The endocranial anatomy of Buriolestes schultzi (Dinosauria: Saurischia) and the early evolution of brain tissues in sauropodomorph dinosaurs

Abstract

Our knowledge on the anatomy of the first dinosaurs (Late Triassic, 235–205 Ma) has drastically increased in the last years, mainly due to several new findings of exceptionally well‐preserved specimens. Nevertheless, some structures such as the neurocranium and its associated structures (brain, labyrinth, cranial nerves, and vasculature) remain poorly known, especially due to the lack of specimens preserving a complete and articulated neurocranium. This study helps to fill this gap by investigating the endocranial cavity of one of the earliest sauropodomorphs, Buriolestes schultzi, from the Upper Triassic (Carnian—c. 233 Ma) of Brazil. The endocranial anatomy of this animal sheds light on the ancestral condition of the brain of sauropodomorphs, revealing an elongated olfactory tract combined to a relatively small pituitary gland and well‐developed flocculus of the cerebellum. These traits change drastically across the evolutionary history of sauropodomorphs, reaching the opposite morphology in Jurassic times. Furthermore, we present here the first calculations of the Reptile Encephalization Quotient (REQ) for a Triassic dinosaur. The REQ of B. schultzi is lower than that of Jurassic theropods, but higher than that of later sauropodomorphs. The combination of cerebral, dental, and postcranial data suggest that B. schultzi was an active small predator, able to track moving prey.

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

“…21, 25 ; see 24 for an extreme reached in the titanosaur specimen CCMGE 628/12457 with a short anterior semicircular canal and an enormous pituitary). The finding of a relatively small pituitary fossa in Europasaurus and early-diverging sauropodomorphs seem to support a close connection of body and pituitary size 3, 36 . The microCT data of DFMMh/FV 581.1 suggest that the right CN VI canal closely passes by the pituitary fossa without a penetration, whereas the left CN VI canal tangents on the pituitary fossa and opens into the latter (Supplementary Fig.…”

“…117). The anterodorsally incomplete endocranial cavity of DFMMh/FV 581.1, 2 & 3 comprises a volume of about 35 cm 3 (including the pituitary fossa). A small funnel-like depression anterior to the occipital condyle on the ventral aspect of DFMMh/FV 581.1 ends blindly (Fig.…”

“…1, 2 ).The oldest indubitable sauropod taxa are known from Early Jurassic strata; the youngest representatives went extinct during the end-Cretaceous disaster 2 . Whereas bipedal early sauropodomorphs (in which sauropods are phylogenetically nested) were probably capable of swiftly tracking down prey 3 , the later evolutionary history of the group is characterized by an unrivaled increase in body size (among land-dwelling vertebrates), accompanied with herbivory, an extreme elongation in neck length and graviportal quadrupedality (e.g. 1, 4, 5 ).…”

Issi saaneq gen. et sp. nov.—A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland

“…Bagualosaurus agudoensis UFRGS-PV-1099-T [39] Buriolestes schultzi CAPPA/UFSM 0035; ULBRA-PVT280 [40][41][42] Coloradisaurus brevis PVL 3967 [43,44] Table 1. Cont.…”

“…This morphology differs from the dorsoventrally short, anteroposteriorly elongated and gently dorsally convex dorsoposterior process of the articular in Mac. itaquii (CAPPA/UFSM 0001b) [42] and the short (or even absent) and posteriorly convex dorsoposterior process of Pl. trossingensis (AMNH FARB 6810) [52].…”