Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king

Grillo, Orlando Nelson; Delcourt, Rafael

doi:10.1016/j.cretres.2016.09.001

Cited by 40 publications

(30 citation statements)

References 52 publications

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“… Lametasaurus indicus has a highly robust tibia (Matley ; Carrano ) that provides our highest estimated mass among ceratosaurian theropods. However, Pycnonemosaurus , which was not included in our dataset, has comparable measurements of the tibia shaft and is likely to be of comparable body mass (Kellner & Campos ; Grillo & Delcourt ). …”

Section: Discussionmentioning

confidence: 99%

Cope's rule and the adaptive landscape of dinosaur body size evolution

et al. 2017

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The largest known dinosaurs weighed at least 20 million times as much as the smallest, indicating exceptional phenotypic divergence. Previous studies have focused on extreme giant sizes, tests of Cope's rule, and miniaturization on the line leading to birds. We use non-uniform macroevolutionary models based on Ornstein-Uhlenbeck and trend processes to unify these observations, asking: what patterns of evolutionary rates, directionality and constraint explain the diversification of dinosaur body mass? We find that dinosaur evolution is constrained by attraction to discrete body size optima that undergo rare, but abrupt, evolutionary shifts. This model explains both the rarity of multilineage directional trends, and the occurrence of abrupt directional excursions during the origins of groups such as tiny pygostylian birds and giant sauropods. Most expansion of trait space results from rare, constraint-breaking innovations in just a small number of lineages. These lineages shifted rapidly into novel regions of trait space, occasionally to small sizes, but most often to large or giant sizes. As with Cenozoic mammals, intermediate body sizes were typically attained only transiently by lineages on a trajectory from small to large size. This demonstrates that bimodality in the macroevolutionary adaptive landscape for land vertebrates has existed for more than 200 million years.

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Section: Discussionmentioning

confidence: 99%

Cope's rule and the adaptive landscape of dinosaur body size evolution

et al. 2017

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“…We performed an estimation of body length for the specimen MMCh-PV 67 using the method proposed by Grillo and Delcourt (2016), which is based on the dimensions of the axis centrum (length: 30 mm, width: 17.5 mm, height: 24. Both centra are anteroposteriorly elongated, almost three times longer than the height of the central sector (Fig.…”

Section: Its General Morphology Closely Resembles That Ofcarnotaurus mentioning

confidence: 99%

“…Using the method proposed by Grillo and Delcourt (2016), we estimated the body length of specimen MMCh-PV 66 using bivariate equations with two measurements of the tibial shaft (anteroposterior diameter: 84 mm, lateromedial width: 70 mm). This approach suggested a body length of 7.6 m based on anteroposterior diameter of the shaft, and 5.6 m based on the shaft width (probably an underestimated value, given some lateral crushing of the tibial shaft).…”

Section: Figure 11mentioning

confidence: 99%

The oldest theropods from the Neuquén Basin: Predatory dinosaur diversity from the Bajada Colorada Formation (Lower Cretaceous: Berriasian–Valanginian), Neuquén, Argentina

Canale

Apesteguı́a

Gallina

et al. 2017

Cretaceous Research

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Here, wedescribe newtheropod materials (several isolated teeth, an axis, two caudal centra anda proximal left tibia) fromthe type locality of theBajada Colorada Formation (Lower Cretaceous, Berriasian-Valanginian).Although fragmentary, the recovered material shows a diverse association of meat-eating dinosaurs for this poorly undestood period of time. Three techniques were used to assess the phylogenetic position of the isolated teeth: multivariate (PCA), discriminant and phylogenetic analyses. The morphotypes 1, 2 and 3 (small non-recurved isolated crowns) were regarded as Theropoda indet.,as our analyses failed to supporta more precise classification. Two large almost complete ziphodont crowns, considered morphotype 4, were identified as belonging to megalosaurid tetanurans by phylogenetic, discriminantand multivariate analyses, thus likely representing the first record of this ancient family in South America, and the youngest worldwide. We refer the axis to a small abelisauroid ceratosaurian based on the following suite ofcharacters; long and pointed epipophyses,a pneumatic foramen in the centrum,the invaginated spinopostzygapophyseal lamina, and the anteroposteriorly long, dorsally convex, anddorsally/posteriorly unexpanded neural spine. The caudal centra can be referred to a theropod, and tentatively to Abelisauroidea, suggesting that theymay belong to the same taxon than that represented by the axis.The tibia lacks the incisura tibialis, presents a low, sharp and proximally positioned fibular crest,and has a deep lateral fossa, which islimited dorsally by a coarse, rounded in section and anteriorly directed crest.This combination of features allowsto refer it to a large abelisaurid. The Bajada Colorada dinosaur recordincludes so fara small abelisauroid, a large abelisaurid,aprobably medium to large megalosaurid tetanuran,diplodocid and dicraeosaurid sauropods. It shows some similarities with Middle and Upper Jurassic units in centralPatagonia, Africa and Portugal,suggesting that no significant dinosaur faunal turnover took place through the Jurassic-Cretaceous event inthe southern part of South America.

