Data from: Neuroanatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993

Although our knowledge on crocodylomorph palaeoneurology has experienced
considerable growth in recent years, the neuroanatomy of many
crocodylomorph taxa has yet to be studied. This is true for Australian
taxa, where thus far only two crocodylian crocodylomorphs have had aspects
of their neuroanatomy explored. Here, the neuroanatomy of the Australian
mekosuchine crocodylian Trilophosuchus rackhami is described for the first
time, which significantly increases our understanding on the
palaeoneurology of Australian crocodylians. The palaeoneurological
description is based on the taxon’s holotype specimen (QMF16856), which
was subjected to a µCT scan. Because of the exceptional preservation of
QMF16856, most neuroanatomical elements could be digitally reconstructed
and described in detail. Therefore, the palaeoneurological assessment
presented here is hitherto the most in-depth study of this kind for an
extinct Australian crocodylomorph. Trilophosuchus rackhami has a brain
endocast with a distinctive morphology that is characterized by an acute
dural peak over the hindbrain region. While the overall morphology of the
brain endocast is unique to T. rackhami, it does share certain
similarities with the notosuchian crocodyliforms Araripesuchus wegeneri
and Sebecus icaeorhinus. The endosseous labyrinth displays a morphology
that is typical for crocodylians, although a stand-out feature is the
unusually tall common crus. Indeed, the common crus of T. rackhami has one
of the greatest height ratios among crocodylomorphs with currently known
endosseous labyrinths. The paratympanic pneumatic system of T. rackhami is
greatly developed and most similar to those of the extant crocodylians
Osteolaemus tetraspis and Paleosuchus palpebrosus. The observations on the
neuroanatomy of T. rackhami are also discussed in the context of
Crocodylomorpha. The comparative palaeoneurology reinforces previous
evaluations that the neuroanatomy of crocodylomorphs is complex and
diverse among species, and T. rackhami has a peculiar neuromorphology,
particularly among eusuchian crocodyliforms.