S40, while forbs, shrubs and other ligneous vegetation are the least used forage resource. This alternative implies therefore that an abiotic (external) factor caused its ecological range to expand. Finally, and although only one sample is existent in biozone 6–and this is certainly not due to limitations related to sampling because species normally present in all biozones are lacking in this last interval22–, much lower levels of A-836339 solubility dietary abrasion and a return to a soft-leafy browsing diet are seen, as denoted by the very low scores (MS = 0) of Hoplitomeryx sp. 2. The rates and trajectories of body size diversification are also modeled (Fig. 4B), showing that ecological diversification rates occur without significant change in body size, although slightly smaller body size is observed to occur with a pulse of increased dietary abrasion (from biozone 4 to 5) in some species. Thus, results show that Hoplitomeryx sp. 2. and Hoplitomeryx sp. 4 are 10.5 and 7 smaller, respectively, than their preceding relatives.Environmental change and co-evolution of Hoplitomeryx with micromammals. Changes in the feeding spectrum here detected through the dental mesowear of Hoplitomeryx perfectly match changes of the whole small-mammal community, also GS-4059 site easily affected by climate instability–although less than ruminants42. Figure 4C combines the evolution in diet of Hoplitomeryx (through the representation of the wear pattern of its most widespread Hoplitomeryx sp. 2) with the main changes in the micromammal association of Gargano. A first evidence of the existence of a phase of aridification that intervened in the continuous insular evolution of Gargano is the significant evolutionary change undergone by the murid Mikrotia. The record of this highly ubiquitous genus is characterized by an abundance of well-preserved material, representing several (at least five) species/ lineages that exhibit a high degree of evolutionary differentiation43. Small-sized and less derived Mikrotia species are widespread in the most ancient fissures, whereas larger-sized and morphologically derived lineages occurred in the youngest ones. The first appearance of the largest Mikrotia (M. magna) lineage in latest biozone 3 (Chiro 27) coincides with dietary homogeneity in Hoplitomeryx (Fig. 4C). Changes through time in Mikrotia include a very marked growth in size, development of propalinal chewing, increasing hypsodonty, and an increase in size and complexity of m1 and M344,45. These macroscopic changes, accompanied by a tendency to thicken the enamel wall of molars46, appear to be an adaptation to a very abrasive diet driven by climatic deterioration43,47. Thus, the most morphologically derived teeth of Mikrotia belong to specimens from San Giovannino (biozone 5)44,45, and reflect a diet that included grasses and the ingestion of dust and grit as a consequence of new environmental conditions43. The most derived Mikrotia populations coincide therefore with the maximum dietary abrasion reached by Hoplitomeryx. Besides findings from Mikrotia, a marked trend towards aridification on Gargano archipelago has been also invoked through the evolutionary pattern found in the lagomorph Prolagus (a very distant relative of extant pikas)44, and the disappareance in biozone 4 of micromammals normally present in all localities, as is the case of the cricetids that cease to exist in the area interval44. Although determining the age of the fissures of Gargano is largely a matter of conjectur.S40, while forbs, shrubs and other ligneous vegetation are the least used forage resource. This alternative implies therefore that an abiotic (external) factor caused its ecological range to expand. Finally, and although only one sample is existent in biozone 6–and this is certainly not due to limitations related to sampling because species normally present in all biozones are lacking in this last interval22–, much lower levels of dietary abrasion and a return to a soft-leafy browsing diet are seen, as denoted by the very low scores (MS = 0) of Hoplitomeryx sp. 2. The rates and trajectories of body size diversification are also modeled (Fig. 4B), showing that ecological diversification rates occur without significant change in body size, although slightly smaller body size is observed to occur with a pulse of increased dietary abrasion (from biozone 4 to 5) in some species. Thus, results show that Hoplitomeryx sp. 2. and Hoplitomeryx sp. 4 are 10.5 and 7 smaller, respectively, than their preceding relatives.Environmental change and co-evolution of Hoplitomeryx with micromammals. Changes in the feeding spectrum here detected through the dental mesowear of Hoplitomeryx perfectly match changes of the whole small-mammal community, also easily affected by climate instability–although less than ruminants42. Figure 4C combines the evolution in diet of Hoplitomeryx (through the representation of the wear pattern of its most widespread Hoplitomeryx sp. 2) with the main changes in the micromammal association of Gargano. A first evidence of the existence of a phase of aridification that intervened in the continuous insular evolution of Gargano is the significant evolutionary change undergone by the murid Mikrotia. The record of this highly ubiquitous genus is characterized by an abundance of well-preserved material, representing several (at least five) species/ lineages that exhibit a high degree of evolutionary differentiation43. Small-sized and less derived Mikrotia species are widespread in the most ancient fissures, whereas larger-sized and morphologically derived lineages occurred in the youngest ones. The first appearance of the largest Mikrotia (M. magna) lineage in latest biozone 3 (Chiro 27) coincides with dietary homogeneity in Hoplitomeryx (Fig. 4C). Changes through time in Mikrotia include a very marked growth in size, development of propalinal chewing, increasing hypsodonty, and an increase in size and complexity of m1 and M344,45. These macroscopic changes, accompanied by a tendency to thicken the enamel wall of molars46, appear to be an adaptation to a very abrasive diet driven by climatic deterioration43,47. Thus, the most morphologically derived teeth of Mikrotia belong to specimens from San Giovannino (biozone 5)44,45, and reflect a diet that included grasses and the ingestion of dust and grit as a consequence of new environmental conditions43. The most derived Mikrotia populations coincide therefore with the maximum dietary abrasion reached by Hoplitomeryx. Besides findings from Mikrotia, a marked trend towards aridification on Gargano archipelago has been also invoked through the evolutionary pattern found in the lagomorph Prolagus (a very distant relative of extant pikas)44, and the disappareance in biozone 4 of micromammals normally present in all localities, as is the case of the cricetids that cease to exist in the area interval44. Although determining the age of the fissures of Gargano is largely a matter of conjectur.