Notes on the axial skeleton of the titanosaur Bonitasaura salgadoi (Dinosauria-Sauropoda)

Abstract

Sauropod axial anatomy is particularly important in understanding morphological features and phylogenetic analyses. Spatial arrangement of zygapophyses and rib articulations, as well as their complex laminar development, help to recognize the relative position of isolated vertebral elements. The presence of anterior, mid and posterior elements along the cervical, dorsal and caudal series in Bonitasaura salgadoi allows the analysis of several anatomical characteristics. These include the pattern of neurocentral closure with unfused, partially fused and completely fused elements in a peculiar temporal sequence, as well as several neural spine modifications and the laminar arrangement. The variations in neural spine morphology include a lateral expansion of the distal tip in cervico-dorsal region, different lateral constituents of these lateral expansions, and a marked deviation in spine angulation. The spinal inclination allows the division into three easily recognizable vertebral regions separated by two landmarks, which adds support in the determination of an accurate vertebral position for isolated elements. Finally, an analysis of the vertebral laminae reveals the importance of examining vertebral series in order to recognize laminar homologies and developmental series. Two vertebral laminae are analyzed here.

A new multi-faceted framework for deciphering diplodocid ontogeny

“…The lack of a cortex consisting entirely of Haversian bone and the lack of an EFS indicates that skeletally, MOR 592 is immature (Figure 14). Klein and Sander (2008) and Gallina (2011Gallina ( , 2012 correlate HOS 9 with sexual maturity in sauropods. While vertebrate reproductive biology favors the onset of sexual maturity prior to skeletal maturity (van Tienhoven, 1983), no histologic indicators of sexual viability was observed (e.g., medullary tissue), therefore, we will not address the reproductive nature of MOR 592.…”

The youngest sauropod evidence in Europe

“…However, this feature may change along the axial skeleton of sauropods (e.g. see Gallina 2011). For instance, the angle between pocdl and podl of the anterior cervical series (from cv2 to cv6) of Jobaria increases from 208 to 508.…”

El Registro De Sauropodomorpha (Dinosauria) De La Argentina

“…Una de las características más notables de este taxón es la presencia del margen posterior del dentario edéntulo y afilado, con evidencias de alta vascularización, lo que permitió a Apesteguía (2004) inferir la presencia de un "pico", o una estructura similar. La presencia de centros vertebrales no fusionados al arco neural, sumado al abundante tejido fibrolamelar y a la ausencia de un Sistema Fundamental Externo, sugieren que el animal representado por el material holotipo de Bonitasaura salgadoi continuaba su crecimiento al momento de morir (Apesteguía, 2004;Gallina, 2011Gallina, , 2012 et al (2005), quedando pendiente la revisión del esqueleto axial para corroborar definitivamente la identidad taxonó-mica de N. robustus (Otero, 2010) (Fig. 6).…”