Paleozoic Avalon microcontinent. The sub-trilobitic Lower Cambrian Chapel Island and Random Formations are unconformably overlain by the mafic volcanic-dominated Wade's Lane Formation (new). Late Early Cambrian trilobites and small shelly taxa in the lowest Wade's Lane demonstrate a long Random–Wade's Lane hiatus (middle Terreneuvian–early Branchian). Latest Early–middle Middle Cambrian pyroclastic volcanism produced a volcanic edifice at Beaver Harbour that is one of three known volcanic centers that extended 550 km along the northwest margin of Avalon. Middle Middle Cambrian sea-level rise, probably in theParadoxides eteminicusChron, mantled the extinct volcanics with gray-green mudstone and limestone of the Fossil Brook Member. Black, dysoxic mudstone of the upper Manuels River Formation (upper Middle Cambrian,P. davidisZone) is the youngest Cambrian unit in the Beaver Harbour inlier.Lapworthella cornu(Wiman, 1903) emend., a senior synonym of the genotypeL. nigra(Cobbold, 1921),Hyolithellus sinuosusCobbold, 1921, and probablyAcrothyra seraMatthew, 1902a, range through the ca. 8 m.y. of the trilobite-bearing upper Lower Cambrian, andH. sinuosusandA. serapersist into the middle Middle Cambrian.Lapworthella cornuandH. sinuosusreplaced the tropical taxaL. schodackensis(Lochman, 1956) andH. micansBillings, 1872, in cool-water Avalon.

A new early Cambrian bradoriid (Arthropoda) from East Antarctica

2003 ◽  
Vol 77 (4) ◽  
pp. 691-697 ◽  
Author(s):  
Alycia L. Rode ◽  
Bruce S. Lieberman ◽  
A. J. Rowell
Keyword(s):  
Lower Cambrian ◽  
New Genus ◽  
Sister Group ◽  
East Antarctica ◽  
Sister Group Relationship ◽  
Early Cambrian ◽  
New Genus And Species ◽  
The Family ◽  
Relationship Of

Although bradoriids locally are common components of the Cambrian biota, they have been reported previously from Antarctica only from Tertiary glacial deposits. Here, we describe the bradoriid,Bicarinella evansinew genus and species, collected in situ from the upper Lower Cambrian (Botomian) of the Pensacola Mountains in East Antarctica.Bicarinella evansin. gen and sp. is characterized by a subtriangular carapace with a well-defined marginal rim, subequal anterior and posterior lobes that are elongated into sharp ridges extending one-third the length of the carapace, and a broad dorsal node placed between the anterior and posterior lobes. The surface of the carapace exhibits three kinds of ornamentation: fine pitting, pustules, and reticulae. Several smaller carapaces with reduced ornamentation collected from the same bed are interpreted as instars of this species.Bicarinellan. gen. is assigned to the family Hipponicharionidae and appears to be closely related toAlbrunnicolaMartinsson, 1979, orHipponicharionMatthew, 1886. Although strong archaeocyath faunal similarities demonstrate a close biogeographic relationship between Australia and Antarctica in the Early Cambrian, the possible sister group relationship ofBicarinellan. gen. toHipponicharion, which is otherwise unknown from Gondwana, may suggest a separate biogeographic pathway to East Antarctica that did not involve Australia.

Infants Diagnosed with Athyreosis on Scintigraphy May Have a Gland Present on Ultrasound and Have Transient Congenital Hypothyroidism

2021 ◽  
pp. 1-8
Author(s):  
Niamh McGrath ◽  
Colin Patrick Hawkes ◽  
Stephanie Ryan ◽  
Philip Mayne ◽  
Nuala Murphy
Keyword(s):  
Thyroid Gland ◽  
Congenital Hypothyroidism ◽  
Thyroid Tissue ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Ultrasound ◽  
Free T4 ◽  
Median Serum ◽  
Thyroid Glands ◽  
Rule Out

