Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage

Benson, Roger B. J.; Campione, Nicolás E.; Carrano, Matthew T.; Mannion, Philip D.; Sullivan, Corwin; Upchurch, Paul; Evans, David C.

doi:10.1371/journal.pbio.1001853

Cited by 339 publications

(463 citation statements)

References 86 publications

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“…Along with the phylogenetic proximity of the two taxa, this suggests that the holotypic individual of T. euotica was roughly the same body size as Xiongguanlong, whose mass has been estimated at 170-270 kg (14,15). Although most sutures on the holotype of T. euotica are fused, part of the broken parabasisphenoid was not fused to the remainder of the braincase, perhaps suggesting that the individual was not yet osteologically mature and adults of the species may have been somewhat larger.…”

Section: Body Sizementioning

confidence: 89%

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

Brusatte

Averianov

Sues

et al. 2016

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

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Tyrannosaurids-the familiar group of carnivorous dinosaurs including Tyrannosaurus and Albertosaurus-were the apex predators in continental ecosystems in Asia and North America during the latest Cretaceous (ca. 80-66 million years ago). Their colossal sizes and keen senses are considered key to their evolutionary and ecological success, but little is known about how these features developed as tyrannosaurids evolved from smaller basal tyrannosauroids that first appeared in the fossil record in the Middle Jurassic (ca. 170 million years ago). This is largely because of a frustrating 20+ millionyear gap in the mid-Cretaceous fossil record, when tyrannosauroids transitioned from small-bodied hunters to gigantic apex predators but from which no diagnostic specimens are known. We describe the first distinct tyrannosauroid species from this gap, based on a highly derived braincase and a variety of other skeletal elements from the Turonian (ca. 90-92 million years ago) of Uzbekistan. This taxon is phylogenetically intermediate between the oldest basal tyrannosauroids and the latest Cretaceous forms. It had yet to develop the giant size and extensive cranial pneumaticity of T. rex and kin but does possess the highly derived brain and inner ear characteristic of the latest Cretaceous species. Tyrannosauroids apparently developed huge size rapidly during the latest Cretaceous, and their success in the top predator role may have been enabled by their brain and keen senses that first evolved at smaller body size.dinosaur | Tyrannosauroidea | Uzbekistan | phylogenetics | evolution

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Section: Body Sizementioning

confidence: 89%

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

Brusatte

Averianov

Sues

et al. 2016

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

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“…et al 2014b). These body masses are much lower than those of many bipedal dinosaurs, including those that reached body masses [ 1000 kg, as in many allosauroids, megalosauroids, tyrannosauroids and a variety of basal sauropodomorphs (Benson et al 2014). …”

Section: Evolutionary Drivers Of Ornithischian Quadrupedalitymentioning

confidence: 92%

“…However, a brief survey of dinosaur evolutionary history demonstrates that increased body size per se cannot have been the primary driver for ornithischian quadrupedality in the majority of cases. In most ornithischian clades, including Ceratopsia, Rhabdodontidae and Thyreophora, these transitions occurred at relatively small body sizes: quadrupedal basal ceratopsians, such as Leptoceratops and Protoceratops, range from around 80-400 kg in weight (Benson et al 2014), rhabdodontid ornithopods weigh 31-120 kg (Benson et al 2014) and Scelidosaurus weighed up to 320 kg (Maidment. et al 2014b).…”

Section: Evolutionary Drivers Of Ornithischian Quadrupedalitymentioning

confidence: 99%

The evolution of ornithischian quadrupedality

Barrett

Maidment

2017

J Iber Geol

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Ornithischian dinosaurs were primitively bipedal, but reverted to quadrupedality on at least three (and potentially several more) occasions: in Ceratopsia, Thyreophora and Hadrosauriformes. Each of these reversals was accompanied by anatomical changes to the whole skeleton that enabled the forelimb to function in weight bearing and that also resulted in numerous changes to the hip and hind limb musculature. Each quadrupedal clade acquired a suite of similar biomechanical characters, although they varied in terms of function and in how these character complexes were assembled. Some similar changes occurred in parallel among sauropodomorph dinosaurs as they transitioned from bipedality to quadrupedality. It is unclear why bipedal ornithischians reverted to quadrupedalism, but neither increases in body size nor the acquisition of dermal armour seem to have played a significant role. Increased head size might have influenced the position of the centre of mass and stance in ceratopsians and it is plausible that the evolution of herbivory played an important role in both ornithischians and sauropods, but the latter hypothesis is difficult to test.Resumen Los dinosaurios Ornitísquios, bípedos en origen, revertieron a la condición cuadrúpeda en al menos tres (y potencialmente más) ocasiones: en Ceratopsia, Thyreophora y Hadrosauriformes. Cada una de estas reversiones vino acompañada de cambios anatómicos en el resto de esqueleto que permitieron a la extremidad anterior funcionar para soportar su peso y llevaron a cambios en la cadera y la musculatura dela extremidad posterior. Cada clado cuadrúpedo adquirió una serie de caracteres biomecánicos parecidos, aunque variaron en su función y en la manera en la que estos conjuntos de caracteres encajaban. Cambios parecidos aparecieron paralelamente entre los dinosaurios sauropodomorfos durante su transición de bípedos a cuadrúpedos. Aunque no queda claro por qué los ornitísquios revertieron al cuadrupedismo, ni el aumento de masa corporal ni la adquisición de armadura parecen haber jugado un papel significativo. Un mayor tamaño de la cabeza pudo haber repercutido en el cambio de posición del centro de masas y cambio en la postura en los ceratopsios, y es posible que la evolución de la fitofagia jugara un papel importante, tanto en ornitísquios como saurópodos, aunque sea una hipótesis difícilmente contrastable.Palabras clave Ornithischia Á Dinosauria Á Locomoción Á Cuadrupedismo Á Biomecánica Á Morfología funcional Á Evolución

