Hadrosaur-like vascularisation in the dentary of an early diverging iguanodontian dinosaur

ABSTRACT

Virtual palaeontology is a growing field, leading palaeontologists to better understand the microanatomy of many extinct species. The application of techniques such as CT and μCT-scanning allows the researchers to study micro-anatomical features in a non-invasive way and make inferences on the palaeobiology of animals. Dinosaurs have been extensively studied using these techniques, with particular focus on the microanatomy of the cranium, whereas relatively little is known of other cranial elements, such as the lower jaw. Here, we aim to fill this gap, describing the microanatomy of the specimen ML 768, an isolated dentary belonging to a dryosaurid iguanodontian dinosaur from the Upper Jurassic of Lourinhã Fm. The dentary ML 768 was subjected to μCT-scanning, and subsequently the data were segmented in Avizo and rendered in Blender. We identified functional and replacement teeth, recognising remnants of old replacement cycles. Furthermore, we mapped a rich neurovascular network present in the dentary and compared it with reference literature. We found that the high vascularisation is shared with other cerapodan dinosaurs with high tooth replacement rates, although homoeostasis may have also played a role in the development of this condition. Further evidence is needed to appreciate the macroevolutionary significance of these findings.

KEYWORDS:

• Vascularisation
• tooth replacement
• Ornithischia
• homeostasis
• Iguanodontia
• Jurassic

Acknowledgments

We deeply thank all the workers and volunteers of Museu da Lourinhã, where the specimen is deposited. Moreover, we thank the CT-scan technical staff at CENIEH for the assistance during data acquisition. We would like to thank three anonymous reviewers that greatly improved the quality of this manuscript. This work is funded by national funds through the Fundação para a Ciência e a Tecnologia (FCT), I.P., through the Research Unit GeoBioTec UIDB/04035/2020; the project BioGeoSauria PTDC/CTA-PAL/2217/2021 and the fellowship SFRH/BD/146230/2019 PhD fellowship (FMR); MMA is supported by the MCIN/AEI/10.13039/501100011033 and co-financed by the NextGeneration EU/PRTR, Ramón y Cajal contract RYC2021-034473-I, and by the Ministerio de Ciencia e Innnovación with the grant PID2021-122612OB-100. FB is supported by BELSPO BRAIN-be 2.0 , with the project Iguanodon 2.0.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Fundação para a Ciência e a Tecnologia [SFRH/BD/146230/2019]; [UIDB/04035/2020]; [PTDC/CTA-PAL/2217/2021]; Ministerio de Ciencia e Innovación [PID2021-122612OB-100]; MCIN/AEI/10.13039/501100011033 NextGeneration EU/PRTR [RYC2021-034473-I]; BELSPO BRAIN-be 2.0 [Iguanodon 2.0].