Saturday, July 11, 2020

Size Calculations for Allosaurus.

Allosaurus:
Size calculations for Allosaurus.

 The Percentage Increase/Decrease Method:
1. Take new number and subtract it from original number.
2. Take that number and divide it by the original number and multiply by 100.
3. That number will by your percentage increase or decrease if it's negative.

Ex.: "Stan's" Femur is 130 and has a body length of 12.2 meters. "Wyrex" has a femur length of 132.7 cm.

132.7 - 130 = 2.7.
2.7 divided by (represented by "/") and multiplied by (represented by "*") equals 2.1.
(2.7/130*100 = 2.1)
2.1 is your percentage increase, or 2.1% increase.
12.2 m + 2.1% = 12.5 meters for "Wyrex."

Links:
Percentage Increase/Decrease Method Links:
"Percentage Change - Percentage Increase and Decrease." SkillsYouNeed:
https://www.skillsyouneed.com/num/percent-change.html
"Relative Increase." percentage.calculators.ro:
https://percentages.calculators.ro/15-percentage-increase-from-original-number-to-new-value.php

According to Evers et al., (2020), there doesn't seem to be any diagnostic features between the multiple species of Allosaurus, based on a study of multiple skulls (mainly cheek or jugal bones) ("Introduction," Figure 5, "Discussion," and "Conclusion"). It seems that Allosaurus fragilis is the only valid species of Allosaurus so far. Therefore, all specimens listed below belong to Allosaurus fragilis.

Links:
Evers et al., (2020) ("Introduction," Figure 5, "Discussion," and "Conclusion"):
How Many Species of Allosaurus Are There!?:

Update (7/28/25):
All specimens have been updated. I based the new body lengths by comparing them to their closer relative Meraxes instead of Suchomimus. Also, I'm going to keep Allosaurus europaeus and jimmadseni as valid species for now. If there isn't another Allosaurus species, or "sp.," written next to the specimen, then the specimen is Allosaurus fragilis.

Femurs:
1. NMMNH P-26083:
Femur: 103.0 cm. (Measured on 9/8/19 in Heckert et al., 2003, p. 319 Figure 4B)
Tibia: 94 cm (at best) (Measured on 3/9/26 in Figure 4C).

Originally called an unidentified allosauridae in Heckert et al., (2003), the paper says that the bones are too large to belong to Allosaurus. However, the specimen doesn't share any similar features to Saurophaganax (pg. 320-321). Mickey Mortimer from the Theropod Database also identified this specimen as Allosaurus fragilis. Interestingly, Lucas and Heckert (2015) said that the specimen was "Saurophaganax-like," but still calls it an allosaurid instead of directly calling it Saurophaganax (pg. 100). Since Saurophaganax is a carcharodontosaurid now, it seems more likely than ever that this specimen is Allosaurus.

Suchomimus:
Femur: 107.5 cm.
Body: 10.0 meters.

107.5 - 103 = 4.5.
4.5/107.5*100 = 4.2% decrease.
10.0 m - 4.2% = 32 feet (9.6 meters).

Update (7/28/25):
Meraxes holotype MMCh-PV 65:
-Femur: 106 cm.
-Body: 9.6 meters.
-Skull: 122.5 cm (at best).

106 - 103 = 3.
3/106*100 = 2.8% decrease.
9.6 m - 2.8% = 30.5/31 feet (9.3 meters).

NMMNH P-26083's Total Length: 31 feet (9.3 meters).
Theropod Database:
From Foster and Chure (2006):
Femur: 1.008 meters.
Tibia: 85.6 cm.

NMMNH P-26083:
Femur: 103 cm.
Body: 9.6 meters.

103 - 100.8 = 2.2.
2.2/103*100 = 2.1% decrease.
9.6 m - 2.2% = 31 feet (9.4 meters).

Update (7/28/25):
NMMNH P-26083:
Femur: 103.0 cm.
Body: 9.3 m.

103 - 100.8 = 2.2.
2.2/103*100 = 2.1% decrease.
9.3 m - 2.1% = 30 feet (9.1 m).

AMNH 680's Total Length: 30 feet (9.1 meters).

Link:
Foster and Chure (2006):

3. DNM: 
Femur: 91.0 cm. (Madsen (1976, p. 43)

AMNH 680:
Femur: 1.008 meters.
Tibia: 85.6 cm.
Body: 9.4 meters.

91 - 100.8 = 9.8.
9.8/100.8*100 = 9.7% decrease.
9.4 m - 9.7% = 28 feet (8.5 meters).

Update (7/28/25):
AMNH 680:
Femur: 1.008 meters.
Body: 9.1 m.

100.8 - 91 = 9.8.
9.8/100.8*100 = 9.7% decrease.
9.1 m - 9.7% = 26.9/27 feet (8.2 m).

DNM's Total Length: 27 feet (8.2 meters).

Link:
Madsen, Jim. Allosaurus Fragilis: A Revised Osteology. Originally published in 1976, re-published in 1993. Web.:
4. UUVP 6000:
Femur: 88 cm. (Madsen (1976, p. 43)

DNM:
Femur: 91.0 cm. 
Body: 8.5 m.

91 - 88 = 3.
3/91*100 = 3.3% decrease.
8.5 m - 3.3% = 27 feet (8.2 meters).

Update (7/28/25):
DNM:
Femur: 91.0 cm. 
Body: 8.2 m.

91 - 88 = 3.
3/91*100 = 3.3% decrease.
8.2 m - 3.3% = 25.9/26 feet (7.9 meters).

UUVP 6000's Total Length: 26 feet (7.9 meters).

Link:
Madsen, Jim. Allosaurus Fragilis: A Revised Osteology. Originally published in 1976, re-published in 1993. Web.:

DNM: 
Femur: 91.0 cm.
Body: 8.5 meters.
85 - 91 = 6.
6/91*100 = 6.6% increase.
8.5 m - 6.6% = 26 feet (7.9 meters).

UUVP 6000:
Femur: 88 cm.
Body: 8.2 m.

88 - 85 = 3.
3/88*100 = 3.4% decrease.
8.2 m - 3.4% = 26 feet (7.9 meters).

Update (7/28/25):
UUVP 6000:
Femur: 88 cm.
Body: 7.9 m.

88 - 85 = 3.
3/88*100 = 3.4% decrease.
7.9 m - 3.4% = 24.9/25 feet (7.6 meters).

USNM 4734's Total Length; 25 feet (7.6 meters).

USNM's Stats:
Humerus: 31.0 cm. (Gilmore 1920, pg. 59)
Femur: 85 cm. (Gilmore, 1920, pg. 69)
Tibia: 69 cm. (Gilmore, 1920, pg. 71)
Fibula: 62.3 cm. (Gilmore, 1920, pg. 71)
Coracoid (Gilmore, 1920, pg. 58):
Length: 12 cm.
Width: 17 cm.
Scapula-Coracoid (Gilmore, 1920, pg. 58): 
Length: 79.5 cm.
Skull: 60.5 cm. (Gilmore, 1920, pg. 9)
Body: 26 feet (7.9 meters).

Gilmore (1920) (pg. 9-71):

Humerus:
6. UUVP 3607 (Largest Femur in Madsen, 1976):
Humerus: 38.6 cm. (Madsen, 1976, p. 41)

USNM 4734:
Humerus: 31.0 cm. 
Body: 26 feet (7.9 meters).

38.6 - 31 = 7.6.
7.6/31*100 = 24.5% increase.
7.9 m + 24.5% = 32 feet (9.8 meters).

