[D] Adeopapposaurus mognai [sG] [T]
Saurischia Sauropodomorpha Prosauropoda Massospondylidae
Canon del Colorado Formation, Upper Pelitic Member, Argentina
Diagnostic autapomorphies and combination of characters of Adeopapposaurus include a series of large foramina in a sub-vertical row on the lateral surface of the premaxilla; strongly rugose depression bordered by a protuberance with a series of foramina in a sub-vertical row, on the lateral surface of the anterior end of the dentary; eleven anteroposteriorly elongated cervical vertebrae and thirteen dorsal vertebrae with neural arches taller than the respective centra.
Phylogenetically Adeopapposaurus is resolved as the sister group to Massospondylus; differing from the latter based on differences in mandible and premaxilla and addition of one dorsal vertebra to the neck. The specimens described here reveal numerous herbivorous adaptations, including the presence of a highly vascularized bony plate in the premaxilla and dentary, which indicates that it had a horny beak.
Etymology: Adeopapposaurus from the Latin adeo, meaning ‘far,’ pappo, ‘eating,’ and saurus, ‘lizard.’ The name refers to the long neck characteristic of this taxon. The specific epithet refers to the locality of Mogna in San Juan province, Argentina.
Diagnosis: Sauropodomorph with the following autapomorphies and combination of characters: series of large foramina in a sub-vertical row on the lateral surface of the premaxilla; strongly rugose depression bordered by a protuberance with a series of foramina in a sub-vertical row, on the lateral surface of the anterior end of the dentary; eleven anteroposteriorly elongated cervical vertebrae and thirteen dorsal vertebrae with neural arches taller than the respective centra.
Holotype: PVSJ610, an incomplete skeleton including complete skull with mandible in occlusion; complete cervical, dorsal and sacral vertebral series; nine articulated caudal vertebrae with corresponding chevrons, pectoral girdle, forelimbs, incomplete pelvic girdle and incomplete hindlimbs.
Hypodigm: PVSJ568: Partial skeleton consisting of partially articulated skull; atlas-axis complex; four articulated caudal vertebrae, presumably tenth to thirteenth, and fragments of indeterminate vertebral bodies; distal end of right femur; tibia, fibula, astragalus, calcaneum, distal tarsals III and IV and articulated right hindfoot. PVSJ569: partial skeleton, smaller than the holotype, consisting of 2nd and 3rd sacral vertebrae without neural spines; six sacral ribs; sequence of first 46 caudal vertebrae, articulated; incomplete pelvis, lacking part of right ilium and pubis; hindlimbs lacking right tibia and the full complement of right phalanges. PVSJ570: right and left humeri, left with only proximal posterior border, and centrum of 2nd sacral vertebra.
Horizon and Locality: All specimens found within the Upper Pelitic Member (Martınez, 2002b) of the Lower Jurassic Canon del Colorado Formation (Martınez, 1999b), from outcrops situated in southwestern Sierra de Mogna, San Juan, Argentina.
The holotype specimen, PVSJ610, and PVSJ570 and VSJ568 were found 148 m from the base of the formation, while PVSJ569 was found 10 m below the first site.