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“…Larger animals generally have access to larger prey due to their increased gape and greater absolute muscular power, and size is further related to morphology via allometry, the tendency of traits to vary with size throughout a morphological structure. Allometry has been demonstrated to be a key contributing factor to craniofacial form across a range of mammalian (17, 18) and avian (15, 19) clades, and evolvability of body size is proposed to be a major evolutionary pathway in the avian stem (20).In this study, we quantified the role of adaptation versus constraint in avian craniofacial evolution. Using diurnal birds of prey ("raptors"), we quantified the degree to which morphological convergence in feeding ecology can be attributed to variation controlled by evolutionary allometry (size), phylogeny, and integration between the beak and braincase.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

The shapes of bird beaks are highly controlled by nondietary factors

Bright

Marugán‐Lobón

Cobb

et al. 2016

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

201

259

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Bird beaks are textbook examples of ecological adaptation to diet, but their shapes are also controlled by genetic and developmental histories. To test the effects of these factors on the avian craniofacial skeleton, we conducted morphometric analyses on raptors, a polyphyletic group at the base of the landbird radiation. Despite common perception, we find that the beak is not an independently targeted module for selection. Instead, the beak and skull are highly integrated structures strongly regulated by size, with axes of shape change linked to the actions of recently identified regulatory genes. Together, size and integration account for almost 80% of the shape variation seen between different species to the exclusion of morphological dietary adaptation. Instead, birds of prey use size as a mechanism to modify their feeding ecology. The extent to which shape variation is confined to a few major axes may provide an advantage in that it facilitates rapid morphological evolution via changes in body size, but may also make raptors especially vulnerable when selection pressures act against these axes. The phylogenetic position of raptors suggests that this constraint is prevalent in all landbirds and that breaking the developmental correspondence between beak and braincase may be the key novelty in classic passerine adaptive radiations.geometric morphometrics | integration | allometry | birds | modularity T he avian beak offers a classic example of adaptation to feeding ecology, with beak morphology frequently considered to represent evolutionary adaptation to specialized trophic niches [e.g., Galápagos finches (1), Hawaiian honeycreepers (2), and Madagascan vangas (3)]. Despite this axiom, we lack quantitative data on the degree to which skull and beak morphology is influenced not only by feeding ecology, but also by other sources of variation or constraint (4). Although the beak is often seen as the target of selection mechanisms closely allied to feeding ecology, such as prey type, feeding style, or beak use, evidence also suggests that beak morphology and variation may be constrained by a number of other factors, including evolutionary history (phylogeny) and development on the component parts of the entire skull. Breakthrough experiments in molecular genetics have shown that the mechanisms driving beak shape variation encompass modifications to the timing of expression of conserved developmental pathways (5-9), resulting in beak diversity described by a few relatively simple geometric transformations (10). However, pleiotropic associations between different skull structures can also contribute to the shape of the avian beak (11), and Sonic hedgehog signaling from the forebrain also relates to the spatial organization of, and changes to, face and beak shape (12)(13)(14). Furthermore, assessments of bird skull phenotypic variation suggest that beak morphology may evolve cohesively with cranial morphology (15,16). Size is also an important consideration when assessing morphological variation. Larger animals gene...

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Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage

Abstract: Early dinosaurs showed rapid evolutionary rates, which were sustained on the line leading to birds. Maintenance of evolvability in key lineages might explain the uneven distribution of trait diversity among groups of animal species.

Cited by 339 publications

References 86 publications

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

The evolution of ornithischian quadrupedality

The shapes of bird beaks are highly controlled by nondietary factors

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