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List of Species and their Body Masses in Genera Shared between Contemporaneous (either Middle Hemphillian or Latest Hemphillian) Gulf Coastal Plain and Great Plains faunas
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There is disagreement among ecologists as to whether ecosystem system behavior in general is the net result of all of the
complex internal system interactions (bottom-driven) or if the behavior is driven by a limited number of key processes (top-driven).
If ecosystems are primarily bottom-driven in nature, then it is unlikely that any two complex e...
Context in source publication
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... if many or most of these genera contain species in a relatively narrow size range then these overlaps could definitely create a bias in favor of similarity. To check for this possibility, the body masses of species in genera shared between middle and latest Hemphillian Gulf Coastal Plain and Great Plains faunas were compared ( Table 2). The intrageneric size similarity was considerable for the middle Hemphillian faunas, particularly if a 20% error factor is incorporated to compensate for body mass estimation errors. ...
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Citations
... Even though body mass estimations were not made in this work, the taxa presented here for the Jalisco fossil record have been recognized as megaherbivores in several previous publications. The body mass of Teleoceras has been estimated at 963-1139 kg (Lambert, 2006); Gomphotherium at 6682-7169 kg (Larramendi, 2015); and Megatylopus between 710 and 1336 kg (Lambert, 2006). We were unable to find references where the body mass of Rhynchotherium or Stegomastodon was estimated, except for Christiansen (2004) who reported a body mass for Stegomastodon platensis from South America of 6035 kg. ...
... Even though body mass estimations were not made in this work, the taxa presented here for the Jalisco fossil record have been recognized as megaherbivores in several previous publications. The body mass of Teleoceras has been estimated at 963-1139 kg (Lambert, 2006); Gomphotherium at 6682-7169 kg (Larramendi, 2015); and Megatylopus between 710 and 1336 kg (Lambert, 2006). We were unable to find references where the body mass of Rhynchotherium or Stegomastodon was estimated, except for Christiansen (2004) who reported a body mass for Stegomastodon platensis from South America of 6035 kg. ...
... Published body masses (BM) were used for those taxa for which estimations exist: Prosthennops serus (88 ± 26 kg; ±1σ) (Lambert, 2006), Table 1 Summary of results of carbon and oxygen isotope analyses of tooth enamel samples from Yepómera, Mexico. (Dalquest, 1992;Janis et al., 2002;Lambert, 2006), Astrohippus stockii (127 ± 38 kg; ±1σ), Dinohippus mexicanus (245 ± 74 kg; ±1σ), Nannippus aztecus (previously N. minor) (89 ± 27 kg; ±1σ), and Neohipparion eurystyle (141 ± 42 kg; ±1σ) (MacFadden, 1986;Alberdi et al., 1995;MacFadden et al., 1999;Lambert, 2006), and Stegomastodon (6030 ± 1809 kg; ±1σ) (Christiansen, 2004;Larramendi, 2015). ...
... Published body masses (BM) were used for those taxa for which estimations exist: Prosthennops serus (88 ± 26 kg; ±1σ) (Lambert, 2006), Table 1 Summary of results of carbon and oxygen isotope analyses of tooth enamel samples from Yepómera, Mexico. (Dalquest, 1992;Janis et al., 2002;Lambert, 2006), Astrohippus stockii (127 ± 38 kg; ±1σ), Dinohippus mexicanus (245 ± 74 kg; ±1σ), Nannippus aztecus (previously N. minor) (89 ± 27 kg; ±1σ), and Neohipparion eurystyle (141 ± 42 kg; ±1σ) (MacFadden, 1986;Alberdi et al., 1995;MacFadden et al., 1999;Lambert, 2006), and Stegomastodon (6030 ± 1809 kg; ±1σ) (Christiansen, 2004;Larramendi, 2015). The body mass of Agriotherium schneideri was calculated using the carnivore tooth crown area-body mass regression and measured crown area of teeth sampled (900 mm 2 ) to calculate a body mass of 510, which seems reasonable given similar estimates of other species of Agriotherium (Legendre and Roth, 1988;Sorkin, 2006). ...
