Bonapartesaurus rionegrensis , a new hadrosaurine dinosaur from South America: implications for phylogenetic and biogeographic relations with North America

CRUZADO-CABALLERO, PENÉLOPE; POWELL, JAIME

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Año: 2017 vol. 37

0272-4634

The Gondwanan hadrosaurid dinosaur record is relatively poorly known and very complicated. A newhadrosaurid, Bonapartesaurus rionegrensis, gen. et sp. nov., from the late Campanian?early Maastrichtian of the SalitralMoreno site, Argentina, is characterized by the following combination of characters: the ratio between the height of theneural spines and that of the centrum of the sacral vertebrae greater than 3.5; neural spines of the anterior section of thecaudal vertebrae extremely long and evenly expanding distally; a preacetabular process of the ilium slightly deflectedventrally, with the angle greater than 150; the ratio between the maximum dorsoventral depth of the posterior end of thepreacetabular process and the dorsoventral distance from the pubic peduncle to the dorsal margin of the ilium less than 0.50;the ratio between the dorsoventral height and anteroposterior length of the iliac blade 0.8 or greater; asymmetrical lateralprofile of the supraacetabular process; the posterior portion of the postacetabular process markedly thicker mediolaterally asa result of the dorsomedial twist of the postacetabular process; an anteriorly expanded cnemial crest restricted to theproximal end of the tibia; and articular surface of the astragalus for the internal malleolus of the tibia moderately expandedmedially, articulating with only part of the ventral surface of the tibial internal malleolus. Our phylogenetic analysis indicatesthat Bonapartesaurus is located within the Tribe Saurolophini. Paleobiogeographically, its presence suggests at least twosaurolophine dispersal events from North America, one toward South America and another toward Asia, no later than thelate Campanian.