My Prehistoric Saga: Is Saurophaganax a Carcharodontosaurid?

Update (11/4/24):
There is a possibility that "Saurophaganax" was a chimera, made up of jumbled Allosaurus bones, sauropod bones, and possibly another unknown theropod. 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 here:

https://www.academia.edu/101770036/Saurophaganax_is_a_Carcharodontosaurid_An_Abstract

Saurophaganax (Planet Dinosaur):

I've been perplexed by Saurophaganax for a while now. When I first learned about this particular theropod years ago (back in the early 2010's), it was depicted as being a larger version of Allosaurus. However, when I learned that some scientists considered it to be a species of Allosaurus, "Allosaurus maximus," I thought that that made more sense instead of calling it a different genus. However, I learned later on that there is one major difference in its vertebrae that separated it from being a species of Allosaurus: the horizontal lamina on the top of its vertebrae. These lamina are absent on Allosaurus' vertebrae, so many other scientists have concluded that Saurophaganax is its own genus.

Saurophaganax Specimen OMNH 01123 Mid-Dorsal Neural Arch With Horizontal Lamina Indicated by Arrows) (Daniel J. Chure, 1995, pg. 104, Cranial View):

There are some other differences listed by Chure (1995), but they aren't mentioned in Carrano et al., (2012) or in Dalman (2014). Those two other papers name a few more differences that separate Saurophaganax from Allosaurus, but the horizontal laminae is the most noted difference. David K. Smith (1998) and Smith et al., (1999) have tried to place Saurophaganax as a species of Allosaurus, which is where "Allosaurus maximus" comes from. This is due to Saurophaganax having the same growth rate as Allosaurus, and since individual specimens of Allosaurus have different physical attributes from each other, the physical differences seen in Saurophaganax could be due to individual variation and sexual dimorphism.

Many scientists have rejected Smith (1998) and Smith et al., (1999), and kept Saurophaganax as its own genus. We will come back to the lamina later. The main focus of this post is this... Is Saurophaganax a carcharodontosaurid? Chure (1995), and every other publication, have placed Saurophaganax as an allosaurid. This is due to Saurophaganax having a similar morphology to Allosaurus fragilis, despite having differently-shaped vertebra and being overall more robust than Allosaurus. However, the differences in Saurophaganax's bones (most notably as described in Chure, 1995) seemed to indicate to me that Saurophaganax was more advanced than Allosaurus. I decided to check this out, and here's what I've found:

A Tyrannosauroid?
Before I considered Saurophaganax to be a carcharodontosaurid, I thought that Saurophaganax might have been a tyrannosauroid. This is due to what Chure (1995) said:

-An atlas (cervical vertebrae that connects skull to spine) that resembles those of the tyrannosaurid Tarbosaurus (pg. 103 and 104).

-Mid-caudal and caudal chevrons resemble Tarbosaurus and Tyrannosaurus rex (pg. 103).

With those two things in mind, I figured that Saurophaganax could have been a tyrannosauroid. It wouldn't have been the only tyrannosauroid around. Stokesosaurus was another tyrannosauroid that lived during the Kimmeridgian-Tithonian of late-Jurassic North America (Delcourt and Grillo, 2018). It sounded cool to me that there might have been two tyrannosauroids around, and one of them rivaled Allosaurus in size. However, on pg. 104 of Chure (1995), Chure says that Saurophaganax's chevrons evolved independently of tyrannosaurids, but the atlas is still similar to tyrannosaurids. He also says that Saurophaganax's morphology is similar to Allosaurus (pg. 104).

However, since Saurophaganax had a similar morphology to Allosaurus, there is another branch of carnivorous theropods (that I've mentioned before) that we can check out.

A Carcharodontosaurid?
I came across this post from Andrea Cau's blog that was written back in 2009. In it, he talks about a phylogenetic tree that he did on Saurophaganax, and it appears that Saurophagananx is a basal carcharodontosauridae. I was surprised to learn about that, but as I thought about it, it made sense.

1. Other carcharodontosaurids like Acrocanthosaurus and Concavenator had weird vertebrae too. Acrocanthosaurus had a ridge on its back created by tall neural spines (Riley Black, 2010) (J. Willis Stovall and Wann Langston, Jr., 1950, "Abstract"), and Concavenator had a hump (Ortega et al., 2010) or sail like Spinosaurus, but it wasn't as long as Spinosaurus' (Black, 2010).

