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| Tethyshadros insularis Dalla Vecchia, 2009 in Chiarenza, Fabbri, Consorti, ... et Fanti, 2021. |
Abstract
During the latest Cretaceous, the European Archipelago was characterized by highly fragmented landmasses hosting putative dwarfed, insular dinosaurs, claimed as fossil evidence of the “island rule”. The Villaggio del Pescatore quarry (north-eastern Italy) stands as the most informative locality within the palaeo-Mediterranean region and represents the first, multi-individual Konservat-Lagerstätte type dinosaur-bearing locality in Italy. The site is here critically re-evaluated as early Campanian in age, thus preceding the final fragmentation stages of the European Archipelago, including all other European localities preserving hypothesized dwarfed taxa. New skeletal remains allowed osteohistological analyses on the hadrosauroid Tethyshadros insularis indicating subadult features in the type specimen whereas a second, herein newly described, larger individual is likely somatically mature. A phylogenetic comparative framework places the body-size of T. insularis in range with other non-hadrosaurid Eurasian hadrosauroids, rejecting any significant evolutionary trend towards miniaturisation in this clade, confuting its ‘pygmy’ status, and providing unmatched data to infer environmentally-driven body-size trends in Mesozoic dinosaurs.
Systematic palaeontology
Dinosauria Owen (1842)
Ornithischia Seeley (1887)
Ornithopoda Marsh (1881)
Hadrosauriformes Sereno (1997)
Hadrosauroidea Cope (1870) sensu Madzia et al. 2020
Hadrosauromorpha Norman (2014)
Tethyshadros insularis Dalla Vecchia 2009
Locality and horizon: Liburnian facies (Fig. 1a; Fig. S1) of the Villaggio del Pescatore site (45.8° N, 13.6° E), referred by means of the associated foraminifera and lithostratigraphy to an interval comprised between the lower Campanian and the lowermost middle Campanian (see Geology and revised age of the VdP fossil assemblage section above and Supplementary information S1).
Revised diagnosis:
Here we reformulate the diagnosis for this taxon based on the seven recently discovered articulated skeletons attributed to Tethyshadros collected at the type locality. Newly identified unique characters are highlighted with an asterisk (*). Tethyshadros insularis is a non-hadrosaurid hadrosauroid dinosaur characterised by the following autapomorphies: proximalmost caudal centra (Fig. S11) are anteroposteriorly longer than dorsoventrally tall, apart from the 3rd and 4th centra*; distal caudal centra transition to becoming more elongated and cylindrical (Figs. S12, S13) in shape halfway through the caudal series (between caudal 23rd–33rd)*; apically broad neural spines in lateral view: haemal arch shape in lateral view vary from rod-like to boot-like to bilobate along the caudal series; flat distal articular end of metacarpals; only two phalanges in manual digit IV, distal one very reduced (lost phalanx 2 of other hadrosauriforms).
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Alfio Alessandro Chiarenza, Matteo Fabbri, Lorenzo Consorti, Marco Muscioni, David C. Evans, Juan L. Cantalapiedra and Federico Fanti. 2021. An Italian Dinosaur Lagerstätte reveals the Tempo and Mode of Hadrosauriform Body Size Evolution. Scientific Reports. 11, 23295. DOI: 10.1038/s41598-021-02490-x
