Histology and postural change during the growth of the ceratopsian dinosaur Psittacosaurus lujiatunensis

Zhao, Qi; Benton, Michael J.; Sullivan, Corwin; Sander, P. Martin; Xu, Xing

doi:10.1038/ncomms3079

Cited by 57 publications

(76 citation statements)

References 26 publications

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“…The quadrupedal to bipedal shift inferred for Psittacosaurus is predicated upon the differential allometry of the fore-and hind limbs, which results in forelimbs that are relatively longer in young juveniles and shorter in older juveniles and adults (Zhao et al 2013). A similar phenomenon has also been documented in a growth series of the sauropodomorph Massospondylus (Reisz et al 2005).…”

Section: Determining Stance In Ornithischiansmentioning

confidence: 68%

“…Moreover, ontogenetic shifts in stance have been posited for some ornithopod taxa (e.g. Iguanodon, Maiasaura) and Scelidosaurus, with juveniles interpreted as bipeds and adults as quadrupeds (Norman 1980;Dilkes 2001;Maidment and Barrett 2014); a converse quadrupedal to bipedal shift has been proposed for the ceratopsian Psittacosaurus (Zhao et al 2013).…”

Section: Determining Stance In Ornithischiansmentioning

confidence: 99%

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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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Section: Determining Stance In Ornithischiansmentioning

confidence: 68%

Section: Determining Stance In Ornithischiansmentioning

confidence: 99%

The evolution of ornithischian quadrupedality

Barrett

Maidment

2017

J Iber Geol

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“…) and the ornithischian clades Thyreophora, Ceratopsia (Chinnery ; Chinnery & Horner ; Zhao et al . ) and Iguanodontia (Galton , ; Norman , ; Sereno ; Maidment et al . ).…”

Section: Resultsmentioning

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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“…This normalization method must be applied cautiously, as comparing different skeletal elements from taxa with different limb allometries, gaits, and ecologies can lead to erroneous conclusions about growth (see Zhao et al 2013;Cullen et al 2014). Tight correlations with limb element dimensions and body length/mass, as well as maximum appositional growth rates, as noted with the alligator femora, must be demonstrated before being utilized in such normalized comparisons to ensure that the same growth characteristics are being compared.…”

Section: Discussionmentioning

confidence: 99%

Maiasaura, a model organism for extinct vertebrate population biology: a large sample statistical assessment of growth dynamics and survivorship

Woodward¹,

Fowler²,

Farlow³

et al. 2015

Paleobiology

185

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Abstract.-Fossil bone microanalyses reveal the ontogenetic histories of extinct tetrapods, but incomplete fossil records often result in small sample sets lacking statistical strength. In contrast, a histological sample of 50 tibiae of the hadrosaurid dinosaur Maiasaura peeblesorum allows predictions of annual growth and ecological interpretations based on more histologic data than any previous large sample study. Tibia length correlates well (R 2 > 0.9) with diaphyseal circumference, cortical area, and bone wall thickness, thereby allowing longitudinal predictions of annual body size increases based on growth mark circumference measurements. With an avian level apposition rate of 86.4 μm/day, Maiasaura achieved over half of asymptotic tibia diaphyseal circumference within its first year. Mortality rate for the first year was 89.9% but a seven year period of peak performance followed, when survivorship (mean mortality rate = 12.7%) was highest. During the third year of life, Maiasaura attained 36% (x = 1260 kg) of asymptotic body mass, growth rate was decelerating (18.2 μm/day), cortical vascular orientation changed, and mortality rate briefly increased. These transitions may indicate onset of sexual maturity and corresponding reallocation of resources to reproduction. Skeletal maturity and senescence occurred after 8 years, at which point the mean mortality rate increased to 44.4%. Compared with Alligator, an extant relative, Maiasaura exhibits rapid cortical increase early in ontogeny, while Alligator cortical growth is much lower and protracted throughout ontogeny. Our life history synthesis of Maiasaura utilizes the largest histological sample size for any extinct tetrapod species thus far, demonstrating how large sample microanalyses strengthen paleobiological interpretations.Holly N. Woodward*. Museum of the Rockies,

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Histology and postural change during the growth of the ceratopsian dinosaur Psittacosaurus lujiatunensis

Cited by 57 publications

References 26 publications

The evolution of ornithischian quadrupedality

The evolution of ornithischian quadrupedality

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

Maiasaura, a model organism for extinct vertebrate population biology: a large sample statistical assessment of growth dynamics and survivorship

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