The Gargano faunal complex is likely the result of one single migration wave, which took place during the low sea-level phase of the Messinian, and migration events suggested by differences among some of the Gargano localities can be referred to faunal exchange between neighbouring islands rather than to multiple migrations from the mainland (Freudenthal 1976).

De Giuli et al. 1987 said that Gargano was populated in two migration waves, one during the Early Miocene (ochotonids, erinaceids, glirids, cervoids), and one during the Messinian (Apodemus, Cricetus, Microtia, Eliomys) respectively.

In support of their hypothesis, de Giuli et al. 1987 said that Butler 1980 suggested an Early Miocene age for the immigration of Deinogalerix. In fact, however, Butler 1980 carefully avoided such a suggestion, and only said Deinogalerix most likely was an immigrant entering Gargano from the East, across the Adriatic. Similarly, Leinders 1984 did not state that Amphimoschus is the ancestor of Hoplitomeryx.

For the ochotonids, de Giuli et al. 1987  noted that Prolagus oeningensis is not recorded later than the Vallesian, which is quite different from suggesting an Early Miocene migration. Furthermore, according to López Martínez and Thaler 1975, P. oeningensis - P. michauxi form an evolutionary lineage, and P. apricenicus may be derived from that lineage, which is documented in El Arquillo (MN13, Spain) and Maramena (MN13, Greece); possibly related forms have been reported from Monte Castellaro, Capo di Fiume and Brisighella (MN13, Italy).

The Gargano glirids do not support the hypothesis of an Early Miocene immigration.  Possible ancestors like Myomimus dehmi and M. maritsensis were reported from Messinian (MN13) deposits in Spain and Greece (Azanza et al. 1989, de Bruijn 1989, Daxner-Höck 1995).

Not only do Prolagus and Myomimus occur in El Arquillo and Maramena, but these localities have also yielded material of species related to the other micromammals of Gargano that were supposed to represent the second migration wave. Thus, potential ancestors of all the micromammals of Gargano belong to the normal Messinian mainland fauna, and may have reached Gargano simultaneously, during the Messinian sea-level lowstand. For the larger mammals (Deinogalerix and Hoplitomeryx) potential ancestors are not known, neither in Messinian, nor in older deposits. Concluding an Early Miocene migration on the basis of lack of evidence is not justified.

Rook et al. 2000 also said that the Gargano faunas were the result of various immigration phases because of the presence of the endemic genus Hoplitomeryx Leinders, 1984 in Lower Tortonian calcarenites of Scontrone (Abruzzi), deposited before the arrival of Muridae in Europe. However, the dating of the Scontrone mammal bed seems to be unreliable, and the only thing one can say is that they are not older than Early Tortonian.

Thus, there is no conclusive evidence  that supports the hypothesis of various migration waves, all the available data are in good accord with the hypothesis of one single migration. 

The presence in Biancone 1 of two species of Stertomys, both much bigger than their supposed common ancestor on the mainland, demonstrates that there must be an undocumented time span between the moment of immigration from the mainland, and the age of that locality. Unfortunately the amount of time is unknown, but certainly the area was submerged during the Pliocene, because the fissure fillings are covered by a Pliocene calcarenite. The best current estimate is that the faunas are of Late Miocene age, though an Early Pliocene age cannot be ruled out.