Written on 5/12/23.
Link:
https://www.academia.edu/101770036/Saurophaganax_is_a_Carcharodontosaurid_An_Abstract
Saurophaganax is a Carcharodontosaurid: An Abstract
Saurophaganax maximus is a carnivorous theropod from the late Jurassic of North America. In the past, the genus has either been listed as a basal allosaurid that was a sister taxon to Allosaurus, or as a species of Allosaurus called Allosaurus maximus. This author proposes a different classification: Saurophaganax was a carcharodontosaurid, and was probably the first member of the clade to inhabit North America. The fossils were found in Quarry 1 in Oklahoma, but were not excavated at once or by professionals. With all due respect to the original excavators, to be as thorough as possible, this author decided to examine every bone individually to see if they belonged to a basal allosaurid or a carcharodontosaurid. OMNH 01135, an atlas, is morphologically similar to Tyrannotitan/Giganotosaurus chubutensis, exhibiting a “V-shaped” morphology. In comparison, the atlas of Allosaurus is linear in profile. The holotype specimen of Saurophaganax, OMNH 01123, is a mid-dorsal neural arch that has two horizontal laminae projecting off of it. This is not documented in Allosaurus. The overall morphology of OMNH 01123 is similar to Tyrannotitan/Giganotosaurus chubutensis’ first dorsal vertebra. Tyrannotitan/Giganotosaurus chubutensis also had an accessory lamina on its second and third dorsal vertebrae. Lusovenator had a lamina on the prezygapophysis on the second caudal vertebra, and a lateral lamina on the mid-posterior caudal vertebrae. Veterupristisaurus exhibited two “V-shaped” spinoprezygapophyseal laminae that are connected to the prezygapophysis, and two short laminae that are connected to the spinoprezygapophyseal laminae, on its caudal vertebrae. Laminae like these are typically not seen in other carnivorous theropod clades, but in carcharodontosaurids they had a wide range of forms and placements on the vertebral column. The mid to distal caudal chevrons (OMNH 01685) are morphologically similar to Acrocanthosaurus’, Meraxes’, and Lusovenator’s, but not Allosaurus’. The ilium (OMNH 01338) resembles Concavenators’, Meraxes’, and Acrocanthosaurus’. The tibia (OMNH 01370) looked similar to Acrocanthosaurus’. OMNH 01708/0112, a femur, had a head pointing upwards and a shaft that was bowed/convex laterally, as seen in many carcharodontosaurid taxa. This is not present in Allosaurus’ femur. OMNH 01425, a partial right pubis, is closer in form to Mapusaurus/Giganotosaurus roseae’s than to Allosaurus’. Previously, this author assigned a partial left pubis (OMNH 01707), and a left pes (OMNH 01708), to possibly belonging to Allosaurus. However, these bones could belong to either Allosaurus or a carcharodontosaurid. Tyrannotitan exhibited a similar morphology in its pubis to OMNH 01707. Therefore, both OMNH 01425 and OMNH 01707 can be assigned to a carcharodontosaurid. OMNH 01708 has a similar morphology to both Lusovenator’s and Meraxes’, with the fourth metatarsal being concave. Currently, a giant humerus (OMNH 01935), and a manual ungual (OMNH 780), don’t seem to exhibit carcharodontosaurid traits so far. They appear characteristically similar to Allosaurus, so they could belong to Allosaurus or to a carcharodontosaurid. This author will keep both possibilities open. In summation, Saurophaganax exhibits numerous skeletal features that could place it within the carcharodontosaurid clade.