Update (7/28/25):
USNM 4734:
Humerus: 31.0 cm.
Body: 7.6 meters.

38.6 - 31 = 7.6.
7.6/31*100 = 24.5% increase.
7.6 m + 24.5% = 31 (31.2) feet (9.5 meters).

UUVP 3607's Total Length; 31 feet (9.5 meters).

Link:
Madsen, Jim. Allosaurus Fragilis: A Revised Osteology. Originally published in 1976, re-published in 1993. Web.:
Link 2:
https://digitallibrary.utah.gov/awweb/awarchive?type=file&item=39079
Link 3:
https://pdfs.semanticscholar.org/7f14/5dfab1a6a66f15bdd22791dfec34d8b5c927.pdf?_ga=2.101699777.1756070742.1594155942-1908276041.1593232121

7. SMA 0005 ("Big Al TWO/2"):
Size estimate: 7.6 meters. (Foth et al., 2015, "Materials and Methods") (BHIGR)

Stated to have been 12% larger than MOR 693 ("Big Al"). (Foth et al., 2015, "Materials and Methods") However, "Big Al" was stated to have been 8.0 meters long (Breithaupt, Retrieved in 2019, stated near "Figure 5"). I got 10.6 meters. Foth et al., (2015) said that SMA was a large, and possibly an adult, specimen ("Abstract"), so SMA would have to be a large specimen.

Coracoid Length (Up to beginning of gleniod facet [marked]): 17.2 cm. (Measured in Foth et al., 2015, Figure 8, "A")

USNM 4734:
Coracoid (Gilmore, 1920, pg. 58):
Length: 12 cm.
Width: 17 cm.
Scapula-Coracoid (Gilmore, 1920, pg. 58): 
Length: 79.5 cm.
Body: 7.9 meters.

17.2 - 12 = 5.2.
5.2/12*100 = 43.3% increase.
7.9 m + 43.3% = 37 feet (11.3 meters).

I thought that 11.3 meters might have been a little too big, but if SMA was a "large, almost complete, possibly adult" specimen, then 11.3 meters does fall within the adult size range for an average. As I've said before, I got 10.6 meters for "Big Al," so I'll keep this length.

Update (5/8/21):
Skull: 79 cm (BHIGR).

Allosaurus (?)lucasi Specimen YPM PV 57589 (Holotype):
Skull: 77.5 cm.
Body: 33 feet (10.1 meters).

77.5 - 79 = 1.5.
1.5/77.5*100 = 1.9% increase.
10.1 m + 1.9% = 34 feet (10.3 meters).

Update (7/28/25):
Allosaurus sp. Specimen YPM PV 57589 (A. "lucasi" holotype):
Skull: 77.5 cm.
Body: 33 feet (9.7 meters).

77.5 - 79 = 1.5.
1.5/77.5*100 = 1.9% increase.
9.7 m + 1.9% = 32.5/33 feet (9.9 meters).

Big Al Two's Total Length: 33 feet (9.9 meters).
Skull: 79 cm.

Link:
Foth et al., (2015):
BHIGR:
Evers et al., (2020) ("Introduction," Figure 5, "Discussion," and "Conclusion"):
8. AMNH 5767:
Originally called "Epanterias amplexus" (Cope, 1878, pg. 406), and considered a sauropod. However, it was revealed to have been a theropod (Osborn and Mook, 1912, pg. 282). It's now considered either to be indistinguishable from Allosaurus fragillis (Osborn and Mook, 1912, pg. 282), or a nomen dubium by Paul and Carpenter (2010) (pg. 54). However, aside from the holotype, Paleontologists Robert Bakker is said to have discovered a second specimen (called CPS 99 by Theropod Database) (Browne, 1990). Therefore, Epanterias might be its own species after all. I can't find any measurements for CPS 99, so I'll just stick with the holotype.

Size:
Size estimate: 50 feet. (Dr. Bakker in Browne, 1990) (Lee Dye, 1990) (Popular Science, 1990, pg. 26) (Real Colorado Travel, 2012) (North Forty News, 2017)

Coracoid (On Bottom) (Paleofile): 
Length: 24 cm. (I got it twice on 9/3/19)
Width: 34.0 cm. 
Scapula-coracoid (Paleofile):
Length: 132 cm.
Allosaurus fragilis Specimen USNM 4734:
Coracoid (Gilmore, 1920, pg. 58):
Length: 12 cm.
Width: 17 cm.
Scapula-Coracoid (Gilmore, 1920, pg. 58): 
Length: 79.5 cm.
Body: 7.9 meters.

*Coracoid Length:
24 - 12 = 12.
12/12*100 = 100% increase.
7.9 m + 100% = 52 feet (15.8 meters).

Scapula-coracoid Length:
79.5 - 132 = 52.5.
52.5/79.5*100 = 66% increase.
7.9 m + 66% = 43 feet (13.1 meters).

Allosaurus fragilis Specimen SMA 0005 ("Big Al 2"):
Coracoid Length (Up to gleniod facet): 17.2 cm.
Body: 11.3 meters.

24 - 17.2 = 6.8.
6.8/17.2*100 = 39.5% increase.
11.3 m + 39.5% = 52 feet (15.8 meters).

I'm a bit torn on this. The coracoid is huge. I thought part of the scapula was broken off with the coracoid. However, Osborn and Mook (1912) (pg. 284) said that only the coracoid was broken off from the scapula. I was skeptical when I got the 15.8-meter length from USNM, but I got the same length using "Big Al TWO." Therefore, based on the length of the coracoid, Epanterias was a whooping 15.8 meters! It also seems consistent with the 50-foot estimate by Bakker. Paleontologist Mickey Mortimer in 2003 said that Epanterias was larger than Saurophaganax. Plus, the coracoid is the only part of the scapulacoracoid that exists, so I'll go with that length.

Is It Allosaurus?
As for being its own species, I don't know whether to call this animal Epanterias or Allosaurus. As stated before, Paul and Carpenter (2010) said that it was a nomen dubium at best (pg. 54). Osborn and Mook (1912) said that Epanterias cannot be distinguished from Allosaurus (fragilis) (pg. 282). With that quote in mind, I'm going to assign "Epanterias" to Allosaurus fragilis.

Notes: 
-North Forty News (2017) said that the bones discovered in 1990, originally designated to Epanterias, are now assigned to Allosaurus.

 -In a dml.cmnh.org email from 2000, it was also stated that the 1990's Epanterias fossil was a large specimen of Allosaurus fragilis.

-Paleontologist Andrea Cau (2009) also says that Epanterias is Allosaurus fragilis.

-Weishampel et al., (2004) says that Epanterias is Allosaurus fragilis (Pg. 74-75).

-Madsen (1976/1993) also said that Epanterias was Allosaurus fragilis (pg. 5). 

Personal Observation: The 1st or 2nd dorsal vertebrae of AMNH 5767 (Osborn and Mook, 1912, pg. 283) is identical to a normal 2nd Allosaurus fragilis dorsal vertebrae seen in Madsen (1976/1993) (pg. 85, "A"-"C"). Therefore, AMNH 5767 is Allosaurus fragilis.

Update (3/15/21): 
Acrocanthosaurus NCSM 14345:
Scapulacoracoid: 118 cm (Currie and Carpenter, 1999, Table 1).
Body: 12.0 meters.

118 - 132 = 14.
14/118*100 = 11.9% increase.
12 m + 11.9% = 44 feet (13.4 meters).

Update (7/20/24):
The scapula isn't present, but the coracoid is. To be safe, it would be best for me to stick with the coracoid length.

