Monday, November 1, 2021

My Ontogenetic Growth Series for T. rex (Excluding Nanotyrannus).

Update (1/29/23):
I wrote a paper on UCMP 119853:
https://www.academia.edu/96575022/A_Baby_Tyrannosaurus_rex_Premaxillary_or_First_Maxillary_Tooth

Update (8/11/23):
I wrote a description of the baby T. rex specimen BHI 6439:
https://www.academia.edu/105502160/A_Description_of_the_Baby_T_rex_Specimen_BHI_6439

I've decided to make my very own ontogenetic growth series for T. rex (excluding the Nanotyrannus individuals). Honestly, I don't know why I didn't do this before. T. rex is my favorite dinosaur, so I should have dome this eons ago. 

The purpose of this post is to examine actual young specimens of T. rex, and see how this animal grew. I am excluding the Nanotyrannus specimens because, as I've mentioned in another post, that whole debate is built on bias and willful ignorance. Also, based on my own investigation, Nanotyrannus isn't even a derived tyrannosaurid, but a basal tyrannosauroid that was closely related to Dryptosaurus and Appalachiosaurus. 

Using other tyrannosaurids as a guide, I hope to uncover how this animal truly matured as it aged. My ages for each specimen are as followed:

Baby: 0-9.
Juvenile: 10-15.
Subadult: 16-18.
Adult: 19 and onward.

1. UCMP 119853:
Age: Baby (Age is unknown, but judging from the size of the tooth, it's the youngest T. rex specimen I've found. It's definitely a baby, or better yet, a hatchling).
Tooth:
-Position: More likely a premaxillary tooth (also backed up by Joshua B. Smith in 2023, author of Smith, 2005). However, it could potentially be a first maxillary tooth (confirmed by Professor Holtz and Sebastian Dalman on 9/29-30/22).
-Length/Height: 8 mm.
-Width: 4 mm.

Baby T. rex UCMP 119853 first maxillary tooth (Carpenter, 1982):
P. 128 Figure 5 (A is side/lateral view, B is posterior (back) view). Scale bar is 2 mm:

P. 130:

Subadult T. rex "Stan's" 4th premaxillary and 1st maxillary teeth (Smith, 2005, p. 875 Figure 8 F-G; both are side views) (Arrows indicate serrations). Scale bar is 1 cm:

Nanotyrannus "Jane's" first maxillary tooth (posterior/rear view) (Larson, 2013, p. 35, Figure 2.14 D):

Nanotyrannus specimen LACM 28471 first and second maxillary teeth (Molnar, 1978, p. 76 Figure 5, A and C):
Note: Premaxillary tooth is the first maxillary tooth (Carr and Williamson, 2004, p. 489).

Smith (2005) said that the first maxillary tooth has serrations on the sides of it, is larger than the premaxillary teeth, and has an oval-shaped base (pp. 872 and 875). It has one of the largest crowns (length, I assume), having almost the same length as the fourth tooth in the dentary (p. 872). The fourth dentary tooth is the largest tooth in the dentary (p. 876). As for the location of the serrations, the fourth dentary tooth has them on the anterior (front) and posterior (back) views of it, unlike in the first maxillary tooth. "Stan's" fourth dentary tooth varies slightly, with the serrations towards the bottom of the tooth appearing on the sides (pp. 875-877; p. 879 Figure 13 D, F-G; p. 880 Figure 14 A). This to me supports the baby T. rex tooth as being a first maxillary tooth. Having a D-shaped cross section may also support this too (Carpenter, 1984, p. 130). Tarbosaurus' first maxillary tooth is the same as T. rex's (Smith, 2005, p. 872).

Voris et al., (2022) stated that juvenile, and adult, Gorgosaurus specimens had a first maxillary tooth that was incisiform, and had similar morphology to the premaxillary tooth.

