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opencc-zeroSep 2019View details →

Data from: Hierarchical controls on extinction selectivity across the diplobathrid crinoid phylogeny

Identifying correlates of extinction risk is important for understanding the underlying mechanisms driving differential rates of extinction and variability in the temporal durations of taxa. Increasingly, it is recognized that the effects of multiple, potentially interacting variables and phylogenetic relationships should be incorporated when studying extinction selectivity to account for covariation of traits and shared evolutionary history. Here, I explore a variety of biological and ecological controls on genus longevity in the global fossil record of diplobathrid crinoids by analyzing the combined effects of species richness, habitat preference, body size, filtration fan density, and food size selectivity. I employ a suite of taxic and phylogenetic approaches to (1) quantitatively compare and rank the relative effects of multiple factors on taxonomic longevity, and (2) determine how phylogenetic comparative approaches alter interpretations of extinction selectivity. I find controls on diplobathrid genus duration are hierarchically structured, where species richness is the primary predictor of duration, habitat is the secondary predictor, and a combination of ecological and biological traits are tertiary controls. Ecology plays an important but complex role in the generation of crinoid macroevolutionary patterns. Notably, tolerance of environmental heterogeneity promotes increased genus duration across diplobathrid crinoids, and the effects of traits related to feeding ecology vary depending on habitat lithology. Finally, I find accounting for phylogeny does not consistently decrease the significance of correlations between traits and genus duration, as is commonly expected. Instead, the strength of relationships between traits and duration may increase, decrease, or remain statistically similar, and both the magnitude and direction of these shifts are generally unpredictable. However, traits with strong correlations and/or moderately large effect sizes (Cohen's f2 > 0.15) under taxic approaches tend to remain qualitatively unchanged under phylogenetic approaches.

opencc-zeroDec 2017View details →

Data from: Climate change and the latitudinal selectivity of ancient marine extinctions

Geologically rapid climate change is anticipated to increase extinction risk non-uniformly across the Earth's surface. Tropical species may be more vulnerable than temperate species to current climate warming because of high tropical climate velocities and reduced seawater oxygen levels. To test if rapid warming indeed preferentially increased the extinction risk of tropical fossil taxa, we combine a robust statistical assessment of latitudinal extinction selectivity (LES) with the dominant views on climate change occurring at ancient extinction crises. Using a global dataset of marine fossil occurrences, we assess extinction rates for tropical and temperate genera, applying log-ratios to assess effect size and Akaike weights for model support. Among the classical 'Big Five' mass extinction episodes, the end-Permian mass extinction exhibits temperate preference of extinctions, whereas the Late Devonian and end-Triassic selectively hit tropical genera. Simple links between the inferred direction of climate change and LES are idiosyncratic, both during crisis and background intervals. More complex models, including sampling patterns and changes in the latitudinal distribution of continental shelf area, show tropical LES to be generally associated with raised tropical heat and temperate LES with global cold temperatures. With implications for the future, our paper demonstrates the consistency of high tropical temperatures, habitat loss and the capacity of both to interact in generating geographic patterns in extinctions.

opencc-zeroDec 2012View details →

Data from: 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

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.

opencc-zeroDec 2013View details →

Data from: Phylogenetic signal in extinction selectivity in Devonian terebratulide brachiopods

Determining which biological traits affect taxonomic durations is critical for explaining macroevolutionary patterns. Two approaches are commonly used to investigate the associations between traits and durations and/or extinction and origination rates: analyses of taxonomic occurrence patterns in the fossil record and comparative phylogenetic analyses, predominantly of extant taxa. By capitalizing upon the empirical record of past extinctions, paleontological data avoid some of the limitations of existing methods for inferring extinction and origination rates from molecular phylogenies. However, most paleontological studies of extinction selectivity have ignored phylogenetic relationships because there is a dearth of phylogenetic hypotheses for diverse non-vertebrate higher taxa in the fossil record. This omission inflates the degrees of freedom in statistical analyses and leaves open the possibility that observed associations are indirect, reflecting shared evolutionary history rather than the direct influence of particular traits on durations. Here we investigate global patterns of extinction selectivity in Devonian terebratulide brachiopods and compare the results of taxonomic vs. phylogenetic approaches. Regression models that assume independence among taxa provide support for a positive association between geographic range size and genus duration but do not indicate an association between body size and genus duration. Brownian motion models of trait evolution identify significant similarities in body size, range size, and duration among closely related terebratulide genera. We use phylogenetic regression to account for shared evolutionary history and find support for a significant positive association between range size and duration among terebratulides that is also phylogenetically structured. The estimated range size–duration relationship is moderately weaker in the phylogenetic analysis due to the down-weighting of closely related genera that were both broadly distributed and long lived; however, this change in slope is not statistically significant. These results provide evidence for the phylogenetic conservatism of organismal and emergent traits, yet also the general phylogenetic independence of the relationship between range size and duration.