Update (7/28/25):
AMNH 5767's coracoid measurements:
Coracoid (Measured on Paleofile):
Length: 24 cm. (I got it twice on 9/3/19)
Width: 34.0 cm. 
Scapula-coracoid: 132 cm.
Note: Only the coracoid is preserved, although the outer edge has eroded.

I'm assuming that the long way is the length, using Acrocanthosaurus as a comparison.

Acrocanthosaurus specimen NCSM 14345:
Coracoid length: 36 cm (Currie and Carpenter, 1999, p. 214 Table 1).
Body: 11.5 meters.

36 - 34 = 2.
2/36*100 = 5.6% decrease.
11.5 m - 5.6% = 35.8/36 feet (10.9 meters).

However, Allosaurus specimen USNM 4734's coracoid has a length of 12 cm, and a width of 17 cm (Gilmore, 1920, p. 58). Maybe Acrocanthosaurus' coracoid length is actually the width (36 cm), and the height is the length (21 cm)? Using the way I measured AMNH's coracoid, the width of Acrocanthosaurus' coracoid is longer than the length. Therefore, I'm putting Acrocanthosaurus' coracoid "height" as its length, and the "length" as its width. 

Acrocanthosaurus specimen NCSM 14345:
Coracoid length ("height"): 21 cm (Currie and Carpenter, 1999, p. 214 Table 1).
Body: 11.5 meters.

24 - 21 = 3.
3/21*100 = 14.3% increase.
11.5 m + 14.3% = 43 (43.3) feet (13.2 meters).

AMNH 5767's total length: 43 feet (13.2 meters).

Links: 
Cope (1878) (pg. 406):
https://www.journals.uchicago.edu/doi/10.1086/272127
Paleofile:
http://www.paleofile.com/Dinosaurs/Theropods/Allosaurus.asp
Paul and Carpenter (2010) (pg. 54):
http://gspauldino.com/images/BZN67(1)Case3506.pdf
Browne (1990):
Osborn and Mook (1912) (pg. 282 and 284):
https://babel.hathitrust.org/cgi/pt?id=uc1.c087390587&view=1up&seq=136&size=200
Mickey Mortimer (2003):
http://dml.cmnh.org/2003Jul/msg00355.html
Allosaurus fragilis Discovery Date:
NMNH Paleontology Department (2018):
https://www.si.edu/es/object/nmnhpaleobiology_3451298
North Forty News (2017):
https://northfortynews.com/the-monster-of-masonville/
Lee Dye (1990):
Real Colorado Travel (2012):
"Epanterias Amplexus." dml.cmnh.org. 2000:
http://dml.cmnh.org/2000Aug/msg00404.html
Andrea Cau (2009):
http://translate.google.com/translate?u=https%3A//theropoda.blogspot.com/search%3Fq%3Depanterias&hl=en&langpair=it|en&tbb=1&ie=UTF-8
Weishampel et al., (2004) (Pg. 74-75):
https://books.google.com/books?id=h4WRTHfTzXsC&printsec=frontcover&dq=neovenator+miwg+4199&hl=en&sa=X&ved=0ahUKEwivy66r7ILjAhVpmuAKHVHOBKIQ6AEIMjAB#v=onepage&q=tyrannosaurus&f=false
Link 2:
Link 2:
https://digitallibrary.utah.gov/awweb/awarchive?type=file&item=39079
Link 3:
https://pdfs.semanticscholar.org/7f14/5dfab1a6a66f15bdd22791dfec34d8b5c927.pdf?_ga=2.101699777.1756070742.1594155942-1908276041.1593232121

Skulls:
9. MOR 693 ("Big Al") (Allosaurus jimmadseni): 
Estimated length: 8.0 meters. (Breithaupt, no date, stated near "Figure 5")

Skull (From Serjoscha Ever's Twitter page): 
Length: 81.3 cm. (Measured myself on 9/6/19 from premaxilla to quadrate)

USNM 4734:
Skull: 60.5 cm.
Body: 7.9 meters.

60.5 - 81.3 = 20.8.
20.8/60.5*100 = 34.4% in.
7.9 m + 34.4% = 35 feet (10.6 meters).

Allosaurus (?)lucasi Specimen YPM PV 57589 (Holotype):
Skull: 77.5 cm.
Body: 33 feet (10.1 meters).

77.5 - 81.3 = 3.8.
3.8/77.5*100 = 4.9% increase.
10.1 m + 4.9% = 35 feet (10.6 meters).

Update (7/28/25):
Allosaurus sp. specimen YPM PV 57589 (A. "lucasi" holotype):
Skull: 77.5 cm.
Body: 33 feet (9.7 meters).

77.5 - 81.3 = 3.8.
3.8/77.5*100 = 4.9% increase.
9.7 m + 4.9% = 33.5/34 feet (10.2 meters).

"Big Al" was 87% grown (Laws, 1996, p. 51).

Adult Length:
10.2 m + 13% = 37.7/38 feet (11.5 meters).

Note: "Big Al" was said to be 10.0 meters long in the documentary Allosaurus: Walking With Dinosaurs Special (2000) (21:20).

Links:
Evers et al., (2020) ("Introduction," Figure 5, "Discussion," and "Conclusion"):
Chure and Loewen (2020):
https://peerj.com/articles/7803/
Breithaupt. Retrieved in 2019. (Stated Near "Figure 5"):
Theropod Database:

10. AMNH 666:
Skull: 88.5 cm. (Gilmore, 1920, pg. 9) (Osborn, 1903, pg. 697)

MOR 693 ("Big Al"):
Skull: 81.3 cm.
Body: 10.6 meters.

88.5 - 81.3 = 7.2.
7.2/81.3*100 = 8.9% in.
10.6 m + 8.9% = 38 feet (11.5 meters).

Update (7/28/25):
USNM 4734:
Skull: 60.5 cm. 
Body: 7.6 meters.

88.5 - 60.5 = 28.
28/60.5*100 = 46.3% increase.
7.6 m + 46.3% = 36 (36.4) feet (11.1 meters).

YPM PV 57589:
Skull: 77.5 cm.
Body: 9.7 m.

88.5 - 77.5 = 11.
11/77.5*100 = 14.2% increase.
9.7 m + 14.2% = 11.1 meters.

A. europaeus holotype ML415:
Skull: 78 cm.
Body: 9.8 m.

78 - 88.5 = 10.5.
10.5/78*100 13.5% increase.
9.8 m + 13.5% = 11.1 meters.

MOR 693 ("Big Al"):
Skull: 81.3 cm.
Body: 10.2 meters.

88.5 - 81.3 = 7.2.
7.2/81.3*100 = 8.9% in.
10.6 m + 8.9% = 11.1 meters.

AMNH 666's Total Length: 36 feet (11.1 meters).

Link:
Osborn (1903) (Pg. 697):
http://digitallibrary.amnh.org/bitstream/handle/2246/1510//v2/dspace/ingest/pdfSource/bul/B019a31.pdf?sequence=1&isAllowed=y
Gilmore (1920) (Pg. 9):
https://repository.si.edu/handle/10088/10107

11. YPM PV 57589 (Allosaurus sp.) (Holotype of A. "lucasi") (Largest/Adult Specimen):
Skull: 77.5 cm. (Dalman, 2014, p. 162)

Allosaurus fragilis Specimen USNM 4734:
Skull: 60.5 cm.
Body: 7.9 meters.
77.5 - 60.5 = 17.
17/60.5*100 = 28.1% increase.
7.9 m + 28.1% = 33 feet (10.1 meters).

Update (7/28/25):
USNM 4734:
Skull: 60.5 cm. 
Body: 7.6 meters.

