Readily identifiable based on their large, “spatulate” teeth with diagnostic “heart”-shaped crowns, turiasaurians are non-neosauropodan eusauropods known from varied Jurassic and Cretaceous formations across Laurasia and Gondwana. Recently, three teeth with turiasaurian features were collected from the Middle Jurassic El Mers III Formation in the Middle Atlas Mountains of north-central Morocco. Although these teeth are superficially similar to those of the Late Jurassic Turiasaurus riodevensis from Spain, the absence of rounded denticles presence of a prominently peaked apex and a mesially flared margin, differ from other known turiasaurians. Turiasaurians have not previously been described from the El Mers III Formation, and the only named sauropod from the El Mers Group, which lacks preserved teeth, is the dubious taxon “Cetiosaurus mogrebiensis”. Due to lack of overlapping material and its lack of clear diagnostic characters, we refrain from referring these teeth to the latter, and identify them as Turiasauria indeterminate instead. These teeth represent the first definitive turiasaurian remains from Morocco, as well as the geologically oldest occurrence of Turiasauria from mainland Africa.

Key words: Dinosauria, Sauropoda, Turiasauria, teeth, Middle Jurassic, Morocco.

D. Cary Woodruff [sauropod4@gmail.com; ORCID: https://orcid.org/0000-0002-3728-134X], Phillip and Patricia Frost Museum of Science, Miami, FL, USA; Museum of the Rockies, Bozeman, MT, USA. Paul M. Barrett [p.barrett@nhm.ac.uk; ORCID: https://orcid.org/0000-0003-0412-3000], Fossil Reptiles, Amphibians, and Birds Section, Natural History Museum, Cromwell Road, London, UK; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa. Driss Ouarhache [driss.ouarhache@usmba.ac.ma; ORCID: https://orcid.org/0000-0001-5941-0977], Abdessalam El Khanchoufi [abdessalam.elkhanchoufi@usmba.ac.ma; ORCID: https://orcid.org/0000-0003-2664-267X], Khadija Boumir [khadija.boumir@usmba.ac.ma; ORCID: https://orcid.org/0000-0003-4837-5410], Kawtar Ech-Charay [kawtar. echcharay@usmba.ac.ma; ORCID: https://orcid.org/0000-0003-4421-4214], and Ahmed Oussou [ahmed.oussou@ usmba.ac.ma; ORCID: https://orcid.org/0000-0001-8016-9735], GERA Laboratory, Faculty of Sciences Dhar El Mahraz, Université Sidi Mohamed Ben Abdellah, Fez, Morocco. Richard J. Butler [r.butler.1@bham.ac.uk; ORCID: https://orcid.org/0000-0003-2136-7541] and Luke Meade [l.e.meade@ bham.ac.uk; ORCID: https://orcid.org/0000-0001-7829-5193], School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK. Simon Wills [s.wills@nhm.ac.uk; ORCID: https://orcid.org/0000-0002-2012-1016] and Mike Smith [Mike.Smith@nhm. ac.uk; ORCID: https://orcid.org/0009-0007-0049-9162], Fossil Reptiles, Amphibians, and Birds Section, Natural History Museum, Cromwell Road, London, UK. Susannah C.R. Maidment [susannah.maidment@nhm.ac.uk; ORCID: https://orcid.org/0000-0002-7741-2500], Fossil Reptiles, Amphibians, and Birds Section, Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK; School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.