xquisite air sac histological traces in a hyperpneumatized nanoid sauropod dinosaur from South Americ

Author(s)

Aureliano, Tito ^{[1, 2, 3]} ; Ghilardi, Aline M. ^[2] ; Navarro, Bruno A. ^{[3, 4]} ; Fernandes, Marcelo A. ^[3] ; Ricardi-Branco, Fresia ^[1] ; Wedel, Mathew J. ^{[5, 6]}

Affiliation

^[1] Univ Estadual Campinas, Inst Geosci, Lab Paleontol & Paleohidrogeol, UNICAMP, Campinas, SP - Brazil

^[2] Fed Univ Rio Grande do Norte URFN, Dept Geol, Divers Ichnol & Osteohistol Lab DINOlab, Natal, RN - Brazil

^[3] Fed Univ Sao Carlos UFSCar, Dept Ecol & Biol Evolut DEBE, Lab Paleoecol & Paleoicnol LPP, Sao Carlos - Brazil

^[4] Univ Sao Paulo, Lab Paleontol, Museu Zool, Sao Paulo - Brazil

^[5] Western Univ Hlth Sci, Coll Osteopath Med Pacific, Pomona, CA - USA

^[6] Western Univ Hlth Sci, Coll Podiatr Med, Pomona, CA - USA

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 11, n. 1 DEC 17 2021.
• Web of Science Citations: 0

Abstract

This study reports the occurrence of pneumosteum (osteohistological structure related to an avian-like air sac system) in a nanoid (5.7-m-long) saltasaurid titanosaur from Upper Cretaceous Brazil. We corroborate the hypothesis of the presence of an air sac system in titanosaurians based upon vertebral features identified through external observation and computed tomography. This is the fifth non-avian dinosaur taxon in which histological traces of air sacs have been found. We provided a detailed description of pneumatic structures from external osteology and CT scan data as a parameter for comparison with other taxa. The camellate pattern found in the vertebral centrum (ce) of this taxon and other titanosaurs shows distinct architectures. This might indicate whether cervical or lung diverticula pneumatized different elements. A cotylar internal plate of bone tissue sustains radial camellae (rad) in a condition similar to Alamosaurus and Saltasaurus. Moreover, circumferential chambers (cc) near the cotyle might be an example of convergence between diplodocoids and titanosaurs. Finally, we also register for the first time pneumatic foramina (fo) and fossae connecting camellate structures inside the neural canal in Titanosauria and the second published case in non-avian dinosaurs. The extreme pneumaticity observed in this nanoid titanosaur contrasts with previous assumptions that this feature correlates with the evolution of gigantic sizes in sauropodomorphs. This study reinforces that even small-bodied sauropod clades could present a hyperpneumatized postcranial skeleton, a character inherited from their large-bodied ancestors. (AU)

• FAPESP's process: 19/16727-3 - Tafonomical landscapes
• Grantee: Fresia Soledad Ricardi Torres Branco
• Support Opportunities: Regular Research Grants