History of Polish Canidae (Carnivora, Mammalia) and Their Biochronological Implications on the Eurasian Background.

The remains of 12 canid species that date back ca. 4.9 myr have been found at 116 paleontological localities. Among these localities, eight are dated to the Pliocene age, 12 are dated to the Early Pleistocene age, 12 are from the Middle Pleistocene age, while the most numerous group includes 84 sites from the Late Pleistocene-Holocene age. Some, especially older forms such as Eucyon odessanus and Nyctereutes donnezani , have only been found at single sites, while the remains of species from the genus Lycaon , Canis and Vulpes have been recorded at numerous sites from the last 2 myr. Ancient canids such as Eucyon and Nyctereutes had already vanished from Poland in the Earliest Pleistocene, between 2.5 and 2.2 myr ago. Poland's extant canid fauna is characterised by the presence of two new species, which spread into the territory due to a human introduction ( Nyctereutes procyonoides ) or natural expansion ( Canis aureus ). Research indicates a strong competition between dogs, especially between Lycaon , Canis and Cuon , with a strong lycaon-limiting effect on the wolf between 2.5 and 0.4 myr ago. After the extinction of Lycaon lycaonoides , Canis lupus evolved rapidly, increasing in number and size, and taking over the niche occupied by Lycaon . In order to reduce competition, the body size of Cuon alpinus gradually reduced, and it became an animal adapted to the forest, highland and mountain environments. Generally, the history of canids in Poland is similar to that known of Eurasia with some noteworthy events, such as the early occurrence of Canis cf. etruscus from Węże 2 (2.9-2.6 myr ago), Lycaon falconeri from Rębielice Królewskie 1A or one of the latest occurrences of L. lycaonoides from Draby 3 (430-370 kyr). Predominantly lowland or upland in the southern part and devoid of significant ecological barriers, Poland is also an important migration corridor in the East-West system. This 500-600 km wide corridor was the Asian gateway to Europe, from where species of an eastern origin penetrated the continent's interior. In colder periods, it was in turn a region through which boreal species or those associated with the mammoth steppe retreated.