Scintigraphy using technetium-99m (<sup>99m</sup>Tc) is the gold standard for imaging the thyroid gland in infants with congenital hypothyroidism (CHT) and is the most reliable method of diagnosing an ectopic thyroid gland. One of the limitations of scintigraphy is the possibility that no uptake is detected despite the presence of thyroid tissue, leading to the spurious diagnosis of athyreosis. Thyroid ultrasound is a useful adjunct to detect thyroid tissue in the absence of <sup>99m</sup>Tc uptake. <b><i>Aims:</i></b> We aimed to describe the incidence of sonographically detectable in situ thyroid glands in infants scintigraphically diagnosed with athyreosis using <sup>99m</sup>Tc and to describe the clinical characteristics and natural history in these infants. <b><i>Methods:</i></b> The newborn screening records of all infants diagnosed with CHT between 2007 and 2016 were reviewed. Those diagnosed with CHT and athyreosis confirmed on scintigraphy were invited to attend a thyroid ultrasound. <b><i>Results:</i></b> Of the 488 infants diagnosed with CHT during the study period, 18/73 (24.6%) infants with absent uptake on scintigraphy had thyroid tissue visualised on ultrasound (3 hypoplastic thyroid glands and 15 eutopic glands). The median serum thyroid-stimulating hormone (TSH) concentration at diagnosis was significantly lower than that in infants with confirmed athyreosis (no gland on ultrasound and no uptake on scintigraphy) (74 vs. 270 mU/L), and median free T4 concentration at diagnosis was higher (11.9 vs. 3.9 pmol/L). Six of 10 (60%) infants with no uptake on scintigraphy but a eutopic gland on ultrasound had transient CHT. <b><i>Conclusion:</i></b> Absent uptake on scintigraphy in infants with CHT does not rule out a eutopic gland, especially in infants with less elevated TSH concentrations. Clinically, adding thyroid ultrasound to the diagnostic evaluation of infants who have athyreosis on scintigraphy may avoid committing some infants with presumed athyreosis to lifelong levothyroxine treatment.

scholarly journals Effects of Rifaximin on Luminal and Wall-Adhered Gut Commensal Microbiota in Mice

2021 ◽  
Vol 22 (2) ◽  
pp. 500
Author(s):  
Marina Ferrer ◽  
Mònica Aguilera ◽  
Vicente Martinez
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Fragment Length Polymorphism ◽  
Functional Gastrointestinal Disorders ◽  
Antibacterial Properties ◽  
Broad Spectrum Antibiotic ◽  
Commensal Microbiota ◽  
Bacterial Biodiversity ◽  
Rule Out

Rifaximin is a broad-spectrum antibiotic that ameliorates symptomatology in inflammatory/functional gastrointestinal disorders. We assessed changes in gut commensal microbiota (GCM) and Toll-like receptors (TLRs) associated to rifaximin treatment in mice. Adult C57BL/6NCrl mice were treated (7/14 days) with rifaximin (50/150 mg/mouse/day, PO). Luminal and wall-adhered ceco-colonic GCM were characterized by fluorescent in situ hybridization (FISH) and microbial profiles determined by terminal restriction fragment length polymorphism (T-RFLP). Colonic expression of TLR2/3/4/5/7 and immune-related markers was assessed (RT-qPCR). Regardless the period of treatment or the dose, rifaximin did not alter total bacterial counts or bacterial biodiversity. Only a modest increase in Bacteroides spp. (150 mg/1-week treatment) was detected. In control conditions, only Clostridium spp. and Bifidobacterium spp. were found attached to the colonic epithelium. Rifaximin showed a tendency to favour their adherence after a 1-week, but not 2-week, treatment period. Minor up-regulation in TLRs expression was observed. Only the 50 mg dose for 1-week led to a significant increase (by 3-fold) in TLR-4 expression. No changes in the expression of immune-related markers were observed. Rifaximin, although its antibacterial properties, induces minor changes in luminal and wall-adhered GCM in healthy mice. Moreover, no modulation of TLRs or local immune systems was observed. These findings, in normal conditions, do not rule out a modulatory role of rifaximin in inflammatory and or dysbiotic states of the gut.

