Mammals across the K/Pg boundary in northeastern Montana, U.S.A.: dental morphology and body-size patterns reveal extinction selectivity and immigrant-fueled ecospace filling

Paleobiology ◽  
10.1666/12041 ◽  
2013 ◽  
Vol 39 (3) ◽  
pp. 429-469 ◽  
Author(s):  
Gregory P. Wilson
Keyword(s):  
Body Size ◽  
Size Structure ◽  
Morphological Diversity ◽  
Dental Morphology ◽  
Continental Scale ◽  
Size Disparity ◽  
Mammalian Faunas ◽  
Body Sizes ◽  
Extinction Selectivity ◽  
Spatiotemporal Scales

The Cretaceous/Tertiary (K/Pg) mass extinction has long been viewed as a pivotal event in mammalian evolutionary history, in which the extinction of non-avian dinosaurs allowed mammals to rapidly expand from small-bodied, generalized insectivores to a wide array of body sizes and ecological specializations. Many studies have used global- or continental-scale taxonomic databases to analyze this event on coarse temporal scales, but few studies have documented morphological diversity of mammalian paleocommunities on fine spatiotemporal scales in order to examine ecomorphological selectivity and ecospace filling across this critical transition. Focusing on well-sampled and temporally well-constrained mammalian faunas across the K/Pg boundary in northeastern Montana, I quantified dental-shape disparity and morphospace occupancy via landmark- and semilandmark-based geometric morphometrics and mean body size, body-size disparity, and body-size structure via body-mass estimates.My results reveal several key findings: (1) latest Cretaceous mammals, particularly metatherians and multituberculates, had a greater ecomorphological diversity than is generally appreciated, occupying regions of the morphospace that are interpreted as strict carnivory, plant-dominated omnivory, and herbivory; (2) the decline in dental-shape disparity and body-size disparity across the K/Pg boundary shows a pattern of constructive extinction selectivity against larger-bodied dietary specialists, particularly strict carnivores and taxa with plant-based diets, that suggests the kill mechanism was related to depressed primary productivity rather than a globally instantaneous event; (3) the ecomorphological recovery in the earliest Paleocene was fueled by immigrants, namely three multituberculate families (taeniolabidids, microcosmodontids, eucosmodontids) and to a lesser extent archaic ungulates; and (4) despite immediate increases in the taxonomic richness of eutherians, their much-celebrated post-K/Pg ecomorphological expansion had a slower start than is generally perceived and most likely only began 400,000 to 1 million years after the extinction event.

scholarly journals Palaeoenvironmental analysis of the Aragonian (middle Miocene) mammalian faunas from the Madrid Basin based on body-size structure

2014 ◽  
Vol 40 (1) ◽  
Author(s):  
B.A. García Yelo ◽  
A.R. Gómez Cano ◽  
J.L. Cantalapiedra ◽  
G.M. Alcalde ◽  
O. Sanisidro ◽  
...  
Keyword(s):  
Body Size ◽  
Middle Miocene ◽  
Size Structure ◽  
Mammalian Faunas

Comparative paleoecology of Paleogene and Neogene mammalian faunas: body-size structure

1995 ◽  
Vol 115 (1-4) ◽  
pp. 287-317 ◽  
Author(s):  
Michele E. Morgan ◽  
Catherine Badgley ◽  
Gregg F. Gunnell ◽  
Philip D. Gingerich ◽  
John W. Kappelman ◽  
...  
Keyword(s):  
Body Size ◽  
Size Structure ◽  
Mammalian Faunas

scholarly journals Evolution of body size in Crocodylomorpha in a multi-regime evolutionary landscape

2017 ◽  
Author(s):  
Pedro L Godoy ◽  
Roger B J Benson ◽  
Mario Bronzati ◽  
Richard J Butler
Keyword(s):  
Body Size ◽  
Body Length ◽  
Regime Shifts ◽  
Surface Model ◽  
Time Calibration ◽  
Calibration Methods ◽  
Size Disparity ◽  
Body Sizes ◽  
Tree Topologies ◽  
Length Data

