The record of cavity-dwelling (coelobiontic) organisms in the Paleozoic

1981 ◽  
Vol 18 (2) ◽  
pp. 181-190 ◽  
Author(s):  
David R. Kobluk
Keyword(s):  
Lower Cambrian ◽  
Community Organization ◽  
Patch Reef ◽  
Early Cambrian ◽  
Marine Environments ◽  
Patch Reefs ◽  
History Of

In modern marine environments coelobiontic (cavity-dwelling) organisms are ubiquitous and abundant. However, little is known of modern coelobionts and even less of their geologic history.The oldest known coelobionts are found in archaeocyathid patch reef cavities from the Lower Cambrian of Nevada and Labrador, where the cavity communities are dominated by algae; foraminifera, brachiopods, pelmatazoans, sponges, archaeocyathids, Bija, Archaeotrypa, and an infauna of burrowers in cavity sediments are accessories in upper Lower Cambrian cavities from the Forteau Formation of Labrador. Earlier cavities in patch reefs from the Poleta Formation of Nevada are much less diverse and are dominated by algae and an infauna of burrowers.From the Lower Cambrian to the present day the history of coelobionts has not been one of major innovation but rather has been conservative. Even as far back as the early Cambrian, coelobiontic communities were similar to their modern counterparts if viewed in terms of community organization and trophic structure.Dans les milieux marins modernes, les organismes coelobiontiques (habitant les cavités) se retrouvent partout et en abondance. Toutefois, on connaît peu de choses sur les coelobiontes modernes et encore moins sur leur histoire géologique.

A probable late Neoproterozoic age for the Kennedy Channel and Ella Bay formations, northeastern Ellesmere Island and its implications for passive margin history of the Canadian Arctic

2004 ◽  
Vol 41 (9) ◽  
pp. 1013-1025 ◽  
Author(s):  
Keith Dewing ◽  
J C Harrison ◽  
Brian R Pratt ◽  
Ulrich Mayr
Keyword(s):  
Lower Cambrian ◽  
Canadian Arctic ◽  
Passive Margin ◽  
Early Cambrian ◽  
Channel Formation ◽  
Type Section ◽  
Small Shelly Fossils ◽  
History Of ◽  
Basin Formation ◽  
Late Neoproterozoic

The Kennedy Channel and Ella Bay formations are the two oldest stratigraphic units exposed in the Franklinian margin sedimentary sequence in the Canadian Arctic Islands. An Early Cambrian age had previously been accepted by the occurrence of trilobites and small shelly fossils in the type section of the Kennedy Channel Formation. Reinvestigation of the area around the type section shows that several large strike-slip faults cut the succession and that the olenelloid trilobites are from an infaulted slice of a younger unit, the Lower Cambrian Kane Basin Formation. Thus, there is no unambiguous paleontological evidence for the age of either the Kennedy Channel or Ella Bay formations. However, the abundance of stromatolites, absence of trace fossils, and separation from overlying Lower Cambrian clastics by a regional angular unconformity indicate a probable late Neoproterozoic age for these two formations. The Ella Bay Formation likely correlates with the Portfjeld Formation in North Greenland, the Spiral Creek Formation in East Greenland, and the Risky Formation of the Mackenzie Mountains in northwestern Canada. The passive margin that existed in northern Laurentia during the early Paleozoic was, therefore, established in the late Neoproterozoic, and the onset of rifting must have preceded this, rather than occurring in the Early Cambrian as some authors have suggested.

Early Cambrian Ediacaran-type fossils from California

2000 ◽  
Vol 74 (4) ◽  
pp. 731-740 ◽  
Author(s):  
James W. Hagadorn ◽  
Christopher M. Fedo ◽  
Ben M. Waggoner
Keyword(s):  
United States ◽  
Great Basin ◽  
Lower Cambrian ◽  
Trace Fossils ◽  
Early Cambrian ◽  
Marine Environments ◽  
Southwestern United States ◽  
White Mountains ◽  
Lower Member ◽  
Middle Member

