Taphonomic Signature of Petroleum Seep Assemblages on the Louisiana Upper Continental Slope: Recognition of Autochthonous Shell Beds in the Fossil Record

Palaios ◽  
1992 ◽  
Vol 7 (4) ◽  
pp. 388 ◽  
Author(s):  
W. Russell Callender ◽  
Eric N. Powell
Keyword(s):  
Continental Slope ◽  
Fossil Record ◽  
Shell Beds ◽  
Petroleum Seep

scholarly journals Time averaging and temporal persistence in chemoautotrophic molluscan-dominated death assemblages on the Louisiana continental slope

1992 ◽  
Vol 6 ◽  
pp. 49-49
Author(s):  
W. Russell Callender ◽  
Eric N. Powell
Keyword(s):  
Continental Slope ◽  
Amino Acid Content ◽  
Local Variation ◽  
Cold Seep ◽  
Time Averaging ◽  
Time Since Death ◽  
Sample Collection ◽  
Death Assemblages ◽  
Mussel Shells ◽  
Petroleum Seep

Petroleum seeps on the Louisiana continental slope produce luxurious communities based on chemoautotrophic symbiotic bacteria. Petroleum seeps are typical cold seep communities and generate classic autochthonous death assemblages. Fossil cold seep communities are well-known, common and widespread. Most fossil analogues are dominated by lucinids, but petroleum seeps are not. A combination of sample collection and in situ experimentation has been used to determine rates of taphonomy and time averaging in petroleum seep assemblages.Cores were obtained and sectioned from seep sites in Green Canyon lease blocks 272, 234, and 184 and Garden Banks lease block 386. Lucinids and thyasirids were selected for dating time-since-death to determine the importance of time averaging in these assemblages. Dating was accomplished by measuring the free amino acid content of the shells. Time-since-death became progressively older with depth; accordingly little time averaging had occurred in these autochthonous assemblages. Lucind and mussel shells were placed on the sea floor and recovered 3 yr later. Comparison of each species to the controls left on a laboratory shelf for 3 yr shows that taphonomic alteration was rapid. Mussels were more severely altered than lucinids. Mussels were more heavily dissolved, had more altered edges, were more prone to fragmentation and exhibited greater weight loss than lucinids. The rapid taphonomic loss of the mussels suggests that the preponderance of lucinids in the fossil record is an artifact of preservation. Taphofacies analysis suggests the same; thus verifying an important assumption of taphofacies analysis that taphonomic signatures record biases in preservation by identifying inter-species differences in the rates of important taphonomic processes. Significant variability in taphonomic rates exists between shells from locations 10 m apart indicating significant local variation in the taphonomic process. Local variability in taphonomic and community attributes is characteristic of many autochthonous assemblages.

Molecular clock tied to fossil record

Nature ◽  
2004 ◽  
Author(s):  
Emma Marris
Keyword(s):  
Molecular Clock ◽  
Fossil Record

Darwin's two competing phylogenetic trees: marsupials as ancestors or sister taxa?

2012 ◽  
Vol 39 (2) ◽  
pp. 217-233 ◽  
Author(s):  
J. David Archibald
Keyword(s):  
Fossil Record ◽  
Evolutionary Biology ◽  
Phylogenetic Trees ◽  
Charles Darwin ◽  
The Other ◽  
Charles Lyell ◽  
Single Origin ◽  
Molecular Studies ◽  
Richard Owen ◽  
First Time

Studies of the origin and diversification of major groups of plants and animals are contentious topics in current evolutionary biology. This includes the study of the timing and relationships of the two major clades of extant mammals – marsupials and placentals. Molecular studies concerned with marsupial and placental origin and diversification can be at odds with the fossil record. Such studies are, however, not a recent phenomenon. Over 150 years ago Charles Darwin weighed two alternative views on the origin of marsupials and placentals. Less than a year after the publication of On the origin of species, Darwin outlined these in a letter to Charles Lyell dated 23 September 1860. The letter concluded with two competing phylogenetic diagrams. One showed marsupials as ancestral to both living marsupials and placentals, whereas the other showed a non-marsupial, non-placental as being ancestral to both living marsupials and placentals. These two diagrams are published here for the first time. These are the only such competing phylogenetic diagrams that Darwin is known to have produced. In addition to examining the question of mammalian origins in this letter and in other manuscript notes discussed here, Darwin confronted the broader issue as to whether major groups of animals had a single origin (monophyly) or were the result of “continuous creation” as advocated for some groups by Richard Owen. Charles Lyell had held similar views to those of Owen, but it is clear from correspondence with Darwin that he was beginning to accept the idea of monophyly of major groups.

The fossil record of Sternorrhyncha

2016 ◽  
Author(s):  
Bo Wang
Keyword(s):  
Fossil Record

Analysis of trace metals in bottom sediments in support of deep water biological processes studies on the U.S. North Atlantic continental slope and rise

1987 ◽  
Author(s):  
Michael H. Bothner ◽  
E.Y. Campbell ◽  
C.M. Parmenter ◽  
W. Dangelo ◽  
G.P. DiLisio ◽  
...  
Keyword(s):  
Trace Metals ◽  
Continental Slope ◽  
Bottom Sediments ◽  
North Atlantic ◽  
Deep Water ◽  
Biological Processes ◽  
The U.S

Preliminary lithostratigraphy of piston cores from the Beaufort Sea continental slope off northeastern Alaska

1991 ◽  
Author(s):  
R.L. Phillips ◽  
Arthur Grantz ◽  
M.W. Mullen ◽  
J.M. White
Keyword(s):  
Continental Slope ◽  
Beaufort Sea
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