77.5 - 60.5 = 17.
17/60.5*100 = 28.1% increase.
7.6 m + 28.1% = 31.8/32 feet (9.7 meters).

YPM PV 57589's Total Length: 32 feet (9.7 meters).

Link:
Dalman (2014) (pg. 162):
http://webcache.googleusercontent.com/search?q=cache:BIvP0C4_wd8J:9048.indexcopernicus.com/fulltxt.php%3FICID%3D1130141+&cd=1&hl=en&ct=clnk&gl=us&client=safari
Theropod Database:
("A. lucasi"):
https://www.theropoddatabase.com/Carnosauria.htm#Allosaurusfragilis
Chure and Loewen (2020) ("Discovery and exavational history," p. 5):
https://peerj.com/articles/7803/
Evers et al., (2020) ("Introduction," Figure 5, "Discussion," and "Conclusion"):
12. MNHNUL/AND.001 (Allosaurus europaeus):
Femur: 43.5 cm (at best). (Measured in Perez-Moreno et al., 1999)

USNM 4734:
Femur: 85 cm. 
Body: 7.9 meters.

85 - 43.5 = -41.5.
-41.5/85*100 = 48.8% decrease.
7.9 m - 48.8% = 14 feet (4.1 meters).

Femur: 84.5 cm (at best). (Measured on 5/3/20 in Malafaia et al., 2007, pg. 260, Figure 2, "C," anterior; measured with scale bar from "B")

MNHNUL/AND.001's Femur (Malafaia et al., 2007, pg. 260, Figure 2, "C," anterior; measured with scale bar from "B"). Scale bar is 9 cm:
USNM 4734:
Femur: 85 cm. 
Body: 7.9 meters.

85 - 84.5 = 0.5.
0.5/85*100 = 0.6% decrease.
7.9 m + 0.6% = 26 feet (7.9 meters).

Update (7/28/25):
USNM 4734:
Femur: 85 cm.
Body: 7.6 m.

85 - 84.5 = 0.5.
0.5/85*100 = 0.6% decrease.
7.6 m - 0.6% =  24.9/25 feet (7.6 meters).

MNHNUL/AND.001's Total Length: 25 feet (7.6 meters).

Links:
Perez-Moreno et al., (1999):
http://hazy.cs.wisc.edu/hazy/share/zifeipdf/10381/input_k2opt.pdf
Malafaia et al., (2007):

13. ML415 (Holotype of Allosaurus europaeus): 
Skull: 81 cm (Measured on 11/27/19 in Mateus et al., 2006, p. 5)

A. fragilis Specimen MOR 693 ("Big Al"):
Skull: 81.3 cm.
Body: 35 feet (10.6 meters).

81 - 81.3 = -0.3.
-0.3/81.3*100 = 0.4% decrease.
10.6 m - 0.4% = 35 feet (10.6 meters). 

Update (7/28/25):
Skull: 78 cm (Measured myself on 5/28/25 in Mateus et al., 2006, p. 5 Figure 7. Up to paraoccipital process):
Note: The snout, dentary, and front of surangular, are missing. 

A. sp. specimen YPM PV 57589:
Skull: 77.5 cm.
Body: 9.7 m.

78 - 77.5 = 0.5.
0.5/77.5*100 = 0.7% increase.
9.7 m + 0.7% = 32 (32.2) feet (9.8 meters).

ML415's Total Length: 32 feet (9.8 meters).

Links:
Mateus et al., (2006) (P. 5):
https://docentes.fct.unl.pt/sites/default/files/omateus/files/mateus_walen_antunes_-_2006_-_the_large_theropod_fauna_of_the_lourinha_formation__portugal__and_its_similarity_to_the_morrison_formation__with_a_description_of_a_new_species_of_allosaurus.pdf
Fossilworks:
http://fossilworks.org/bridge.pl?a=taxonInfo&taxon_no=94354
Link 2:
http://fossilworks.org/bridge.pl?a=collectionSearch&taxon_no=94354&max_interval=Jurassic&country=Portugal&is_real_user=1&basic=yes&type=view&match_subgenera=1
Time:
Mateus et al., (2006) (pg. 5):
https://docentes.fct.unl.pt/sites/default/files/omateus/files/mateus_walen_antunes_-_2006_-_the_large_theropod_fauna_of_the_lourinha_formation__portugal__and_its_similarity_to_the_morrison_formation__with_a_description_of_a_new_species_of_allosaurus.pdf

14. YPM VP.1879/1892 (Holotype of Allosaurus (?)amplus):
Skull: 88 cm (Estimated from a quadrate). (Galton et al., 2015, pg. 327 and 329; p. 330 for the name)

A. fragilis Specimen AMNH 666:
Skull: 88.5 cm. (Gilmore, 1920, pg. 9)
Body: 38 feet (11.5 meters).

88 - 88.5 = 0.5.
0.5/88.5*100 = 0.6% decrease.
11.5 m - 0.6% = 37 feet (11.4 meters).

Update (7/28/25):
AMNH 666:
Skull: 88.5 cm.
Body: 11.1 meters.

88 - 88.5 = 0.5.
0.5/88.5*100 = 0.6% decrease.
11.1 m - 0.6% = 36 (36.1) feet (11.0 meters).

YPM VP.1879/1892's Total Length: 36 feet (11.0 meters). 
Link:
Galton et al., (2015):
https://www.researchgate.net/publication/273334027_The_holotype_pes_of_the_Morrison_dinosaur_Camptonotus_amplus_MARSH_1879_Upper_Jurassic_western_USA_-_Is_it_Camptosaurus_Sauropoda_or_Allosaurus
Chure and Loewen (2020):
Evers et al., (2020) ("Introduction," Figure 5, "Discussion," and "Conclusion"):
15. DINO 11541 (Holotype of A. jimmadseni):
Femur: 59.9 cm. (NPS)

Allosaurus fragilis Specimen USNM 4734:
Femur: 85 cm. 
Body: 7.9 meters.

85 - 59.9 = 25.1.
25.1/85*100 = 29.5% decrease.
7.9 m - 29.5% = 18 feet (5.6 meters).

Update (7/28/25):
Allosaurus fragilis Specimen USNM 4734:
Femur: 85 cm. 
Body: 7.6 meters.

85 - 59.9 = 25.1.
25.1/85*100 = 29.5% decrease.
7.6 m - 29.5% = 17.7/18 feet (5.4 meters).

DINO 11541's Total Length: 18 feet (5.4 meters).
This seems to have been a juvenile. It was also concluded that the holotype was not fully grown in Chure and Loewen (2020) (Ontogenetic Assessment of Dino 11541, para. 4-5).

Links:
Femur:
https://www.nps.gov/museum/exhibits/dino/exb/femur_dino11541p_exb.html
Phalange (Hand Claw):
Metatarsals:
Humerus:
Left:
Right (Larger):
Scapula-Coracoid:
https://www.nps.gov/museum/exhibits/dino/exb/tibia_fibula_dino11541n_exb.html
Age:
Chure and Loewen (2020):
Species:
Evers et al., (2020) ("Introduction," Figure 5, "Discussion," and "Conclusion"):
16. OMNH 01935 (Allosaurus sp.): 
Humerus: 59 cm. (Measured in Chure, 1995, pg. 105, "N," Caudal)
Note: Mickey Mortimer in 2015 said that she got 54.5 cm for the humerus, but said she might have been wrong. From my size estimate, she wasn't off.

