I personally find Hilmi Aydın's book not a very good source. I have the same book and I only use it for its pictures. Because he makes lots and lots of mistakes, misreadings of Ottoman Turkish scripts, misjudgements about origins of weaponry and terminology. Also, existing arms and armour terminology is not as clear cut as European counterpart(due to lack of interest in art history and archeology community in Turkey about arms and armour studies; most of my professors did not even consider it as a subject of study) Aydın must have made that mistake because of the shortness of the blade relative to later longer yataghans.
There is a Timurid period yataghan in display in Topkapı armoury about same blade length and shape with the Ahmet Tekeli yataghan, with a earless jade handle(which might be a later addition) That yataghan is older than Kanuni ones, even maybe older than Bayazid one, but it is categorized by the curator(who knows absolutely nothing about arms and armour; believe me, I met him) as a "knife".
Below are some paintings in "Saz Yolu" or "Saz Üslubu" by Ottoman painter Şahkulu, inventor of the style:
Dragon in Leaves, 16th century
Dragon fighting unicorns, 16th century