The problematic fossil Triplicatella from the Early Cambrian of Greenland, Canada, and Siberia

2004 ◽  
Vol 41 (11) ◽  
pp. 1273-1283 ◽  
Author(s):  
Christian B Skovsted ◽  
John S Peel ◽  
Christian J Atkins
Keyword(s):  
New Species ◽  
Functional Morphology ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
Taxonomic Affinity ◽  
East Greenland ◽  
North East ◽  
Close Proximity ◽  
Two New Species

The cap-shaped Early Cambrian fossil Triplicatella, previously known only from Australia, is reported from the upper Lower Cambrian of North and North-East Greenland, western Newfoundland, and Siberia. The occurrence of Triplicatella in Laurentia strengthens faunal ties between Laurentia and the Australian margin of Gondwana in late Early Cambrian times and supports hypotheses advocating the close proximity for the two palaeocontinents. Two new species, Triplicatella sinuosa n. sp., and T. peltata n. sp. are described, morphological details of which help elucidate the functional morphology and taxonomic affinity of the group. Three opercular types attributable to Triplicatella are left in open taxonomy. The postulated affinity of Triplicatella to hyoliths is confirmed, although the genus can not be placed within either of the two orders of hyoliths currently recognized.

Lower Cambrian (Branchian) trilobites and biostratigraphy of the Hanford Brook Formation, southern New Brunswick

2000 ◽  
Vol 74 (5) ◽  
pp. 858-878 ◽  
Author(s):  
Stephen R. Westrop ◽  
Ed Landing
Keyword(s):  
New Species ◽  
Nova Scotia ◽  
North America ◽  
New Brunswick ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
The West ◽  
Middle Cambrian ◽  
Sequence Stratigraphic ◽  
Two New Species

The Hanford Brook Formation, one of the classic Cambrian units of Avalonian North America, contains at least eight species of endemic trilobites, including Berabichia milleri Westrop n. sp., that are assigned to seven genera. The vertical succession of faunas is far more complex than has been recognized previously, with each member containing a lithofacies-specific assemblage. These are, in ascending order: a bradoriid-linguloid Association without trilobites in the nearshore St. Martin's Member, a Protolenus Association in dysaerobic siltstones and sandstones of the Somerset Street Member, and a Kingaspidoides-Berabichia Association in hummocky cross-stratified sandstones of the Long Island Member that overlie a parasequence boundary at Hanford Brook. Due to the breakdown of biogeographic barriers in the late Early Cambrian, two new species-based zones, the Protolenus elegans and Kingaspidoides cf. obliquoculatus zones, share trilobite genera with the Tissafinian Stage of Morocco. This generic similarity has been the basis for correlation of this upper Lower Cambrian interval on the Avalon continent with the West Gondwanan lowest Middle Cambrian. However, the clear facies control on the occurrence of genera in the Hanford Brook Formation and the presence of an abrupt faunal break and unconformity at the base of the Tissafinian in Morocco makes this correlation questionable. The Hanford Brook Formation may represent a late Early Cambrian interval unknown in Gondwana. Sequence-stratigraphic criteria even raise the possibility that the Protolenus Association is the biofacies equivalent of Callavia broeggeri Zone faunas of the Brigus Formation of Newfoundland, Nova Scotia and Massachusetts.

scholarly journals Taxonomic diversity and faunal turnover in the Early Cambrian: Did the most severe mass extinction of the Phanerozoic occur in the Botomian stage?

1992 ◽  
Vol 6 ◽  
pp. 272-272 ◽  
Author(s):  
Philip W. Signor
Keyword(s):  
Lower Cambrian ◽  
Substantial Reduction ◽  
Taxonomic Diversity ◽  
Early Cambrian ◽  
Shelf Area ◽  
Extinction Rate ◽  
Mass Extinctions ◽  
High Turnover ◽  
Faunal Turnover ◽  
Global Correlation