Gorgosaurus had incisiform premaxillary, and first maxillary, teeth, and the first maxillary tooth had ridges and a groove, on it throughout the animal's lifetime (Voris et al., 2022, Systematic Paleontology, Description of Juvenile Gorgosaurus Skulls, Dentition, para. 2):

Note: They said that juvenile T. rex had this because they lumped Nanotyrannus into T. rex. 

Size estimation:
TD-13-251:
Height:
2.8 cm (C).
3.15 cm (T).

"Stan":
Pm 4 (M-Li): 4.1 cm (C) (Smallest).

1.) TD-31-251:
Crown height:
4.1 - 2.8 = 1.3.
1.3/4.1*100 = 31.7% decrease.
12.2 m - 31.7% = 27 feet (8.3 meters).

2.) UCMP 119853:
Total height:
3.15 - 0.8 = 2.35.
2.35/3.15*100 = 74.6% decrease.
8.3 m - 74.6% = 7 feet (2.1 meters).

UCMP 119853's total length: 7 feet (2.1 meters).

Observations:
1. Very serrated, unlike Nanotyrannus' (Carr and Williamson, 2004, p. 517), or lightly serrated (Molnar, 1978, p. 77) (Larson, 2013, pp. 33-35) (Larson's Twitter post).
2. Serrations are located on the lateral/side views and not the anterior (front) and posterior (back) views, just like adult T. rex's and Tarbosaurus' (Bakker et al., 1988, p. 24) (Tsuihiji et al., 2011, p. 17) (Larson, 2013, pp. 33-35). 
3. The front/anterior/mesial serrations (Figure 5 A) do not reach the base of the tooth, as in other T. rex specimens (Samman et al., 2005, pp. 762 and 768).

4. Tooth has an "incisiform appearance," or is either incisiform or sub-incisiform (Carpenter, 1982, p. 130) (Samman et al., 2005, p. 762). 
5. No ridges on the sides of the tooth that contain serrations (?Lambe, 1917, p. 19) (Larson, 2013, p. 35, Figure 2.14 D) (Larson's Twitter post). This is present in T. rex's premaxillary teeth, but not the first maxillary tooth (Smith, 2005, p. 870 Figure 3 B; p. 875 Figure 8 F-G).


Links:
Lambe (1917):

https://ia800804.us.archive.org/19/items/b29809940/b29809940.pdf
Molnar (1978):

https://www.jstor.org/stable/1303791

Carpenter (1982):

https://www.researchgate.net/publication/281039198_Baby_dinosaurs_from_the_Late_Cretaceous_Lance_and_Hell_Creek_Formations_and_a_description_of_a_new_species_of_theropod

Bakker et al., (1988) (P. 24):

https://zenodo.org/record/1037529#.YiYc4yVOmEc

Smith (2005) (P. 875 Figure 8 F-G):

https://www.researchgate.net/publication/249023627_Heterodonty_in_Tyrannosaurus_rex_Implications_for_the_taxonomic_and_systematic_utility_of_theropod_dentitions

Tsuihiji et al., 2011 (P. 17):

https://people.ohio.edu/witmerl/juvenile_tyrannosaur/2011_Tsuihiji_et_al._Tarbosaurus_juvenile_skull_PROOF.pdf

Larson (2013) (P. 34):

https://www.geokniga.org/bookfiles/geokniga-tyrannosaurid-paleobiology.pdf
Larson's Twitter post:

https://mobile.twitter.com/PeteLarsonTrex/status/1217195208921747463?cxt=HHwWjsC0of6lrOQhAAAA
Samman et al., (2005):

https://www.app.pan.pl/archive/published/app50/app50-757.pdf

Carr and Williamson (2004):

https://www.academia.edu/2291683/Diversity_of_late_Maastrichtian_Tyrannosauridae_Dinosauria_Theropoda_from_western_North_America

Link 2:
https://academic.oup.com/zoolinnean/article/142/4/479/2632290
Voris et al., (2022):
https://www.tandfonline.com/doi/full/10.1080/02724634.2021.2041651