... Published body masses (BM) were used for those taxa for which estimations exist: Prosthennops serus (88 ± 26 kg; ±1σ) (Lambert, 2006), Table 1 Summary of results of carbon and oxygen isotope analyses of tooth enamel samples from Yepómera, Mexico. (Dalquest, 1992;Janis et al., 2002;Lambert, 2006), Astrohippus stockii (127 ± 38 kg; ±1σ), Dinohippus mexicanus (245 ± 74 kg; ±1σ), Nannippus aztecus (previously N. minor) (89 ± 27 kg; ±1σ), and Neohipparion eurystyle (141 ± 42 kg; ±1σ) (MacFadden, 1986;Alberdi et al., 1995;MacFadden et al., 1999;Lambert, 2006), and Stegomastodon (6030 ± 1809 kg; ±1σ) (Christiansen, 2004;Larramendi, 2015). The body mass of Agriotherium schneideri was calculated using the carnivore tooth crown area-body mass regression and measured crown area of teeth sampled (900 mm 2 ) to calculate a body mass of 510, which seems reasonable given similar estimates of other species of Agriotherium (Legendre and Roth, 1988;Sorkin, 2006). ...
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... Diverging from optimal growing conditions, links in the networks weaken and disappear. This behaviour can be understood as the functional convergence of ecosystems, which corroborates the hypothesis that ecosystems have a low number of key processes that deter- mine ecosystem behaviour (Lambert, 2006;Meinzer, 2003;Shaver et al., 2007), rendering their behaviour transparent and predictable. Criticism might rise, as the larger part of the biosphereatmosphere interaction network indeed is a pure atmospheric network, i.e. ...
Understanding the dependencies of the terrestrial carbon and water cycle with meteorological conditions is a prerequisite to anticipate their behaviour under climate change conditions. However, terrestrial ecosystems and the atmosphere interact via a multitude of variables across temporal and spatial scales. Additionally these interactions might differ among vegetation types or climatic regions. Today, novel algorithms aim to disentangle the causal structure behind such interactions from empirical data. The estimated causal structures can be interpreted as networks, where nodes represent relevant meteorological variables or land-surface fluxes and the links represent the dependencies among them (possibly including time lags and link strength). Here we derived causal networks for different seasons at 119 eddy covariance flux tower observations in the FLUXNET network. We show that the networks of biosphere–atmosphere interactions are strongly shaped by meteorological conditions. For example, we find that temperate and high-latitude ecosystems during peak productivity exhibit biosphere–atmosphere interaction networks very similar to tropical forests. In times of anomalous conditions like droughts though, both ecosystems behave more like typical Mediterranean ecosystems during their dry season. Our results demonstrate that ecosystems from different climate zones or vegetation types have similar biosphere–atmosphere interactions if their meteorological conditions are similar. We anticipate our analysis to foster the use of network approaches, as they allow for a more comprehensive understanding of the state of ecosystem functioning. Long-term or even irreversible changes in network structure are rare and thus can be indicators of fundamental functional ecosystem shifts.
... However, the discontinuity hypothesis (Holling, 1992) provides a framework to quantify resilience as it explicitly accounts for the intricate organization across multiple dimensions and nonlinear behavior of ecosystems (Angeler et al., 2015a;Gunderson, 2000). This non-linear behavior is manifested in the discontinuous (scale-specific) distribution of body size across different groups of organisms and ecosystems (phytoplankton: Angeler et al., 2019;zooplankton;Baho et al., 2015;fish;Havlicek and Carpenter, 2001;mammals;Lambert, 2006;birds;Wardwell et al., 2008). ...
The use of discontinuity analysis to assess resilience and alternative regimes of ecosystems has mostly been based on animal size. We so far lack systematic comparisons of size-based and abundance-based approaches necessary for assessing the performance and suitability of the discontinuity analysis across a broader range of organism groups. We used an outdoor mesocosm setup to mimic shallow lake ecosystems with different depths (1.2 m deep, “shallow”; 2.2 m deep, “deep”) and trophic status (i.e. low and high nutrient status characteristic of mesotrophic and hypertrophic lakes, respectively). We compared resilience assessments, based on four indicators (cross-scale structure, within-scale structure, aggregation length and gap size) inferred from the size and abundance (biovolume) structure of phytoplankton communities. Our results indicate that resilience assessments based on size and biovolume were largely comparable, which is likely related to similar variability in the size and abundance of phytoplankton as a function of nutrient concentrations. Also, nutrient enrichment rather than water depth influenced resilience, manifested in decreased cross-scale structure and increased aggregation lengths and gap sizes in the high-nutrient treatment. These resilience patterns coupled with decreased phytoplankton diversity and dominance of cyanobacteria in the high nutrient treatment support the use of discontinuity analysis for testing alternative regimes theory. Concordance of size-based and abundance-based results highlights the approach as being potentially robust to infer resilience in organism groups lacking discrete size structures.
