My Prehistoric Saga: Dino Bios: "Saurophaganax".

Update (11/4/24):
There is a huge possibility that "Saurophaganax" was a chimera. For more information, read my post here:

https://psdinosaurs.blogspot.com/2024/11/news-is-saurophaganax-not-valid-taxon.html

Update (5/14/23):
I wrote an abstract on Saurophaganax being a carcharodontosaurid:
https://www.academia.edu/101770036/Saurophaganax_is_a_Carcharodontosaurid_An_Abstract

Saurophaganax:

(Illustration is owned by me)

Time: 157-145 million years ago, Kimmeridgian-Tithonian of the late Jurassic period.

Place: North America.

Size: 28-36 feet (8.4-11.1 meters).
Weight: 3 tons.

Diet: Carnivore.

Description:

Saurophaganax is a carcharodontosaurid from the late Jurassic period of North America. It lived during the Kimmeridgian-Tithonian (Smith, 1998, pg. 126) (Sebastian G. Dalman, 2014, pg. 173-174) (Matthew T. Carrano et al., 2012, pg. 241). Its fossils came from rocks that seem to be from the Brushy Basin Member of the Morrison Formation (Chure, 1995, pg. 106). The Morrison Formation is made up of three major members: Tidwell, Salt Wash, and Brushy Basin (Kowallis et al., 1998, "Abstract") (Scott et al., 2001, pg. 12-14) (The University of Utah, "Morrison Formation"). According to Kowallis et al., (1998), the Tidwell Member is 155 million years old. The Brushy Basin Member is 150-148 million years old. Thus, the Morrison Formation is Kimmeridgian-Tithonian in age ("Abstract"). The Salt Wash Member is located in between the Tidwell and Brushy Basin Members (Chure and Loewen, 2020, "Age"), so it must be around 155-150 million years old. However, the Brushy Basin's maximum age seems to be 153-145 million years old (Kowallis et al., 1991, "Abstract") (Irmis et al., 2013, pg. 282). Therefore, the Salt Wash Member seems to be 155-153 million years old. In total, the Tidwell Member is 157-155 million years old, the Salt Wash Member is 155-153 million years old, and the Brushy Basin Member is 153-145 million years old. In total, the Morrison Formation is Kimmeridgian-Tithonian in age, ranging from 157-145 million years ago. Palynomorphs and calcareous microfossils prove this as well (Turner and Peterson, 1999, pg. 89-90) (Marjanovic and Laurin, 2014, pg. 2) (Dinosaur National Monument, "Rhadinosteus parvus"). Therefore, Saurophaganax lived during the Kimmeridgian-Tithonian of the late Jurassic period.

Saurophaganax is usually said to have looked liked a larger version of Allosaurus. However, a phylogenetic analysis of Saurophaganax in 2009, and my own personal investigation, seems to place it as a member of the carcharodontosaurids. This means that Saurophaganax might have look a bit more different than Allosaurus, and more like Acrocanthosaurus or some other carcharodontosaurids. At 28-36 feet in length (8.4-11.1 meters), Saurophaganax was the second-largest predator during the late-Jurassic period of North America. However, it was overshadowed by the 52-foot long (15.8-meter) Allosaurus.

Carnivorous theropod dinosaurs had enamel in their teeth, so they must have had lips to cover and protect their teeth (Reisz and Larson, 2016, pg. 64-66) (Blake Eligh, 2016) (Mindy Weisberger, 2016) (Emanuela Grinberg, 2016) (Phys, 2016). Therefore, Saurophaganax would have had lips covering its teeth. Interestingly, dinosaurs couldn't move its tongues (Mindy Weisberger, 2018) (ScienceDaily, 2018).

According to Kenneth Carpenter (2002), in most predatory theropods used their mouths first to grab prey first, and then they would grab their prey "in a 'bear hug'" with their hands (pg. 72, "Conclusion"). For Allosaurus, a relative of Saurophaganax, its arms were relatively long and robust. The range of motion in its arms seems to have allowed it to grab and pull "moderately large prey" towards it. Carpenter says that evidence of Allosaurus using its arms to hunt large sauropods isn't present ("Biomechanical Analysis," pg. 71). Text-figure 9 shows Allosaurus', and other theropod's, range of motion for their hands (pg. 69). Apparently, it can bend its hand quite well outward. Perhaps this was the same for Saurophaganax. Matt A. White et al., (2015) says that carcharodontosaurid arms were similar to tyrannosaurs, in which they used their jaws to grab their prey first and used their arms to secure it ("Discussion," p. 6). Therefore, it seems that carcharodontosaurids like Saurophaganax used their hands to help their jaws capture prey mainly. However, their hands might have been able to bend slightly like Allosaurus'.