Update (12/9/19): OMNH 01935 Humerus ("A") (Cuesta et al., 2018) (Scale bar is 5 cm):
Note: Allosaurus fragilis humeri ("B" and "C") are both identical to OMNH's humerus. 

Length: 51 cm. (Measured in Cuesta et al., 2018, "Discussion," Figure 16, "A," Anterior)
Still not too off from Mickey Mortimer's original measurement of 54.5 cm.

Allosaurus fragilis Specimen UUVP 3607: 
Humerus: 38.6 cm.
Body: 9.8 meters.

59 - 38.6 = 20.4.
20.4/38.6*100 = 52.9% increase.
9.8 m + 52.9% = 49 feet (15.0 meters).

51 - 38.6 = 12.4.
12.4/38.6*100 = 32.1% increase.
9.8 m + 32.1% = 43 feet (13.0 meters).

Update (7/28/25):
Allosaurus fragilis Specimen UUVP 3607: 
Humerus: 38.6 cm.
Body: 9.5 meters.

51 - 38.6 = 12.4.
12.4/38.6*100 = 32.1% increase.
9.5 m + 32.1% = 41 (41.3) feet (12.6 meters).

OMNH 01935's Total Length: 41 feet (12.6 meters).

Links:
Cuesta et al., (2018) ("Discussion"):
Chure (1995) (Pg. 105):
Which Saurophaganax specimens are Allosaurus:
https://psdinosaurs.blogspot.com/2019/12/is-saurophaganax-carcharodontosaurid_21.html

17. OMNH 01708 (Allosaurus sp.):
Metatarsal 3 (Longest Metatarsal): 45 cm (at best). (Measured on 6/29/29 in Chure, 1995, Figure 2, "I").

USNM 4734:
Metatarsal 3 Length: 32.7 cm (Gilmore, 1920, pg. 75).
Body Length: 7.9 meters.

32.7 - 45 = 12.3.
12.3/32.7*100 = 37.6% increase.
7.9 m + 37.6% = 36 feet (10.9 meters).

Update (3/21/25):
All metatarsals that originally belonged to "Saurophaganax" are actually Allosaurus sp. (Danison et al., 2024b, pp. 106 and 109).

Update (7/28/25):
USNM 4734:
Metatarsal 3 Length: 32.7 cm (Gilmore, 1920, pg. 75).
Body Length: 7.6 meters.

32.7 - 45 = 12.3.
12.3/32.7*100 = 37.6% increase.
7.6 m + 37.6% = 34.5/35 feet (10.5 meters).

OMNH 01708's Total Length: 35 feet (10.5 meters).

 Links:
Chure (1995) (Figure 2, "I"):
Which Saurophaganax specimens are Allosaurus:
https://psdinosaurs.blogspot.com/2019/12/is-saurophaganax-carcharodontosaurid_21.html

18. OMNH 01370 (Allosaurus sp.):
Tibia: 101 cm. (Measured in Chure, 1995, p. 105, Medial View).
Note: Danison et al., (2024b) placed this specimen as Allosaurus sp. (pp. 104 and 109).

USNM 4734:
Tibia: 69 cm. (Gilmore, 1920, pg. 71).
Size: 26 feet (7.9 meters).

69 - 101 = 32.
32/69*100 = 46.4% increase.
7.9 m + 46.4% = 38 feet (11.6 meters).

Acrocanthosaurus holotype OMNH 10143:
Tibia: 86.5 cm.
Length: 10.4 meters.

86.5 - 101 = 14.5.
14.5/86.58100 = 16.8% increase.
10.4 m + 16.8% = 39.850/40 feet (12.1472/12.2 meters).

(?)T. rex specimen "Sue":
Right Tibia: 124 cm.
Size: 13.6 meters.

124 - 101 = 23.
23/124*100 = 18.6% decrease.
13.6 m - 18.6% = 36 feet (11.1 meters).

Update (3/9/26):
NMMNH P-26083:
Femur: 103.0 cm.
Tibia: 94 cm.
Body: 9.3 m.

101 - 94 = 7.
7/94*100 = 7.4468/7.5% increase.
9.3 m + 7.5% = 32.8/33 feet (9.9975/10.0 meters).

OMNH 01370's Total Length: 33 feet (10 meters).

Links:
Chure (1995):

19. OMNH 01708/0112:
Femur: 113.5 cm. (Chure, 1995, p. 105) (Zanno and Makovicky, 2013).
Note: Danison et al., (2024b) placed this specimen as Allosaurus sp. (pp. 102 and 109).

Tyrannotitan Specimen MPEF-PV 1156 (Holotype):
Femur: 114 cm.
Body: 10.6 meters.

113.5 - 114 = 0.5.
0.5/114*100 = 0.4% decrease.
10.6 m - 0.4% = 35 feet (10.6 meters).

Update (3/9/26):
NMMNH P-26083:
Femur: 103.0 cm.
Tibia: 94 cm.
Body: 9.3 m.

113.5 - 103 = 10.5.
10.5/103*100 = 10.19/10.2% increase.

Allosaurus' Adult Total Length: 
-All specimens: 18-43 feet (5.4-13.2 meters).
-Adult specimens: 31-43 feet (9.3-13.2 meters).
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Wednesday, March 4, 2020

Dino Bios: Ceratosaurus.

Ceratosaurus:
Time: Kimmeridgian-Tithonian of the late Jurassic period: 157-145 million years ago.
Place: North America, Europe, and possibly Africa.
Length: 18-31 feet (5.4-9.5 meters).
Diet: Carnivore.

Let's talk about one of my favorite carnivorous theropods that I like to call, "the three-horned killer!"

Description:
Ceratosaurus was a medium-sized carnivorous dinosaur. It was 18-31 feet long (5.4-9.5 meters). 
There are three species of Ceratosaurus from North America: C. nasicornis, C. magnicornis, and C. 
dentisulcatus. There is an unnamed species of Ceratosaurus, C. sp, from Europe, and the questionable (?)C. roechlingli and (?)C. stechowi from Africa. C. nasicornis is 18-19 feet long (5.4-5.8 meters), 
C. magnicornis is 20 feet long (6.2 meters), C. dentisulcatus is 23 feet long (7.1 meters), and C. sp 
is 19 feet long (5.9 meters). (?)C. roechlingli and C. stechowi are too fragmentary to get a size estimate, but it could have been as large as the other species of Ceratosaurus were (of course, if it indeed is Ceratosaurus). However, Carrano et al., (2012) said that there is only one species of Ceratosaurus in North America: C. nasicornis (pg. 226).

Ceratosaurus has a large nasal horn on the top of its snout, and two large lachrymals (or lachrymal horns) in front of its eyes (Gilmore, 1920, pg. 76 and 80). It also has four fingers on its hands (Gilmore, 1920, pg. 76). This is a trait that older carnivorous dinosaurs had (Carrano and Choiniere, 2015, "Abstract"), such as Herrerasaurus (Sereno and Novas, 1992, pg. 1138). However, the fourth digit might have been useless. The second and third fingers were larger than the first and fourth ones. Its arms were also short compared to its contemporary, Allosaurus (Gilmore, 1920, pg. 103-105), but they were probably still good for grabbing prey (Carrano and Choiniere, 2015, "Abstract").

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, Ceratosaurus would have had lips covering its teeth. Interestingly, dinosaurs couldn't move its tongues (Mindy Weisberger, 2018) (ScienceDaily, 2018).

 Ceratosaurus also had body armor, called dermal ossicles or osteoderms, running down its back (Madsen and Welles, 2000, pg. 32, "Dermal Ossicles") (Brian Switek, 2018, p. 2) (Joshua Lively, 2012, "Description") (Rogers et al., 2011, "Introduction," p. 1). Perhaps this might've given it some protection.

