In addition, the surface vowels and were extremely common, and syllabic sonorants existed. All of them alternated in a syllabic position with sonorant consonants For example, the root of the PIE word ('yoke') with a also appears in the verb ('to yoke, harness, join') with Similarly, the PIE word ('tree, wood') is reconstructed with genitive singular and dative plural Some authors (e.g. ) have argued that there is substantial evidence for reconstructing a non-alternating phoneme in addition to an alternating phoneme as well as weaker evidence for a non-alternating phoneme