... The assembling of ecological communities takes place through the sorting of organisms with different characteristics while they strive to occupy available niches in a system (Soberón 2007). Discontinuous body size distributions are observed in many terrestrial and aquatic ecosystems, including birds (Wardwell et al. 2008), reptiles (Allen et al. 1999), mammals (Lambert 2006), and plankton and fish (Havlicek and Carpenter 2001). A few hypotheses have been formulated to explain why discontinuity occurs, which include biotic interactions (Hutchinson 1959) spanning short timescales (i.e., ecological responses) to longer timescales (including evolutionary processes; Smith et al. 2004). ...
Freshwaters are increasingly exposed to complex mixtures of pharmaceutical and personal care products (PPCPs) from municipal wastewater. PPCPs are known to alter freshwater communities’ structure and functioning, however, their interaction with other disturbances and whether their combined effects can impact ecological resilience (i.e. the ability of a system to tolerate disturbances without altering the system's original structure and processes) remain unexplored. Using in situ mesocosms in two lakes with different nutrient levels (mesotrophic and eutrophic), we assessed whether a pulse exposure to sub‐lethal concentrations of 12 PPCPs affects the ecological resilience of natural phytoplankton communities that experienced an abrupt environmental change involving the destabilization of the water column through mixing. Such mixing events are predicted to increase as the effects’ climate change unfold, leading to more frequent storms, which disrupt stratification in lakes and force communities to restructure. We assessed their combined effects on community metrics (biomass, species richness and composition) and their relative resilience using four indicators (cross‐scale, within scale, aggregation length and gap length), inferred from phytoplankton communities by discontinuity analysis. The mixing disturbance alone had negligible effects on the community metrics, but when combined with chemical contaminants significant changes were measured: reducing total biomass, species richness and altered community composition of phytoplankton. Once these changes occurred, they persisted until the end of the experiment (day 20) where the communities’ structures from the two highest exposure levels diverged from the controls. The resilience indicators were not affected by PPCPs, but differed significantly between lakes, with lower resilience found in the eutrophic lake. PPCPs can significantly alter community structures and reinforce mechanisms that maintain ecosystems in a “degraded state”. This article is protected by copyright. All rights reserved.
... Because environments select organisms on the basis of their adaptations, and these are expressed simultaneously in their morphology, physiology and ecology, then different assemblages of species inhabiting similar environments should also have predictable properties. Thus, convergent evolution may also extend to patterns of organization and structure at the community level [71,72], and may produce similarities in resource utilization and diversity in geographically distinct communities dependent on similar environments [73][74][75][76]. Therefore, since communities developing under similar environmental conditions have similar community structures, it makes it possible to implement palaeoclimatic studies at the community scale [19,20,23,35,39,53,77,78]. ...
[This corrects the article DOI: 10.1371/journal.pone.0186762.].
... Each bar plots the frequency of a distinct category of things, say, a particular species or kind of skeletal element. Bar length signifies frequency, either absolute or relative; bar width is meaningless unless it signifies something about magnitude of the category (e.g., temporal duration or supra-category richness; Lambert, 2006;Lyman, 2013). Bars can be aligned vertically or horizontally; in our experience most bar graphs show bars aligned vertically such that higher (longer) bars represent greater frequencies; the x-axis can be nominal scale or categorical (e.g., species), ordinal scale (e.g., subaerial weathering stages), or ratio scale (e.g., show the passage of time). ...
Paleozoologists have long used graphs of diverse styles to describe, analyze, and summarize their data. Some of these graphs provide excellent visual representations of complex data and are readily deciphered. Other graph styles require close study to be interpreted. Ease of visual decoding of information contained in a graph – graph perception – varies from graph style to graph style. Historical instances of graphing paleozoological data indicate some difficult to decipher graph styles have been used for at least a century. Graphs with three-dimensions, moiré effects, superimposed lines, or segmented bars, or which demand simultaneous decipherment of position and magnitude, are ill-advised. Temporal trends in data are best graphed following the principle of superposition such that data from old material is graphed at the bottom and data from younger material is graphed at the top of the diagram.
