Shape of Mesozoic dinosaur richness: Comment and Reply: REPLY

Fastovsky, David E.; Huang, Yifan; Hsu, Jason C.; Martin-McNaughton, Jamie; Sheehan, Peter M.; Weishampel, David B.

doi:10.1130/0091-7613-33.1.e75

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…Perhaps the most intriguing of these is the diminution of ornithischian and theropod dinosaur lineages several million years prior to the K-P extinction event: both clades underwent a drastic decline in both absolute terms (as shown in TDE and PDE) and relative to their predicted diversities (as shown by comparisons between TDE/PDE and MDE, although this decline is only statistically significant in the case of theropods; figure 2a,b and the electronic online supplementary material). This result contrasts strongly with other recent analyses that either found no evidence for a reduction in dinosaur diversification prior to the K-P boundary ( Wang & Dodson 2006;Lloyd et al 2008), or that explained the drop in diversity from the Campanian to the Maastrichtian as a consequence of sampling issues (Fastovsky et al 2004(Fastovsky et al , 2005: this difference that may be due to the fact that the diversity estimates presented herein are not based on methods that extensively resample the raw diversity/collections data (such as rarefaction). This observation supports the suggestion that factors other than the end-Cretaceous bolide impact were responsible for instigating a downward trend in taxonomic richness that preceded the unquestionably abrupt disappearance of many dinosaur taxa at the boundary itself (see also Archibald 1996;Archibald & MacLeod 2008).…”

Section: Discussioncontrasting

confidence: 99%

Dinosaur diversity and the rock record

2009

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Palaeobiodiversity analysis underpins macroevolutionary investigations, allowing identification of mass extinctions and adaptive radiations. However, recent large-scale studies on marine invertebrates indicate that geological factors play a central role in moulding the shape of diversity curves and imply that many features of such curves represent sampling artefacts, rather than genuine evolutionary events. In order to test whether similar biases affect diversity estimates for terrestrial taxa, we compiled genus-richness estimates for three Mesozoic dinosaur clades (Ornithischia, Sauropodomorpha and Theropoda). Linear models of expected genus richness were constructed for each clade, using the number of dinosaur-bearing formations available through time as a proxy for the amount of fossiliferous rock outcrop. Modelled diversity estimates were then compared with observed patterns. Strong statistically robust correlations demonstrate that almost all aspects of ornithischian and theropod diversity curves can be explained by geological megabiases, whereas the sauropodomorph record diverges from modelled predictions and may be a stronger contender for identifying evolutionary signals. In contrast to other recent studies, we identify a marked decline in dinosaur genus richness during the closing stages of the Cretaceous Period, indicating that the clade decreased in diversity for several million years prior to the final extinction of non-avian dinosaurs at the Cretaceous-Palaeocene boundary.

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Section: Discussioncontrasting

confidence: 99%

Dinosaur diversity and the rock record

2009

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“…This was based primarily upon the higher species richness of several Campanian formations from southern Canada, including what is now recognized as the Dinosaur Park Formation (42 valid species), than that of the late Maastrichtian Hell Creek Formation (25–33 valid species). Simple comparisons of species richness do not, however, take into account possible variations in sampling intensity or preservation potential of rocks of different geological ages (Russell, ; Fastovsky et al , ), the fact that not all Campanian taxa were directly contemporaneous, or that the faunas being compared might represent different environments (Fastovsky et al , ).…”

Section: How Were Dinosaurs Changing During the Latest Cretaceous?mentioning

confidence: 99%

“…All major groups of Campanian dinosaurs survived into the late Maastrichtian, so there was no gradual loss of major components of dinosaur diversity through the latest Cretaceous. Moreover, it is worth stressing that even if some groups declined in diversity through this time interval, similar (and often more extreme) waxing and waning in the diversity of particular clades occurred repeatedly across dinosaur evolutionary history (Fastovsky et al , , ; Barrett et al , ; Upchurch et al , ), and does not indicate that dinosaurs, or particular groups of them, were doomed to extinction.…”

Section: How Were Dinosaurs Changing During the Latest Cretaceous?mentioning

confidence: 99%

The extinction of the dinosaurs

et al. 2014

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Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult.

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“…Mosasaur richness appears generally stable throughout the Campanian, and falls slightly during the Maastrichtian. This may indicate that mosasaur richness during the latest Maastrichtian (8 genera) was lower than the early or late Campanian (10 genera), or alternatively, it may be an artifact of uneven sampling intensity (e.g., Fastovsky et al, 2005).…”

Section: Mosasaur Richness Through Timementioning

confidence: 99%

Charting the Late Cretaceous seas: mosasaur richness and morphological diversification

Ross

2009

Journal of Vertebrate Paleontology

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ABSTRACT-Abundant, readily identifiable, and biostratigraphically resolved specimens make mosasaurs ideal candidates to test fluxes in generic richness and morphological trends among marine vertebrates during the late Cretaceous. More than 1800 globally distributed mosasaur specimens are allocated to fifteen substage-level stratigraphically correlated assemblages. These data are quantitatively analyzed to illuminate trends within the group. Following their first appearance in the Cenomanian, mosasaurs experienced a significant radiation in the Coniacian and Santonian. Richness levels continued increasing into the Maastrichtian while mosasaurs incrementally exploited new predatory niches recognized via accumulation of novel dental morphologies. Their extinction at the end of the Cretaceous occurred at the zenith of mosasaur morphological and ecological diversity.

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Shape of Mesozoic dinosaur richness: Comment and Reply: REPLY

Cited by 4 publications

References 6 publications

Dinosaur diversity and the rock record

Dinosaur diversity and the rock record

The extinction of the dinosaurs

Charting the Late Cretaceous seas: mosasaur richness and morphological diversification

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