As for speed, Dececchi et al., (2020) says that theropods over 1000 kg would not be able to run fast, despite their different limb lengths. Instead, they were speed-walkers (Dececchi et al., 2020, "Abstract;" "Discussion," "Getting up to speed" p. 3; "Why tyrannosaurids?" p. 2) (EurekAlert, 2020). They could do this for a long time (The Canadian Press, 2020). The young seem to have been faster ("Results," "Relative leg length" p. 1), and pack-hunting was also suggested to help large theropods take down prey (The Canadian Press, 2020) (Dececchi et al., 2020, "Discussion," "Why tyrannosaurids?" p. 2-3).

"Allosaurus maximus?"

David K. Smith (1998) and Smith et al., (1999) called Saurophaganax "Allosaurus maximus," and said that the differences between Allosaurus and Saurophaganax are due to morphotypes (or individual variation, as seen in individual Allosaurus skeletons) and sexual dimorphism. He also says that Saurophaganax and Allosaurus had a similar growth rate, which seems to mean that the two genera grew at the same rate and maybe to similar sizes. Gregory S. Paul in 2010/2016 said that there is "insufficient information" for its anatomical characteristics (pg. 101).

After a personal investigation, it seems that Allosaurus maximus might indeed be a valid species of Allosaurus. Chure (1995) states that the retrieval of Saurophaganax's bones is uncertain. It is not known for certain if all of the bones were collected from the same quarry, Quarry 1, since the bones were not collected by professionals and no maps of the quarry exist (pg. 103). This was also stated in Riley Black (2011). A a humerus, a manus, a manal digit 1 claw, a half right pubis, two femurs, a pedal phalanx I-1, and a left pes/metatarsals are all similar to Allosaurus' (Chure, 1995, pg. 103-104) (Smith, 1998, pg. 131, 134, and 140) (Dalman, 2014, pg. 173-174). Therefore, I've separated those bones and put them as Allosaurus maximus. An atlas, a mid-dorsal neural arch, an ilium, a proximal half left pubis, and a tibia, I say, belong to Saurophaganax.

Update (7/7/20): The only species of Allosaurus that seems to be valid is Allosaurus fragilis (refer to Evers et al., 2020). Therefore, the Allosaurus bones attributed to Saurophaganax are A. fragilis until further notice.

Distinguishing Characteristics from Allosaurus:

Only fragmentary specimens of Saurophaganax have been found. Of these, the best specimen is the holotype, OMNH 01123, which consists of just a fragmented neural arch. It has two horizontal lamina at the top of it, which is something Allosaurus doesn't have (Chure, 1995, pg. 103).

Saurophaganax's Neural Arch (OMNH 01123) (Chure, 1995, pg. 104):

Other characteristics include different caudal chevrons (tail vertebrae), and an atlas (cervical vertebrae that connects skull to spine) that resembles those of the tyrannosaurid Tarbosaurus (Chure, 1995, pg. 103, "Description"). Interestingly, Carrano et al., (2012) has only two differences that say distinguishes Saurophaganax from Allosaurus: The lamina and an atlas lacking prezygapophyses (pg. 241). They also state that Saurophaganax is "located higher in the Morrison Formation than most Allosaurus specimens." This isn't true, considering that Allosaurus (?)lucasi lived during the Tithonian as well as Saurophaganax. However, Dalman (2014) says that Saurophaganax's condyle on its tibia head is more centered than Allosaurus lucasi, and it takes up most of its femoral head. Interestingly, both Saurophaganax and Allosaurus lucasi have a "slightly divergent fourth metatarsal." Other than that, there is "minimal..., or incomplete overlapping material" between Allosaurus lucasi and Saurophaganax. Size might be a differentiating factor as well, but it might not matter (pg. 174).

