Morphological Disparity of Ammonoids and the Mark of Permian Mass Extinctions

  title={Morphological Disparity of Ammonoids and the Mark of Permian Mass Extinctions},
  author={Loïc Villier and Dieter Korn},
  pages={264 - 266}
The taxonomic diversity of ammonoids, in terms of the number of taxa preserved, provides an incomplete picture of the extinction pattern during the Permian because of a strongly biased fossil record. The analysis of morphological disparity (the variety of shell shapes) is a powerful complementary tool for testing hypotheses about the selectivity of extinction and permits the recognition of three distinct patterns. First, a trend of decreasing disparity, ranging for about 30 million years, led… 
Taxonomic Diversity and Morphological Disparity of Paleozoic Ammonoids
The Ammonoidea are well represented in terms of numbers of species over a large range of time and they have survived many extinction events. The time interval from the Early Devonian through to the
Permian-Triassic Extinctions and Rediversifications
Ammonoids were a major component of Permian marine faunas, but were on the verge of extinction during the Permian-Triassic crisis ~ 252 myr ago. Despite the severity of this extinction, their
Ammonoid recovery after the Permian–Triassic mass extinction: a re-exploration of morphological and phylogenetic diversity patterns
The explosive ammonoid rediversification after the Permian–Triassic mass extinction is now well understood in terms of taxonomic richness and biogeography. Using an updated dataset of Early Triassic
Abstract:  The rapid diversification of ceratitid ammonoids during the earliest Mesozoic has been taken at face value as an example of explosive radiation following the Permian/Triassic mass
Species richness and disparity of parareptiles across the end-Permian mass extinction
This study investigates both the species richness and morphological diversity (disparity) of parareptiles over the course of their history and examines the observations in the context of other metazoan clades, in order to identify post-extinction survivorship patterns that are present in the Parareptilia clade.
Disparity fluctuations in Jurassic ammonoids by means of conch geometry
Evolutionary Trends of Triassic Ammonoids
It seems that taxonomic diversity and morphological disparity of Triassic ammonoids are uncoupled, at least during part of the Early Triassic recovery.
Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids
The results highlight three main aspects of adaptive radiations: diversity and disparity are generally decoupled; models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.
Morphologic and taxonomic history of Paleozoic ammonoids in time and morphospace
Although mass extinction events severely condensed the range of morphologic variation and taxonomic diversity, the effects were short lived and most extinct morphotypes were usually iterated within 5 Myr, and Intervals between mass extinctions seem to have been relatively static in terms of morphotype numbers, in contrast to numbers of genera.
The complex effects of mass extinctions on morphological disparity
It is found that morphological change over mass extinction is best studied by quantifying multiple aspects of morphospace occupation, and support for phylogenetic comparative methods away from the simulated Brownian motion toward Ornstein‐Uhlenbeck and Early Burst models is found.


Determinants of extinction in the fossil record
A new compilation of the amount of exposed marine sedimentary rock is used to predict how the observed fossil record of extinction would appear if the time series of true extinction rates were in fact smooth, and supports the hypothesis that much of the observed short-term volatility in extinction rates is an artefact of variability in the stratigraphic record.
A Double Mass Extinction at the End of the Paleozoic Era
Three tests based on fossil data indicate that high rates of extinction recorded in the penultimate (Guadalupian) stage of the Paleozoic era are not artifacts of a poor fossil record. Instead, they
Selective extinction among Early Jurassic bivalves: A consequence of anoxia
Analyses of taxonomically standardized data sets demonstrate several statistically robust extinction patterns in Early Jurassic bivalve species from northwest Europe and the Andean basins of South
Selectivity of extinction among sea urchins at the end of the Cretaceous period
A global analysis of a major marine invertebrate group, the sea urchins, indicates that nutrient supply was a crucial factor in driving K/T-boundary extinctions, with selection more strongly focused on benthic adult than on larval planktotrophic stages.
Measuring changes in articulate brachiopod morphology before and after the Permian mass extinction event: do developmental constraints limit morphological innovation?
  • C. Ciampaglio
  • Geography, Environmental Science
    Evolution & development
  • 2004
The results indicate that developmental constraints may not be responsible for the decreasing disparity in this group, and the more likely scenario is that increasingly structured ecological guilds have made it much more difficult for large increases in disparity to occur.
Evolution of Complexity in Paleozoic Ammonoid Sutures.
The septal sutures of 588 genera of Paleozoic ammonoids showed a 1600 percent increase in mean complexity over 140 million years, compatible with an active or driven system of long-term bias for increased complexity.
The evolutionary history of shell geometry in Paleozoic ammonoids
Abstract Tracking the geometry of all 597 ammonoid genera from the Lower Devonian into the Lower Triassic, a 145-Myr period that spans three mass extinctions, shows that Paleozoic ammonoid shell
Biodiversity in the Phanerozoic: a reinterpretation
Abstract Many features of global diversity compilations have proven robust to continued sampling and taxonomic revision. Inherent biases in the stratigraphic record may nevertheless substantially
Background and Mass Extinctions: The Alternation of Macroevolutionary Regimes
Comparison of evolutionary patterns among Late Cretaceous marine bivalves and gastropods during times of normal, background levels of extinction and during the end-Cretaceous mass extinction
Survival without recovery after mass extinctions
  • D. Jablonski
  • Geography, Environmental Science
    Proceedings of the National Academy of Sciences of the United States of America
  • 2002
Dead Clade Walking patterns are not evenly distributed among four regional molluscan time-series following the end-Cretaceous extinction, demonstrating the importance of spatial patterns in recovery dynamics.