Turtles Have Hair In The Mario World
So something people don't realize is turtles are capable of growing hair. Now while one might think it's just what I've dubbed the Boss Shell Creepers that have hair, it's not just them. Bowser and Bowser Junior obviously have hair, and so too do the Koopalings not all of them do. Roy and Wendy like many turtles don't have hair. But what about the other species of turtles like Koopas? That is the claim that turtles as a whole can grow hair.
Well in Super Mario Odyssey when you knock off a Hammer or Fire Brother's headgear you get to see that they have hair.
The Common Koopa also can grow hair as seen in Koopley and Kuzzle. Also, the reason I call them the Common Koopa is because of the following. Koopa Troopas are members of Bowser's army, and not all Koopas of this species let alone in general work for Bowser. Meanwhile simply calling them Koopas can make things confusing when talks about different Koopa species. With all that and the fact this species of Koopas is so common I've dubbed them the Common Koopa.
Anyways back on track. Lakitus are another species of turtles that have hair, and it's pretty common. In fact other members of the species like Lakilester have more obvious hair. I'd also note Morton's hair is like that of a Lakitu.
Now finally to mention the OVA, while non canon it this has many useful parallels to the games. For example, several Koopa Troopas in this animation can be seen having hair. This could indicate from the start all Koopas from the start have had the ability to grow hair.