To the general public and for many scientists, Saurophaganax is its own species of allosaurid. However, some scientists still say that more bones are needed (Paul, 2010/2016). It's not a popular theory that Saurophaganax is a carcharodontosaurid, mainly because, aside from Cau (2009), no one else has even considered it. Everyone agrees with Chure's conclusion that Saurophaganax is a allosaurid (Chure, 1995), but some people think that it resembles too much like Allosaurus to be its own genus (Smith, 1998) (Paul, 2010/2016).

I'd say that the Allosaurus-like fossils should be separated from the material that does not look like Allosaurus fossils. The Allosaurus-like fossils should be called Allosaurus maximus, and the dorsal neural arch, atlas, ilium, and tibia should be called Saurophaganax. As stated before, we don't know for certain if all of the fossils attributed to Saurophaganax came from the same place. Therefore, it seems easier just to separate the material.

A Carcharodontosaurid:

Saurophaganax has been described as morphologically similar to Allosaurus (Chure, 1995, pg. 104). A skeleton of Saurophaganax has been assembled at the Oklahoma Natural History Museum, Utah Museum of Natural History, and New Mexico Museum of Natural History and Science. However, bones from Allosaurus were used to help create the skeleton.

Saurophaganax Skeleton (Oklahoma Natural History Museum):

Saurophaganax Skeleton (Utah Museum of Natural History):

Saurophaganax Skeleton (New Mexico Museum of Natural History and Science):

Saurophaganax was also featured in the 2011 documentary, Planet Dinosaur.

Saurophaganax in Planet Dinosaur:

In 2009, Paleontologist Andrea Cau has determined that Saurophaganax is a "basal carcharodontosauridae," due to a phylogenetic analysis. Through a personal study, I've also found out that Saurophaganax's atlas and dorsal vertebrae are very similar to the carcharodontosaurid Tyrannotitan. This, along with Cau's phylogenetic analysis, means that Saurophaganax is the first carcharodontosaurid that evolved in North America, and might be the ancestor of Acrocanthosaurus, a later carcharodontosaurid from the early Cretaceous of North America. Additionally, this means that Saurophaganax might have looked more different from Allosaurus than previous depictions have given. Also, the carcharodontosaurids have a variety of vertebra designs. Acrocanthosaurus had tall neural spines that create a ridge on its back, and Concavenator had a hump/sail. Perhaps Saurophaganax's horizontal lamina help to place it in the carcharodontosauridae, and it might have led to the evolution of Acrocanthosaurus' tall neural spines on its back. That, or it's a unique trait, as stated by Chure (1995) (pg. 103).

However, the carcharodontosaurid Veterupristisaurus had two "V"-shaped spinoprezygapophyseal lamina, joined by two parallel lamina, on its caudal vertebra (Rauhut, 2011, pg. 224). This isn't usual in other theropods.

Veterupristisaurus' Caudal Vertebra (Dorsal View) With Spinoprezygapophyseal Lamina (SPRL) and Parallel/Additional Lamina (ALL) (Rauhut, 2011, pg. 224):

A new species of carcharodontosaurid called Lusovenator, discovered in 2019 in Europe, has anterior centrodiapophyseal lamina, and centropostzygapophyseal lamina, on the top of its caudal vertebra (Figure 4). It also has spinopostzygapophyseal lamina as well ("Caudal Vertebrae," p. 4).

Lusovenator Specimen SHN.019's Caudal Vertebra (Malafaia et al., 2019, Figure 4) ("acdl" and "cpol" are lamina):

The carcharodontosaurid Giganotosaurus (Mapusaurus) roseae also has lamina on its vertebra:

1. "smaller and less elaborate prespinal lamina on midline of cervicals," (Coria and Currie, 2006, pg. 75, "Diagnosis")

2. Prespinal and spinoepipophysial lamina on its axis neural arch (Coria and Currie, 2006, pg. 88, Figure 13):

3. Infradiapophysial and infraprezygapophysial laminae on its cervicodorsal vertebra (Coria and Currie, 2006, pg. 89, Figure 14):

4. Anterior spinodiapophysial and posterior spinodiapophysial lamina on its dorsal vertebra (Coria and Currie, 2006, pg. 90, Figure 15):

As for Tyrannotitan, it has "accessory laminae" in its second and third dorsal vertebrae, and has "medial and curved laminae" on its first dorsal vertebra (Canale et al., 2015):

1. "...second to third dorsal vertebrae with well-developed accessory lamina connecting anterior and posterior centrodiapophyseal laminae," (Novas et al., 2015, "Systematic paleontology: Emended diagnosis;" "Description: Second dorsal" pg. 10; "Description: Third dorsal" pg. 10-11). These accessory lamina on the third dorsal vertebra are seen in Acrocanthosaurus, but are less developed ("Description: Third dorsal," pg. 10-11).