Body size is strongly related to physiology and ecology, and its evolution has been studied intensely for many animal groups. Crocodylomorphs occupy the intermediate–large range of body sizes among extant tetrapods, and have a rich and diverse fossil record, ranging in size from less than 30 centimetres to over 10 metres in length. To investigate crocodylomorph body size evolution, we used maximum-likelihood to fit macroevolutionary models to body length data within a phylogenetic context. We focused on non-uniform Ornstein-Uhlenbeck (OU) models (“SURFACE” model). Under an OU process, lineages are attracted towards an adaptive trait optimum (theta, θ) through time. SURFACE allows multiple adaptive regimes (i.e. shifts in trait optima). We also fitted other models, and conducted analyses using alternate body length proxies, tree topologies and time-calibration methods, to assess the influence of analytical choices on results. The SURFACE model fit best to our data, suggesting convergent evolution of body size among macroevolutionary adaptive zones. Although different trees identify regime shifts in phylogenetically distinct positions, we recognized some shared patterns. For instance, non-Mesoeucrocodylia crocodylomorphs maintained relatively small sizes (θ = 0.646 m), and experienced no or few shifts, thriving until the Late Cretaceous. During the Late Jurassic and Cretaceous, crocodylomorph body size disparity increased, with a high number of regime shifts, particularly within Notosuchia and Thalattosuchia. Another important regime shift, towards larger body sizes (θ = 5.561 m), occurred in the lineage leading to extant crocodylians (Eusuchia), potentially related to an adaptive radiation of the group after the Cretaceous-Paleogene extinction.

scholarly journals Geohistorical records indicate no impact of the Deepwater Horizon oil spill on oyster body size

2016 ◽  
Vol 3 (11) ◽  
pp. 160763 ◽  
Author(s):  
Gregory P. Dietl ◽  
Stephen R. Durham
Keyword(s):  
Body Size ◽  
Oil Spill ◽  
Impact Analysis ◽  
Size Structure ◽  
Eastern Oyster ◽  
Deepwater Horizon ◽  
Long Term Effects ◽  
Before And After ◽  
Body Sizes ◽  
Average Body

Documentation of the near- and long-term effects of the Deepwater Horizon (DWH) oil spill, one of the largest environmental disasters in US history, is still ongoing. We used a novel before-after-control-impact analysis to test the hypothesis that average body size of intertidal populations of the eastern oyster ( Crassostrea virginica ) inhabiting impacted areas in Louisiana decreased due to increased stress/mortality related to the oil spill. Time-averaged death assemblages of oysters were used to establish a pre-spill baseline of body-size structure for four impacted and four control locations along a 350 km stretch of Louisiana's coastline. Post-spill body sizes were then measured from live oysters at each site in order to evaluate the differences in body size between oiled (i.e. impact) and unoiled (i.e. control) locations before and after the spill. Our results indicate that average body size of oysters remained relatively unchanged after the oil spill. There were also no temporal patterns in temperature, salinity or disease prevalence that could have explained our results. Together, these findings suggest that oysters either recovered rapidly following the immediate impact of the DWH oil spill, or that its impact was not severe enough to influence short-term population dynamics of the oyster beds.

scholarly journals Evolution of body size in Crocodylomorpha in a multi-regime evolutionary landscape

2017 ◽  
Author(s):  
Pedro L Godoy ◽  
Roger B J Benson ◽  
Mario Bronzati ◽  
Richard J Butler
Keyword(s):  
Body Size ◽  
Body Length ◽  
Regime Shifts ◽  
Surface Model ◽  
Time Calibration ◽  
Calibration Methods ◽  
Size Disparity ◽  
Body Sizes ◽  
Tree Topologies ◽  
Length Data

