NEW REMAINS OF THYREOPHORAN DINOSAURS (ORNITHISCHIA) FROM THE MIDDLE JURASSIC RED BEDS OF MOROCCO

ZAFATY, O.; OUKASSOU, M.; PEREDA-SUBERBIOLA, XABIER; RIGUETTI, FACUNDO; COMPANY, J.; BENDRIOUA, S.; TABUCE, R.; CHARRIÈRE, A.

Tétouene

Jornada; 4èmes Journées Jeunes Chercheurs en Géosciences; 2022

Thyreophora is a diverse clade of herbivorous ornithischian dinosaurs composed ofstegosaurs, ankylosaurs, and basal forms. Thyreophorans have an extensive fossil record,spanning from the Lower Jurassic to the Upper Cretaceous, which is best known from wellpreserved specimens in Laurasia. In contrast, the remains are extremely rare and mostlypartial in Gondwana.The Boulahfa locality of the folded Middle Atlas (Morocco), near Boulemane, hasproduced a diverse dinosaur assemblage from the Middle Jurassic (Bathonian-Callovian) of ElMers Group. The specimens described in this region contain the remains of sauropod(Cetiosaurus mogrebiensis Lapparent, 1955), stegosaurian (Adratiklit boulahfa Maidment etal., 2020), and ankylosaurian (Spicomellus afer Maidment et al., 2021) dinosaurs.Herein, we describe a new specimen discovered in 2021 and collected over consecutivefield trips. The preserved material is composed by a disarticulated partial skeleton found ingrey siltstones of the El Mers III Formation, consisting of dorsal and caudal vertebrae, ribs,osteoderms, and several incomplete elements. The new thyreophoran shows stegosaurianvertebral characters (e.g., elongated pedicels of the dorsal neural arches), but the externaltexture of osteoderms is reminiscent of that of some nodosaurid ankylosaurs. An ongoingpalaeohistological analysis may provide new information. These new data represent anextremely important point to understand the diversity of thyreophoran (armoured) dinosaurs,their palaeobiogeography, and evolutionary relationships.