Why was the hasta dropped in the first time

[Paulus Claudius Damianus]

Hello
I don't know if we can say "pilum transition to the hasta" in late roman times. Vegetius talk to the spiculum like a pilum or new late name for pilum characterisation. In late latin text (Ammianus Marcellinus, anonymous panegyrics, Nazarius and co) the "missibilia", "Iaculis" and heavy javelins are calling "pila" too. In other case, In all late roman litterrary souces they don't appears Hasta use like a thrusting spears, only for fighting technics against charges cavalry (exemple: Andrinople battle...) In late primary textes the Hasta is a launching heavy javelins too.

In archéological records, no proof to a long long wood spear. In graphic records too. The late roman army fighting like a old phalangical greec army is a myth with no occurences!