Acrocanthosaurus Skeleton:

Concavenator:

2. Saurophaganax's atlas is basically identical to the carcharodontosaurid Tyrannotitan.

Saurophaganax's Atlas (Chure, 1995, pg. 104, "A" is Cranial View, "B" is Right Lateral View"):

Tyrannotitan's Atlas (Canale et al., 2015, pg. 8, "A" is Anterior View, "B" is Right Lateral View):

3. Of course, Saurophaganax's vertebrae was different from Allosaurus due to horizontal lamina (Chure, 1995, pg. 103-104) (Matthew T. Carrano et al., 2012, pg. 240-241). In fact, Carcharodontosaurids had weird lamina on their vertebra in general.

Tyrannotitan's dorsal vertebrae looks very similar to Saurophaganax's, minus the horizontal lamina.

Saurophaganax's (Chure, 1995, pg. 104) and Tyrannotitan's (Canale et al., 2015, pg. 10) First Dorsal Vertebrae (Anterior Views):

On Tyrannotitan's first dorsal vertebrae, there are (at best) three lamina present. As Canale et al., (2015) describes, there is a "medial lamina located on the ventral end of the hyposphene that extend down to the dorsal edge of the neural canal." On the sides of that lamina are "deep fossae, which are laterally bounded by two curved, robust laminae." These (either just those two, or possibly all three) laminae are also present in Giganotosaurus (Mapusaurus) roseae, but are less developed (p. 10).

There was another late-Jurassic carcharodontosaurid that had interesting lamina on its vertebra. Veterupristisaurus, from the Kimmeridgian of the Middle Dinosaur Member of the Tendaguru Formation, Africa (Rauhut, 2011, pg. 223) (Bussert et al., 2009, "Members of the Tendaguru Formation," "Middle Dinosaur Member," pg. 160-162), had two spinoprezygapophyseal laminae that are connected to the prezygapophysis (one of them is slightly broken), and two short laminae that are connected laterally (on the sides) of the spinoprezygapophyseal lamina, on its caudal vertebrae (Rauhut, 2011, pg. 223 and 225). The spinoprezygapophyseal lamina form a "'V'-shape to define a narrow, deep fossa," (pg. 224). In other words, they form a "V." The spinoprezygapophyseal lamina in Veterupristisaurus is placed differently than in other theropods (pg. 223).

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). The authors describe these lamina as follows:

1. "A well-developed spinopostzygapophyseal lamina (spol) projects from the dorsomedial surface of the postzygapophysis, connecting it with the posterior surface of the spine. This lamina extends along most of the height of the neural spine," ("Caudal Vertebrae," p. 4).

*2. "In the second caudal vertebra of the preserved caudal series, a well-developed lamina projects from the lateral surface of the base of the prezygapophysis and apparently would have connected with the caudal rib, bounding a small, but deep fossa bellow the caudal rib (Fig. 4.1). These lamina and fossa are interpreted as corresponding to the prezygodiapophyseal lamina (prdl) and centroprezygapophyseal fossa (cprf), respectively. A well-developed centroprezygapophyseal lamina (cprl) is visible in some vertebrae, projecting from the anterior margin of the prezygapophysis up to the level of the base of the caudal rib on the centrum. Some vertebrae (e.g., the sixth and eighth of the preserved series) show well-developed centropostzygapophyseal laminae (cpol) extending from the posterior part of the postzygapophysis up to the dorsal surface of the centrum above the level of the caudal rib (Fig. 4.2, 4.3). In the eighth preserved caudal vertebra, the cpol connects with the posterior surface of the caudal rib, forming a well-developed longitudinal and uninterrupted lamina," ("Caudal Vertebrae," p. 6).

