A unique predator in a unique ecosystem: modelling the apex predator from the late cretaceous crocodyliform-dominated fauna in brazil

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>Theropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators. Baurusuchids exhibited a series of morphological adaptations hypothesised to be associated with this ecological role, but quantitative biomechanical analyses of their morphology have so far been lacking. Here, we employ a biomechanical modelling approach, applying finite element analysis (FEA) to models of the skull and mandibles of a baurusuchid specimen. This allowed us to characterise the craniomandibular apparatus of baurusuchids, as well as to compare the functional morphology of the group to that of other archosaurian carnivores, such as theropods and crocodylians. Our results support the ecological role of baurusuchids as specialised apex predators in the continental Late Cretaceous ecosystems of South America. With a relatively weak bite force (∼600 N), baurusuchids’ predation strategies likely relied on other morphological specializations, such as ziphodont dentition and strong cervical musculature. Comparative assessments of the stress distribution and magnitude of scaled models of other predators (the theropod <jats:italic>Allosaurus fragilis</jats:italic> and the living crocodylian <jats:italic>Alligator mississippiensis</jats:italic>) consistently show different responses to loadings under the same functional scenarios, suggesting distinct predatory behaviours for these animals. The unique selective pressures in the arid to semi-arid Late Cretaceous ecosystems of southeast Brazil, which were dominated by crocodyliforms, possibly drove the emergence and evolution of the biomechanical features seen in baurusuchids, which are distinct from those previously reported for other predatory taxa.</jats:p>

A unique predator in a unique ecosystem: modelling the apex predator within a Late Cretaceous crocodyliform‐dominated fauna from Brazil

“…Baurusuchids are phylogenetically included within Notosuchia, a group of highly diverse crocodyliforms which thrived mainly in Gondwana during the Cretaceous (Pol & Leardi 2015;Mannion et al 2015). Exhibiting a wide range of morphological variation, from gracile omnivores to pug-nosed herbivores, notosuchians contributed significantly to the highest peak of morphological disparity experienced by crocodyliforms across their evolutionary history (Wilberg 2017; Godoy 2019; Godoy et al 2019;Melstrom & Irmis 2019).…”

3D skull modelling and description of a new baurusuchid (Crocodyliformes, Mesoeucrocodylia) from the Late Cretaceous (Bauru Basin) of Brazil

“…The genus name is composed of the Greek words ἀφαυρός (aphauros), = feeble/powerless, and σοῦχος (souchos), = Egyptian name for crocodile, in reference to the week bite of the animal as demonstrated by Montefeltro et al, (2020). The species epithet is composed of ἐσχάρα (eschara), = Greek for scar, and facies, = Latin for face, in reference to the cut on the left jugal and dentary made by the rock saw during the collection of the specimen, which promptly gave the fossil its nickname “Scarface.”…”

“…The holotype of Aph . escharafacies (LPRP 0697) was recently examined in a revision of the osteoderm patterns in Baurusuchidae (Montefeltro, 2019) and was also modeled and studied with the Finite Element Analysis (FEA) of its skull (Montefeltro et al, 2020). Both works tentatively assigned the specimen to Ba .…”

“…Baurusuchidae is a group of terrestrial crocodyliforms that were top predators during the Cretaceous of what is South America today (Godoy et al, 2014; Montefeltro et al, 2020; Riff & Kellner, 2011). The fossil record of the group is mostly limited to the Adamantina/Vale do Rio do Peixe Formation, in Brazil, and the Bajo de La Carpa Formation, in Argentina.…”

“…dinizi . Additionally, the specimen described herein was used as a digital model in the work of Montefeltro et al, (2020), which employed tridimensional images of LPRP 0697 for Finite Element Analyses (FEA) in order to characterize cranial functional morphology. Here, we present the first tridimensional description of individual skull bones for a baurusuchid, and notosuchians in general, using CT scan image stacks and digital reconstructions.…”