I would like to talk with a friend about some classification problems such as :

1 - Is Acrocanthosaurus an Allosaurid or a Carcharodontosaurid.
2 - Is there any "Prosauropod" families or they are all in same informal group "Prosauropa".
3 - What about Alvarezsaurids?... Were they birds or dinosaurs?.

I used to be really attune in palaeontology, but Atlantis grabbed my attention later in life. I wish I could help you more. But I think the answer to #1 is an Allosaurid. #2 Yes. Their are families. Google will he able to help. Just look up Prosauropod families. #3 Not sure. I think they were lizards? Got me on that one.

1. allosaurid
2. yes
3. i think a precursor to birds

At first thank you for everything......
Acrocanthosaurus atokensis sometimes classificated as Carcharodontosaurid. I think it's true becouse its skull characters are much more like Carcharodontosaurids and also it lived much later than Allosaurids. But some articles about dinosaur's classification (and also you & Frogfish) take it near to Allosauridae (only with Allosaurus not more species).

About "Prosauropoda" : They are really hard to classificate, and it always chages....
DinoData says there are a lot of "Prosauroda" families which includes in basal Sauropodomorpha :

Anchisauridae (Anchisaurus)
Blikanasauridae (Bliakanasaurus)
Melanorosauridae (Camelotia, Chinshakiangosaurus, Melanorosaurus, Riojasaurus, Thotobolosaurus)
Plateosauridae (Ammosaurus, Coloradisaurus, Euskelosaurus, Lufengosaurus, Mussaurus, Plateosaurus, Ruehleia, Sellosaurus, Yimenosaurus)
Thecodontosauridae (Azendohsaurus & Thecondontosaurus)

and then the problems begin :

Sauropodomorpha
Sauropoda

just check it - u will see what i mean

Alvarezsauridae..... Who knows!!! they have soem characters that just seen in Avean (true) birds.... Some articles take them near to Ornithomimosauria or even Oviraptorosauria!!!!!!!!! ....... BUT no way to lizards!!!! lizards much more near to snakes & Mosasaurs!!!!!

I like to talk about dinosauria, classification and evolution

thank you again

same here