You’re all wrong

Star Trek: Voyager has a specific answer to this question.

EDIT: To anyone unfamiliar with Star Trek, this episode of Voyager is “Distant Origin” (season 3 episode 23). In the episode, a species named Voth, encounter the remains of a Provisional Ensign Hogan who had died back in “Basics, Part II” (season 3 episode 1). Among a slim minority of the Voth science community is what is known as the Distant Origin Theory which suggest the species came from a far away place, which goes against The Doctrine, a narrow minded belief that Voth have always lived in the part of the galaxy they are currently located. During the episode it is determined that Voth and Humans share related DNA, which is later hypothesized to mean dinosaurs on Earth evolved to a point which they left the planet to live elsewhere.
now that I think about it, how would that fit into the progenitor lore?
Another option:

I remember the first time I saw the ‘evolved Troodon’ as a little girl and it terrified me. I’m curious what it would be updated to, since we’ve learned so much in the last 30 years
I saw this and thought, “pretty sure that’s from that documentary I saw a long, long time ago.” Then I saw your comment, and felt vindicated.
I humbly submit Enik the Altrusian https://youtu.be/S7aJE6BgY1o
They’d be smart enough not to be upright and bipedal to avoid back problems.
How’s a quadrupedal animal gonna have thumbs?
Bipedal dinosaurs with grasping hands are pretty common. Velociraptors, for example.
So back problems
Humans have back problems because we took a spine that had evolved for billions of years to be horizontal and stacked it up like a bunch of dinner plates.
I think the T-rex did it first.









