[D] Antetonitrus ingenipes [sG] [T]
Yates and Kitching. 2003
Triassic Late, Norian
Saurischia Sauropodomorpha Sauropoda
Lower Elliot Formation, Ladybrand District, Orange Free State, South Africa
8–10 m [ hip height of 1.5–2 m]
Genus - Typespecies
Partial dinosaur skeleton. Antetonitrus ingenipes provides the first informative look at a basal sauropod that was beginning to show adaptations towards graviportal quadrupedalism such as an elongated forelimb, a modified femoral architecture, a shortened metatarsus and a changed distribution of weight across the foot.
These adaptations allowed the clade to produce the largest-ever terrestrial animals. However, A.ingenipes lacked specializations of the hand found in more derived sauropods that indicate it retained the ability to grasp. Antetonitrus is older than the recently described Isanosaurus from Thailand and is the oldest known definitive sauropod.
Etymology: The generic name is from Latin, ante (before); tonitrus (thunder) and refers to the early occurrence of this sauropod relative to Brontosaurus (Greek, thunder lizard) one of the most familiar sauropod names. The species name is from Latin, ingens (massive) and pes (paw, or foot) and refers to its robust hands and feet.
Holotype: (initially identified as Euskelosaurus sp. (Kitching & Raath 1984).: Partial disarticulated skeleton (BP/1/4952) including a cervical centrum, four dorsal vertebrae, sacral vertebra, caudal vertebrae, dorsal ribs, chevrons, scapulae, right humerus, both ulnae, left radius, left metacarpal I, both metacarpals II, left manual phalanx I1, two ?manual unguals, left pubis, left femur, left tibia, left fibula, left metatarsal I, right metatarsal II, left metatarsal III, right metatarsal V, two pedal phalanges, right pedal ungual I, right pedal ungual ?III. The specimen was disarticulated but closely associated in situ. The fossils are thought to belong to a single individual because they are all from a large (for the Triassic), robust sauropodomorph representing most skeletal regions with no duplication of parts.
Referred specimens: A right scapula, right humerus (with a deep sulcus on the lateral distal margin of the deltopectoral crest), left ulna, left fibula and a right metatarsal II that are smaller (ca. 80%) than their counterparts in the holotype. Found at the same site as the holotype and catalogued as (BP/1/4952b).