Stephan Pickering wrote-
I do not accept "Carnosauria" as a valid taxon -- as yet. There are a plethora of taxa whose affinities are in flux, primarily because of convergences in a number of character traits. For example, I would position Coelophysis and its allies outside of Ceratosauria, with Ceratosaurus and abelisaurs as sister taxa to Tetanurae. I would, also, place Megalosauridae within Avetheropoda (Megalosaurus = Torvosaurus, Eustreptospondylus, Metriacanthosaurus, Poecilopleuron, Gasosaurus?, Piatnitzkysaurus?), with the "spinosaurs" as a closely related group. Although it would create enormous taxonomic headaches, I believe it possible Allosaurus and Streptospondylus and Neovenator could be synonymized.
Technically, your Megalosauridae Spinosauridae + Allosauridae clade would be Carnosauria (everything closer to Allosaurus than to birds). I like the paraphyletic Ceratosauria. I don't see how you could justify synonymizing Streptospondylus with Allosaurus, as Allain did a good job of showing it was a spinosauroid closely related to Eustreptospondylus. Synonymizing Allosaurus and Neovenator much makes virtually all allosaurids Allosaurus, as Neovenator is thought to be closer to carcharodontosaurines(-ids) than Allosaurus. I don't find the thought of Allosaurus saharicus, A. atokensis or A. carolini very appealing.