*3. "SHN.019 shares... an unusual feature in the mid-posterior caudal vertebrae, a strongly developed lateral lamina projecting from the posterior articular facet to the base of the caudal rib. In some vertebrae, especially those near the “transition point,” a lower lateral lamina extending from the base of the prezygapophysis along the anterior end of the centrum is also present. A similar anterior lateral lamina is interpreted as a synapomorphy for Carcharodontosauria (Brusatte et al., 2008) and is visible in some anterior mid-caudal vertebrae of Concavenator (E. Malafaia, personal observation, 2016) and in Veterupristisaurus (Rauhut, 2011). However, in these taxa the anterior lateral lamina is more developed than the posterior lamina, whereas the specimens from the Lusitanian Basin, SHN.019 and SHN.016, show the opposite condition. In conclusion, the morphology of the femur and the presence of a lateral lamina extending from the base of the prezygapophysis along the anterior end of the centrum in the mid-posterior caudal vertebrae suggest that SHN.019 is a member of the clade Carcharodontosauria," ("Remarks," p. 9).

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

Those are the best examples, but here's two more that I just wanted to mention. I have no idea which laminae are more distinct from other theropod laminae, but I chose what I thought would help to prove my case.

As mentioned previously, the carcharodontosaurid Mapusaurus 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.

I think this helps to prove that Saurophaganax's horizontal lamina on its mid-dorsal neural arch places it as a carcharodontosaurid, not an allosaurid.

Saurophaganax being the first carcharodontosaurid from North America during the Jurassic could explain how Acrocanthosaurus, another carcharodontosaurid, appeared in North America during the Cretaceous. Saurophaganax's weird vertebrae might also explain how Acrocanthosaurus evolved its peculiar vertebra as well. That, or it's just a unique trait that carcharodontosaurids had. The physical similarities between Saurophaganax's atlas and dorsal vertebrae compared to Tyrannotitan's, and its lamina compared to Veterupristisaurus' and SHN.019's, indicates that it was, not only not a species of Allosaurus, but a member of the carcharodontosauridae.

One problem that I have with Saurophaganax is that we don't have a skull. NOT A SINGLE ONE! We do have a "postorbital, two partial quadrates, and three poorly-preserved tooth crowns" (Chure, 1995, pg. 103), but there aren't any pictures of them. What's even worse is that most drawings or other depictions of Saurophaganax have it with a skull similar to Allosaurus. Therefore, I would hypothesize that Saurophaganax had a skull similar to other carcharodontosaurids, in particular Acrocanthosaurus since I think Saurophaganax is the ancestor of Acrocanthosaurus. This means no large pointy crests on the top of its head. They might have been smoother and rounder.

Acrocanthosaurus Skull:

Here's my drawing of what I think Saurophaganax's face would have looked like (inspired by Acrocanthosaurus' skull):

(Illustration is owned by me)

Conclusion 1:
Saurophaganax was the first carcharodontosaurid from North America. Andrea Cau (2009) did a phylogenetic tree and concluded that Saurophaganax was a basal carcharodontosaurid. The horizontal lamina on Saurophaganax's vertebrae is unique, similarly to other weird spinal features seen in other carcharodontosaurid vertebrae, such as Acrocanthosaurus' ridge and Concavenator's hump or sail. The physical similarities seen in Allosaurus and Saurophaganax seem to be only ancestral attributes. The physical differences in Saurophaganax that are not seen in Allosaurus point towards a more advanced theropod, especially since its atlas and dorsal vertebrae are very similar to Tyrannotitan. Therefore, along with the phylogenetic tree done by Andrea Cau (2009), it seems that Saurophaganax is a carcharodontosaurid, and the first carcharodontosaurid that evolved in North America. Its appearance in the late Jurassic would have led to the evolution of Acrocanthosaurus later on in the early Cretaceous.

Concerning (?)Allosaurus maximus (Update 12/12/19):
I read Chure (1995) again today, and came across something interesting: The bones attributed to Saurophaganax were discovered in Quarry 1 from Oklahoma, but the original location of the bones is unknown because no maps exist for the quarry, and no evidence exists to conclude that the bones were found together. Also, during the original excavation and preparation of the fossil material in the 1930's-1940's, the bones were not collected by professionals. Paleontologist Daniel J. Chure assumes that all of the bones were found together (Chure, 1995, pg. 103). This was also stated in Riley Black (2011).

This is interesting because, as stated in Smith (1998), some of Saurophaganax's bones are identical to Allosaurus'. I re-read Smith (1998) as well, and found four important pieces of information:

1. Pg. 131: Saurophaganax's pedal phalanx I-1 falls within the expected range of variation for Allosaurus fragilis. It's just larger.

