So no, the title is not really wrong unless there is a yet undiscovered bird that's even larger. The elephant bird was the biggest bird (or avian-dinosaur) that ever existed. It was smaller than other non-avian dinosaurs but these were not birds so no point comparing.
The confusion you are making is sometimes described as politician's syllogism. [0]
1) All birds are dinosaurs
2) All land dinosaurs are dinosaurs
3) Therefore, land dinosaurs are birds
"Other prehistoric animals, including mosasaurs, ichthyosaurs, pterosaurs, plesiosaurs, and Dimetrodon, while often popularly conceived of as dinosaurs, are not taxonomically classified as dinosaurs. Pterosaurs are distantly related to dinosaurs, being members of the clade Ornithodira. The other groups mentioned are, like dinosaurs, members of Sauropsida (the reptile and bird clade), with the exception of Dimetrodon (which is a synapsid)."
If you ever look at different "artist's depiction" drawings about "dinosaurs" you might notice plenty of misconceptions: anatomically incorrect (and impossible) positions, strange mixes of species living in vastly different time periods, animals that aren't actually dinosaurs, etc.
'There has been a recent revival of interest in the famous Early Triassic thecodont Euparkeria, and Welman (1995) has discovered a suite of avian-like anatomical features in the basicranium. Paul (2002:179), an ardent advocate of the “birds-are-dinosaurs,” and more recently, “dinosaurs-are-birds” school, admits that, “Euparkeria is a suitable ancestral type for birds … and … Euparkeria is a good ancestral type for all archosaurs.”' https://doi.org/10.1642/0004-8038(2002)119[1187:BADSAT]2.0.C...
I still don't see what this has to do with a "time vector descriptor".
birds are dinosaurs and dinosaurs aren't birds
you've reversed the vectored direction of time in your claim
Edit: And what does "vector" add to your sentences?
A: "you've reversed the vectored direction of time in your claim"
B: "you've reversed the direction of time in your claim"