... Countless animal communities have been tested for discontinuities with affirming results (Holling 1992;Havlicek & Carpenter 2001;Lambert 2006;Allen et al. 2006;Nash et al. 2013b). ...
This dissertation is focused on scaling and resilience of complex adaptive systems, including ecological and economic systems. In particular it is concerned with the textural discontinuity hypothesis (hereafter called the discontinuity hypothesis), which describes how the distinct spatial and temporal scales of processes that shape systems in turn generates distinct spatial and temporal scales in system structure and entities interacting with that structure; the cross-scale resilience model, which uses the discontinuity hypothesis as the foundation of a theory about specific system features that drive ecological resilience; panarchy and adaptive cycles, which articulate how system dynamics at the above-mentioned scales change over time and how feedbacks across those scales informs system behavior; and the notion of spatial regimes in ecological structure. I both expand existing frameworks to accommodate non-ecological complex systems, and test my hypotheses in a variety of economic and ecological systems. ^ Some general findings of my analyses are that the objective identification of scale domains in many types of complex systems can be useful for understanding how pattern and process shape structure and impact system-level resilience. Economic systems, for example, as expressed by Gross Domestic Product, fall into distinct, non-random size classes that suggest there are scale-specific processes generating basins of attraction. I expand the cross-scale resilience model to incorporate abundance, a species and community attribute that is mechanistically related to the provision of function and resilience. The coral reef fish communities of the Hawaiian archipelago were analysed to see if their cross-scale resilience differed amongst coral dominated and macroalgal and turf dominated reefs, with the surprising result that the macroalgal-turf communities were more resilient. In a twist on classic regime shift theory, which typically focuses on temporal shifts within a single ecosystem, I used a novel information theory method to successfully detect spatial boundaries and transition zones between types of ecological systems by using animal community data. Finally, I argue why the adaptive cycle may be a result of endogenous processes in complex adaptive systems, and is not just a convenient metaphor for cycling behavior and dynamics.
... Because environments select organisms on the basis of their adaptations, and these are expressed simultaneously in their morphology, physiology and ecology, then different assemblages of species inhabiting similar environments should also have predictable properties. Thus, convergent evolution may also extend to patterns of organization and structure at the community level [71,72], and may produce similarities in resource utilization and diversity in geographically distinct communities dependent on similar environments [73][74][75][76]. Therefore, since communities developing under similar environmental conditions have similar community structures, it makes it possible to implement palaeoclimatic studies at the community scale [19,20,23,35,39,53,77,78]. ...
We developed new quantitative palaeoclimatic inference models based on the body-size structure of mammal faunas from the Old World tropics and applied them to the Somosa-guas fossil site (middle Miocene, central Iberian Peninsula). Twenty-six mammal species have been described at this site, including proboscideans, ungulates, carnivores, insecti-vores, lagomorphs and rodents. Our analyses were based on multivariate and bivariate regression models correlating climatic data and body-size structure of 63 modern mammal assemblages from Sub-Saharan Africa and the Indian subcontinent. The results showed an average temperature of the coldest month higher than 26˚C for the Somosaguas fossil site, a mean annual thermal amplitude around 10˚C, a drought length of 10 months, and an annual total precipitation greater than 200 mm per year, which are climate conditions typical of an ecotonal zone between the savanna and desert biomes. These results are congruent with the aridity peaks described over the middle Aragonian of Spain and particularly in the local biozone E, which includes Somosaguas.
... These body mass groups are separated by gaps, which reflect a scale break (discontinuity), or transition to a new scale domain. Many animal communities have been tested for discontinuities with affirming results [38,[59][60][61][62]. ...
The cross-scale resilience model was developed in ecology to explain the emergence of resilience from the distribution of ecological functions within and across scales, and as a tool to assess resilience. We propose that the model and the underlying discontinuity hypothesis are relevant to other complex adaptive systems, and can be used to identify and track changes in system parameters related to resilience. We explain the theory behind the cross-scale resilience model, review the cases where it has been applied to non-ecological systems, and discuss some examples of social-ecological, archaeological/anthropological, and economic systems where a cross-scale resilience analysis could add a quantitative dimension to our current understanding of system dynamics and resilience. We argue that the scaling and diversity parameters suitable for a resilience analysis of ecological systems are appropriate for a broad suite of systems where non-normative quantitative assessments of resilience are desired. Our planet is currently characterized by fast environmental and social change, and the cross-scale resilience model has the potential to quantify resilience across many types of complex adaptive systems.