2. Pg. 134: Saurophaganax's humerus is larger than A. fragilis', but wasn't unusual and falls within the same non-size-related variation for Allosaurus.

3. Pg. 134: Some post-cranial elements (lacrimals?) of A. fragilis are similar to Saurophaganax's.

4. Pg. 140: Saurophaganax lies on the same growth trajectory for Allosaurus in almost every way.

Therefore, it has occurred to me that there is only one answer to Smith (1998)'s conclusions: Some Allosaurus bones must have been jumbled up with Saurophaganax's bones. Here's what I've come up with:

Definitely Saurophaganax Material:
The best evidence for Saurophaganax is the mid-dorsal neural arch and the atlas, which are definitely not Allosaurus (Chure, 1995, pg. 103-104) (Carrano et al., 2012, pg. 240-241) (My personal observation). They are similar to Tyrannotitan's, a carcharodontosaurid (Canale et al., 2015).

Possible Saurophaganax Material:
Since the femur seems to be "more laterally bowed" than Allosaurus' (Chure, 1995, pg. 104), I'll also assume that the femur belongs to Saurophaganax. The tibia is also different from Allosaurus' (Dalman, 2014, pg. 174), so I'll consider it as Saurophaganax as well.

Allosaurus maximus Material:
The humerus (Chure, 1995, pg. 103) (Smith, 1998, pg. 134), manus (Chure, 1995, pg. 103), pedal phalanx I-1 (Smith, 1998, pg. 131), and a manal digit 1 claw (Chure, 1995, pg. 103) are all similar to Allosaurus'. The humerus' shape is different from the carcharodontosaurids Acrocanthosaurus' (Elena Cuesta et al., 2018, "Discussion") and Tyrannotitan's (Canale et al., 2017, pg. 19).

Cuesta et al., (2018) ("Discussion") shows the extreme similarities between Saurophaganax's humerus and two Allosaurus fragilis specimens. They're identical, aside from the large size and robustness in the Saurophaganax humerus. Compared to Acrocanthosaurus's, you can clearly see the differences.

Allosaurus maximus' ("Saurophaganax's") ("A"), Allosaurus fragilis' ("B" and "C"), and Acrocanthosaurus' ("E") Humeri (Cuesta et al., 2018, "Discussion"):

Allosaurus maximus ("Saurophaganax") (Left) and Allosaurus fragilis (Right) (Madsen, 1976/1993, pg. 137) Humeri:

Allosaurus maximus ("Saurophaganax") (Left) and Acrocanthosaurus (Right) Humeri:

Tyrannotitan's humerus is fragmentary, but it is hypothesized to have looked similar to Acrocanthosaurus'.

Tyrannotitan's Humerus (Canale et al., 2015, pg. 19):

It's clear that the humerus attributed to Saurophaganax is not a carcharodontosaurid humerus. Therefore, the humerus is being assigned to Allosaurus. Saurophaganax's real humerus must have been similar in shape to Acrocanthosaurus' and Tyrannotitan's.

The claw on manal digit 1 is large, but it's the same length as Allosaurus' (Chure, 1995, pg. 103).

Allosaurus maximus ("Saurophaganax") OMNH 780 Hand Claw (Cast) (2nd One) from SVPOW:

Allosaurus fragilis Hand Claw:

Acrocanthosaurus Hand Claw:

The bottom of the underside of Allosaurus maximus' ("Saurophaganax's") and Allosaurus fragilis' claws are more circular and larger than in Acrocanthosaurus', which is more straight. In fact, both Allosaurus' claws are curvier than Acrocanthosaurus' in general. Acrocanthosaurus' claw is more straight all around.

Here's another hand claw from another carcharodontosaurid, Giganotosaurus (Mapusaurus) roseae.

Giganotosaurus (Mapusaurus) roseaes's (?)Left Manual Ungual/Hand Claw (Coria and Currie, 2006, pg. 98):

Once again, we can see that carcharodontosaurids have a more linear-shaped hand claw than Allosaurus', and the supposed "Saurophaganax's," hand claw. Therefore, the claw is being assigned to Allosaurus.

