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23 de marzo de 2017
Morfología y un nuevo análisis de la filogenia de los dinosaurios
The proposed new family tree of dinosaurs. The group to the left is for close relatives but not true dinosaurs. The old tree grouped the theropods, purple, with the Saurischia, green, and viewed the Saurischia and the Ornithischia as the two major branches of the tree. The scale to the left shows the placement of the tree in geological time. A is the branchpoint that includes all the dinosaurs, B represents the joint ancestor of Ornithischia and the theropods, and C is the joint ancestor of Saurischia and an early group known as herrerasaurs. Credit Baron et al./Nature
Hay una nota interesante en NYTimes aqui: > https://www.nytimes.com/2017/03/22/science/dinosaur-family-tree.html?_r=0
El resumen del articulo original esta aqui:
A new hypothesis of dinosaur relationships and early dinosaur evolution. 2017.
Matthew G. Baron, David B. Norman & Paul M. Barrett.
Nature 543, 501–506 (23 March 2017) doi:10.1038/nature21700
Abstract. For 130 years, dinosaurs have been divided into two distinct clades—Ornithischia and Saurischia. Here we present a hypothesis for the phylogenetic relationships of the major dinosaurian groups that challenges the current consensus concerning early dinosaur evolution and highlights problematic aspects of current cladistic definitions. Our study has found a sister-group relationship between Ornithischia and Theropoda (united in the new clade Ornithoscelida), with Sauropodomorpha and Herrerasauridae (as the redefined Saurischia) forming its monophyletic outgroup. This new tree topology requires redefinition and rediagnosis of Dinosauria and the subsidiary dinosaurian clades. In addition, it forces re-evaluations of early dinosaur cladogenesis and character evolution, suggests that hypercarnivory was acquired independently in herrerasaurids and theropods, and offers an explanation for many of the anatomical features previously regarded as notable convergences between theropods and early ornithischians.
Puesto en linea por Efrain De Luna