Brunson (2023a):
https://www.researchgate.net/publication/367390306_A_Baby_Tyrannosaurus_rex_Premaxillary_or_First_Maxillary_Tooth

2. RSM P2347.1:
RSM P2347.1's maxilla (photo from Dr. Holtz's Twitter account). Scale bar is 30 cm:

RSM's maxilla pic. 2 (Jack Milligan's Twitter post):

RSM's maxilla and reconstructed skull (Jack Milligan's Twitter post):

Age: 0-9 (Baby) (True age is unknown, but it was probably 4 or younger due to the maxilla possibly being about 20 or so cm long).
Maxilla:
-Length: ~20 cm (maybe more or less).
-Tooth Count: Teeth were not found, but reconstruction shows that about 13 can fit.

Observations:
Characteristics of the maxilla:
1. Large maxillary fenestra closer to the maxillary strut and not the antorbital fenestra.
2. Weak maxillary strut.
3. Maxillary strut is circular, and straight, in the beginning. This is near the front of the maxilla.

Links:

Dalman (pers. comm.).

Holtz's Twitter post:
https://mobile.twitter.com/TomHoltzPaleo/status/1305854281896132609

Jack Milligan's Twitter post:
Pic. 1:

https://twitter.com/Pieceofasaurus/status/1235964731380252672

Pic. 2:
https://mobile.twitter.com/Pieceofasaurus/status/1235964731380252672


3. "Baby Bob": 

"Baby Bob" Dentary (Deak and McKenzie, 2016, slide 12):

Dentary with tooth sockets showing (Keblog):

Skull length (Detrich Fossil Co's Twitter post):

Femur and Tibia (Peter Larson's Twitter post):

"Baby Bob's" age (Michael Deak's Twitter post):

Skull fragments (FossilForum):

Age: 4 (maybe 5) (Baby) (Michael Deak's Twitter post) (Deak and McKenzie, 2016, slide 12).

Dentary:
-Tooth count: 12.
Mandible/Dentary: 55.9 cm (22 inches). 
Skull: 53.3 cm (21 inches).
Femur: 64.5 cm.
Tibia: 65 cm.


Size estimate:

Ceratosaurus nasicornis Holotype:
Femur: 62.0 cm.
Length: 19 feet (5.8 meters).

64.5 - 62 = 2.5.
2.5/62 * 100 = 4% increase.
5.8 m + 4% = 20 feet (6.0 meters). 


Observations:
Characteristics of the lacrimal:
1. No lacrimal horn seem to be present. 
Characteristics of the dentary:
2. Lingual bar covers the first two dentary teeth.
3. 12 alveoli are present.
Characteristics of the teeth:
4. Wide and "D-shaped."
Traits in the femur and tibia:
5. Femur and tibia are basically the same length. Tibia is not drastically longer than the femur.

Links:
Dentary and tooth count info.:
Deak and McKenzie (2016) (Slide 12):

https://www.researchgate.net/publication/309340780_HYPOTHETICAL_DIVERGENT_EVOLUTION_OF_TWO_APEX_PREDATORS_FROM_THE_HELL_CREEK_FORMATION_NANOTYRANNUS_LANCENSIS_AND_TYRANNOSAURUS_REX

Dalman (pers. comm.).
Keblog:

https://www.keblog.it/fossili-t-rex-cucciolo-in-vendita-su-ebay/

Skull Length:
Detrich Fossil Co Twitter post:

https://mobile.twitter.com/kingfossil/status/1121904029095866370

Skull pic from FossilForum:

Image:

https://images.app.goo.gl/bkcNXKVNCkuFi3d88

Link:

http://www.thefossilforum.com/index.php?/topic/61245-bob-the-baby-t-rex/

Femur and Tibia pic:
Peter Larson's Twitter post:
https://mobile.twitter.com/PeteLarsonTrex/status/1226656066177523717
Age:

