Neltneriidae and Holmiidae (Trilobita) from Morocco and the problem of Early Cambrian intercontinental correlation

1995 ◽  
Vol 69 (3) ◽  
pp. 459-474 ◽  
Author(s):  
Gerd Geyer ◽  
Allison R. Palmer
Keyword(s):  
New Taxa ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
Middle Cambrian

Previously undescribed Holmiidae from the Sectigena Zone of Morocco indicate correlation of this zone with other zones bearing Holmiidae on Baltica, Avalonia, Siberia, and Laurentia. The occurrence of the youngest Antatlasiinae in the Sectigena Zone and the oldest Protoleninae in the overlying Hupeolenus Zone suggests correlations of the Sectigena Zone with upper Atdabanian beds bearing the youngest Antatlasiinae and the Hupeolenus Zone with Botomian beds bearing the oldest Protoleninae in Siberia. The occurrence, in the overlying Hupeolenus and Cephalopyge Zones, of Paradoxides s.l. in association with the olenelloid Cambropallas and with trilobites characteristic of the Lower Cambrian “Protolenus” Zone of Avalonia calls into question the major criteria for recognition of strata of Early and Middle Cambrian age. New taxa include lyouella contracta n. gen. and sp. of the Holmiidae and Bondonella sdzuyi n. sp. of the Neltneriidae. The known species of Neltneria, N. jacqueti and N. termieri, are revised.

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.

Early Cambrian palaeoscolecid cuticles from Shaanxi, China

1996 ◽  
Vol 70 (2) ◽  
pp. 275-279 ◽  
Author(s):  
Xi-Guang Zhang ◽  
Brian R. Pratt
Keyword(s):  
New Species ◽  
Geographic Distribution ◽  
Lower Cambrian ◽  
New Genus ◽  
Three Dimensional ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
High Diversity

Phosphatized, three-dimensional cuticle fragments of the palaeoscolecids Houscolex lepidotus new genus and new species, Houscolex species indeterminate, and an unidentified form are described from the Lower Cambrian Qiongzhusi Formation of Shaanxi, China. These segmented worms, characterized by regularly arranged simple plates and platelets, small circular pores and fine pits, and irregularly distributed nipplelike protuberances, are unique among known palaeoscolecids. The occurrence of such cuticles as seemingly persistent elements of phosphatized faunas suggests that wormlike organisms achieved a fairly high diversity and widespread geographic distribution during the Early and Middle Cambrian.

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.

scholarly journals New Cambrian faunas from Peary Land, eastern North Greenland

1979 ◽  
Vol 91 ◽  
pp. 29-36
Author(s):  
A.R Palmer ◽  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
Middle And Late Cambrian ◽  
North Greenland

Early, Middle and Late Cambrian faunas from Peary Land, eastern North Greenland, are briefly documented. The Early Cambrian faunas of the lower Brønlund Fjord Group are assigned to the Bonnia-Olenellus Zone, although olenellids from the underiying Buen Formation may be older. Strata from the upper Brønlund Fjord Group with Middle Cambrian faunas are seemingly separated from the Lower Cambrian by a discontinuity, without representation of early Middle Cambrian zones. Faunas from lower beds of the overlying Tavsens Iskappe Group span the Middle-Late Cambrian boundary. Upper beds ofthe Tavsens Iskappe Group are assigned to the Late Cambrian, but corroborative faunal evidence is not yet available.

scholarly journals Occurrence ofMicrodictyonfrom the lower Cambrian Xinji Formation along the southern margin of the North China Platform

2017 ◽  
Vol 92 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Bing Pan ◽  
Timothy P. Topper ◽  
Christian B. Skovsted ◽  
Lanyun Miao ◽  
Guoxiang Li
Keyword(s):  
Lower Cambrian ◽  
North China ◽  
Ontogenetic Variation ◽  
Early Cambrian ◽  
North China Platform ◽  
Middle Cambrian ◽  
The North ◽  
Formation Stage ◽  
Inadequate Knowledge ◽  
Stage 4

AbstractDisarticulated net-like plates of the lobopodMicrodictyonhad a near cosmopolitan distribution from the early to middle Cambrian but are yet to be documented from the North China Platform. Here we report isolated plates ofMicrodictyonfrom the lower Cambrian Xinji Formation (Stage 4, Series 2) of the North China Platform, extending the paleogeographic distribution ofMicrodictyonin the early Cambrian. The plates ofMicrodictyonfrom the Xinji Formation are similar to those of other species established on the basis of isolated plates but do bear some new characters, such as mushroom-shaped nodes with a single inclined platform-like apex and an upper surface that displays radial lines. However, the plates documented here are left under open nomenclature due to inadequate knowledge of intraspecific and ontogenetic variation and low specimen numbers. Through comparison of the node shapes of the isolated plates of differentMicrodictyonspecies, we consider that low mushroom-shaped nodes could be a primitive and conservative character ofMicrodictyonwhile tall mushroom-shaped nodes may be a derived character. Subtle differences in shape and number of node apices may also represent intraspecific or ontogenetic variation.

