Dinosaur morphological diversity and the end-Cretaceous extinction

Brusatte, Stephen L.; Butler, Richard J.; Prieto-Márquez, Albert; Norell, Mark A.

doi:10.1038/ncomms1815

Cited by 76 publications

(81 citation statements)

References 48 publications

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“…Our results showing high levels of speciation in hadrosauriforms and ceratopsids, although consistent with previous findings (8), seem to contradict more recent work that suggests that these groups underwent a decline in morphological diversity during the last two stages of the Cretaceous of North America (13,26). These dinosaur species are morphologically and ecologically (at least at the family level) conserved (27), with most of the derived characteristics concentrated in their crania (24).…”

Section: Significancesupporting

confidence: 71%

Dinosaurs in decline tens of millions of years before their final extinction

Sakamoto

Benton

Venditti

2016

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

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Whether dinosaurs were in a long-term decline or whether they were reigning strong right up to their final disappearance at the Cretaceous-Paleogene (K-Pg) mass extinction event 66 Mya has been debated for decades with no clear resolution. The dispute has continued unresolved because of a lack of statistical rigor and appropriate evolutionary framework. Here, for the first time to our knowledge, we apply a Bayesian phylogenetic approach to model the evolutionary dynamics of speciation and extinction through time in Mesozoic dinosaurs, properly taking account of previously ignored statistical violations. We find overwhelming support for a long-term decline across all dinosaurs and within all three dinosaurian subclades (Ornithischia, Sauropodomorpha, and Theropoda), where speciation rate slowed down through time and was ultimately exceeded by extinction rate tens of millions of years before the K-Pg boundary. The only exceptions to this general pattern are the morphologically specialized herbivores, the Hadrosauriformes and Ceratopsidae, which show rapid species proliferations throughout the Late Cretaceous instead. Our results highlight that, despite some heterogeneity in speciation dynamics, dinosaurs showed a marked reduction in their ability to replace extinct species with new ones, making them vulnerable to extinction and unable to respond quickly to and recover from the final catastrophic event.dinosaurs | evolution | speciation | phylogeny | Bayesian methods N onavian dinosaurs met their demise suddenly, coincident with the Chicxulub impact in Mexico around 66 Mya; however, whether there was any long-term trend toward declining diversity leading to the Cretaceous-Paleogene (K-Pg) boundary has been controversial and debated for decades (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). This longstanding dispute has been prolonged partly because of differences in fossil datasets from different parts of the world and difficulties in rock dating but most importantly, methodological weaknesses-previous attempts have been nonphylogenetic, and analyses were conducted on simple time-binned tabulated data, resulting in a lack of statistical rigor (phylogenetic and temporal nonindependence have not been considered), and did not truly investigate evolutionary dynamics, such as speciation and extinction rates. In fact, patterns of speciation and extinction in dinosaurs have gone largely unstudied (8). Here, we study speciation dynamics (relationship between speciation and extinction rates) using an exclusively phylogenetic approach in a Bayesian framework.If speciation and extinction rate were constant (but speciation was higher), we would expect to see a linear increase through time in the logarithm of the number of speciation events along each path of a phylogenetic tree (linear) (Materials and Methods and Fig. 1, model A). If speciation rate decreased through time but remained above extinction rate, then we would expect a curvilinear relationship (Fig. 1, models B and C). Such a relationship would reach an asymptote ...

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Section: Significancesupporting

confidence: 71%

Dinosaurs in decline tens of millions of years before their final extinction

Sakamoto

Benton

Venditti

2016

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

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“…Between the latest Campanian and earlyemid Maastrichtian there was a decline in the species richness and morphological disparity of western North American ceratopsids and hadrosauroids, the two groups of largebodied plant-eaters at the base of the food chain (Barrett, McGowan, & Page, 2009;Brusatte, Butler, Prieto-M arquez, & Norell, 2012;Brusatte et al, 2014;Upchurch, Mannion, Benson, Butler, & Carrano, 2011). Other dinosaur groups, including smaller-bodied plant-eaters and carnivorous theropods, did not exhibit such changes.…”

Section: Diversity and Faunal Changes In The Maastrichtianmentioning

confidence: 97%

Diversity and faunal changes in the latest Cretaceous dinosaur communities of southwestern Europe

Vila

Sellés

Brusatte

2016

Cretaceous Research

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“…North America and Asia clearly experienced faunal interchange during the latest Cretaceous, but the presence of the inland Western Interior Sea, extensive mountain building and potential biogeographic provincialism may have uniquely shaped North American dinosaur evolution relative to other regions of the northern hemisphere, and the world, at this time 41 . It appears as if Asian and North American dinosaurs were undergoing distinct biodiversity trajectories during the latest Cretaceous 42,43 , meaning that the well-sampled North American record, which has long been used as a standard to understand dinosaur evolution during the run-up to their extinction, may not be a reasonable proxy for the global record.…”

Section: Sinotyrannusmentioning

confidence: 99%

A new clade of Asian Late Cretaceous long-snouted tyrannosaurids

Lü

Yi²,

Brusatte

et al. 2014

Nat Commun

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The iconic tyrannosaurids were top predators in Asia and North America during the latest Cretaceous, and most species had deep skulls that allowed them to generate extreme bite forces. Two unusual specimens of Alioramus from Mongolia seem to indicate a divergent long-snouted body plan among some derived tyrannosaurids, but the rarity and juvenile nature of these fossils leaves many questions unanswered. Here, we describe a remarkable new species of long-snouted tyrannosaurid from the Maastrichtian of southeastern China, Qianzhousaurus sinensis. Phylogenetic analysis places Qianzhousaurus with both species of Alioramus in a novel longirostrine clade, which was geographically widespread across latest Cretaceous Asia and formed an important component of terrestrial ecosystems during this time. The new specimen is approximately twice the size as both Alioramus individuals, showing that the long-snouted morphology was not a transient juvenile condition of deep-snouted species, but a characteristic of a major tyrannosaurid subgroup.

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Dinosaur morphological diversity and the end-Cretaceous extinction

Cited by 76 publications

References 48 publications

Dinosaurs in decline tens of millions of years before their final extinction

Dinosaurs in decline tens of millions of years before their final extinction

Diversity and faunal changes in the latest Cretaceous dinosaur communities of southwestern Europe

A new clade of Asian Late Cretaceous long-snouted tyrannosaurids

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