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Geologic (A) and paleontological (B) records of the K/Pg mass extinction. Paleothermometer (A) showing the Deccan-induced warming with the two main episodes of volcanism highlighted by the black arrows and symbols of volcanoes. The last phase extends beyond the end of the Cretaceous, characterized by the bolide impact in Chicxulub. Fossil remains of non-avian dinosaurs (body fossils, egg fragments, and nesting sites) occur throughout the whole stratigraphic record of prolonged volcanism episodes (dinosaur silhouettes). Numbers represent upper Maastrichtian dinosaur bearing localities, mapped on a late Maastrichtian paleogeography in B. 1, Hell Creek Formation (United States); 2, Lameta Formation (India); 3, Tremp Formation (Spain); 4, Phosphorite beds (Morocco); 5, Marilía Formation (Brazil); 6, Nemegt Formation (Mongolia). Dinosaur silhouette image credit: Phylopic/Jack Mayer Wood, which is licensed under CC BY 3.0.
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Significance
We present a quantitative test of end-Cretaceous extinction scenarios and how these would have affected dinosaur habitats. Combining climate and ecological modeling tools, we demonstrate a substantial detrimental effect on dinosaur habitats caused by an impact winter scenario triggered by the Chicxulub asteroid. We were not able to obt...
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... (3) prior to their extinction, their fossil record demonstrates global survival until the terminal Cretaceous and unambiguous absence thereafter. The Cretaceous/Paleogene (K/Pg) mass extinction coincided with two major global environmental perturbations: heightened volcanism associated with the Deccan Traps and the Chicxulub asteroid impact (Fig. 1A) (4). The relative roles of these two potential kill mechanisms on the timing and magnitude of the extinction have been fiercely debated for decades (4,5). The Maastrichtian has been shown to have a relatively high climate sensitivity (6), meaning even relatively small perturbations to the system could potentially have a catastrophic ...
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... asteroid, ∼10 km in diameter, impacted at Chicxulub, in the present-day Gulf of Mexico, 66 Ma (4, 18, 19), leaving a crater ∼180 to 200 km in diameter (Fig. 1A). This impactor struck carbonate and sulfate-rich sediments, leading to the ejection and global dispersal of large quantities of dust, ash, sulfur, and other aerosols into the atmosphere (4,(18)(19)(20). These atmospheric contaminants led to prolonged sunlight screening and global cooling (19)(20)(21)(22), with severe ecological cascade ...
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... cascade effects (4,13,23). The impact is hypothesized to have precipitated an extremely cold "impact winter" that was beyond the thermophysiological limits of much of the end-Cretaceous biota (23). A globally ubiquitous ejecta layer (23) overlies the latest Cretaceous fossiliferous horizons, marking a biotic change after the K/Pg boundary (Fig. 1A). The size of this impact, its hypothesized global climatic effects, and the worldwide absence of non-avian dinosaurs after ...
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... able to obtain such an extinction state with several modeling scenarios of Deccan volcanism. We further show that the concomitant prolonged eruption of the Deccan traps might have acted as an ameliorating agent, buffering the negative effects on climate and global ecosystems that the asteroid impact produced at the Cretaceous-Paleogene boundary. (Fig. 1B) suggest a direct causal relationship between these phenomena ...
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... independent run using MaxEnt (32, 33) was performed to test whether these results would corroborate the outcome from the Ensemble simulations (Materials and Methods and SI Appendix). The 5% solar dimming experiment leads to a substantial, but noncatastrophic, 50% reduction in peak habitability from pre-K/Pg values (SI Appendix, Fig. S18 A and B). With 10% solar dimming, potential habitat is reduced to 4% of pre-K/Pg values (SI Appendix, Fig. S18C) and extinguished at ≥15% dimming. Global habitability is higher in models simulating constant CO 2 injection due to Deccan volcanism (SI Appendix, Fig. S18 D and E): maximum dinosaur habitat suitability increases by ∼27% at ...
