[Agema]

It's certainly true that the bayonet put pikemen on the road to obsolescence. However, it also involved improvements in gun technology (flintlocks, Adolphus' powder & shot cartridges) such that muskets became more efficient battlefield weapons, and firepower started to become more dominant for infantry. Pikemen were no more vulnerable to cannons than musketeers, and the threat of gun-owning cavalry was already minimal because of mixed-troop formations such as the Spanish tercio.

My point about "meaningful sense" is that the sarissa was equivalent to a pike in virtually every way except that it was specific to a set of nations at a different point in history. Encyclopaedias are not academic sources, but they are based on academic sources. I own two books on ancient warfare that refer to sarissas as pikes, and I've read others also describing them as such: I expect the authors to be adequate authorities.

The sacred band was only 150 strong. It's very unlikely it fought 50 ranks deep!