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“…Bertini (1996) described a fragment of a right premaxilla and Brum et al (2016) described a fragmentary left ilium and distal portion of a right femur. These latter specimens were estimated to belong to separate individuals that were each approximately 2-3 meters long in total body length, making them relatively small abelisaurids compared to giants such as Carnotaurus that were approximately 8 meters long (Grillo and Delcourt 2017) and had body masses in excess of 1.5 tons (Benson et al 2014).…”

Section: Latest Cretaceous Dinosaurs From Brazilmentioning

confidence: 99%

“…Sometimes in the literature, the Cretaceous rocks of Mato Grosso state are said to be correlated with the Adamantina Formation based on the aeolosaurin specimen (e.g., Candeiro et al 2012b), but the correlations to the similaraged Presidente Prudente and Marília formations are not explicitly mentioned. Grillo and Delcourt (2017) used bone scaling equations to estimate the body length of Pycnonemosaurus at 8.9 meters, which would make it the largest known abelisaurid. It is possible that this size estimate may be overinflated, because the bones used to calculate it are fragmentary, but what is clear is that Pycnonemosaurus is among the largest abelisaurids yet found and would have been a top-of-the-food-chain predator probably quite similar to Carnotaurus in its size and behaviors.…”

Section: Latest Cretaceous Dinosaurs From Brazilmentioning

confidence: 99%

The last dinosaurs of Brazil: The Bauru Group and its implications for the end-Cretaceous mass extinction

Brusatte

Candeiro

Simbras

2017

An. Acad. Bras. Ciênc.

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The non-avian dinosaurs died out at the end of the Cretaceous, ~66 million years ago, after an asteroid impact. The prevailing hypothesis is that the effects of the impact suddenly killed the dinosaurs, but the poor fossil record of latest Cretaceous (Campanian-Maastrichtian) dinosaurs from outside Laurasia (and even more particularly, North America) makes it difficult to test specific extinction scenarios. Over the past few decades, a wealth of new discoveries from the Bauru Group of Brazil has revealed a unique window into the evolution of terminal Cretaceous dinosaurs from the southern continents. We review this record and demonstrate that there was a diversity of dinosaurs, of varying body sizes, diets, and ecological roles, that survived to the very end of the Cretaceous (Maastrichtian: 72-66 million years ago) in Brazil, including a core fauna of titanosaurian sauropods and abelisaurid and carcharodontosaurid theropods, along with a variety of small-to-mid-sized theropods. We argue that this pattern best fits the hypothesis that southern dinosaurs, like their northern counterparts, were still diversifying and occupying prominent roles in their ecosystems before the asteroid suddenly caused their extinction. However, this hypothesis remains to be tested with more refined paleontological and geochronological data, and we give suggestions for future work.

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Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king

Cited by 40 publications

References 52 publications

Cope's rule and the adaptive landscape of dinosaur body size evolution

Cope's rule and the adaptive landscape of dinosaur body size evolution

The oldest theropods from the Neuquén Basin: Predatory dinosaur diversity from the Bajada Colorada Formation (Lower Cretaceous: Berriasian–Valanginian), Neuquén, Argentina

The last dinosaurs of Brazil: The Bauru Group and its implications for the end-Cretaceous mass extinction

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