Cambrian detrital zircon signatures of the northern Cordilleran passive margin, Liard area, Canada: evidence of sediment recycling, non-Laurentian ultimate sources, and basement denudation

2017 ◽  
Vol 54 (6) ◽  
pp. 609-621
Author(s):  
Margot McMechan ◽  
Lisel Currie ◽  
Filippo Ferri ◽  
William Matthews ◽  
Paul O’Sullivan
Keyword(s):  
North American ◽  
Detrital Zircon ◽  
Lower Cambrian ◽  
Probability Distributions ◽  
Detrital Zircons ◽  
Passive Margin ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Middle Member

Detrital zircon U–Pb age probability distributions for the Cambrian Vizer formation (informal) and Mount Roosevelt Formation (middle member) of the northern Canadian Cordilleran passive margin indicate extensive recycling from ∼1.7 to 1.6 Ga Paleoproterozoic sandstones and Proterozoic and Lower Cambrian strata, respectively. The units have minor or no first cycle input from Laurentian basement. The lower part of the Vizer formation contains North American magmatic gap (1610–1490 Ma) detrital zircons and lacks ultimate Grenvillian sourced grains, indicating that the grains were likely sourced from a nearby Mesoproterozoic basin and have an ultimate non-Laurentian source. Detrital zircon U–Pb ages of 670–640 Ma from the middle member of the Mount Roosevelt Formation indicate associated volcanic clasts were locally sourced, and are not of syn-sedimentary Middle Cambrian age. Provenance of these units was indirectly impacted by the Liard Line basement feature. Detrital zircon U–Pb age probability distributions from the northern Canadian Cordilleran passive margin indicate sediments were sourced from the east in the Early Cambrian (Terreneuvian; Vizer formation and correlatives) and the northeast during Early Cambrian (Series 2) deposition of Sekwi Formation and correlative strata. In the early Middle Cambrian, the middle member of the Mount Roosevelt Formation was primarily locally sourced, whereas the upper member was derived from Laurentian basement to the east and southeast. The change from reworked Paleoproterozoic cover in the Terrenuvian to primary basement sources in the Middle Cambrian suggests significant denudation of the basement occurred southeast of the Liard Line.

scholarly journals Acritarchs from the Buen Formation (Lower Cambrian), North Greenland

1988 ◽  
Vol 137 ◽  
pp. 54-54
Author(s):  
G Vidal ◽  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Trace Fossils ◽  
Early Cambrian ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Siliciclastic Sediments ◽  
North Greenland

Siliciclastic sediments of the Buen Formation of North Greenland yield the earliest Cambrian fossils known from North Greenland, with the exception of cyanobacteria described from dolomites of the underlying Portfjeld Formation (see Peel, this report). The fauna is dominated by olenellid and nevadiid trilobites indicating an Early Cambrian age (Poulsen, 1974; Blaker, this report) but hyolithids, bradoriids, sponges and other fossils also occur. Bergstrom & Peel (this report) described trace fossils from the Buen Formation. Of particular interest is the recent discovery of lightly skeletised arthropods comprising an assemblage similar to that of the Middle Cambrian Burgess shale of Canada (Conway Morris et al., 1987).

scholarly journals An Early Cambrian problematic fossil: Vetustovermis and its possible affinities

2005 ◽  
Vol 272 (1576) ◽  
pp. 2003-2007 ◽  
Author(s):  
Jun-yuan Chen ◽  
Di-ying Huang ◽  
David J Bottjer
Keyword(s):  
South China ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
Animal Group ◽  
Middle Cambrian ◽  
Animal Groups ◽  
Anatomical Features ◽  
Anatomical Analysis ◽  
Evolutionary Level ◽  
Well Differentiated

The Early Cambrian problematic fossil Vetustovermis (Glaessner 1979 Alcheringa 3 , 21–31) was described as an annelid or arthropod. Anatomical analysis of 17 new specimens from the Lower Cambrian Maotianshan Shale at Anning, Kunming (South China) does not support its affinities with annelids or arthropods. Anatomical features instead resemble other animal groups including modern flatworms, nemertines and molluscs. The presence of a pelagic slug-like form and ventral foot, as well as a head with eyes and tentacles indicates a possible affinity with molluscs, but these characters are not present only in molluscs; some of them are shared with other animal groups, including flatworms and nemertines. For example, a ventral foot-like structure is found in nemertines, ‘turbellarians’, and some polychaete groups. The well differentiated head is seen in separate bilaterian groups, but among molluscs it did not occur before the evolutionary level of the Conchifera. Unlike the ctenia-gills in molluscs, the gills in Vetustovermis are bar-like. All the characters displayed in this 525 million-year old soft-bodied animal fail to demonstrate clear affinity with molluscs or any other known extant or extinct animal groups, but argue for representing an independently evolved animal group, which flourished in Early Cambrian and possibly in Middle Cambrian time.

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.

Ptychopariid trilobites of the Lower-Middle Cambrian boundary interval, Pioche Shale, southeastern Nevada

2000 ◽  
Vol 74 (4) ◽  
pp. 604-630 ◽  
Author(s):  
Frederick A. Sundberg ◽  
Linda B. Mccollum
Keyword(s):  
New Taxa ◽  
Lower Cambrian ◽  
Middle Cambrian

Twelve ptychopariid species assigned to five genera occur in the Lower-Middle Cambrian boundary interval, Pioche Shale, eastern Nevada. New taxa include one genus, Eokochaspis, and seven species, Eokochaspis nodosa, E. delamarensis, E. metalaspis, E. longspina, Kochina? walcotti, Mexicella antelopea, and M. robusta. Two new biozones, the Eokochaspis nodosa and overlying Amecephalus arrojosensis Biozones, are proposed between the Lower Cambrian Olenellus Biozone and the Middle Cambrian Plagiura-Poliella Biozone. In addition, the three remaining informal shale members of the Pioche Shale are formally named.

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