2. First Dorsal Vertebra: "The hyposphene is well developed and has a short medial lamina at its ventral end that extends down to the dorsal edge of the neural canal. On both sides of the above-mentioned lamina, deep fossa are present. These are laterally bounded by a pair of curved lamina that have a similar disposition to that described of the seventh cervical, but are proportionally more robust (Figure 10(C)). These same laminae are present in Mapusaurus (MCF-PVPH 108.82) but in this taxon they are less developed than in Tyrannotitan, ("Description: First dorsal," pg. 10).

Tyrannotitan's 2nd-7th Dorsal Vertebrae (Canale et al., 2015, Figure 11) ("al" means Additional Lamina):

For Allosaurus, Gilmore (1920) says that the third dorsal has laminae on the neural arch that "converge" and "form a single vertical plate that support the diapophysis at the central line throughout its entire length" (pg. 38-39). The fourth dorsal is the last time in which two laminae are seen, and they "give support to the transverse process" (pg. 40). Pg. 40 shows the fourth dorsal vertebra. Madsen (1976/1993) doesn't list any lamina on Allosaurus' vertebra. Allosaurus doesn't seem to have horizontal, or other, lamina on its vertebra.

For T. rex, Brochu (2003) lists centrodiapophyseal, intrapostzygapophyseal, intraprezygapophyseal, and prezygodiapophyseal lamina on its vertebra (pg. 135-136). It doesn't have horizontal, spinoprezygapophyseal or additional, spinodiapophysial, prespinal and spinoepipophysial, or other unusual lamina that the carcharodontosaurids have on its vertebra.

This helps to prove that carcharodontosaurs have unusual lamina in their vertebra, and that Saurophaganax is a carcharodontosaurid. Also, Saurophaganax's dorsal vertebra and atlas are identical to the carcharodontosaurd Tyrannotitan's.

Saurophaganax's Atlas (Chure, 1995):

Tyrannotitan's Atlas (Canale et al., 2015):

Saurophaganax's (Right) and Tyrannotitan's (Left) Dorsal Vertebra:

No complete skull of Saurophaganax has been discovered, only fragments (Chure, 1995, pg. 103). However, instead of Allosaurus', I personally think it would like something akin to Acrocanthosaurus' skull, since Saurophaganax appears to be its ancestor. This means that it would have smoother, circular-shaped crests on the top of its head instead of tall, pointed ones like Allosaurus.

Update (12/18/19): Paleontologist Mickey Mortimer in 2018 did a Lori analysis on her Theropod Database blog, and placed Saurophaganax as a relative of Acrocanthosaurus and Concavenator.

In summary, Saurophaganax is a carcharodontosaurid due to phylogenetic and Lori analyses, an atlas that is similar to the carcharodontosaurid Tyrannotitan's, a mid-dorsal neural arch with horizontal lamina than is similar to Veterupristisaurus' spinoprezygapophyseal and parallel lamina on its caudal vertebra, has an ilium similar to Acrocanthosaurus', a partial right pubis that looks like Mapusaurus', a femur that look like many carcharodontosaurid taxa, and a tibia that looks like Acrocanthosaurus'.

Just to see what it might have looked like, I drew a picture of what I think Saurophaganax's head might have looked like (shown in the beginning of this post). It was inspired by Acrocanthosaurus' skull.

Prey:

Saurophaganax hunted the various sauropods that roamed the late Jurassic period of North America. This included Barosaurus, Brachiosaurus and Camarasaurus, and Maraapunisaurus. Other animals on the menu were Stegosaurus, Camptosaurus, and Mymoorapelta.

Enemies: