In short : what's the final -t in déḱm̥t?
Full details : The Proto-Indo-European root for ten is traditionally defined as déḱm̥/déḱm̥t(ᵃ). The final -t may be analyzed as a casual ending, e.g. as a "collective form"; Szemerényi describes déḱm̥ as derived from déḱm̥t(ᵇ).
The final -t is required by various languages, like OCS desętĭ and Lithuanian dešimt(ᵃ). Likewise, according to Don Ringe, the Proto-Germanic form for ten is derived from déḱm̥t, surfaced as déḱm̥d(ᶜ), hence tekun(ᵈ) leading to Gothic taíhun(ᵉ).
My question : I would like to know the details behind this -t : if it's a collective form ("marking collective number (group of ten)"), is there any other example of a PIE word using -t as a collective form? The only way I know to create collective PIE forms is (for direct cases) by adding the ending -h₂ to the stem.
Any help, any reference would be appreciated !
related question here.
(a) See e.g. (Szemerényi) Introduction to Indo-European Linguistics, 8.5.2 p.223
(b) (Szemerényi) Introduction to Indo-European Linguistics, 8.5.3 p.226 Reconstruction:Proto-Indo-European/déḱm̥ (Wikipedia)
(c) Don Ringe, From Proto-Indo-European to Proto-Germanic, 2.2.4(iv) p.20
(d) Don Ringe, From Proto-Indo-European to Proto-Germanic, 3.2.2(i) p.81
(e) Don Ringe, From Proto-Indo-European to Proto-Germanic, 3.2.2(ii) p.87