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... the outcome from the Ensemble simulations (Materials and Methods and SI Appendix). The 5% solar dimming experiment leads to a substantial, but noncatastrophic, 50% reduction in peak habitability from pre-K/Pg values (SI Appendix, Fig. S18 A and B). With 10% solar dimming, potential habitat is reduced to 4% of pre-K/Pg values (SI Appendix, Fig. S18C) and extinguished at ≥15% dimming. Global habitability is higher in models simulating constant CO 2 injection due to Deccan volcanism (SI Appendix, Fig. S18 D and E): maximum dinosaur habitat suitability increases by ∼27% at 1,120 ppm of CO 2 and ∼32% at 1,680 ppm of CO 2 , confirming the previous Ensemble results in which long-term ...
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... S18 D and E): maximum dinosaur habitat suitability increases by ∼27% at 1,120 ppm of CO 2 and ∼32% at 1,680 ppm of CO 2 , confirming the previous Ensemble results in which long-term Deccan volcanism alone cannot be found responsible for complete dinosaur climatic niche extirpation. The simulated transient asteroid impact experiments (SI Appendix, Fig. S18 F-H) confirm the same trends of the Ensemble outputs ( Fig. 3 F and H) in providing an almost complete eradication of dinosaur abiotic niche. Even here, habitat suitability for these taxa (SI Appendix, Table S4) reestablishes more quickly and at higher "preextinction levels" when active Deccan volcanism-induced CO 2 injection is ...
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... the timing of Deccan volcanism pulses and global climate changes (9, 10), or a large pulse 10 4 y prior to the bolide impact, questioning Deccan volcanism's influence as an abiotic driver of extinction (8). It is noteworthy that even the stratigraphic interbeds of the Deccan Traps have yielded dinosaur and other terrestrial fossil remains (39,40) (Fig. 1), indicating that animals were able to survive previous high-intensity eruptions, even within the epicenter of the Deccan region itself. Given India's geographic isolation at this time, these fossil-bearing beds cannot be explained by biotic restocking via dispersal events (39). Short-term Deccan volcanism (aerosol release), even in ...
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... effects in the ocean. One major implication of such a rapid event for the marine realm is that the extinction driver must have been in play for a duration shorter than the mixing time of ocean waters (∼1,000 y) (45,49). Our simulations (Tables 1 and 2) suggest that sea surface temperatures would have been reduced for all scenarios (SI Appendix , Figs. S1, S3, S5, and S7) but that the rest of the water column (>1,000 m) was unaffected (SI Appendix, Fig. S7B). After the extinction, the marine environment recovered relatively fast, between a few thousand years to ∼1 My (9, 45, 46, ...
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... lithology of the target rocks collided by the Chicxulub asteroid led to a massive release of hundreds of Gigatonnes (Gt) of sulfates (21, 22, 51), yet it is unknown how much reached the stratosphere (16), with a correlated cooling effect of 27 °C (22). This would have led to 3 to 16 y of subfreezing temperatures and a recovery time of more than 30 y. Results from the most recent IODP (International Ocean Discovery Program) drilling expedition (51) suggest that the estimate of sulfur injected to the atmosphere by the impact should be much higher (325 ± 130 Gt of sulfur and 425 ± 160 Gt of CO 2 ), which might have generated cooling for centuries (36). ...
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... While this caused one of the five largest mass extinctions, leading to the disappearance of ~ 70% of species including the non-avian dinosaurs [54,55], several taxa were less affected and were able to diversify and thrive, including mammals, birds, worm lizards, spinyrayed fishes and freshwater species [56][57][58][59][60][61]. In particular, freshwater environments acted as a refuge for biota due to their higher thermal inertia, and because the detritus-based food web of riverine systems was less affected than terrestrial and marine primary production [56,60,[62][63][64]. This would allow them to occupy ecological roles left by extinct forms and thus diversify [57,58]. ...
Background To unravel the evolutionary history of a complex group, a comprehensive reconstruction of its phylogenetic relationships is crucial. This requires meticulous taxon sampling and careful consideration of multiple characters
to ensure a complete and accurate reconstruction. The phylogenetic position of the Orestias genus has been estimated partly on unavailable or incomplete information. As a consequence, it was assigned to the family Cyprindontidae, relating this Andean fish to other geographically distant genera distributed in the Mediterranean, Middle East and North and Central America. In this study, using complete genome sequencing, we aim to clarify the phylogenetic position of Orestias within the Cyprinodontiformes order.