Ediacara-type fossils are rare in the southwestern United States, and Cambrian occurrences of soft-bodied Ediacaran-type fossils are extremely rare. We report both discoidal and frondlike fossils comparable to Ediacaran taxa from the western edge of the Great Basin. We describe one specimen of a discoidal fossil, referred to the form species ?Tirasiana disciformis, from the upper member of the Lower Cambrian Wood Canyon Formation from the Salt Spring Hills, California. Two fragmentary specimens of frond-like soft-bodied fossils are described from the middle member of the Lower Cambrian Poleta Formation in the White Mountains, California, and the upper member of the Wood Canyon Formation in the southern Kelso Mountains, California. On the basis of similarities with fossils from the lower member of the Wood Canyon Formation and from the Spitzkopf Member of the Urusis Formation of Namibia, these specimens are interpreted as cf. Swartpuntia. All fossils were collected from strata containing diagnostic Early Cambrian body and trace fossils, and thus add to previous reports of complex Ediacaran forms in Cambrian marine environments. In this region, Swartpuntia persists through several hundred meters of section, spanning at least two trilobite zones.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

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.

The significance of the boundary between the Rhoscolyn and New Harbour formations on Holy Island, North Wales, to the deformation history of Anglesey

2012 ◽  
Vol 150 (3) ◽  
pp. 519-535 ◽  
Author(s):  
JACK E. TREAGUS ◽  
SUSAN H. TREAGUS ◽  
NIGEL H. WOODCOCK
Keyword(s):  
Lower Cambrian ◽  
Depositional Environment ◽  
High Strain ◽  
The Other ◽  
Deformation History ◽  
Two Phase ◽  
Phase Deformation ◽  
North Wales ◽  
History Of ◽  
Tectonic Features

AbstractThe boundary between the Rhoscolyn and New Harbour formations on Holy Island, Anglesey, has been described as a high strain zone or as a thrust. The boundary is here described at four localities, with reference to the contrasting sedimentary and deformational character of the two formations. At one of these localities, Borth Wen, sandstones and conglomerates at the top of the Rhoscolyn Formation are followed, without any break, by tuffs and then mudstones of the New Harbour Formation. It is concluded that there is clear evidence of depositional continuity across the boundary here, and that both formations subsequently shared a common two-phase deformation. The first (D1) was manifestly different in intensity and scale in the two formations, whereas the second (D2) produced very similar structures in both. The other three localities provide continuity of sedimentary and tectonic features at this boundary in a traverse along the length of Holy Island, leading us to identify two previously unrecognized major D1 folds in addition to the Rhoscolyn Anticline. At one of these localities (Holyhead), we confirm the presence of Skolithos just below the boundary, supporting radiometric evidence for a lower Cambrian or later age for the Rhoscolyn Formation. A turbidite interpretation for both the Rhoscolyn and New Harbour formations best fits the available evidence. A deep-water depositional environment is still compatible with the sporadic presence of Skolithos burrows, but less so with reported observations of hummocky and swaley cross-stratification lower down the South Stack Group.

scholarly journals Coral transplantation on a multilevel substrate of Artificial Patch Reefs: effect of fixing methods on the growth rate of two Acropora species

2020 ◽  
Vol 21 (5) ◽  
Author(s):  
M Munasik ◽  
AGUS SABDONO ◽  
AZELIA N. ASSYFA ◽  
DIAH PERMATA WIJAYANTI ◽  
SUGIYANTO SUGIYANTO ◽  
...  
Keyword(s):  
Growth Rate ◽  
Environmental Changes ◽  
Patch Reef ◽  
Concrete Block ◽  
Coral Growth ◽  
Growth And Survival ◽  
Lower Survival Rate ◽  
Shallow Reef ◽  
Patch Reefs ◽  
Central Java

Abstract. Munasik, Sabdono A, Assyfa AN, Wijayanti DP, Sugiyanto, Irwani, Pribadi R. 2020. Coral transplantation on a multilevel substrate of Artificial Patch Reefs: effect of fixing methods on the growth rate of two Acropora species. Biodiversitas 21: 1816-1822. Branching Acropora is generally used in coral transplantation to rehabilitate coral reefs. However, these corals are sensitive to environmental changes. Artificial Patch Reef  (APR) is an artificial structure that provides a multilevel hard substrate. The purpose of the study was to investigate the effectiveness of the APR structure to facilitate the growth and survival of Acropora branching. Two species Acropora aspera and Acropora copiosa were transplanted vertically and horizontally on a modular concrete block in different levels of APR situated in the shallow reef of Panjang Island, Central Java. The results showed that the coral growth rate varied from 96.7 to 346.9 cm3/month, while survival ranged from 30 to 100% after 8 months. Lower survival rate mostly was found in the upper level of APR. The statistical analyses showed that the growth rate of A. copiosa fragment was significantly higher than that of A. aspera  (p<0.05). Moreover, there were also significant differences in the treatments of transplantation method  (p<0.05) to enhance coral growth. However, multilevel substrates were not significantly influenced by coral growth. This study suggested that A. copiosa which has high-level complexity in branching pattern will be selected to apply in shallow reef rehabilitation with transplanted vertically.

