Biogeography of Triassic tetrapods: evidence for provincialism and driven sympatric cladogenesis in the early evolution of modern tetrapod lineages

Ezcurra, Martín D.

doi:10.1098/rspb.2010.0508

Cited by 74 publications

(59 citation statements)

References 33 publications

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“…The documentation of latitudinal separation of distinct vertebrate biotic provinces is consistent with the suggestion that Late Triassic archosaurs also show latitudinal differences (2,4,54,55). These data show clear differences between taxa from the tropical semiarid zone of the American Southwest in comparison to the more humid high-latitude assemblages of South America.…”

Section: Discussionsupporting

confidence: 75%

“…It is likely that the coupling of the double rainy season that is linked to the approximately 10-ky cyclicity with more intense equatorial insolation was responsible for the greater mean humidity and less intense dry periods of the region, which favored the traversodont cynodonts and coal formation. Support for this hypothesis that humidity was critical comes from Gondwanan high latitudes, where Late Triassic assemblages with abundant traversodont cynodonts also occur (4,51). These specifically include the Ischigualastian assemblages of Argentina and the Santa Maria assemblages of Brazil associated with abundant gray, plant-bearing strata (52).…”

Section: Discussionmentioning

confidence: 96%

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Climatically driven biogeographic provinces of Late Triassic tropical Pangea

Whiteside

Grogan

Olsen

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Although continents were coalesced into the single landmass Pangea, Late Triassic terrestrial tetrapod assemblages are surprisingly provincial. In eastern North America, we show that assemblages dominated by traversodont cynodonts are restricted to a humid 6°equatorial swath that persisted for over 20 million years characterized by "semiprecessional" (approximately 10,000-y) climatic fluctuations reflected in stable carbon isotopes and sedimentary facies in lacustrine strata. More arid regions from 5-20°N preserve procolophonid-dominated faunal assemblages associated with a much stronger expression of approximately 20,000-y climatic cycles. In the absence of geographic barriers, we hypothesize that these variations in the climatic expression of astronomical forcing produced latitudinal climatic zones that sorted terrestrial vertebrate taxa, perhaps by excretory physiology, into distinct biogeographic provinces tracking latitude, not geographic position, as the proto-North American plate translated northward. Although the early Mesozoic is usually assumed to be characterized by globally distributed land animal communities due to of a lack of geographic barriers, strong provinciality was actually the norm, and nearly global communities were present only after times of massive ecological disruptions.biotic provinciality | Cynodontia | orbital forcing | Procolophonidae | latitudinal gradient G eographic and climatic barriers are among the main constraints on the distribution of organisms. During the Late Triassic, Pangea lacked significant geographic barriers nearly pole-to-pole, and was warm and equable without glaciation or sea ice (1). Nonetheless, when correlated temporally by nonbiostratigraphic means, diverse Late Triassic continental faunal and floral assemblages display dramatic differences across paleolatitude (e.g., refs. 2-4) (Fig. 1). Although the equator-to-pole temperature gradients may have been relatively weak, Milankovitchtype climatic variability expressed in precipitation and evaporation was nonetheless very important (5-8). Then, as now (9,10), this scale of temporal variability may have played a critical role in structuring terrestrial communities, and thus early Mesozoic sequences provide a unique window into the link between climate variability and biotic provinciality.Here, we focus on the tropical regions of Late Triassic central Pangea and the role of traversodont cynodonts (basal synapsids) and procolophonids (parareptiles) as possible ecologically equivalent herbivores (Fig. 2) under different climatic regimes. We test the correlation between climate variability and biotic provinces within narrow swaths of time constrained by astrochronology, paleomagnetic polarity stratigraphy, and paleomagnetically determined plate position from long [>5 million years (My)] lacustrine and associated fluvial records spanning 30°of paleolatitude. We show that faunal composition tracks different modes of orbitally forced climate variability that maintained Pangean faunal provinces and suggest that this may...

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Section: Discussionsupporting

confidence: 75%

Section: Discussionmentioning

confidence: 96%

Climatically driven biogeographic provinces of Late Triassic tropical Pangea

Whiteside

Grogan

Olsen

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…As recently pointed out, analyses of the origin and early diversification of dinosaurs have suffered from an overreliance on low-resolution (both stratigraphic and taxonomic) vertebrate biostratigraphy that obscures real faunal differences in time and space (10). This situation is particularly problematic for Triassic nonmarine communities, where tetrapod composition across Pangea appears to be particularly heterogeneous (11)(12)(13). Without precise independent age control (other than vertebrate biostratigraphic correlations), it is impossible to determine if these faunal differences vary across time, space, or a combination of both.…”

