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Is there any evidence for the presence of extensive fibrolamellar complex in Notosuchia? New data on Araripesuchus wegeneri

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Faure-Brac, Mathieu, G | Cubo, Jorge

Edité par CCSD ; Wiley -

International audience. Here we describe the bone histology of a femur of Araripesuchus wegeneri, using both cross and longitudinal thin sections. The parasagittal stance and high maximum metabolic rate inferred for this taxon is often linked to the capacity of formation of sustained fibrolamellar complex (FLC), as it occurs in extant endotherms. This paper aims to test this hypothesis. The cross section of the sampled specimen MNHN.F.GDF660 revealed it was subadult, an ideal ontogenetic stage to check the presence of FLC as this tissue is formed mainly during early ontogenetic stages and is often eroded or remodelled in the adult stage. Although localized areas of FLC have been described in other Notosuchia, no evidence was found here for the presence of this tissue type in A. wegeneri. The hypothesis of the formation of sustained FLC in this taxon was, thus, ruled out, even though these animals were characterized by an upright position and very high maximum metabolic rates. These organisms have, therefore, no extant equivalences.

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