. Is the frontoparietal foramen present in rebbachisaurid sauropods? New materials from patagonia shed light on this anatomical feature

LERZO, L.; GALLINA, P.A.; OTERO, A.; CANALE, J. I.

Mendoza

Jornada; 34º Jornadas Argentinas de Paleontología de Vertebrados; 2021

IANIGLA-CONICET

Barremian to Turonian (Lower to Upper Cretaceous). In the last two decades, the knowledge about the anatomy ofRebbachisauridae has increased, although skull remains are frequently incomplete and poorly known; out of 17 speciesaround the world, only four taxa preserved cranial remains (Limaysaurus, Nigersaurus, Lavocatisaurusand MMCh-PV 71).Except for Lavocatisaurus, remaining rebbachisaurids preserved the neurocranium and would seem to share the absence ofa frontoparietal foramen, which is also known as ?pineal?, ?postfrontal?, ?parietal?, ?interfrontal foramen? or ?frontoparietalfenestra?. The presence of this opening is usually considered as a synapomorphy of Dicraeosauridae and, outside this family,it is also present in Apatosaurus(BYU-17096) and the basal sauropod Spinophorosaurus. Skull roof materials of an adultrebbachisaurid (MMCh-PV 70) from Huincul Formation, collected near Villa El Chocón, present a conspicuous frontoparietalforamen. The preserved fused frontals exhibit the anterior margin of this foramen. After a careful examination, this featureis also recognized in the rebbachisaurid specimen MMCh-PV 71, although not mentioned in its original description. Whilesome authors hypothesized that this foramen is related to the parietal-pineal complex of the forebrain, others consideredthis structure related to ontogeny and present in young individuals. This novel evidence indicates that this frontoparietalforamen is present in some adult specimens of Rebbachisauridae and shows a wider distribution within Diplodocoidea,with a clear potential as a morphological character to analyze in future phylogenetic studies of this group.