Double dactyl
Milli-grandiloquent
Herm 'Hellmutt' Baskerville,
Having a crack at a
new form of verse,
Blames double dactyls for
brashly inciting a
sesquipedalian
poet to worse.
Interesting form. Can't say it's one I'd normally have tried… although it looks like it'd be great for comic nonsense poetry, my favourite genre.

Yay. You said "sesquipedalian" – a word which I sometimes use to mean 18-inches (~="Yay-big") even in more mundane circumstances it's become one of my favourite words.
But I like the whole quirkiness of the rhyme, despite being slightly scared of (ptero)-dactyls.