Notes:

Artist's description:

Flying deinonychosaurs were the obvious choice for pegasi in the original My Little Maniraptor drawing. (I could have also used avialians, but I wanted overall body plans to be fairly constant.) Rainbow Dash is a microraptorine deinonychosaur, her head crest being inspired by one that was thought to be present on Microraptor. Unfortunately, at around the same time I posted the original My Little Maniraptor, a new study came out showing that the "crest" of Microraptor was a preservational artifact caused by the flattening of dead Microraptor and wasn't present in life. Fortunately, none of the My Little Maniraptor characters are intended to actually be real species, just inspired by them, so I'm still safe. Incidentally, some ongoing research suggests that Microraptor was a very capable flier, a worthy basis for maniraptor!Rainbow Dash. And once again I've wriggled out of drawing Rainbow's cutie mark in full.

In My Little Maniraptor, most of the characters, even those within the same broad "type" (caenagnathoid/flightless deinonychosaur/flying deinonychosaur), are clearly of different species, but in the original show the different pony types can interbreed and can even give birth to young that are a different type from their own, as demonstrated by Pound and Pumpkin Cake (a pegasus and unicorn with earth pony parents). I'd probably try to keep established couples as being members of the same species in My Little Maniraptor. Interspecies romance is possible (read: unavoidable) in some instances, but would in most cases not produce fertile young. As for Pound and Pumpkin Cake, I'd postulate that maniraptor!Pound Cake is capable of flying due to larger wing-body ratio and will lose this ability as he grows up (this is something that's been speculated for at least some deinonychosaurs), while magic is an innate ability possessed by all maniraptors, and is prone to overt expression in some young individuals (hence Pumpkin Cake; I'll ignore the horn), but can only be effectively harnessed by adult caenagnathoids, which can channel it through their crests. Of course, depending on how the original show develops any of my placeholder ideas here can be shattered to bits.

Also, quadruple rainbow!