The Apex predator of the Sea of Grass biome from planet Andromeda is mostly bipedal, but capable of facultative quadrupedalism, it has long limbs, powerful claws on its hands and is roughly the size of an utahraptor, but with a neck that can be from twice to thrice as long. It is a pursuit predator, running after its prey (which usually has similar size or is slightly larger) on all fours until it is close enough to it. It will then hold it with its forelimbs while using its Jaws to slice chunks of meat off until it can no longer run away. It's neck is usually very close to the body, like a green heron's, extending only once it has a hold of it's prey, in order to bite at more strategic places. It's Jaws, on the other hand, are toothless, being composed of bladed, self-sharpening plates much like those of the dunkleosteus, which are meant for cutting pieces of swallowable size.
Now, could such Jaws be used alongside a long neck? I feel like it would need strong muscles to hold the head like terrorbirds did, but I'm not sure if such fearsome Jaws would truly work well with an "extendable" neck. It's cranium has a crest on its back, serving as an anchor point for muscles while Making its head similar to a long snouted dunkle.
NOTES-It's planet has earth like conditions, safe for a slightly denser atmosphere, and it's main habitat is composed of plains much like the African Savanah, except for larger, yet more separated trees. Prey is composed of creatures much alike earth's ungulates.