Results We sequenced the genome of three Orestias species from the Andean Altiplano. Our analysis revealed that the small genome size in this genus (~ 0.7 Gb) was caused by a contraction in transposable element (TE) content, particularly in DNA elements and short interspersed nuclear elements (SINEs). Using predicted gene sequences, we generated a phylogenetic tree of Cyprinodontiformes using 902 orthologs extracted from all 32 available genomes as well as three outgroup species. We complemented this analysis with a phylogenetic reconstruction and time calibration considering 12 molecular markers (eight nuclear and four mitochondrial genes) and a stratified taxon sampling to consider 198 species of nearly all families and genera of this order. Overall, our results show that phylogenetic closeness is directly related to geographical distance. Importantly, we found that Orestias is not part of the Cyprinodontidae family, and that it is more closely related to the South American fish fauna, being the Fluviphylacidae the closest sister group.
Conclusions The evolutionary history of the Orestias genus is linked to the South American ichthyofauna and it should no longer be considered a member of the Cyprinodontidae family. Instead, we submit that Orestias belongs to the Orestiidae family, as suggested by Freyhof et al. (2017), and that it is the sister group of the Fluviphylacidae family, distributed in the Amazonian and Orinoco basins. These two groups likely diverged during the Late Eocene concomitant with hydrogeological changes in the South American landscape.
... The model simulations were conducted in a similar vein as comprehensively described in Lunt et al., 88 Valdes et al., 89 and Farnsworth et al. 90 The implications of deep-time studies of these GCM constraints were discussed in previous studies. 12,21,[91][92][93] In summary, the model simulations ran for at least 6,000 (often many thousands of years more) model years until they reached full equilibrium in both the atmosphere and deep ocean. Equilibrium is determined by passing three criteria: i) the globally and volume-integrated annual mean ocean temperature trend is less than 1 C per 1,000 years; ii) trends in surface air temperature are less than 0.3 C per 1,000 years and; iii) net energy balance at the top of the atmosphere, averaged over a 100-year period at the end of the simulation, is less than 0.25/W m 2 . ...
A fundamental question in dinosaur evolution is how they adapted to long-term climatic shifts during the Mesozoic and when they developed environmentally independent, avian-style acclimatization, becoming endothermic. The ability of warm-blooded dinosaurs to flourish in harsher environments, including cold, high-latitude regions, raises intriguing questions about the origins of key innovations shared with modern birds, indicating that the development of homeothermy (keeping constant body temperature) and endothermy (generating body heat) played a crucial role in their ecological diversification. Despite substantial evidence across scientific disciplines (anatomy, reproduction, energetics, biomechanics, osteohistology, palaeobiogeography, geochemistry, and soft tissues), a consensus on dinosaur thermophysiology remains elusive. Differential thermophysiological strategies among terrestrial tetrapods allow endotherms (birds and mammals) to expand their latitudinal range (from the tropics to polar regions), owing to their reduced reliance on environmental temperature. By contrast, most reptilian lineages (squamates, turtles, and crocodilians) and amphibians are predominantly constrained by temperature in regions closer to the tropics. Determining when this macroecological pattern emerged in the avian lineage relies heavily on identifying the origin of these key physiological traits. Combining fossils with macroevolutionary and palaeoclimatic models, we unveil distinct evolutionary pathways in the main dinosaur lineages: ornithischians and theropods diversified across broader climatic landscapes, trending toward cooler niches. An Early Jurassic shift to colder climates in Theropoda suggests an early adoption of endothermy. Conversely, sauropodomorphs exhibited prolonged climatic conservatism associated with higher thermal conditions, emphasizing temperature, rather than plant productivity, as the primary driver of this pattern, suggesting poikilothermy with a stronger dependence on higher temperatures in sauropods.