Ceratosaurus with Osteoderms (When Dinosaurs Roamed America):
Time and Place:
Ceratosaurus lived 157-145 million years ago, during the Kimmeridgian-Tithonian of the late Jurassic period. It lived in North America, Europe, and possibly Africa. However, the African species, (?)C. roechlingli and . stechowi, are considered to be a nomen dubium (Oliver W. M. Rauhut, 2011, pg. 199-202; 202-205).

In North America, Ceratosaurus fossils come from the Morrison Formation of the late Jurassic period. 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"). Thus, Ceratosaurus lived in the Kimmeridgian-Tithonian of the Morrison Formation (Dinosaur National Monument, "Ceratosaurus").

In Europe, Ceratosaurus sp. remains come from the Lourinha Formation. The timing of the Lourinha Formation seems to be Kimmeridgian-Tithonian in age (Mateus et al., 2006, pg. 5) (Octavio Mateus, 2006, pg. 2) (Russo et al., 2017, pg. 4) (Mateus et al., 2017, "Lithostratigraphic framework," pg. 80). Therefore, it seems to be the same age as the Morrison Formation (Octavio Mateus, 2006, pg. 2).

In Africa, possible Ceratosaurus remains come from the Tendaguru Formation. The Tendaguru Formation is Kimmeridgian-Tithonian (Octavio Mateus, 2006, pg. 2) (Kristian Remes, 2006, "Abstract") (Sattler and Schwarz, 2015, "Material"). (?)Ceratosaurus remains come from the Lower Dinosaur, Middle Dinosaur, and Uppder Dinosaur Members of the Tendaguru Formation, which are both Kimmeridgian in age (Bussert et al., 2009, "Members of the Tendaguru Formation," "Lower Dinosaur Member," "Middle Dinosaur Member," and "Upper Dinosaur Member," pg. 156-157, 160-162, 164-165). However, the Ceratosaurus fossils discovered there are considered nomen dubium (questionable) (Oliver M. W. Rauhut, 2011, pg. 199-202; 202-205).

Recently, teeth discovered in the late Jurassic Tacuarembo Formation of South America have been attributed to Ceratosaurus, along with some Torvosaurus teeth (Soto et al., 2020, "Abstract").

In summary, Ceratosaurus lived during the Kimmeridgian-Tithonian of late-Jurassic North and South America, and Europe. It might have also lived in Africa, but it's not for certain.

Ceratosaurus Couple (Jurassic Fight Club):
Prey:
Since Ceratosaurus was one of the smaller carnivorous dinosaurs during its time, it doesn't seem like it would have hunted sauropods like Barosaurus and etc. Instead, it probably would have gone after smaller prey. In North America, the ornithopod Camptosaurus, the stegosaur Stegosaurus, and the ankylosaur Mymoorapelta would have been easier targets. In Africa, the stegosaur Kentrosaurus would probably have been it's prey of choice as well.

Ceratosaurus vs. Stegosaurus:
Enemies:
Ceratosaurus' enemies were numerous. They included Allosaurus, Saurophaganax, Torvosaurus, and Stokesosaurus in North America, (?)Allosaurus and Veterupristisaurus in (?)Africa, and Allosaurus, SHN.019 (a European carcharodontosaurid), and Torvosaurus in Europe.

Allosaurus vs. Ceratosaurus (Jurassic Fight Club):
Links:
Size:
https://psdinosaurs.blogspot.com/2018/10/calculations-for-largest-theropods.html
Description:
Carrano et al., (2012) (Pg. 226):
https://www.researchgate.net/profile/Matthew_Carrano/publication/230808558_The_phylogeny_of_Tetanurae_Dinosauria_Theropoda/links/0912f504a5960e5645000000/The-phylogeny-of-Tetanurae-Dinosauria-Theropoda.pdf?origin=publication_detail
Gilmore (1920):
https://www.biodiversitylibrary.org/item/125786#page/18/mode/1up
Carrano and Choiniere (2015) ("Abstract"):
https://www.tandfonline.com/doi/abs/10.1080/02724634.2015.1054497?journalCode=ujvp20
Sereno and Novas (1992):
https://www.researchgate.net/publication/6051640_The_Complete_Skull_and_Skeleton_of_an_Early_Dinosaur
Brian Switek (2018) (P. 2):
https://nhmu.utah.edu/blog/2018/ceratosaurus
Joshua Lively (2012) ("Description"):
https://nhmu.utah.edu/ceratosaurus-nasicornis
Rogers et al., (2011) ("Introduction," p. 1):
https://www.nature.com/articles/ncomms1578
Madsen and Welles (2000) (Pg. 32, "Dermal Ossicles"):
https://digitallibrary.utah.gov/awweb/awarchive?type=file&item=41293
Link 2:
https://www.google.com/books/edition/Ceratosaurus_Dinosauria_Theropoda/7WoJl_VDO6EC?hl=en&gbpv=1&bsq=osteoderm
Lips:
Reisz and Larson (2016) (Pg. 64-66):
Blake Eligh (2016):
Mindy Weisberger (2016):
Emanuela Grinberg (2016):
Phys (2016):
Times and Places:
Morrison Formation:
Kowallis et al., (1991) ("Abstract"):
https://www.sciencedirect.com/science/article/pii/019566719190003U
Full:
http://geology.byu.edu/Home/sites/default/files/kowallis_agebrushybasin_91.pdf
Kowallis et al., (1998) ("Abstract"):
http://geology.byu.edu/home/sites/default/files/kowallis_morrison_age_98.pdf
Turner and Peterson (1999) ("Age," pg. 89-90):
https://books.google.com/books?hl=en&lr=&id=qeRM16ndBx4C&oi=fnd&pg=PA77&ots=W5Kj88zd2x&sig=CZ76lISv4Bbi3BXBoWcGMHGg124#v=onepage&q&f=false
Scott et al., (2001) (Pg. 12-14):
https://pubs.usgs.gov/imap/i-2740/i-2740pm.pdf
Irmis et al., (2013) (Pg. 282):
https://www.researchgate.net/publication/260632793_Early_Crocodylomorpha
Marjanovic and Laurin (2014) (Pg. 2):
https://www.researchgate.net/publication/260075695_69_Marja_Laurin_App_comp
Chure and Loewen (2020) ("Age"):
https://peerj.com/articles/7803/
The University of Utah ("Morrison Formation"):
https://sed.utah.edu/Morrison.htm
Dinosaur National Monument ("Rhadinosteus parvus"):
https://www.nps.gov/dino/learn/nature/rhadinosteus-parvus.htm
Dinosaur National Monument ("Ceratosaurus"):
Lourinha Formation:
Russo et al., (2017) (Pg. 4):
Mateus et al., (2006) (pg. 5):
https://docentes.fct.unl.pt/sites/default/files/omateus/files/mateus_walen_antunes_-_2006_-_the_large_theropod_fauna_of_the_lourinha_formation__portugal__and_its_similarity_to_the_morrison_formation__with_a_description_of_a_new_species_of_allosaurus.pdf
Octavio Mateus (2006) (Pg. 2):
https://www.researchgate.net/publication/40662981_Late_Jurassic_dinosaurs_from_the_Morrison_formation_USA_the_Lourinha_and_Alcobaca_Formations_Portugal_and_the_Tendaguru_Beds_Tanzania_a_comparison
Tendaguru Formation:
Sattler and Schwarz (2015) ("Material"):
Oliver M. W. Rauhut (2011) (Pg. 199-202; 202-205)
https://www.academia.edu/25456862/Theropod_dinosaurs_from_the_Late_Jurassic_of_Tendaguru_Tanzania
Bussert et al., (2009) ("Members of the Tendaguru Formation," "Lower Dinosaur Member" and "Middle Dinosaur Member," pg. 156-157, 160-162, 164-165):
https://www.researchgate.net/publication/307714593_The_Tendaguru_Formation_Late_Jurassic_to_Early_Cretaceous_southern_Tanzania_definition_palaeoenvironments_and_sequence_stratigraphy
Kristian Remes (2006) ("Abstract"):
https://www.jstor.org/stable/4524611?seq=1
Tacuarembo Formation:
Soto et al., (2020) ("Abstract"):
https://www.sciencedirect.com/science/article/abs/pii/S0895981120303242
International Chronostratigraphic Chart (2020):
https://stratigraphy.org/timescale/
International Commission of Stratigraphy Website:
https://stratigraphy.org/news/130
Prey:
https://psdinosaurs.blogspot.com/2018/12/size-calculations-for-herbivorous.html
Dinosaur National Monument ("The Dinosaurs of Dinosaur"):
Enemies:
Dinosaur National Monument ("The Dinosaurs of Dinosaur"):
Allosaurus:
https://psdinosaurs.blogspot.com/2018/03/allosaurus-facts.html
Saurophaganax:
https://psdinosaurs.blogspot.com/2018/03/saurophaganax-facts.html
Torvosaurus:
https://psdinosaurs.blogspot.com/2018/10/calculations-for-largest-theropods.html
Veterupristisaurus:
Oliver Rauhut (2011) (pg. 223-224):
Time:
Franziska and Daniela (2015):
Kristian Remes (2006):
https://www.jstor.org/stable/4524611?seq=1
SHN.019 (Tithonian Carcharodontosaurid from Europe):
Malafaia et al., (2019):
https://www.cambridge.org/core/journals/journal-of-paleontology/article/carcharodontosaurian-remains-dinosauria-theropoda-from-the-upper-jurassic-of-portugal/52DA60451B9984FBD24B2B4B2390A281/core-reader