Deak and McKenzie (2016) (Slide 12):

https://www.researchgate.net/publication/309340780_HYPOTHETICAL_DIVERGENT_EVOLUTION_OF_TWO_APEX_PREDATORS_FROM_THE_HELL_CREEK_FORMATION_NANOTYRANNUS_LANCENSIS_AND_TYRANNOSAURUS_REX

Michael Deak's Twitter post:

https://twitter.com/deak_michael/status/1075732456412774401


4. BHI 6439:

Dentary length (pic. given to me from Dalman). Photo belongs to "Troodon" from Fossil Forum:

Nanotyrannus "Jane's" (top) and T. rex BHI 6439's (bottom's) dentaries (interior) (photo from Peter Larson's Twitter page):

Note: Interior groove covers the first two teeth/alveoli on BHI 6439's dentary, and in T. rex overall. "Jane's" only covers the first alveoli (Dalman, pers. comm.) (Dalman and Lucas, 2016, p. 23).


Top view (pic. provided by Dalman). Picture belongs to Peter Larson from Instagram:

Age: Between 4 and 9 (estimated) (Baby) (Dentary and tooth row are the same size as "Jane's," but the specimen is only slightly larger than "Baby Bob").
Dentary (incomplete):
-Tooth row length: 33 cm (Measured on 2/12/22).


Dryptosaurus specimen "Jane":
Dentary: 
-Length: 52 cm (Measured in Brusatte et al., 2010 on 5/20/22).

-Tooth row length: 31.5 cm (Measured on 2/12/22 in pic from Dalman).

Skull: 77.7 cm (Measured in Brusatte et al., 2010 on 8/28/21).

Body Length: 22 feet (6.7 meters).


Size estimation:
T. rex specimen "Sue":
Dentary tooth row length: 56 cm.
Body length: 13.6 meters.


56 - 33 = 23.
23/56*100 = 41.1% decrease.
13.6 m - 41.1% = 26 feet (8.0 meters).


"Jane":

Dentary tooth row:
33 - 31.5 = 1.5.
1.5/31.5*100 = 4.8% increase.
6.7 m + 4.8% = 23 feet (7.0 meters).
52 cm + 4.8% = 54.5 cm for the dentary.
77.7 cm + 4.8% = 81.4 cm for the skull.


BHI 6439's Stats:
Dentary:
-Length: 54.5 cm.
-Tooth row length: 33 cm.
-13 alveoli.
Skull: 81.4 cm.
Body length: 23 feet (7.0 meters).


Observations:
Characteristics of dentary:
1. Lingual bar covers the first two dentary teeth/alveoli, unlike in Nanotyrannus "Jane's" dentary.
2. 13 alveoli are present, while 17 are present in "Jane."
3. The first tooth is incisiform, as seen in the adult specimens.
4. Dentary is taller and thicker than Nanotyrannus "Jane's," despite having a similar tooth row size. This shows that T. rex, from an early age, was designed to deliver a bone-crushing blow to its prey.


Links:

Dalman (pers. comm.).
"Troodon" from Fossil Forum:

http://www.thefossilforum.com/index.php?/topic/93287-the-case-for-nanotyrannus/

Peter Larson's Twitter post:

https://twitter.com/PeteLarsonTrex/status/974329880707063810

5. UCRC-PV 1:

UCRC-PV 1's arm (photo from Peter Larson's Twitter page):

Hand (Fran Vidakovic's Twitter post). Scale bar is 10 cm:
Manual ungual 2 claw (Fran Vidakovic's Twitter post):

Age: Baby (Subadult was given by Larson on Twitter, but my measurement places the specimen at being a meter longer than BHI 6439, so I'm placing it as a baby. The length of manual phalanx 1-1 backs this up too when compared to the subadult "Bucky").
Manual phalanx 1-1: 6.8 cm (at best) (Measured on 11/20/21).


