Re-description of the braincase of the rebbachisaurid sauropod Limaysaurus tessonei and novel endocranial information based on CT scans

Abstract

CT scans of the type braincase of Limaysaurus tessonei (MUCPv-205) allowed the first study of the endocranial cavities (brain and inner ear) for this South American taxon. Comparisons of the cranial endocast of L. tessonei with other sauropods indicate that 1) South American rebbachisaurids are more similar to each other than to Nigersaurus, and 2) certain association of traits are present in all known rebbachisaurid cranial endocasts, such as lack of an enlarged dorsal expansion, poorly laterally projected cerebral hemispheres, presence of a small flocculus of the cerebellum, markedly long passage for the facial nerve (CN VII), markedly inclined pituitary, and presence of a passage for the basilar artery communicating the floor of the endocranial cavity and the pituitary fossa. The relatively enlarged olfactory region indicates that smell was an important sense for this group of dinosaurs, suggesting different olfactory capabilities when compared to coeval titanosaurs.

Sauropod dinosaur teeth from the lower Upper Cretaceous Winton Formation of Queensland, Australia and the global record of early titanosauriforms

“…Lower Albian deposits in Neuquén Province have yielded rebbachisaurids and non-titanosaurian somphospondylans including Ligabuesaurus [75,77,88,[172][173][174], whereas upper Albian deposits in Chubut Province have produced the lognkosaurian titanosaur Patagotitan [175,176], but no rebbachisaurids. Rebbachisaurids are represented in the Albian-Cenomanian of Brazil [177], and dominate Cenomanian-Turonian sauropod faunas across Argentina [178][179][180][181][182][183][184][185][186][187][188]. The latter deposits also preserve a variety of titanosaurs, including early branching forms, such as Andesaurus, Epachthosaurus and Sarmientosaurus, as well as lognkosaurians including Argentinosaurus [58,74,84,85,[189][190][191][192][193][194][195][196][197][198].…”

They call me the wanderer – Neurovascular anatomy of dwarfed dinosaur implies precociality in sauropods

“…Similarly, a pronounced concavity is present between the LSC and the PSC (best seen in dorsal view). Both concave gaps (the ASC and the PSC project further laterally than the lateral outline of the LSC reaches medially) are similarly present in many Titanosauriformes (with the exception of FAM 03.064 37 ): Giraffatitan 6 , Malawisaurus 38 , Sarmientosaurus 25 , CCMGE 628/12457 24 , Jainosaurus 38 , Ampelosaurus 22 , Narambuenatitan 23 , Bonatitan , Antarctosaurus , MCF-PVPH 765 and MGPIFD-GR 118 7 , but also in the rebbachisaurids Limaysaurus and Nigersaurus 39 . In contrast to other sauropods, the anterior portion of the LSC, as well as its lateral-most extent (best seen in dorsal view) seems somewhat posteriorly shifted in the macronarians Camarasaurus 29 and Europasaurus (Fig.…”

“…Whereas most sauropod taxa seem not to spot even the slightest floccular recess on the endocast (see e.g. 7, 15 and references therein), there are some exceptions 16,17,18,19 including Giraffatitan 20 . In case the size of the floccular recess at least partly reflects the actual flocculus in fossil taxa, it potentially holds evidence for superior VOR and VCR in Europasaurus and other sauropods that possess this structure (Fig.…”

Neurovascular anatomy of dwarf dinosaur implies precociality in sauropods

“…Similarly, a pronounced concavity is present between the LSC and the PSC (best seen in dorsal view). Both concave gaps (the ASC and the PSC project further laterally than the lateral outline of the LSC reaches medially) are similarly present in many Titanosauriformes (with the exception of FAM 03.064; Knoll et al, 2019 ): Giraffatitan ( Janensch, 1935 ), Malawisaurus ( Andrzejewski et al, 2019 ), Sarmientosaurus ( Martínez et al, 2016 ), CCMGE 628/12457 ( Sues et al, 2015 ), Jainosaurus ( Andrzejewski et al, 2019 ), Ampelosaurus ( Knoll et al, 2013 ), Narambuenatitan ( Paulina-Carabajal et al, 2020 ), Bonatitan , Antarctosaurus , MCF-PVPH 765 and MGPIFD-GR 118 ( Paulina-Carabajal, 2012 ), but also in the rebbachisaurids Limaysaurus and Nigersaurus ( Paulina-Carabajal and Calvo, 2021 ). In contrast to other sauropods, the anterior portion of the LSC, as well as its lateral-most extent (best seen in dorsal view), seems somewhat posteriorly shifted in the macronarians Camarasaurus ( Witmer and Ridgely, 2008a ) and Europasaurus ( Figure 6B,F,J ; for further discussion, see Supplementary file 1 ).…”