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Saturday, February 22, 2020

How Many Species of Allosaurus Are There!?

"Creosaurus atrox" specimen AMNH 600's skull (Paleofile) (Osborn, 1903, pg. 698):
We'll come back to "Creosaurus" later.

Allosaurus (fragilis or jimmadseni?) Specimen MOR 693 ("Big Al"):
Seven Species of Allosaurus?:
When studying how many species of Allosaurus there were, I was able to find seven: A. fragilis, A. europaeus, A. jimmadseni, (?)A. tendagurensis, (?)A. amplus, A. lusasi, and A. maximus, which I, and David K. Smith (1998), thought of as being a large and robust species of Allosaurus. However, Chure and Loewen (2020) stated that there were only two species of Allosaurus from North America, and one species from Europe: Allosaurus fragilis and jimmadseni from North America, and A. europaeus from Europe. Now, Evers et al., (2020) says that there is, more than likely, only ONE species of Allosaurus WORLDWIDE! So my question is... how many species of Allosaurus are there!?

Three Species of Allosaurus?:
Allosaurus fragilis:
Allosaurus has NOT have a good history in terms of how many confirmed species there are. The first species discovered was Allosaurus fragilis, discovered by Othniel Charles Marsh in 1877. The holotype is named YPM 1930 (Paleofile) (Paul and Carpenter, 2010, pg. 53). Marsh says that the species is characterized by "hour-glass-shaped centra, biconcave vertebra with shallow cavities that ensure lightness, and slender feet bones," (Marsh, 1877, pg. 515-516).

Unfortunately, the holotype is not diagnostic enough to be considered as a definitive species, due to fragmentary remains. In 2010, paleontologists Gregory S. Paul and Kenneth Carpenter proposed to designate another specimen, USNM 4734, discovered from the same quarry as YPM 1930, to be the neotype. (Paul and Carpenter, 2010, "Abstract" and pg. 55). This hasn't officially taken place yet though (Evers et al., 2020, "Introduction," p.3).

Other theropods previously thought to be their own species, like Epanterias, Creosaurus, Labrosaurus, Camptonotus, Wyomingraptor, Madsenius, and Antrodemus, have been reassigned to Allosaurus fragilis. Other Allosaurus species from North America (like Allosaurus amplus and A. lucasi) are considered to be Allosaurus fragilis or Allosaurus indeterminate (Chure and Loewen, 2020, "Discovery and excavational history," p. 5). Even Allosaurus maximus, whom paleontologist David K. Smith proposed in 1998 (and I agreed with him), seems to be Allosaurus fragilis now. Allosaurus tendagurensis is considered to be a nomen dubium, since it is only based on a tibia.

 As of right now, there are either one, or three, valid species of Allosaurus, with two being in North America and one in Europe. 

Allosaurus jimmadseni:
Allosaurus jimmadseni was proposed by paleontologist David Chure in 2000 for his thesis. For a LONG time, it had quotation marks around its name because it wasn't officially described in a scientific paper (Theropod Database, "A. 'jimmadseni'"). However, Chure and Loewen (2020) have concluded that Allosaurus jimmadseni is definitive based on:

"(1) in lateral view, a row of neurovascular foramina pierce the medioventral wall of the maxillary antorbital fossa; (2) straight posteroventral jugal ramus of maxilla where it articulates with jugal; (3) laterodorsal margin of nasal “pinched” into low crest continuous from premaxilla to lacrimal; (4) posterior portion of dorsal surface of nasal cup-shaped, producing a median peak in region of nasofrontal contact; (5) relatively taller lacrimal horns than in Allosaurus fragilis; (6) jugal with relatively straight ventral margin and straight-to-slightly-curved outline in dorsal view; a well-developed distinct antarticular, and (7) axial intercentrum is rotated dorsally and has a flared rim in lateral view," ("Diagnosis").

This has been called into question by Evers et al., (2020), but I will talk about that later. The holotype is DINO 11541, which is based on a skull and most of the post-cranial skeleton. There are a few other specimens assigned to A. jimmadseni, with two notable specimens called "Big Al" and "Big Al 2" (Chure and Loewen, 2020, "Holotype" and "Referred material"). Allosaurus jimmadseni lived in North America alongside A. fragilis.

Allosaurus europaeus:
Allosaurus europaeus was discovered by Perez-Moreno et al., (1999), but it wasn't named A. europaeus until 2006 (Mateus et al., 2006, pg. 5). Aside from its geographical location, Mateus et al., (2006) says that A. europaeus is characterized by:
 "jugal participation in the antorbital fenestra; maxilla forked posteriorly; truncated ventroposterior process of the maxilla; nasal with two pneumatic foramina (the anterior foramen twice the size of the posterior); posteroventral pro- jection of the jugal more than twice the posterodorsal projection; large an- terior surangular foramen; no lacrimal-maxillary contact; squamosal con- tacts the quadratojugal by a sigmoidal suture; squamosal projects ventrally into laterotemporal fenestra; lacrimal horn narrow in lateral view; large ventral projection of postorbital; rugose dorsal rim of the nasal; the occipi- tal condyles above the squamosal-quadratojugal contact; the anterior tip of quadratojugal is anterior to the laterotemporal fenestra; the lateral lamina of lacrimal is subtle; palatine contacts the pterygoid dorsoposteriorlly; and ventral tip of the postorbital reaches the lower rim of the orbit," (pg. 5).