mentioning

confidence: 98%

“…The Triassic succession of the Agua de la Peña not only preserves the earliest dinosaur fossils of all three major clades (Ornithischia, Sauropodomorpha, and Theropoda) in the Ischigualasto Formation (21), but it also contains a remarkably diverse assemblage of early dinosauromorphs in the underlying Chañares Formation; this includes nearly complete skeletons of the lagerpetid Lagerpeton chanarensis and early dinosauriforms Marasuchus lilloensis, Pseudolagosuchus, and Lewisuchus (2,20,22). Overlying the Ischigualasto Formation are the redbeds of Los Colorados Formation, representing the first Triassic ecosystem that is dominated by dinosaurs (12,21,23,24). Whereas the chronostratigraphy of the Ischigualasto and Los Colorados strata is now studied in detail (21,24,25), the age of the Chañares Formation has remained poorly constrained to the Middle Triassic by vertebrate biostratigraphy and lithostratigraphic relationships (20,(26)(27)(28)(29), with age estimates ranging from Anisian to Ladinian (247-237 Ma).…”

Section: The Chañares Formationmentioning

confidence: 99%

The precise temporal calibration of dinosaur origins

Marsicano

Irmis

Mancuso

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

148

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Dinosaurs have been major components of ecosystems for over 200 million years. Although different macroevolutionary scenarios exist to explain the Triassic origin and subsequent rise to dominance of dinosaurs and their closest relatives (dinosauromorphs), all lack critical support from a precise biostratigraphically independent temporal framework. The absence of robust geochronologic age control for comparing alternative scenarios makes it impossible to determine if observed faunal differences vary across time, space, or a combination of both. To better constrain the origin of dinosaurs, we produced radioisotopic ages for the Argentinian Chañares Formation, which preserves a quintessential assemblage of dinosaurian precursors (early dinosauromorphs) just before the first dinosaurs. Our new high-precision chemical abrasion thermal ionization mass spectrometry (CA-TIMS) U-Pb zircon ages reveal that the assemblage is early Carnian (early Late Triassic), 5-to 10-Ma younger than previously thought. Combined with other geochronologic data from the same basin, we constrain the rate of dinosaur origins, demonstrating their relatively rapid origin in a less than 5-Ma interval, thus halving the temporal gap between assemblages containing only dinosaur precursors and those with early dinosaurs. After their origin, dinosaurs only gradually dominated mid-to high-latitude terrestrial ecosystems millions of years later, closer to the Triassic-Jurassic boundary.

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“…This discussion of the archosaur radiation takes a global perspective, and measures such as diversity, disparity and morphological rate are calculated for all archosaurs in general. It does not focus on macroevolutionary patterns on a regional scale, but other authors have begun examining how TriassicEarly Jurassic archosaur evolutionary patterns may have differed in different parts of the globe (e.g., Irmis et al 2007;Nesbitt et al 2007Nesbitt et al , 2009Ezcurra 2010;Irmis 2011). As many archosaur faunas are better sampled and their ages more precisely constrained, such regional analyses will become increasingly powerful.…”

Section: The Archosaur Radiation: a General Backgroundmentioning

confidence: 99%

Macroevolutionary patterns in the evolutionary radiation of archosaurs (Tetrapoda: Diapsida)

Brusatte

Benton

Lloyd

et al. 2010

Earth and Environmental Science Transactions of the Royal Socie

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The rise of archosaurs during the Triassic and Early Jurassic has been treated as a classic example of an evolutionary radiation in the fossil record. This paper reviews published studies and provides new data on archosaur lineage origination, diversity and lineage evolution, morphological disparity, rates of morphological character change, and faunal abundance during the Triassic-Early Jurassic. The fundamental archosaur lineages originated early in the Triassic, in concert with the highest rates of character change. Disparity and diversity peaked later, during the Norian, but the most significant increase in disparity occurred before maximum diversity. Archosaurs were rare components of Early-Middle Triassic faunas, but were more abundant in the Late Triassic and pre-eminent globally by the Early Jurassic. The archosaur radiation was a drawn-out event and major components such as diversity and abundance were discordant from each other. Crurotarsans (crocodile-line archosaurs) were more disparate, diverse, and abundant than avemetatarsalians (bird-line archosaurs, including dinosaurs) during the Late Triassic, but these roles were reversed in the Early Jurassic. There is no strong evidence that dinosaurs outcompeted or gradually eclipsed crurotarsans during the Late Triassic. Instead, crurotarsan diversity decreased precipitously by the end-Triassic extinction, which helped usher in the age of dinosaurian dominance.

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Biogeography of Triassic tetrapods: evidence for provincialism and driven sympatric cladogenesis in the early evolution of modern tetrapod lineages

Cited by 74 publications

References 33 publications

Climatically driven biogeographic provinces of Late Triassic tropical Pangea

Climatically driven biogeographic provinces of Late Triassic tropical Pangea

The precise temporal calibration of dinosaur origins

Macroevolutionary patterns in the evolutionary radiation of archosaurs (Tetrapoda: Diapsida)

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