Vrije Universiteit Brussel

Lightning and the thunder: insular dwarfism inferred from long bone histology of the titanosaurian Atsinganosaurus velauciensis Jentgen, Benjamin Paul C; Stein, Koen; Díez Díaz, Verónica; Garcia, Géraldine; Valentin, Xavier; Fischer, Valentin DOI: 10.13140/RG.2.2.15528.01284

Publication date: 2018

Document Version: Final published version

Link to publication

Citation for published version (APA): Jentgen, B. P. C., Stein, K., Díez Díaz, V., Garcia, G., Valentin, X., & Fischer, V. (2018). Lightning and the thunder: insular dwarfism inferred from long bone histology of the titanosaurian Atsinganosaurus velauciensis. Poster session presented at XVI meeting of the European Association of Vertebrate Paleontolgists, Caparica, Portugal. https://doi.org/10.13140/RG.2.2.15528.01284

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Download date: 01. Oct. 2021 Lightning and the thunder: insular dwarfism inferred from long bone histology of the titanosaurian Atsinganosaurus velauciensis

Jentgen-Ceschino B.*, Stein K., Díez Díaz V., Garcia G., Valentin X. & Fischer V.

*Corresponding author. e-mail : [email protected]

Abstract

Titanosaurian sauropods include the largest land that ever Considering the reduced size of the sampled femur and humeri, the walked on Earth. However, some of them evolved into dwarfed species, remodelling process would have begun early in the ontogeny of this linked to their insular habitats. Here, we report on the long bone histology titanosaur compared to non-titanosaurian sauropods, at a rate that of several mature individuals of the small-sized titanosaur Atsinganosaurus surpassed the apposition rate. Thus, size reduction of A. velauciensis has to velauciensis (Garcia et al., 2010) from the Upper of Velaux – La be taken into account to explain the advanced state of its long bone Bastide Neuve (Provence, South-Eastern France). The completely remodelled histology. Insular dwarfism is a consistent hypothesis for this combination of H bone tissue type in all specimens characterizes mature and fully grown features and has been proposed for a series of other titanosaurs from the individuals. Together with the extensive bone remodelling, the samples European archipelago (e.g. the Romanian dacus and the record HOS (Histological Ontogenetic Stages) 14 and range from RS Spanish astibiae) that show comparable long bone histology (Remodeling Stages) 13 to 14. and inferred body size.

Heavy remodelling in the insular sauropod Atsinganosaurus velauciensis Velaux – La Bastide Neuve

Cortex of type H bone tissue remodelled up to 6 generations of 2ry osteons Díez Díaz et al. (in review)

Sampling by core drilling of 2 humeri + 1 femur: • MMS/VBN.09.A.018, .00.12 & .09.126 0.5 mm Crushed trabeculae Main osteo- and histological features: • short propodials (humeri: 470 – 555 mm; femur: ca. 570 mm); • cortex completely remodelled; • type H bone tissue; • Histologic Ontogenetic Stage (HOS) 14; a • Remodelling Stage (RS) b Femur cortex 0.5 mm 13-14. Femur 1.0 mm medullary cavity

a Cortex

b Medullary cavity

5 mm

50 mm Drill

MMS/VBN.00.12 Right humerus (anterior view) 50 mm

MMS/VBN.09.A.018 MMS/VBN.09.126 100 mm Left humerus (anterior view) © A. Beneteau for Palaios/Ville de Velaux Left femur (posterior view) Conclusions Acknowledgements

1. Heavy remodelling indicates that the individuals of Atsinganosaurus velauciensis were fully grown adults at death; 2. The markedly small propodials (humeri: 470 – 555 mm; femur: ca. 570 mm) of Atsinganosaurus velauciensis and its paleogeographic range within the southern part of the European archipelago suggest that this taxon represents an additional case of insular dwarfism within titanosaurs.

Díez Díaz V., Garcia G., Pereda Suberbiola X., Jentgen-Ceschino B., Stein K., Godefroit P. & Valentin X. (in review). The titanosaurian Atsinganosaurus velauciensis () from the Upper Cretaceous of southern France: new material, phylogenetic affinities, and palaeobiogeographical implications, Cretaceous Research Garcia G., Amico S., Fournier F., Thouand E. & Valentin X. (2010). A new titanosaur genus (Dinosauria, Sauropoda) from the of southern France and its paleobiogeographic implications, Bulletin de la Société Géologique de France 3, 269-277. doi: 10.2113/gssgfbull.181.3.269