To my surprise, "Saurophaganax" (I think it's the specimen OMNH 01708) has a left pes/pedal or metatarsals that are identical to Allosaurus lucasi's. This might be Allosaurus maximus as well. Dalman (2014) did say that Saurophaganax had a 4th metatarsal that was similar to Allosaurus lucasi's (pg. 174). To me, the whole left pes of Saurophaganax is identical to Allosaurus lucasi's.

OMNH 01708's (Left) (Chure, 1995, pg. 104) and Allosaurus lucasi's (Right) (Dalman, 2014, pg. 170) Left Pes/Pedals:

Then again, the pes in Allosaurus' fragilis is basically identical to OMNH 01708's as well, as seen in Madsen (1976/1993) (pg. 159). The fourth metatarsal is "diverging" in A. fragilis, as well as OMNH 01708's and A. lucasi's. Therefore, the "Saurophaganax" pes is really an Allosaurus pes.

Allosaurus fragilis Pes (Madsen, 1976/1993, pg. 159):

Note: Mickey Mortimer of the Theropod Database says that A. lucasi is really Allosaurus fragilis.

If the "Saurophaganax" pes is OMNH 01708, then that means the femur attributed to OMNH 01708 also belongs to Allosaurus. The only difference noted by Chure is that the femur is "more laterally bowed" (bending at the sides) than Allosaurus' (pg. 104). However, when I compared them, there's doesn't seem to be any difference between Allosaurus fragilis' and "Saurophaganax's," femurs. In fact, when compared to Tyrannotitan's and Acrocanthosaurus' femurs, there are noticeable differences between theirs and OMNH 01708's femur.

Tyrannotitan's femur head is more cone-shaped (anterior and posterior views) compared to OMNH 01708's (cranial and caudal views) (Canale et al., 2015, pg. 21). In Acrocanthosaurus, its femur also has a "pointy" femur head that is "projected upwards at an angle 15-20 degrees from the proximal part of the shaft," (Michael D. D'Emic et al., 2012, pg. 15). Currie and Coria (2006) said that carcharodontosaurids in general (like Giganotosaurus and Mapusaurus) have femur heads that are "angled upwards from the shaft... This is very different than in most large theropods where the head is perpendicular to the shaft..." (pg. 103). This is not evident on OMNH 01708's femur head, nor is this stated by Chure. OMNH's femur is basically identical to Allosaurus', even if it is "more laterally bowed." Therefore, I think OMNH 01708, in general, is Allosaurus. This specimen includes a pes as well as a femur, according to Chure (1995) (pg. 104).

Smith (1998) says that Saurophaganax has the same growth trajectory as Allosaurus in almost every way, so they appear to have grown to the same lengths (pg. 140). He did this by using "Saurophaganax's" femur (pg. 129-130), pedal phalanx I-1 (pg. 133), and humerus (pg. 138-139). It is noted in D'Emic et al., (2012) that Acrocanthosaurus had the same growth rate as Allosaurus and tyrannosaurids (pg. 13, "Abstract"), but as for the bones named above, they also look identical to Allosaurus bones as well as having a similar growth rate. Therefore, this helps to prove that these bones, along with a manus, a manal digit 1 claw, and a pes/metatarsals support A. maximus's existence, along with what was stated in Chure (1995) about the questionable gathering of the bones (pg. 103).

Whether or not it's guaranteed that A. maximus is a valid species of Allosaurus (along with some other species) is up in the air, but I'll assign it the name Allosaurus maximus for now, especially since its bones are more robust than Allosaurus fragilis', and its femur (might) be more laterally bowed as well. I will say that these bones could just be Allosaurus fragilis, or any other species of Allosaurus, due to the similarities in the bones. I will keep the name Allosaurus maximus for now, but with a question mark next to it.

Conclusion 2:
(?)Allosaurus maximus seems to be a valid species of Allosaurus due to the robustness, and large size, of its bones, and (perhaps) a more laterally bowed femur. It is supported by a humerus, two femurs, a pedal phalanx I-1, a manus, a manal digit 1 claw, and a left pes/metatarsals that are directly identical to Allosaurus fragilis' and lucasi's, or just A. fragilis'. These bones seem to have been mixed with the bones of the carcharodontosaurid Saurophaganax during its excavation and preparation in the 1930's-1940's.

