Afromimus (meaning "Africa mimic") is a genus of theropod dinosaur from the Early Cretaceous Elrhaz Formation of Niger. It contains a single species, A. tenerensis, named in 2017 by Paul Sereno from parts of the right leg, vertebrae, and ribs found in the Ténéré Desert. It was originally classified as an ornithomimosaurian,[1] but subsequently it was argued to be an abelisauroid.[2]
The only known specimen of Afromimus is a partial skeleton consisting of seven tail vertebrae (originating from the middle of the tail and estimated to be the 15th, 16th, 18th, 20th, 22nd, 24th, and 27th tail vertebrae), bones from the right hindlimb (the tibia, fibula, tarsal bones, and phalanges), and part of a rib, all found within a radius of 1 m (3.3 ft). It was discovered in 1997 at the Gadoufaoua locality in the Elrhaz Formation, in the Ténéré Desert of Niger. The specimen is catalogued as MNBH GAD112 in the Musée National Boubou Hama, the national museum of Niger in the city of Niamey. Since the specimen was exposed to the elements when it was found, it may have been more complete when it was still buried. The hindlimb elements were discovered in place, although they were weathered; the tail vertebrae were out of place, and the last vertebra in the sequence was found several meters away from the rest of the specimen.[1]
In 2017, Paul Sereno published a description of MNBH GAD112 as the holotype specimen of a new genus and species, Afromimus tenerensis. The genus name combines the Latin prefix Afro- ("Africa") and the Greek word mimos ("mimic"), in reference to the interpretation of the specimen as a member of the Ornithomimosauria. The species name combines the name of the Ténéré Desert and the Latin suffix -ensis ("from").[1] Subsequently, in 2019, Mauricio Cerroni and colleagues published a reassessment of Afromimus as a member of the Abelisauroidea.[2]
Afromimus was described as "medium-sized" for an ornithomimosaur. Judging by the fusion in the vertebrae and between the fibula and tarsus of the holotype specimen of Afromimus, the individual had reached adult size before it died. The tibia has a length of 40 cm (16 in). Sereno noted that the largest specimen of the ornithomimosaur Sinornithomimus (a subadult at least seven years old) had a tibia of a similar length, and concluded that Afromimus had a somewhat smaller adult size, making it half the size of Gallimimus, twice the size of Shenzhousaurus, and three times the size of Nqwebasaurus.[1]
Sereno identified several distinctive characteristics in the tail vertebrae of Afromimus. The 16th tail vertebra had depressions along the top and bottom surfaces of the broad centrum, which Sereno described as "peanut-shaped". Such a structure would have stabilized the tail from flexing to the side. The depressions on the bottom surfaces are less evident towards the rear of the tail. This trait is shared with Gallimimus and an unnamed ornithomimid from the Dinosaur Park Formation,[1][3] and contrasts with the less-broad centra of the abelisauroids Majungasaurus and Masiakasaurus; however, among the Abelisauroidea, the noasaurid Elaphrosaurus also has similar vertebrae.[2]