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

scholarly journals Body-size structure of Central Iberian mammal fauna reveals semidesertic conditions during the middle Miocene Global Cooling Event

PLoS ONE ◽  
2017 ◽  
Vol 12 (10) ◽  
pp. e0186762 ◽  
Author(s):  
Iris Menéndez ◽  
Ana R. Gómez Cano ◽  
Blanca A. García Yelo ◽  
Laura Domingo ◽  
M. Soledad Domingo ◽  
...  
Keyword(s):  
Body Size ◽  
Middle Miocene ◽  
Size Structure ◽  
Mammal Fauna ◽  
Global Cooling

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

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 Correction: Body-size structure of Central Iberian mammal fauna reveals semidesertic conditions during the middle Miocene Global Cooling Event

PLoS ONE ◽  
2018 ◽  
Vol 13 (8) ◽  
pp. e0202612
Author(s):  
Iris Menéndez ◽  
Ana R. Gómez Cano ◽  
Blanca A. García Yelo ◽  
Laura Domingo ◽  
M. Soledad Domingo ◽  
...  
Keyword(s):  
Body Size ◽  
Middle Miocene ◽  
Size Structure ◽  
Mammal Fauna ◽  
Global Cooling

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 Scaling of growth rate and mortality with size and its consequence on size spectra of natural microphytoplankton assemblages in the East China Sea

2013 ◽  
Vol 10 (8) ◽  
pp. 5267-5280 ◽  
Author(s):  
F. H. Chang ◽  
E. C. Marquis ◽  
C. W. Chang ◽  
G. C. Gong ◽  
C. H. Hsieh
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Growth Rates ◽  
Specific Growth ◽  
Size Structure ◽  
Scaling Exponent ◽  
The East China Sea ◽  
Size Category ◽  
Grazing Mortality ◽  
Specific Growth Rates

Abstract. Allometric scaling of body size versus growth rate and mortality has been suggested to be a universal macroecological pattern, as described by the metabolic theory of ecology (MTE). However, whether such scaling generally holds in natural assemblages remains debated. Here, we test the hypothesis that the size-specific growth rate and grazing mortality scale with the body size with an exponent of −1/4 after temperature correction, as MTE predicts. To do so, we couple a dilution experiment with the FlowCAM imaging system to obtain size-specific growth rates and grazing mortality of natural microphytoplankton assemblages in the East China Sea. This novel approach allows us to achieve highly resolved size-specific measurements that would be very difficult to obtain in traditional size-fractionated measurements using filters. Our results do not support the MTE prediction. On average, the size-specific growth rates and grazing mortality scale almost isometrically with body size (with scaling exponent ∼0.1). However, this finding contains high uncertainty, as the size-scaling exponent varies substantially among assemblages. The fact that size-scaling exponent varies among assemblages prompts us to further investigate how the variation of size-specific growth rate and grazing mortality can interact to determine the microphytoplankton size structure, described by normalized biomass size spectrum (NBSS), among assemblages. We test whether the variation of microphytoplankton NBSS slopes is determined by (1) differential grazing mortality of small versus large individuals, (2) differential growth rate of small versus large individuals, or (3) combinations of these scenarios. Our results indicate that the ratio of the grazing mortality of the large size category to that of the small size category best explains the variation of NBSS slopes across environments, suggesting that higher grazing mortality of large microphytoplankton may release the small phytoplankton from grazing, which in turn leads to a steeper NBSS slope. This study contributes to understanding the relative importance of bottom-up versus top-down control in shaping microphytoplankton size structure.

scholarly journals Resurgence of an apex marine predator and the decline in prey body size

2019 ◽  
Vol 116 (52) ◽  
pp. 26682-26689 ◽  
Author(s):  
Jan Ohlberger ◽  
Daniel E. Schindler ◽  
Eric J. Ward ◽  
Timothy E. Walsworth ◽  
Timothy E. Essington
Keyword(s):  
Life History ◽  
Body Size ◽  
Chinook Salmon ◽  
Marine Mammal ◽  
Marine Mammals ◽  
Size Structure ◽  
Economic Value ◽  
Killer Whales ◽  
Selective Predation ◽  
Marine Predator

In light of recent recoveries of marine mammal populations worldwide and heightened concern about their impacts on marine food webs and global fisheries, it has become increasingly important to understand the potential impacts of large marine mammal predators on prey populations and their life-history traits. In coastal waters of the northeast Pacific Ocean, marine mammals have increased in abundance over the past 40 to 50 y, including fish-eating killer whales that feed primarily on Chinook salmon. Chinook salmon, a species of high cultural and economic value, have exhibited marked declines in average size and age throughout most of their North American range. This raises the question of whether size-selective predation by marine mammals is generating these trends in life-history characteristics. Here we show that increased predation since the 1970s, but not fishery selection alone, can explain the changes in age and size structure observed for Chinook salmon populations along the west coast of North America. Simulations suggest that the decline in mean size results from the selective removal of large fish and an evolutionary shift toward faster growth and earlier maturation caused by selection. Our conclusion that intensifying predation by fish-eating killer whales contributes to the continuing decline in Chinook salmon body size points to conflicting management and conservation objectives for these two iconic species.

scholarly journals Evidence for benthic body size miniaturization in the deep sea

2006 ◽  
Vol 86 (6) ◽  
pp. 1339-1345 ◽  
Author(s):  
Janne I. Kaariainen ◽  
Brian J. Bett
Keyword(s):  
Body Size ◽  
Deep Sea ◽  
Size Structure ◽  
Size Class ◽  
The Body ◽  
Significant Shift ◽  
Individual Biomass ◽  
Wet Weight ◽  
Accumulation Curves ◽  
Average Individual

The benthic body size miniaturization hypothesis states that deep-sea communities are dominated by organisms of smaller body size, although some field studies have produced contradictory results. Using appropriate sample sets, this study tests this hypothesis by contrasting the benthic communities of the Fladen Ground (North Sea, 150 m) and the Faroe–Shetland Channel (1600 m). Samples were collected for large (500 μm) and small macrofauna (250–355 μm), meiofauna (45 μm) as well as an intermediate sized ‘mesofauna’ (180 μm) to ensure comprehensive coverage of the full meio- and macro-faunal body size-range. The body size structure of the benthos was compared using two methods. The more widely used average individual biomass method involves dividing the total sample biomass by sample abundance. Additionally, body size accumulation curves were constructed by assigning all specimens into a logarithmic size-class and then plotting the cumulative percentage of individuals present in each size-class. The results seem to support the hypothesis that the deep-sea environment is a small organism habitat. Although these findings only represent two locations, the overall body size accumulation curves clearly display a statistically significant shift towards smaller body sizes at the deeper site. The magnitude of the effect is appreciable with median metazoan body size reducing from 14.3 μg wet weight in the Fladen Ground to 3.8 μg wet weight in the Faroe–Shetland Channel. The average individual biomass measurements are shown to be of limited value and can lead to potentially misleading conclusions if the underlying size structure is not analysed in detail.

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