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Description
From one giant mess of a giant Morrison theropod to another, Saurophaganax fares even worse than Torvosaurus thanks to historical mishandling of the fossils at the time of their discovery. It seems to have been heavier built than close relatives (and possibly direct ancestors) A.fragilis and A.jimmadseni, with a shorter neck and larger jaws, suggesting that it took over a similar niche as past megalosaurs and later carcharodontosaurids, tackling the large contemporary sauropods. Unlike carcharodontosaurs, though, Saurophaganax shows no evidence of reducing its forelimbs, and in fact the humerus and first manual ungual are some of the biggest of any carnivorous theropod.

Chure (2000) identifies the Stovall's Pit material as coming from a minimum of four individuals, three of which are very similar in size and one smaller (~9.2-9.6 m in length), but some of the limb and hip bones are larger than expected for even those massive allosaurs. Most likely the discrepancies mean that Saurophaganax was simply more robust, as is the general trend in animal bones with increasing size, but the presence of a fifth, larger individual can't be excluded. Because the holotype consists of only a single dorsal vertebra and the referred specimens have their distinguishing features scattered between several different individuals, the validity of the genus has been questioned, but most published literature considers it distinct from Allosaurus.

References:
-Gilmore, Charles W. (1920). "Osteology of the carnivorous dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) andCeratosaurus" (PDF). Bulletin of the United States National Museum. 110 (110): 1–159. doi :10.5479/si.03629236.110.i .
-Madsen, James H. Jr. (1976). Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.).
-Chure, Daniel J. (1995). "A reassessment of the gigantic theropod Saurophagus maximus from the Morrison Formation (Upper Jurassic) of Oklahoma, USA". In A. Sun; Y. Wang (eds.). Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers. Beijing: China Ocean Press. pp. 103–106.
-Smith, David K. (1998). "A morphometric analysis of Allosaurus". Journal of Vertebrate Paleontology. 18 (1): 126–142. doi :10.1080/02724634.1998.10011039 .
-Chure, D., 2000, A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (Utah-Colorado) and a revision of the theropod family Allosauridae. Ph.D. dissertation, Columbia University, pp. 1–964
-Chure, Daniel J. (2000). "Observations on the morphology and pathology of the gastral basket of Allosaurus, based on a new specimen from Dinosaur National Monument". Oryctos. 3: 29–37.

Description
From one giant mess of a giant Morrison theropod to another, Saurophaganax fares even worse than Torvosaurus thanks to historical mishandling of the fossils at the time of their discovery. It seems to have been heavier built than close relatives (and possibly direct ancestors) A.fragilis and A.jimmadseni, with a shorter neck and larger jaws, suggesting that it took over a similar niche as past megalosaurs and later carcharodontosaurids, tackling the large contemporary sauropods. Unlike carcharodontosaurs, though, Saurophaganax shows no evidence of reducing its forelimbs, and in fact the humerus and first manual ungual are some of the biggest of any carnivorous theropod.

Chure (2000) identifies the Stovall's Pit material as coming from a minimum of four individuals, three of which are very similar in size and one smaller (~9.2-9.6 m in length), but some of the limb and hip bones are larger than expected for even those massive allosaurs. Most likely the discrepancies mean that Saurophaganax was simply more robust, as is the general trend in animal bones with increasing size, but the presence of a fifth, larger individual can't be excluded. Because the holotype consists of only a single dorsal vertebra and the referred specimens have their distinguishing features scattered between several different individuals, the validity of the genus has been questioned, but most published literature considers it distinct from Allosaurus.

References:
-Gilmore, Charles W. (1920). "Osteology of the carnivorous dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) andCeratosaurus" (PDF). Bulletin of the United States National Museum. 110 (110): 1–159. doi :10.5479/si.03629236.110.i .
-Madsen, James H. Jr. (1976). Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.).
-Chure, Daniel J. (1995). "A reassessment of the gigantic theropod Saurophagus maximus from the Morrison Formation (Upper Jurassic) of Oklahoma, USA". In A. Sun; Y. Wang (eds.). Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers. Beijing: China Ocean Press. pp. 103–106.
-Smith, David K. (1998). "A morphometric analysis of Allosaurus". Journal of Vertebrate Paleontology. 18 (1): 126–142. doi :10.1080/02724634.1998.10011039 .
-Chure, D., 2000, A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (Utah-Colorado) and a revision of the theropod family Allosauridae. Ph.D. dissertation, Columbia University, pp. 1–964
-Chure, Daniel J. (2000). "Observations on the morphology and pathology of the gastral basket of Allosaurus, based on a new specimen from Dinosaur National Monument". Oryctos. 3: 29–37.