Cataphract, Clibanarii, whatever, against Infantry

[Robert Vermaat]

At Strasbourg in 357 the Romans had 2 units of Cataphracts, who, infamously, were defeated by German troops getting in amoung them and stabbing the horses in their unprotected belllies. whether this was dismounted German cavalry or light infantry attached to the cavalry is debated.

They were not. The right wing cavalry became confused after their commander was wounded. The cavalry then wavered (it did not flee), after which Julian managed to turn them back (37,38).
Further down (42) it is claimed that the Germans defeated and scattered 'the cavalry', but whether this is the left wing cavalry or the right (or both) remains unclear, because earlier Ammianus claimed that the cavalry had rejoined the fight. The wounded cataphract commander Innocentius, did not survive the battle (62).

Never does our only source, Ammianus Marcellinus, say anything about the Germans defeating the cavalry in the manner which you describe. Where is this debated, or that it was dismounted cavalry (only the Alaman leaders seem to have had horses) or even infantry attached to cavalry?
For the source, read this, book XVI, 13:34ff.