Mexidracon longimanus was named by Serrano-Brañas et al. (2025) [long-handed ornithomimid theropod dinosaur characterised by the following combination of characters (autopomorphies are indicated with an asterisk): (1) elongated distal dorsal vertebrae; (2) distal dorsal, sacral and caudal vertebrae without pneumaticity and lacking keeled ventral surfaces; (3*) extreme elongation of the metacarpus, with metacarpal III length being 1.1 times humeral length, 1.072 times metatarsal II length, and 1.018 times metatarsal IV length; (4) metacarpal I shorter than metacarpal II but longer than metacarpal III; (5) metacarpal II is the slenderest of all metacarpals; (6) non-ginglymoid distal articular end of metacarpal II; (7) proximal end of metacarpal II with narrow subtriangular outline; (8) metacarpal III is the shortest of all metacarpals; (9*) iliac pubic peduncle with flared, zig-zag shaped articular margin that is wider anteriorly than posteriorly; (10) ilium with ischiadic peduncle slightly longer proximodistally than pubic peduncle; (11) deeply concave iliac brevis fossa that is expanded posteriorly and overhangs lateral surface of postacetabular process; (12*) distal end of pubis with distal margin of anterior expansion separated from shaft by deep notch; (13) femur slightly longer than tibia; (14) accessory trochanteric crest on distal end of lesser trochanter; (15) distally conical lateral condyle of femur; (16) arctometatarsalian pes; (17) distal tarsal 3 with nearly straight posterolateral edge and convex medial margin; (18) trapezoidal distal tarsal 4 with lateral surface lacking anterolateral projecting flange; (19) metatarsal II with D-shaped cross-section; and (20) metatarsal IV longer than metatarsal II.]. Its type specimen is BENC 32/2-0001, a set of postcrania (a partially articulated skeleton represented by several dorsal, sacral and caudal vertebrae, various haemal arches, left humerus, left metacarpals I-III, partia), and it is a 3D body fossil. Its type locality is Loma Prieta BENC 32/2, which is in a Campanian coastal siltstone/sandstone in the Cerro del Pueblo Formation of Mexico. It is the type species of Mexidracon.