Simple SummaryDomestic pig hybridization with wild boar occurs for different reasons and needs. The ability to distinguish hybrids is important for monitoring of hybrid and purebred populations and for conservation of both rare domestic pig breeds and wild boars. As cranial morphology has a good discrimination power, the aim of this study was to quantify the differences of cranial morphologies between local Lithuanian Indigenous Wattle pigs and their hybrids with wild boar, including first generation hybrid (domestic x wild) animals and second generation animals (backcross of first generation females with domestic and wild males). Most of the craniometric measurements of hybrids were larger than those of purebred local Lithuanian Indigenous Wattle pigs. A particularly pronounced significant elongation of skull length parameters was found in hybrids. Cranial morphology can be used to discriminate between Lithuanian Indigenous Wattle pigs and their hybrid groups for the all measurements of whole crania and for measurements of distinct parts of crania.AbstractThe diversity of domestic pig breeds and their hybridization increases the variety of phenotypes expressed in hybrids. The aim of this study was to quantify the differences of cranial morphologies between local Lithuanian Indigenous Wattle pigs and theirhybrids with wild boar. A total of sixteen craniometric measurements were performed on the lateral, ventral and dorsal sides of 71 skulls of Lithuanian Indigenous Wattle pigs and their hybrids, including 1/4 wild boar (WB), 1/2 wild boar and 3/4 wild boar genotypes. The weight of the skull was affected by the genotype, live weight and sex of the animal. The size of the skull, particularly related to skull length parameters, increased consistently with the increase of the wild boar proportion in the hybrids. However, theSus scrofagenotype did not affect the skull height. Clear discrimination was possible between the local Lithuanian breed pigs and their hybrids with different proportions of wild boar and between individual groups of hybrids. The most correct classification was determined on the basis of the overall and length parameters of the crania. This could contribute to better management and utilization of hybrids.