... Significant fluctuations in global climate and environmental perturbations due to an asteroid impact have been identified as a cause of mass extinctions, leading to the extinction of dinosaurs 66 MYA 46,47 . This asteroid impact was followed by extensive volcanic activity, known as the Deccan Traps, which influenced the atmospheric CO 2 levels 48,49 . Elevated atmospheric CO 2 levels have previously been associated with increased speciation in Culicidae 50 . ...
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... It is thus likely that the endemic Cenozoic lizard fauna of South America could result from the radiation of groups already present by the Late Cretaceous, and which survived the K/Pg mass extinction event. The latter was less severe in South America than in Laurasia, as evidenced by plants (De Benedetti et al. 2023), mammals (Rougier et al. 2011(Rougier et al. , 2012(Rougier et al. , 2021, and the survival of different sphenodontian groups and of madtsoiid snakes among other lepidosaurian clades into the Cenozoic (Albino and Brizuela 2014;Apesteguía et al. 2014), contrasting with the devastating nature of this event as recorded in the northern continents (Longrich et al. 2012;Lyson et al. 2019;Chiarenza et al. 2020). The presence of teiioids in the Upper Cretaceous of Patagonia is consistent with this scenario, making it unnecessary to invoke their immigration from North America around the early Late Cretaceous, as it has been previously conceived (Gao and Fox 1991;Nydam and Voci 2007). ...
... During the ATR, characterized by major global changes (i.e., global cooling, shift in vegetational composition, asteroid impact), many lineages declined or went extinct (13,71,72). The expan sion and diversification of angiosperms coupled with the decline of gymnosperms have played an intricate role in shaping the eco systems (e.g., litter composition: 73). ...
With ~14,000 extant species, ants are ubiquitous and of tremendous ecological importance. They have undergone remarkable diversification throughout their evolutionary history. However, the drivers of their diversity dynamics are not well quantified or understood. Previous phylogenetic analyses have suggested patterns of diversity dynamics associated with the Angiosperm Terrestrial Revolution (ATR), but these studies have overlooked valuable information from the fossil record. To address this gap, we conducted a comprehensive analysis using a large dataset that includes both the ant fossil record (~24,000 individual occurrences) and neontological data (~14,000 occurrences), and tested four hypotheses proposed for ant diversification: co-diversification, competitiontive extinction, hyper-specialization, and buffered extinction. Taking into account biases in the fossil record, we found three distinct diversification periods (the latest Cretaceous, Eocene, and Oligo-Miocene) and one extinction period (Late Cretaceous). The competitive extinction hypothesis between stem and crown ants is not supported. Instead, we found support for the co-diversification, buffered extinction, and hyper-specialization hypotheses. The environmental changes of the ATR, mediated by the angiosperm radiation, likely played a critical role in buffering ants against extinction and favoring their diversification by providing new ecological niches, such as forest litter and arboreal nesting sites, and additional resources. We also hypothesize that the decline and extinction of stem ants during the Late Cretaceous was due to their hyper-specialized morphology, which limited their ability to expand their dietary niche in changing environments. This study highlights the importance of a holistic approach when studying the interplay between past environments and the evolutionary trajectories of organisms.
... As one of the five largest biotic extinctions of the Phanerozoic (e.g., Keller, 1988Keller, , 2014, the end-Cretaceous mass extinction is best known for the demise of non-avian dinosaurs. The Chicxulub asteroid impact and/or Deccan volcanism have been hypothesized as crucial events that drove climate and environment changes (e.g., Alvarez et al., 1980;Hildebrand et al., 1991;Nordt et al., 2002Nordt et al., , 2003Vajda et al., 2003;Keller et al., 2012;Keller, 2014;Barnet et al., 2018;Zhang et al., 2018;Keller et al., 2020;Gilabert et al., 2021b;Gilabert et al., 2021b) and the mass extinction (e.g., MacLeod, 1998;Schulte et al., 2010;Renne et al., 2013;Renne et al., 2013;Hull et al., 2020; and references therein), even though the precise driving mechanism and the role that each event played in the mass extinction are still strongly debated (e.g., Keller et al., 2016;Percival et al., 2018;Sprain et al., 2019;Chiarenza et al., 2020;Dzombak et al., 2020;Gilabert et al., 2021a;Dzombak et al., 2020;Hull et al., 2020;Gilabert et al., 2021a). ...
