Description of newly discovered cranial remains of Decennatherium rex juveniles from Batallones-10 (Late Miocene, Iberian Peninsula)

The identification of additional Late Miocene (MN10, Late Vallesian) Decennatherium rex cranial remains at Batallones-10 (Torrejón de Velasco, Madrid Basin, Spain) provides valuable insights into the ontogenetic variability of this extinct giraffe. Most recovered specimens are adults, making the discovery of calves significant. The 2022 excavation yielded two juvenile hemimandibles, a maxilla, and a juvenile ossicone, likely from different individuals. The dental material represents one of the youngest specimens in the Batallones complex, with an estimated age of 4 months to 4.5 years, based on molar eruption stages seen in modern giraffes. The ossicone, resembling that of an adult male in shape but much smaller, mirrors the growth patterns in extant giraffes, where juvenile ossicones share adult proportions but are smaller. This ossicone was detached from the skull, typical for juveniles, as ossicones do not fuse with the cranial roof until later. This discovery broadens our understanding of giraffe ontogeny and includes the first giraffe calf ossicone found in the Iberian fossil record.