Body size is strongly related to physiology and ecology, and its evolution has been studied intensely for many animal groups. Crocodylomorphs occupy the intermediate–large range of body sizes among extant tetrapods, and have a rich and diverse fossil record, ranging in size from less than 30 centimetres to over 10 metres in length. To investigate crocodylomorph body size evolution, we used maximum-likelihood to fit macroevolutionary models to body length data within a phylogenetic context. We focused on non-uniform Ornstein-Uhlenbeck (OU) models (“SURFACE” model). Under an OU process, lineages are attracted towards an adaptive trait optimum (theta, θ) through time. SURFACE allows multiple adaptive regimes (i.e. shifts in trait optima). We also fitted other models, and conducted analyses using alternate body length proxies, tree topologies and time-calibration methods, to assess the influence of analytical choices on results. The SURFACE model fit best to our data, suggesting convergent evolution of body size among macroevolutionary adaptive zones. Although different trees identify regime shifts in phylogenetically distinct positions, we recognized some shared patterns. For instance, non-Mesoeucrocodylia crocodylomorphs maintained relatively small sizes (θ = 0.646 m), and experienced no or few shifts, thriving until the Late Cretaceous. During the Late Jurassic and Cretaceous, crocodylomorph body size disparity increased, with a high number of regime shifts, particularly within Notosuchia and Thalattosuchia. Another important regime shift, towards larger body sizes (θ = 5.561 m), occurred in the lineage leading to extant crocodylians (Eusuchia), potentially related to an adaptive radiation of the group after the Cretaceous-Paleogene extinction.

scholarly journals The multi-peak adaptive landscape of crocodylomorph body size evolution

2018 ◽  
Author(s):  
Pedro L. Godoy ◽  
Roger B. J. Benson ◽  
Mario Bronzati ◽  
Richard J. Butler
Keyword(s):  
Body Size ◽  
Abiotic Factors ◽  
Large Body ◽  
Size Increase ◽  
Adaptive Landscape ◽  
Evolutionary Trend ◽  
Size Evolution ◽  
Size Disparity ◽  
Body Sizes ◽  
Body Size Evolution

AbstractBackgroundLittle is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller (< 1.2 m). This suggests a pattern of size increase through time that could be caused by multi-lineage evolutionary trends of size increase or by selective extinction of small-bodied species. In this study, we characterise patterns of crocodylomorph body size evolution using a model fitting-approach (with cranial measurements serving as proxies). We also estimate body size disparity through time and quantitatively test hypotheses of biotic and abiotic factors as potential drivers of crocodylomorph body size evolution.ResultsCrocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent essentially continually decreases in disparity since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions.ConclusionsShifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution than do climatic factors, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.

scholarly journals A simple generative model of trilobite segmentation and growth

2019 ◽  
Author(s):  
Melanie J Hopkins
Keyword(s):  
Body Size ◽  
Growth Rates ◽  
Growth Models ◽  
Morphological Diversity ◽  
Generative Model ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Differential Growth ◽  
Body Regions ◽  
Body Sizes

Generative growth models have been the basis for numerous studies of morphological diversity and evolution. Most work has focused on modeling accretionary growth systems, with much less attention to discrete growth systems. Generative growth models for molting organisms, such as arthropods, have remained particularly elusive. However, our understanding of post-embryonic growth in trilobite species is sufficiently mature that it is now possible to model growth in a way that incorporates the addition of new parts as well as differential growth rates for existing parts across the trilobite body plan. Furthermore, body size data for a large sample of specimens of the trilobite species Aulacopleura koninckii (Barrande, 1846) make it possible to generate robust estimates for model parameters. Although the generative model described here was based on a relatively simple segmentation schedule, a diverse array of observed body sizes and relative proportions of body regions can be attained by altering only a few parameters at a time. Notably, small changes in growth rates can have large effects on body size (e.g. an increase of 4% increases body size by 350%). Subsampling of the empirical dataset indicates that parameters describing the growth gradient in the trunk are more sensitive to sample size than input parameters. Increasing the number of stages represented improves parameter estimates more quickly than increasing number of specimens per stage.