Figure 8 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 8. Examples of modern casque analogues suitable for specific non-avian dinosaur ornamentation comparisons in the context of (top row) development, (middle row) structural composition, and (boưom row) homologous structures. Each skull shown in right lateral view. Grey regions depict non-ornamental elements, and orange-highlighted regions depict ornamental elements for each represented species (see main text for relevant osteology); neognathous birds surveyed from the literature collectively represented by hornbill illustration (lowest less).

Figure 7 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 7. Illustrations of bony cranial anatomy among exemplar dinosaurs with skull ornamentation, i.e. Saurolophus osborni (paired nasals, prefrontals, and frontals; Bell 2011), Protoceratops andrewsi (paired parietals and squamosals; Dodson 1976), Stegoceras validum (paired frontals and parietals; Schoư et al. 2011), Citipati osmolskae (paired premaxillae, nasals, and frontals; Clark et al. 2002), Carnotaurus sastrei (paired frontals; Paulina Carabajal 2011), Monolophosaurus jiangi (paired premaxillae, nasals, lacrimals, prefrontals, and frontals; Brusaưe et al. 2010), Numida meleagris (paired frontals), Macrocephalon maleo (paired frontals and parietals); Casuarius casuarius (mesethmoid, median casque element, paired nasals, paired lacrimals, and paired frontals; Green and Gignac 2021). Each skull shown in right lateral (top) and dorsal (boưom) views. Grey regions depict non-ornamental elements and orange-highlighted regions depict ornamental elements for each represented species.

Figure 6 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 6. Three-dimensional renderings from micro-computed tomography data of a developmental series of Casuarius casuarius: A, TLG C025; B, TLG C037; C, TLG C031; D, AMNH SKEL 963; E, AMNH SKEL 962 (see Table 1). Skulls are shown in (top) less lateral and (boưom) dorsal views. Casque elements specific to Casuarius casuarius are indicated by colored cells [dark red (X) = element not participating at specified age; dark green (✓) = element participating at specified age] in the table, and grey cells indicate bones that do not contribute to bones in the species represented in this figure, but do contribute to others in the study. Dashed line divides specimens without (less) and with (right) casques developmentally present.

Figure 5 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 5. Three-dimensional renderings from micro-computed tomography data of a developmental series of Macrocephalon maleo: A, UAZ MM005; B, UAZ MM003; C, UAZ MM004; D, UAZ MM002; E, UAZ MM006 (see Table 1). Skulls are shown in (top) less lateral and (boưom) dorsal views. Casque elements specific to Ma. maleo are indicated by colored cells [dark red (X) = element not participating at specified age; dark green (✓) = element participating at specified age] in the table, and grey cells indicate bones that do not contribute to bones in the species represented in this figure, but do contribute to others in the study. Dashed line divides specimens without (less) and with (right) casques developmentally present.

Figure 3 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 3. Three-dimensional renderings from micro-computed tomography data of immature (A) Numida meleagris (TLG NM002), (B) Macrocephalon maleo (UAZ MM003), and (C) Casuarius casuarius (TLG C004). (Immature specimens are figured to emphasize clearer suture lines.) Broad cranial casque paưerns divided into geminal (sampled neognaths; N. meleagris and Ma. maleo) and disunited (sampled palaeognath; Casuarius casuarius). Skulls are shown in (top) lateral and (boưom) dorsal views with elements that will contribute to the fully matured adult casque false coloured (maroon = nasals; green = median casque element; blue = mesethmoid; orange = lacrimals; purple = frontals; yellow = parietals).

Figure 2 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 2. Three-dimensional renderings from micro-computed tomography data of adult neognaths: A, Gallus gallus (PMG GG001); B, Numida meleagris (TLG NM007); C, Macrocephalon maleo (UAZ MM006); along with palaeognaths: D, Dromaius novaehollandiae (TLG E167); E, Casuarius casuarius (AMNH SKEL 962). In order to determine the cranial bones contributing to casques of ornamented taxa, the cranial osteology of non-casqued neognathous and palaeognathous relatives was used for comparison; (A) G. gallus and (D) D. novaehollandiae, respectively. Micro-computed tomography image data of the two non-casqued taxa were collected via a 2010 GE phoenix v|tome|x s240 high-resolution microfocus computed tomography system (μ-CT) housed in the Microscopy and Imaging Facility of the AMNH and a 2018 Nikon XT H 225 ST μ-CT system housed at the Micro-CT Imaging Consortium for Research and Outreach. Scanning parameters were 110–121 kV, 130–457 μA, ranging from 84.52–101.94 μm, 200–267 ms exposures with isometric voxel size at resolutions, W target, and none or a 0.125 mm filter.

Figure 1 in Osteological comparison of casque ontogeny in palaeognathous and neognathous birds: insights for selecting modern analogues in the study of cranial ornaments from extinct archosaurs

Figure 1. Photographs of adult: A, helmeted guinea fowl (Numida meleagris); B, maleo (Macrocephalon maleo); C, southern cassowary (Casuarius casuarius). All three species possess osseous casques dorsal to their orbits and neurocranium. Photos by T.L.G.