Noun classification occurs in the North Caucasian languages, Burushaski, Yeniseian, and the Na-Dené languages. In Basque and Sino-Tibetan, only fossilized vestiges of the prefixes remain. One of the prefixes, */s/-, seems to be abundant in Haida, though again fossilized. The following table with its footnotes, except for Burushaski, is taken from Bengtson (2008). Footnotes: a In Basque, the class prefixes became fossilized. b In many Caucasian languages (28), systems of this type more or less persist to this day, especially in the East Caucasian languages, whereas in West Caucasian, only Abkhaz and Abaza preserve a distinction human-nonhuman. The Roman numbers are those conventionally used for the East Caucasian noun classes. The forms in parentheses are very rare. c Burushaski seems to have reversed the first two animate classes, which may have parallels in some East Caucasian languages, namely Rutul, Tsakhur, or Kryz. d As with Basque, the class system was already obsolete by the time the languages were recorded. e Objective verb prefixes; /a/ and /i/ are used in the present tense, /o/ and /id/ in the past. Verb morphology In general, many Dené–Caucasian languages (and Sumerian) have polysynthetic verbs with several prefixes in front of the verb stem, but usually few or no suffixes. (The big exceptions are East Caucasian, where there is usually only one prefix and many suffixes, the similarly suffixing Haida, and Sino-Tibetan, for which little morphology can so far be reconstructed at all; Classical Tibetan with its comparatively rich morphology has at most two prefixes and one suffix. In Burushaski, the number of suffixes can surpass the rather large number of prefixes.) The following is an example of a Kabardian (West Caucasian) verb from Bengtson (2008:98): Bengtson (2008) suggests correspondences between some of these prefixes (sometimes suffixes) and between their positions. For example, a preverb /t/- occurs in Yeniseian languages and appears in position −3 (Ket) or −4 (Kott) in the verb template (where the verb stem is in position 0, suffix positions get positive numbers, and prefix positions negative numbers). In Burushaski, a fossilized preverb /d/- appears in position −3. In Basque, an element d- appears in position −3 of auxiliary verbs in the present tense unless a first or second person absolutive agreement marker occupies that position instead. The Na-Dené languages have a "classifier" /d/- (Haida, Tlingit, Eyak) or */də/- (Proto-Athabaskan) that is either fossilized or has a vaguely transitive function (reflexive in