Body size structure in north-western Mediterranean Plio-Pleistocene mammalian faunas

2004 ◽  
Vol 13 (2) ◽  
pp. 163-176 ◽  
Author(s):  
Jesús Rodríguez ◽  
María T. Alberdi ◽  
Beatriz Azanza ◽  
José L. Prado
Keyword(s):  
Body Size ◽  
Size Structure ◽  
Western Mediterranean ◽  
Mammalian Faunas ◽  
North Western

Allometry and Paleoecology of Medial Miocene Dwarf Rhinoceroses from the Texas Gulf Coastal Plain

Paleobiology ◽  
1982 ◽  
Vol 8 (1) ◽  
pp. 16-30 ◽  
Author(s):  
Donald R. Prothero ◽  
Paul C. Sereno
Keyword(s):  
Body Size ◽  
Coastal Plain ◽  
Sympatric Species ◽  
High Plains ◽  
Gulf Coastal Plain ◽  
Canine Tooth ◽  
Positive Allometry ◽  
Mammalian Faunas ◽  
The Common ◽  
Limb Proportions

Barstovian (medial Miocene) mammalian faunas from the Texas Gulf Coastal Plain contained four apparently sympatric species of rhinoceroses: the common forms Aphelops megalodus and Teleoceras medicornutus, a dwarf Teleoceras, and a dwarf Peraceras. Previous work has suggested positive allometry in tooth area with respect to body size in several groups of mammals, i.e., larger mammals have relatively more tooth area. However, dwarfing lineages were shown to have relatively more tooth area for their body size. Our data show no significant allometry in post-canine tooth area of either artiodactyls or ceratomorphs. Similarly, dwarf rhinoceroses and hippopotami show no more tooth area than would be predicted for their size. Limbs are proportionately longer and more robust in larger living ceratomorphs (rhinos and tapirs) than predicted by previous authors. Limb proportions of both dwarf rhinoceroses and dwarf hippopotami are even more robust than in their living relatives.The high rhinoceros diversity reflects the overall high diversity of Barstovian faunas from the Texas Gulf Coastal Plain. The first appearance of several High Plains mammals in these faunas indicates “ecotone”-like conditions as faunal composition changed. Study of living continental dwarfs shows that there is commonly an ecological separation between browsing forest dwarfs and their larger forebears, which are frequently savannah grazers. This suggests that the dwarf rhinoceroses might have been forest browsers which were sympatric with the larger grazing rhinos of the High Plains during the Barstovian invasion. The continental dwarf model also suggests that insular dwarfism may be explained by the browsing food resources that predominate on islands.

scholarly journals A Farewell to the Encephalization Quotient: A New Brain Size Measure for Comparative Primate Cognition

2021 ◽  
pp. 1-12
Author(s):  
Carel P. van Schaik ◽  
Zegni Triki ◽  
Redouan Bshary ◽  
Sandra A. Heldstab
Keyword(s):  
Body Size ◽  
Cognitive Abilities ◽  
Brain Size ◽  
Estimation Error ◽  
Primate Species ◽  
Mammal Species ◽  
Mean Values ◽  
Encephalization Quotient ◽  
Body Sizes ◽  
Size Measure

Both absolute and relative brain sizes vary greatly among and within the major vertebrate lineages. Scientists have long debated how larger brains in primates and hominins translate into greater cognitive performance, and in particular how to control for the relationship between the noncognitive functions of the brain and body size. One solution to this problem is to establish the slope of cognitive equivalence, i.e., the line connecting organisms with an identical bauplan but different body sizes. The original approach to estimate this slope through intraspecific regressions was abandoned after it became clear that it generated slopes that were too low by an unknown margin due to estimation error. Here, we revisit this method. We control for the error problem by focusing on highly dimorphic primate species with large sample sizes and fitting a line through the mean values for adult females and males. We obtain the best estimate for the slope of circa 0.27, a value much lower than those constructed using all mammal species and close to the value expected based on the genetic correlation between brain size and body size. We also find that the estimate of cognitive brain size based on cognitive equivalence fits empirical cognitive studies better than the encephalization quotient, which should therefore be avoided in future studies on primates and presumably mammals and birds in general. The use of residuals from the line of cognitive equivalence may change conclusions concerning the cognitive abilities of extant and extinct primate species, including hominins.

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