Chure and Loewen (2020) kept A. europaeus as a separate species of Allosaurus, since its jugal, maxilla, and nasal differs from A. fragilis and A. jimmadseni (Figure 16) ("Conclusion"). In their conclusion, Chure and Loewen (2020) stated that there were only three species of Allosaurus that exist: A. fragilis, A. jimmadseni, and A. europaeus.

Allosaurus Skulls (Chure and Loewen, 2020, Figure 16):
One Species of Allosaurus?:
Very soon after Chure and Loewen (2020) published their paper, Evers et al., (2020) publish their own on Allosaurus. They studied the skulls, in particular the jugals or cheek bones, of Allosaurus, and have concluded that there aren't any differences, whether or not they belonged to the same or different species of Allosaurus:

"Here, we use the taxon Allosaurus without species epithet due to the unsolved taxonomic issues. However, our observations are based on specimens that have been referred to both species, and we have not found any differences between those for the elements of interest," ("Introduction," p. 3). 

This was also shown and stated in Figure 5, "Data from specimens of Allosaurus" p. 6, and in the "Conclusion." In Figure 5, the jugals for A. jimmadseni ("A" and "B"), A. fragilis ("C"), and A. europaeus ("D") all look the same.

Allosaurus Jugals/Cheek Bones (Evers et al., 2020, Figure 5) (A. jimmadseni are "A" and "B", A. fragilis is "C", and A. europaeus is "D"):
As for A. europaeus, Evers et al., (2020) said that the characteristics listed by Mateus et al., (2006) are only visible in the lateral view, and that there don't seem to be any major differences between its skull and other Allosaurus skulls:

"...the new observations have implications for the diagnosis of the European A. europaeus (Mateus, Walen & Antunes, 2006; Fig. 5D) as a distinct species, for which the jugal participation in the antorbital fenestra was listed as one of the few autapomorphic characters that differentiate it from the North American species. Besides, the authors listed the absence of a lacrimal-maxilla contact as a further apomorphy, which is related to the former character. However, as pointed out above, this is only true for the lateral view, while a medial contact between both bones was almost certainly present. Unfortunately, this cannot be verified at the moment as the internal side of the skull is filled with matrix, but the consistent nature of this contact in regard to Allosaurus specimens examined for this study allow inferring the presence of this contact with high confidence. All other diagnostic features of A. europaeus have been questioned to be truly unique, and some have proven to be variably present in North American Allosaurus specimens (Malafaia et al., 2007). Therefore, a re-evaluation of the European species is necessary, as currently none of the originally proposed diagnostic features are uniquely present in the holotype of Allosaurus europeaus," ("Discussion," p. 3). 

 In their conclusion, it seems that there are no major differences in all of the Allosaurus skulls studied in the paper:

 "The configuration of cheek bones does not vary between the examined specimens in Allosaurus, and our observations furthermore indicate that the European species A. europaeus did not differ in this regard from North American material," ("Conclusion").

 But what's even more interesting is what Allosaurus' skull actually looked like. Based on their new findings, Evers et al., (2020) recreated what Allosaurus' skull really looked like:

 Allosaurus MOR 693 ("Big Al") Skull Reconstruction (Evers et al., 2020):
This was based on the specimen "Big Al," which was originally assigned to A. fragilis but was reassigned to Allosaurus jimmadseni by Chure and Loewen (2020). The big question is: Does this look familiar? Well, remember "Creosaurus?"
It seems that "Creosaurus'" skull was the REAL skull of Allosaurus all along! Not only that, but as stated before, it seems that there might not be more than ONE species of Allosaurus. Since Allosaurus fragilis was named first, it seems that Allosaurus fragilis is the only conclusive species of Allosaurus. However, Evers et al., (2020) was not the only one that seems to have come to this conclusion.

 Kenneth Carpenter came to this conclusion ten years earlier. In 2010, Carpenter said that the differences in the skull bones of multiple Allosaurus specimens seem to be "mostly isometric, with only a slight isometric trend in some of the bones... I view these as extreme variation rather than distinct taxon," (Carpenter, 2010, "Conclusion," p. 1). He also questioned "some autapomorphic characters used to define other theropod taxa," since they appear to be questionable and are a result of "ontogenetic and individual variation" ("Abstract"). It seems that a similar conclusion was decided on in Evers et al., (2020). 

 Paleontologist Mickey Mortimer has stated some similar points on her Theropod Database website, and on other bones said to have belong to other species of Allosaurus. She basically concluded that Allosaurus fragilis was the most valid species of Allosaurus, and other characteristics said to have been diagnostic only in other species of Allosaurus can be seen in other specimens of Allosaurus fragilis as well. Therefore, it seems that she came to the same conclusion as Carpenter (2010) and Evers et al., (2020). Therefore, I'll agree to consider Allosaurus fragilis as the only valid species of Allosaurus until further notice.

 Update (5/3/20): It seems that Allosaurus "europaeus" was considered to be Allosaurus fragilis by some paleontologists before. Malafaia et al., (2007) and (2010) have argued that European fossils of Allosaurus belonged to Allosaurus fragilis (Malafaia et al., 2007, "Abstract") (Malafaia et al., 2010, pg. 202, "Conclusions," p. 2). They even said that A. "europaeus" was a synonym of A. fragilis (Malafaia et al., 2007, "Abstract"). 

 Conclusion:
Based on Evers et al., (2020), Carpenter (2010), Mickey Mortimer from the Theropod Database, and now Malafaia et al., (2007) and (2010), it seems that Allosaurus fragilis is the only valid species of Allosaurus. The supposed different diagnostic characteristics seen in each species of Allosaurus seem to be found in other specimens of different species, and therefore there don't seem to be any differences in the species. Since Allosaurus fragilis was named first, I will consider all other "species" as Allosaurus fragilis until more information is published in the future. This includes "Allosaurus maximus," and even the nomen dubium "Allosaurus tendagurensis." 

Links:
Allosaurus fragilis:
Othniel Charles Marsh (1877):
Paleofile ("Allosaurus"):
Paul and Carpenter (2010):
Other Theropods Assigned to Allosaurus fragilis, and Other Allosaurus Species Either Assigned to Allosaurus fragilis or Are Nomen Dubium:
Chure and Loewen (2020):
https://peerj.com/articles/7803/
Evers et al., (2020):
https://peerj.com/articles/8493/
(?)Allosaurus jimmadseni:
Theropod Database:
("A. 'jimmadseni'"):
Chure and Loewen (2020):
https://peerj.com/articles/7803/
Evers et al., (2020):
https://peerj.com/articles/8493/
(?)Allosaurus europaeus:
Perez-Moreno et al., (1999):
http://hazy.cs.wisc.edu/hazy/share/zifeipdf/10381/input_k2opt.pdf
Mateus et al., (2006) (pg. 5):
Skulls:
Osborn (1903):
http://digitallibrary.amnh.org/bitstream/handle/2246/1510//v2/dspace/ingest/pdfSource/bul/B019a31.pdf?sequence=1&isAllowed=y
Link 2:
http://digitallibrary.amnh.org/handle/2246/1510?show=full
Paleofile:
http://www.paleofile.com/Dinosaurs/Theropods/Allosaurus.asp
Chure and Loewen (2020) (Figure 16):
Evers et al., (2020) (Figure 5 and Figure 6):
https://peerj.com/articles/8493/
Kenneth Carpenter (2010):
Theropod Database ("Allosaurus fragilis"):
https://www.theropoddatabase.com/Carnosauria.htm#Allosaurusfragilis
(?)Other Species:
(?)A. amplus:
Galton et al., (2015) ("Abstract;" "Discussion" pg. 330):
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