Sobre el tamaño de los dinosaurios carnívoros

En un reciente trabajo publicado en el último número del Journal of Vertebrate Paleontology se hace un interesante estudio del tamaño de los terópodos calculado a partir del cráneo. Se propone un modelo obtenido a partir de ejemplares completos en los que se obtiene una formula para conocer el tamaño de los dinosaurios terópodos a partir del cráneo. Obtienen interesantes conclusiones para ejemplares que están incompletos. Así calculan que Carcharodontosaurus y Giganotosaurus tendrían una longitud de unos 13 metros y un peso de 15 y 13 toneladas respectivamente. El mayor tamaño que obtienen es para un ejemplar de Spinosaurus aegyptiacus, que mediría 14,34 metros y pesaría 20,8 toneladas. Por supuesto no podíamos olvidarnos de Tyrannosaurus rex (Sue), considera una longitud de 12 metros y un peso de casí ocho toneladas.

!!!Al final Spielberg tenía razón, Spinosaurus era más grande que Tyrannosaurus!!!

La referencia al artículo es:

Therrien, F. & Henderson, D. M. 2007. My theropod is bigger than yours...or not: estimating body size from skull length in theropods. Journal of Vertebrate Paleontology, 27, 1, 108-115.

El resumen en inglés

To develop a widely applicable method to estimate body size in theropods, the scaling relationship between skull length, body length, and body mass was investigated using 13 strictly carnivorous, non-avialan theropod taxa ranging in size from the 1-m Sinosauropteryx prima to the 12-m Tyrannosaurus rex. Body length was obtained from the literature for complete to nearly-complete specimens and body mass was obtained from three-dimensional mathematical slicing of those same specimens to ensure accurate body length-body mass associations. Least-square regressions reveal a tight correlation between skull length and body length (SK-BL) and skull length and body mass (SK-BM). The SK-BL regression is negatively allometric, which indicates that skulls become longer relative to body length with increasing
body size. In contrast, the SK-BM regression is positively allometric, indicating that body mass increases faster than skull length with increasing body size. These conclusions confirm that the common practice of scaling isometrically smaller relatives of a given taxon to obtain body length and body mass estimates is not valid. Although predictive equations derived from the regressions fail to predict accurately body size in abelisaurids and juvenile theropods due to
their different head/body proportions, they produce accurate body size estimates for theropods of known body size, thus validating their applicability. Body size estimates for Carcharodontosaurus and Giganotosaurus, approaching 13 m and 14 tons, suggest that they may have surpassed Tyrannosaurus in size. A revised body size estimate for a large Spinosaurus specimen suggests a much shorter and heavier animal than recently suggested.