a characteristic of long vowels, which differ between the Baltic and Slavic languages. He had also noted that: In the Baltic languages short vowels *a, *o coincided into a, while in Slavic languages they coincided into o; the differences of long vowels of *ā and *ō in the Baltic languages were maintained, in Slavic languages they ceased to exist. Unlike the Proto-Slavic language, which remained conservative, the vowel gradation in the Proto-Baltic language had been developed extensively. The law of open syllables applies to the Proto-Slavic language that cannot be found in the Proto-Baltic language or in the Baltic languages in general. Regarding the systemic changes of suffixes in Baltic and Slavic languages, Russian linguist A. Dubasova notices that in both cases the following happened: aspirated voiced consonants turned into generic voiced consonants (e. g., *gʰ > *g), iotation (e. g., *d > *di̯ > *dj), palatalization, and later on—the assimilation, dissimilation, metathesis as well as the fallout of some consonants in some instances. According to Dubasova, the aforementioned sequence of common changes in both language groups can be an indication of a special relationship between Baltic and Slavic languages but before making such conclusions it is crucial to scrutinize the basis, consequences and intensity of these processes. For instance, Dubasova emphasizes that there are core differences when it comes to iotation in Baltic and Slavic languages, which is something other scientists had noticed in the past. In fact, there are differences in iotation between Baltic languages themselves, which probably means that this process began after the split of Proto-Baltic while Proto-Slavic is already known to have iotation. With regard to palatalization, Dubasova notices that it is a trivial phonetic change and it cannot be seen as evidence of a genetic link between Baltic and Slavic languages, especially when taking the core palatalization differences in both language groups. She also concludes that researchers face great difficulties when reconstructing the phonological system of the Proto-Baltic mostly due to the problematic nature of examining Old Prussian and contrasting views of researchers. In terms of palatalization similarities between Latvian and Slavic languages, Dubasova notes that the reasons behind the changes of consonants before certain vowels or the lack of them are different. In her work on the assimilation of voiced and voiceless consonants, she states that such assimilation already happened in the Proto-Slavic language, which was caused by the fallout of reduced vowels,