Critical reappraisal of the early diversification of dinosaurs

Although the extinction of non-avian dinosaurs at the end of the Mesozoic has been studied extensively, the origin and rise of early dinosaurs is less well understood. Previous hypotheses for the success of early dinosaurs have generally focused on two different scenarios: competition and contingent...

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Autor principal: Irmis, R. B.
Formato: Objeto de conferencia Resumen
Lenguaje:Inglés
Publicado: 2010
Materias:
Ciencias Naturales
Paleontología
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/16653
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SEDICI (UNLP) de Universidad Nacional de La Plata
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spelling I19-R120-10915-166532023-10-11T20:02:22Z http://sedici.unlp.edu.ar/handle/10915/16653 Critical reappraisal of the early diversification of dinosaurs Irmis, R. B. 2010 2010 2010-11-15T03:00:00Z en Ciencias Naturales Paleontología Although the extinction of non-avian dinosaurs at the end of the Mesozoic has been studied extensively, the origin and rise of early dinosaurs is less well understood. Previous hypotheses for the success of early dinosaurs have generally focused on two different scenarios: competition and contingent events (e.g., bolide impacts, mass extinctions, etc.). Unfortunately, most studies have taken a broad, global view to address these hypotheses, which has lead to over-generalization about patterns of early dinosaur evolution. Here, I examine the occurrences, species diversity, and relative abundance of early dinosaurs at both regional and global scales to elucidate their early evolutionary history. These data reveal several patterns: in Gondwana and Europe, sauropodomorphs are diverse and common by the late Norian, whereas they are absent from North America until the Early Jurassic; ornithischian dinosaurs are absent from the Triassic of Laurasia, and are rare and species-poor worldwide until the Jurassic; dinosaurs are rare in the Late Triassic of North America, and do not become abundant until the Early Jurassic; and dinosaur body size increases gradually throughout the Late Triassic, rather than abruptly across the Triassic-Jurassic boundary. No single hypothesis fully explains these data. There is little evidence for competition with other groups, but there is also no evidence for a Carnian-Norian extinction leading to early dinosaur success. Elevated dinosaur growth rates are consistent with body size increase, but this trend does not necessarily correlate with a synchronous increase in diversity or abundance. These data suggest that early dinosaur diversification was diachronous across Pangaea, and resulted from multiple complex processes with several underlying causes. Future studies must disentangle space (biogeography), time and paleoecology to understand the processes underlying the origin of dinosaurs. Simposio III: Ecosistemas triásicos, su paleobiología y el contexto de recuperación de la gran extinción Facultad de Ciencias Naturales y Museo Objeto de conferencia Resumen http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) application/pdf
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Paleontología
spellingShingle Ciencias Naturales
Paleontología
Irmis, R. B.
Critical reappraisal of the early diversification of dinosaurs
topic_facet Ciencias Naturales
Paleontología
description Although the extinction of non-avian dinosaurs at the end of the Mesozoic has been studied extensively, the origin and rise of early dinosaurs is less well understood. Previous hypotheses for the success of early dinosaurs have generally focused on two different scenarios: competition and contingent events (e.g., bolide impacts, mass extinctions, etc.). Unfortunately, most studies have taken a broad, global view to address these hypotheses, which has lead to over-generalization about patterns of early dinosaur evolution. Here, I examine the occurrences, species diversity, and relative abundance of early dinosaurs at both regional and global scales to elucidate their early evolutionary history. These data reveal several patterns: in Gondwana and Europe, sauropodomorphs are diverse and common by the late Norian, whereas they are absent from North America until the Early Jurassic; ornithischian dinosaurs are absent from the Triassic of Laurasia, and are rare and species-poor worldwide until the Jurassic; dinosaurs are rare in the Late Triassic of North America, and do not become abundant until the Early Jurassic; and dinosaur body size increases gradually throughout the Late Triassic, rather than abruptly across the Triassic-Jurassic boundary. No single hypothesis fully explains these data. There is little evidence for competition with other groups, but there is also no evidence for a Carnian-Norian extinction leading to early dinosaur success. Elevated dinosaur growth rates are consistent with body size increase, but this trend does not necessarily correlate with a synchronous increase in diversity or abundance. These data suggest that early dinosaur diversification was diachronous across Pangaea, and resulted from multiple complex processes with several underlying causes. Future studies must disentangle space (biogeography), time and paleoecology to understand the processes underlying the origin of dinosaurs.
format Objeto de conferencia
Resumen
author Irmis, R. B.
author_facet Irmis, R. B.
author_sort Irmis, R. B.
title Critical reappraisal of the early diversification of dinosaurs
title_short Critical reappraisal of the early diversification of dinosaurs
title_full Critical reappraisal of the early diversification of dinosaurs
title_fullStr Critical reappraisal of the early diversification of dinosaurs
title_full_unstemmed Critical reappraisal of the early diversification of dinosaurs
title_sort critical reappraisal of the early diversification of dinosaurs
publishDate 2010
url http://sedici.unlp.edu.ar/handle/10915/16653
work_keys_str_mv AT irmisrb criticalreappraisaloftheearlydiversificationofdinosaurs
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