... The aforementioned hypotheses support that the Chicxulub impact and/or Deccan Trap eruption caused a very short-term (<1.0 Kyr) instability in the marine environment (e.g., Barnet et al., 2018;Chiarenza et al., 2020;Gilabert et al., 2021a;Gilabert et al., 2021b) and terrestrial system (e.g., Vajda et al., 2001;Vajda et al., 2003;Vajda and McLoughlin, 2007;Gertsch et al., 2011;Spicer and Collinson, 2014;Zhang et al., 2018;Donovan et al., 2020). Other evidence (e.g., Percival et al., 2018;Milligan et al., 2019;Dzombak et al., 2020) suggests that the instability and quick recovery of ecology and environment occurred immediately following the eruption and impact events and that this Quillévéré et al. (2008). ...
... The Chicxulub impact has been notably restressed as a crucial factor cotributing to the end-Cretaceous mass-extinction (e.g., Chiarenza et al., 2020;Hull et al., 2020). ...
... Many species expand their ranges relatively quickly after emergence (relative to their life span or duration on Earth). At their late stages, the species ranges will shrink until extinction except in the cases when catastrophic events occur, such as hits by large bolides (comets or asteroids that lead to dinosaurs' extinctions), and even large ranges could be suddenly lost at once (Chiarenza et al., 2020). Second, our data on both species' age and range size are only a snapshot or one-time observation and thus cannot reflect the history of range dynamics. ...
Species range size is a central topic in macroecology, biogeography and conservation biology. Species age has been frequently regarded as a contributor to range size in previous studies on range size, but this has rarely been specifically examined. Using global data from four living terrestrial vertebrate classes (birds, mammals, reptiles and amphibians) as a case study, we examine how species range size might be related to species age at a global scale. We found statistically significant positive, albeit weak, species age–range size relationships for all four species groups. However, although the age–range relationships were positive, species with young ages had very different range sizes (both large and small), and those with very old ages always had small ranges. The observed age–range relationships were more complex than expected. The weak, rather than strong, species age–range relationships could be because our data set included all living species with different stages of their life spans (durations) that are either expanding or fluctuating or contracting, which would necessarily have minimized or cancelled species age–range relationship when all species in a group are considered collectively. Our findings shed new light on temporal dimension and macroecological correlates of species ranges.
... Are we left with a compound hypothesis, at least for the proximate cause of the totality of end-Cretaceous extinctions? Chiarenza et al. (2020) used a climate model to suggest that a sudden cold event was the cause of the sudden extinction we do see. They point out the Deccan eruption might have warmed the planet suddenly, but perhaps this effect, if anything, would have ameliorated world conditions, rather than deteriorating them. ...
Extinction in the fossil record provides a rich source of history and data useful for understanding extinction in current times. Extinction rates
in the fossil record can be estimated by loss of living species as we go back into the fossil record, but usually is determined by loss of
numbers of taxa (level usually above that of species) past known geological time boundaries. Large-scale extinction events are characteristic
of the fossil record, with 5 major mass extinctions recognized but nearly 20 have been recognized as of unusual magnitude. Recognized
mass extinctions have been related to major environmental change, including large scale igneous activity, changes in climate, relation to
environmental indicators such as isotopic ratios, and extraterrestrial impacts. The presence of Large Igneous Provinces are conspicuously
associated with many major mass extinctions, including the end-Cretaceous extinction, also thought to be caused by an extraterrestrial
impact. Controversy remains as to relating ultimate effects (e.g., large scale igneous eruptions) and proximate effects (e.g., ocean warming,
anoxia, sulfide poisoning) of mass extinctions. Lower rates of extinction are more difficult to explain but might represent a background
probability of extinction related to population processes and typical environmental fluctuation. Speciation and extinction rate appears to
have declined during the Phanerozoic although this could be an artifact of measuring extinction using higher taxonomic units.