Habitat effects on home range and schooling behaviour in a herbivorous fish (Kyphosus bigibbus) revealed by acoustic tracking

2017 ◽  
Vol 68 (8) ◽  
pp. 1454 ◽  
Author(s):  
R. D. Pillans ◽  
R. C. Babcock ◽  
D. P. Thomson ◽  
M. D. E. Haywood ◽  
R. A. Downie ◽  
...  
Keyword(s):  
Home Range ◽  
Patch Reef ◽  
Movement Patterns ◽  
Herbivorous Fish ◽  
Ecological Role ◽  
Patch Reefs ◽  
Poor Understanding ◽  
Schooling Behaviour ◽  
Acoustic Tags

Large mobile herbivorous fish that specialise in browsing large brown algae are particularly important on coral reefs because their activities mediate algal–coral competition. Despite this important ecological role, we have a poor understanding of the movement patterns of such large herbivorous fish, including Kyphosus bigibbus. Nineteen K. bigibbus captured near adjacent but distinct patch reefs were tagged with internal acoustic tags and their movements monitored for up to 20 months by an array of 60 acoustic receivers. Home-range estimates showed that movements of individuals from each patch reef encompassed different spatial extents and resulted in differences in habitat used by the two groups of fish. The average 50 and 95% kernel utilisation distribution for long-term resident fish was 0.27±0.03 and 1.61±0.30km2 respectively, ranges that represent the largest values for a herbivorous coral reef fish recorded to date. There was a significantly higher degree of fidelity among fish from the same school, and to particular patch reefs, despite the proximity of the reefs and substantial overlap between schools of conspecifics. A coefficient of sociality was used on pairs of fish and showed that there was no evidence that individuals were consistently detected together when they were detected by receivers away from their home reef. The variability of movement patterns among individuals of K. bigibbus results in an increased niche footprint for this important browser, potentially increasing reef resilience.

Habitat use and coexistence of three territorial herbivorous damselfish on different-size patch reefs

2013 ◽  
Vol 93 (8) ◽  
pp. 2265-2272 ◽  
Author(s):  
Akihisa Hattori ◽  
Takuro Shibuno
Keyword(s):  
Species Richness ◽  
Habitat Use ◽  
Interspecific Interactions ◽  
Patch Reef ◽  
Back Reef ◽  
Intraspecific Interactions ◽  
Reef Area ◽  
Patch Reefs ◽  
Significant Difference ◽  
Random Placement

In local reef fish communities, species richness increases with increasing reef area. At Ishigaki Island, Japan, species richness is much lower on large reefs in the shallow back reef than that expected from random placement model simulations (RPMS). As three aggressive territorial herbivorous damselfish, Stegastes nigricans, Stegastes lividus and Hemiglyphidodon plagiometopon, coexist only on such large reefs, we focused on these species and examined patterns of their distribution and abundance on 84 patch reefs of various sizes (area and height). We also examined their aggressive intra- and interspecific behavioural interactions and habitat use on the two large reefs (the largest complex patch reef and the large flat patch reef) among the 84 patch reefs. While the abundance of both S. lividus and H. plagiometopon was highly correlated with patch reef area, that of S. nigricans was closely correlated with patch reef height. For S. nigricans and S. lividus, interspecific interactions occurred significantly more frequently than intraspecific interactions on the large flat patch reef. However, there was no significant difference in frequencies of the two interaction types on the largest complex patch reef, where they three-dimensionally segregated conspecific territories. This study suggested that reef height as well as reef area influence the distribution and abundance of these territorial herbivorous damselfish in the shallow back reef. As large patch reefs cannot be tall allometrically in shallow back reefs, relatively flat patch reefs may not have the high species richness expected from RPMS based on reef area.

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.

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