I'm not going to beat around the bush; I think they're Velociraptor because, at the end of the day, The Land Before Time is a Universal property, and given how prominent Velociraptor is in their other dinosaur property, I don't see why Universal would so prominently utilize non-velociraptor dromaeosaurs in their films.
Before anyone cries foul on how the post-art shift raptors look too different from the earlier raptors to be the same species, this weird species dimorphism is also present in Universal's other raptors; like the velociraptors in this franchise, the earlier morphs (in JP's case, the male variant of the earlier morph introduced in The Lost World: Jurassic Park) are brown/red/orange with stripes with slit pupils and are Deinonychus sized (the Big One's size is special to that individual, from memory), while the raptors in Jurassic Park III are more brightly colored with round pupils and are quite a bit bigger than their earlier peers.
Heck, if you ask me, you could make an argument that the TLBT raptor redesign was less drastic than the Jurassic Park raptor redesign, given that the beef raptors at least share markings and don't have quills or such (the biggest difference between the pre- and post-art shift raptors is finger count)...!
I think the same thing happened here that happened to the T. rex; after the art shift, a change in artists/animations/writers resulted in sharpteeth from past movies being changed to suit the new style, resulting in them looking really weird in comparison to their past selves (and leading people to think that they're not even the same genera as their ancestors; less so with the T. rex because we have definite proof they're Rexes).
If Universal has their own bizarre, iconic and marketable interpretation of Velociraptor, why wouldn't they use them in both of their dinosaur franchises?
EDIT: As an odd addition to this:
even ignoring the continued Jurassic parallels, if this is a Velociraptor, Screech and Thud can't be anything other than Velociraptor too.
EDIT 2: In a bizarre twist of fate, it appears that Screech and Thud's kind are canonically closer to this
than they are to the raptors from Jurassic Park III. Disregard this blog post.