Medium sized Ursidae with a more primitive general morphology in the dentition than in the Ursinae and Tremarctinae, with less reduced premolars, and well-developed carnassials, except in some teeth of Ailuropoda melanoleuca, which have severe autapomorphies.
Since the Early Miocene, prior to the appearance of the true bears, the Hemicyonidae show a rapid diversification that made of this group, along with the Amphicyonidae, the predominant medium to large sized carnivorans until the beginning of the Late Miocene, when they became locally extinct, coinciding with the appearance of the Ursidae, Hyaenidae and Machairodontinae felids in the Western Europe faunas.
However, both the first record of the genera Hemicyon and Plithocyon (Family Hemicyonidae), as well as the first record of an Ursidae, with the genus Ballusia and Ursavus isoire, characterize the Ursoidea record in Western Europe.
Only the absence of representatives of Ursidae marks a profound difference with Western Europe's fossil record for this period.
The presence of the first Ursidae in Europe, with smaller size and a more hypo-carnivorous dentition, may have not affected the diversity of Hemicyonidae.
During the biozone MN6 (late Aragonian) the Iberian Ursoidea record is also characterized exclusively by large sized species of the subfamily Hemicyonidae, while in the rest of Western Europe this group shares their geographical distribution with the less diverse members of the Ursidae family (genus Ursavus).
During the latest Aragonian (biozone MN 7/8) the first appearance of Ursidae (Kretzoiarctos) is detected in the Iberian Peninsula (Abella et al.
The oldest record of a large-sized member Ursidae occurs during the early Vallesian (MN9) in the Valles-Penedes Basin (North East of the Iberian Peninsula) with the species Indarctos vireti and then subsequently most likely migrates North towards other parts of Europe.
With the beginning of the Turolian (MN11-13), the diversity of Ursoidea, now restringed only to the Family Ursidae, suffered a gradual fall in the Iberian Peninsula with the extinction of all genera except for Indarctos.
On the other hand, the environmental conditions of Western Europe during this period do not suffer the extreme variations that took place around the Mediterranean Sea so there is no gap in the register of the Ursidae, during the MN13.