A handful of mass extinctions, scattered through the Phanerozoic, forever changed the course of life on Earth, eliminating large numbers of clades from the evolutionary race and allowing the survivors to diversify following the extinction. These ecological-evolutionary upheavals extirpated whole communities and eliminated otherwise successful clades from the evolutionary race. While the mechanism(s) responsible for most mass extinctions remain to be identified, their impact on the biosphere is self-evident. Thus, recognition of a previously overlooked, severe extinction early in the Phanerozoic provides important new insights and perspectives on the history of lifeIn the course of research on the biogeographic distribution of Early Cambrian metazoan taxa, I compiled a database on the geographic and stratigraphic distribution of metazoan genera. The data are derived from the primary literature on the paleogeographic and stratigraphic distributions and systematics of Early Cambrian fossils. The Russian zonation scheme for the Siberian Platform (incorporating four stages, in ascending order: Tommotian, Atabanian, Botomian, and Toyonian) was employed for biostratigraphic correlations. Correlations of other regions to the Siberian stages were based upon work by F. Debrenne and her colleagues on archaeocyathans and upon M. D. Brasier's correlations from small shelly fossils. While there is no accepted global correlation scheme for Lower Cambrian strata, this approach yields results that are useful at the four-stage level of resolution. The data base currently includes more than 850 genera.Examination of the aggregate data reveals a substantial reduction (>60%) in the global total of genera extant in the Toyonian, in comparison to the Botomian stage. The extinction rate of genera at the end of the Botomian exceeds 80 percent. By comparison, the end-Permian extinction eliminated slightly more than 60 percent of the extant genera.In addition to the general reduction in generic diversity, Brasier (1982) has documented a fall in sea level and reduction in the shelf area. Associated with this regression was a loss of reef-forming archaeocyathan genera. While a small number of archaeocyathan genera persisted into the Toyonian (and a few genera have been reported from Late Cambrian strata in Antarctica), the bulk of archaeocyath diversity was lost in the Botomian. The losses in diversity, extermination of reef-forming organisms, and high turnover in conjunction with a marine regression matches the pattern observed at most other mass extinctions.It is remarkable that this relatively severe extinction has gone mostly unnoticed by paleobiologists. Much of the data is relatively new, a product of intense international study of early metazoan faunas. Most likely, the mass of data produced by Lower Cambrian specialists over the past ten years has yet to reach the treatises and monographs where it can be easily summarized. Also, resolution of patterns within the Early Cambrian has waited on the development of correlations and a satisfactory zonation. Indeed, detailed study of the Botomian extinction will await more accurate correlations.

New evidence that the Lower Cambrian Leny Limestone at Callander, Perthshire, belongs to the Dalradian Supergroup, and a reassessment of the ‘exotic’ status of the Highland Border Complex

1995 ◽  
Vol 132 (5) ◽  
pp. 473-483 ◽  
Author(s):  
P. W. G. Tanner
Keyword(s):  
Lower Cambrian ◽  
Alternative Hypothesis ◽  
Structural Relationship ◽  
Early Cambrian ◽  
Minimum Age ◽  
Entire Sequence ◽  
New Evidence ◽  
Critical Sections ◽  
Radiometric Data

AbstractThe Lower Cambrian Leny Limestone at Callander in Scotland lies within a sequence of palecoloured grits and dark slates (here named the Keltie Water Grit Formation (KWGF)) which has lithological similarities with members of the Highland Border Complex (HBC) (Ordovician) seen elsewhere along the Highland Border. The Keltie Water Grit Formation has a transitional boundary with a grit-slate sequence of undoubted Dalradian parentage; as the ‘Leny Grits’ of previous workers include both the KWGF and part of the Dalradian sequence, this term is now rendered invalid. The entire sequence youngs upwards from the Dalradian to the top of the overlying Keltie Water Grit Formation, shares the same structural sequence and geometry, and has the same facing and vergence direction on the main cleavage. All field and petrographic data are consistent with a minimum age of post-early Cambrian for the Grampian event, the main orogenic event to affect the Dalradian. Examination of critical sections elsewhere across the Highland Border shows that there is an apparently consistent stratigraphical and structural relationship between the Highland Border Complex and the Dalradian which, as suggested by some previous workers, would require the Grampian event to be post-Arenig in age. However, we are faced with a so-far unresolved paradox that there are certain palaeontological and radiometric data which are in conflict with this conclusion, and support the alternative hypothesis that the Highland Border Complex docked with the Dalradian in post-Ordovician times.

Sign in / Sign up

Export Citation Format

Share Document