... The Cretaceous was a dynamic period of global climate change, where the Earth experienced a gradual increase in global average temperatures, from a warm ca.20 • C during the Berriasian to a ~24 • C "hothouse" (Scotese, 2021;Martin et al., 2014) during the Cenomanian-Turonian, which translated to tropical sea-surface temperatures of >33 • C (Poulsen et al., 2013) and potentially as high as 42 • C in the equatorial region of the Demerara Rise (Hay & Floegal et al., 2012). The CTM average global temperature began to decline during the Santonian (Late Cretaceous) and the Earth's climate changed dramatically at the end of the Cretaceous at the K/T boundary event, interpreted to be a result of the Chicxulub meteor impact (Whalen et al., 2020), Nadir impact offshore West Africa (Nicholson et al., 2022) and the near-simultaneous eruption of the Deccan-Trap Large Igneous Province (LIP; Chiarenza et al., 2020). ...
Climate change directly impacts the source, mode and volume of sediment generation which can be observed in the rock record. To accurately model source to sink systems, in addition to hinterland geology, tectonics and transport distance, a thorough comprehension of the climate is essential. In this study we evaluate the role of climate on Cretaceous sediment delivery into the Senegal Basin, NW Africa, using data recorded from extensive sampling of basinal sediments. This is achieved through the mineralogical characterisation by X-ray diffraction and 146Nd/144Nd and 86Sr/88Sr isotopic analyses, which are correlated against existing, climate, tectonic and oceanographic models.
Examples of climatic indicators include the change from predominantly smectitic deep marine basinal-clays recorded from the Cretaceous in DSDP wells 367 and 368 to clays with increased illite and kaolinite content, observed during the Albian and Cenomanian-Turonian, interpreted to be representative of higher humidity following the kaolinisation of hinterland source-rocks. Another climate indicator is the observation of palygorskite in deep-marine sediments, noted to be indicative of ocean anoxia related to the authigenesis of marine-smectite, a product of warm saline bottom waters and increased abundancy of silicon. The increase in salinity is interpreted to be a biproduct of elevated temperatures throughout the Cenomanian and increased denudation of the North Atlantic circumjacent continental evaporite-belts. Increase in silicon (biogenic) is related to a result of ocean-wide mass extinction of foraminifera during OAE2 triggered by the eruption of the Caribbean large igneous province.
The results suggest that Cretaceous climate evolution of Senegal can be divided into four stages: 1. Berriasian-Barremian; an arid-period with monsoonal weather producing modest fluvial systems restricted to coastal regions. 2. Aptian-Albian; the establishment of a paleo-Intertropical Convergence Zone began to increase global temperature and humidity as recognised by the increase in kaolinite content. 3. Cenomanian-Turonian; the Cretaceous Thermal Maximum hothouse period incurring exceptional temperatures and humidity. This is represented as an antithetical shift in clay mineralogy from chlorite-illite to smectite-kaolinite throughout most of the onshore and nearshore basinal sediments. 4. Coniacian-Maastrichtian; transitional from tropical-to-tropical swamp-like conditions evidenced by increased onshore basin sediment capture and a shift in vegetation to aquatic-fern species.
The impact of climate change throughout the Cretaceous produced dynamic shifts in both river size and source-catchment, witnessing exception rates of denudation during the hotter and more humid periods, which climaxed during the Cenomanian and Turonian as a result of the Cretaceous Thermal Maximum. This eroded sediment was deposited in both the onshore and offshore basins during the mid-late Cretaceous but became increasingly restricted to the onshore segment of the basin during the Late Cretaceous.
... See A.Chiarenza, A. et al (2020) for a recent account of the evidential support for various causal accounts of this major extinction event. ...
In this essay, I revisit and extend my arguments for a view of science that is pluralistic, perspectival and pragmatist. I attempt to resolve mismatches between metaphysical assumptions, epistemological desiderata, and scientific practice. I consider long-held views about unity of science and reductionism, emergent properties and physicalism, exceptionless necessity in explanatory laws, and in the justification for realism. My solutions appeal to the partiality of representation, the perspectivism of theories and data, and the interactive co-construction of warranted claims for realism.
