Mass Prediction in Theropod Dinosaurs

Christiansen, Per; Fariña, Richard A.

doi:10.1080/08912960412331284313

Cited by 148 publications

(146 citation statements)

References 35 publications

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“…The therizinosaurids Therizinosaurus (6647 kg) and Nanshiungosaurus brevispinus (6280 kg) rank among the largest coelurosaurians, rivalling the mass of most large-bodied tyrannosaurids [35], whereas the therizinosaurians Segnosaurus and Suzhousaurus also achieved massive size (more than 1200 kg). Lower limits on BM in therizinosaurians are also comparatively high.…”

Section: Results (A) Body Mass Estimatesmentioning

confidence: 99%

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No evidence for directional evolution of body mass in herbivorous theropod dinosaurs

Zanno

Makovicky

2013

Proc. R. Soc. B.

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The correlation between large body size and digestive efficiency has been hypothesized to have driven trends of increasing mass in herbivorous clades by means of directional selection. Yet, to date, few studies have investigated this relationship from a phylogenetic perspective, and none, to our knowledge, with regard to trophic shifts. Here, we reconstruct body mass in the three major subclades of non-avian theropod dinosaurs whose ecomorphology is correlated with extrinsic evidence of at least facultative herbivory in the fossil record-all of which also achieve relative gigantism (more than 3000 kg). Ordinary least-squares regressions on natural logtransformed mean mass recover significant correlations between increasing mass and geological time. However, tests for directional evolution in body mass find no support for a phylogenetic trend, instead favouring passive models of trait evolution. Cross-correlation of sympatric taxa from five localities in Asia reveals that environmental influences such as differential habitat sampling and/or taphonomic filtering affect the preserved record of dinosaurian body mass in the Cretaceous. Our results are congruent with studies documenting that behavioural and/or ecological factors may mitigate the benefit of increasing mass in extant taxa, and suggest that the hypothesis can be extrapolated to herbivorous lineages across geological time scales.

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Section: Results (A) Body Mass Estimatesmentioning

confidence: 99%

“…We estimated BM using the theropod-specific equation relating BM to femoral length (FL) [35]. Although mass estimates are subject to large uncertainties [36], we chose to apply a single equation for consistency.…”

Section: Materials and Methods (A) Mass Estimates And Treesmentioning

confidence: 99%

No evidence for directional evolution of body mass in herbivorous theropod dinosaurs

Zanno

Makovicky

2013

Proc. R. Soc. B.

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“…Extensive apex predator guild restructuring in the Early Cretaceous of western North America is evidenced by a shift from well known Late Jurassic assemblages consisting of multiple clades of medium to large-bodied theropods towards terminal Cretaceous ecosystems dominated exclusively by large (2,000-5,000 kg) to gigantic (45,000 kg) tyrannosaurids 4,28 (Fig. 4a).…”

Section: Discussionmentioning

confidence: 99%

“…We interpolated an estimate for the femoral length (FL) of Siats, a widely used proxy for body size in dinosaurs [54][55][56] , from regressions against diaphyseal measurements of the fibula 28 . The fibula exhibits a phylogenetic trend towards diaphyseal reduction across theropod evolution, which we accounted for by employing Phylogenetic Independent Contrasts 57 to find the regressions and their confidence intervals.…”

Section: Methodsmentioning

confidence: 99%

Neovenatorid theropods are apex predators in the Late Cretaceous of North America

Zanno

Makovicky

2013

Nat Commun

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Allosauroid theropods were a diverse and widespread radiation of Jurassic-Cretaceous megapredators. Achieving some of the largest body sizes among theropod dinosaurs, these colossal hunters dominated terrestrial ecosystems until a faunal turnover redefined apex predator guild occupancy during the final 20 million years of the Cretaceous. Here we describe a giant new species of allosauroid -Siats meekerorum gen. et sp. nov. -providing the first evidence for the cosmopolitan clade Neovenatoridae in North America. Siats is the youngest allosauroid yet discovered from the continent and demonstrates that the clade endured there into the Late Cretaceous. The discovery provides new evidence for ecologic sympatry of large allosauroids and small-bodied tyrannosauroids. These data support the hypothesis that extinction of Allosauroidea in terrestrial ecosystems of North America permitted ecological release of tyrannosauroids, which went on to dominate end-Cretaceous food webs.

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“…Epidexipteryx is estimated to be 164 grams in body mass (see SI), smaller than most other basal avialans 3,11 . The holotype probably represents a subadult individual, since the ends of some of the long bones appear imperfectly ossified.…”

Section: Description and Comparisonsmentioning

confidence: 99%