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.

Update (12/19/19): A left ilium (OMNH 01338) is extremely similar to Acrocanthosaurus' (Currie and Carpenter, 1999, pg. 209) and Meraxes' (Canale et al., 2022, Figure 1C). Therefore, an atlas, mid-dorsal neural arch, an ilium, and a tibia belong to the carcharodontosaurid Saurophaganax.

Update (12/30/19): Regarding Saurophaganax's tibia (OMNH 01370), Dalman (2014) says that the "large lateral condyle of tibia that is more centered and occupies almost half the length of the tibial head," (pg. 174). According to Gilmore (1920), Allosaurus fragilis specimen USNM 4734 has a two small condyles on its tibia (pg. 69). However, based on the femur drawn in Madsen (1976/1993), Saurophaganax's tibia doesn't look so different from Allosaurus' (pg. 155). However, the condyle in the inside Saurophaganax's tibia (if it is the condyle that Dalman is talking about) is at the top of its tibia. In Allosaurus', the condyle(?) is not. In fact, Saurophaganax's tibia looks similar to Acrocanthosaurus'. The condyle(?) is missing, but an outline is drawn where it would be located. It seems that the condyle(?) is also located at the top of the tibia, as in Saurophaganax's (Currie and Carpenter, 1999, pg. 231, D and E). If I'm identifying the condyles correctly, then the tibia seems to definitely belong to Saurophaganax.

Update (1/1/20): A distal half of a right pubis (OMNH 01425) is not identical to Allosaurus (Madsen, 1976/1993, pg. 149 and 151) but similar to Mapusaurus' (Currie and Coria, 2006, pg. 100). That makes an atlas, a mid-dorsal neural arch, an ilium, a partial right pubis, and a tibia belong to the carcharodontosaurid Saurophaganax. However, a proximal half of a left pubis (OMNH 01707) looks closely related to Allosaurus' (Madsen, 1976/1993, pg. 149 and 151). It seems that a a humerus, a manus, a manal digit 1 claw, a half left pubis, a pedal phalanx I-1, and a left pes/metatarsals belong to (?)Allosaurus maximus.

Update (2/19/20): Chure and Loewen (2020) said that only two species of Allosaurus seem to be present in North America: A. fragilis and A. jimmadseni. All other species of Allosaurus from North America seem to be either A. fragilis or Allosaurus indeterminate ("Discovery and excavational history," p. 5). Therefore, it seems more likely that A. maximus is actually A. fragilis.

Update (2/24/20): According to Evers et al., (2020), there doesn't seem to be any differences in the multiple species of Allosaurus, based on a review of different Allosaurus skull bones. Therefore, it seems that the ONLY species of Allosaurus that is truly valid is A. fragilis. Therefore, it's even more likely now that A. maximus is really just Allosaurus fragilis.

Update (5/13/23):
Saurophaganax's femur (Chure, 1995, pp. 103-104) was shaped similarly to carcharodontosaurids. It's femoral head pointed upwards, as in Tyrannotitan/G. chubutensis, Giganotosaurus carolini, Mapusaurus/G. roseae, and Carcharodontosaurus. The shaft is bowed laterally, and T./G. chubutensis' shaft is convex laterally.

Update (7/30-8/23/23):
Saurophaganax's caudal chevrons (Chure, 1995, p. 104 Figure 1G-I) are morphologically similar to Acrocanthosaurus' (Currie and Carpenter, 1999, p. 219 Figure 4), Meraxes (Canale et al., 2022, Figure 1E), and Lusovenator (Malafaia et al., 2019, Figures 3-4).

Update (10/19/23):
It has come to my attention that the right pubic bone that I assigned to Saurophaganax might belong to Allosaurus, or Saurophaganax and that allosauroidea had similar pubic morphologies (Madsen, 1976 [1993 edition], p. 149 Plate 48). I'm going to assume that allosauroidea had similar pubic morphologies.

Update (10/22/23):
Lusovenator's 4th metatarsal is curved inward (concave) (Malafaia et al., 2019, pp. 166-167), just like OMNH 01708. Therefore, the metatarsals (OMNH 01708) could belong to a carcharodontosaurid.