scholarly journals The fossil record of ichthyosaurs, completeness metrics and sampling biases

Palaeontology ◽  
2015 ◽  
Vol 58 (3) ◽  
pp. 521-536 ◽  
Author(s):  
Terri J. Cleary ◽  
Benjamin C. Moon ◽  
Alexander M. Dunhill ◽  
Michael J. Benton
Keyword(s):  
Fossil Record ◽  
Sampling Biases

scholarly journals Sea level, dinosaur diversity and sampling biases: investigating the ‘common cause’ hypothesis in the terrestrial realm

2010 ◽  
Vol 278 (1709) ◽  
pp. 1165-1170 ◽  
Author(s):  
Richard J. Butler ◽  
Roger B. J. Benson ◽  
Matthew T. Carrano ◽  
Philip D. Mannion ◽  
Paul Upchurch
Keyword(s):  
Sea Level ◽  
Fossil Record ◽  
Common Factor ◽  
Alternative View ◽  
Data Series ◽  
Short Term ◽  
Common Cause ◽  
Diversity Sampling ◽  
The Common ◽  
Sampling Biases

The fossil record is our primary window onto the diversification of ancient life, but there are widespread concerns that sampling biases may distort observed palaeodiversity counts. Such concerns have been reinforced by numerous studies that found correlations between measures of sampling intensity and observed diversity. However, correlation does not necessarily mean that sampling controls observed diversity: an alternative view is that both sampling and diversity may be driven by some common factor (e.g. variation in continental flooding driven by sea level). The latter is known as the ‘common cause’ hypothesis. Here, we present quantitative analyses of the relationships between dinosaur diversity, sampling of the dinosaur fossil record, and changes in continental flooding and sea level, providing new insights into terrestrial common cause. Although raw data show significant correlations between continental flooding/sea level and both observed diversity and sampling, these correlations do not survive detrending or removal of short-term autocorrelation. By contrast, the strong correlation between diversity and sampling is robust to various data transformations. Correlations between continental flooding/sea level and taxic diversity/sampling result from a shared upward trend in all data series, and short-term changes in continental flooding/sea level and diversity/sampling do not correlate. The hypothesis that global dinosaur diversity is tied to sea-level fluctuations is poorly supported, and terrestrial common cause is unsubstantiated as currently conceived. Instead, we consider variation in sampling to be the preferred null hypothesis for short-term diversity variation in the Mesozoic terrestrial realm.

scholarly journals A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record

2020 ◽  
Vol 16 (11) ◽  
pp. 20200631 ◽  
Author(s):  
Ben T. Kligman ◽  
Adam D. Marsh ◽  
Hans-Dieter Sues ◽  
Christian A. Sidor
Keyword(s):  
North Carolina ◽  
North America ◽  
Fossil Record ◽  
Upper Triassic ◽  
American Southwest ◽  
Biogeographic Pattern ◽  
Early Mesozoic ◽  
Chinle Formation ◽  
Sampling Biases ◽  
Shed Light

The Upper Triassic tetrapod fossil record of North America features a pronounced discrepancy between the assemblages of present-day Virginia and North Carolina relative to those of the American Southwest. While both are typified by large-bodied archosaurian reptiles like phytosaurs and aetosaurs, the latter notably lacks substantial representation of mammal relatives, including cynodonts. Recently collected non-mammalian eucynodontian jaws from the middle Norian Blue Mesa Member of the Chinle Formation in northeastern Arizona shed light on the Triassic cynodont record from western equatorial Pangaea. Importantly, they reveal new biogeographic connections to eastern equatorial Pangaea as well as southern portions of the supercontinent. This discovery indicates that the faunal dissimilarity previously recognized between the western and eastern portions of equatorial Pangaea is overstated and possibly reflects longstanding sampling biases, rather than a true biogeographic pattern.

scholarly journals Colonial history and global economics distort our understanding of deep-time biodiversity

2021 ◽  
Author(s):  
Nussaïbah Raja ◽  
Emma Dunne ◽  
Aviwe Matiwane ◽  
Tasnuva Ming Khan ◽  
Paulina Nätscher ◽  
...  
Keyword(s):  
Fossil Record ◽  
Research Output ◽  
Political Stability ◽  
Colonial History ◽  
Deep Time ◽  
Middle Income ◽  
Middle Income Countries ◽  
Global Power ◽  
Sampling Biases ◽  
Socio Economic Factors

Sampling variations in the fossil record distort estimates of past biodiversity. However, compilations of global fossil occurrences used in these analyses not only reflect the geological and spatial aspects of the fossil record, but also the historical collation of these data. Here, we demonstrate how the legacy of colonialism as well as socio-economic factors such as wealth, education and political stability impact research output in paleontology. Re- searchers in high or upper middle income countries contribute to 97% of fossil occurrence data, not only leading to spatial sampling biases but also generating a global power imbalance within the discipline. This work illustrates that our efforts to mitigate the effects of sampling biases to obtain a truly representative view of past biodiversity are not disconnected from the aim of diversifying our field.

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 FIRST APPEARANCE OF CONTROLLED EUKARYOTIC BIOMINERALIZATION IN THE NEOPROTEROZOIC FOSSIL RECORD

2016 ◽  
Author(s):  
Phoebe Cohen ◽  
◽  
Justin V. Strauss ◽  
Alan D. Rooney ◽  
Mukul Sharma ◽  
...  
Keyword(s):  
Fossil Record
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