Size estimation:
TCM 2001.90.1 ("Bucky"):
Manual phalanx 1-1: 9.2 cm (at best).
Length: 35 feet (10.8 meters).


9.2 - 6.8 = 2.4.
2.4/9.2*100 = 26.1% decrease.
10.8 m - 26.1% = 26 feet (8.0 meters).


Observations:
Characteristics of the arm:
1. Manual unguals (claws) appear short and thick, unlike Nanotyrannus', Dryptosaurus', and Megaraptor's.
2. Short, and skinny, manual phalanx 1-1. It's smaller than adult specimens (7.8-10 cm) (Persons IV et al., 2019, p. 669 Table 1). It's slightly larger than a young Tarbosaurus specimen (5.4 cm) (Brusatte et al., 2011, p. 47 Table 3). Nanotyrannus, Dryptosaurus, and Megaraptor had extremely long manual phalanx 1-1's, with the former two taxa being twice as long as T. rex's, if not longer.
3. Humerus is longer than the radius and ulna, unlike in Nanotyrannus and Dryptosaurus.

Adult T. rex manual phalanx 1-1 lengths (Persons IV et al., 2019, p. 669 Table 1):

Tyrannosauroid limb proportions (Brusatte et al., 2011, p. 47 Table 3):

Larson describing the specimen's age (Twitter):

Larson and Carpenter (2008) wrote about the specimen. Catalogued as UCRC PV1, it was discovered in 1950, and excavated by Paul Sereno and his team in 2001. The specimen is in the University of Chicago. Sereno is quoted as saying that the specimen has both complete forelimbs (p. 41):


Comparison with Albertosaurus sarcophagus hand Mallon et al., (2019) (Figure 8):

Daspletosaurus torosus' arm (Russell, 1970, p. 34 Plate 4) (Scale bar is 5 cm):

Both Albertosaurus and Daspletosaurus had identical hand, and arm, morphology to T. rex specimen UCRC PV1's.


Links:
Peter Larson's Twitter post:
https://mobile.twitter.com/PeteLarsonTrex/status/973346519423246336

Fran Vidakovic's Twitter post:

https://twitter.com/Goji1999/status/1212775954667450373

Larson and Carpenter (2008) (P. 41):
https://books.google.com/books/about/Tyrannosaurus_Rex_the_Tyrant_King.html?id=5WH9RnfKco4C&printsec=frontcover&newbks=1&newbks_redir=0&source=gb_mobile_entity#v=onepage&q=ucrc%20pv1&f=false

Mallon et al., (2019):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7079176/
Russell (1970) (P. 9):

https://www.biodiversitylibrary.org/page/36032001#page/27/mode/1up

Brusatte et al., (2011):

https://digitallibrary.amnh.org/bitstream/handle/2246/6117/N3717.pdf?sequence=1&isAllowed=y


6. MOR 009:

Age: 10-14 (Juvenile) (0.4 meters smaller than "Tinker") (11-19 in total from Padian and Horner, 2004, p. 1876 Table 1 and p. 1877, and Erickson et al., 2006, Supplementary Materials, p. 13).

Femur: 110 cm (Persons IV et al., 2019, p. 669 Table 1).
Tibia: 110.5 cm (Persons IV et al., 2019, p. 669 Table 1).


Size:
Acrocanthosaurus Holotype OMNH 10143:

Femur: 115.3 cm.
Body Length: 35 feet (10.7 meters).


115.3 - 110 = 5.3.
5.3/115.3*100 = 4.6% increase.
10.7 m - 4.6% = 34 feet (10.2 meters).


Observations:
Characteristics in the femur and tibia:
1. Femur and tibia are about the same length (Persons IV et al., 2019, p. 669 Table 1), just like "Baby Bob" and LACM 23845. This suggests that MOR 009 is a juvenile. The age range for this specimen are 11-19 (Padian and Horner, 2004, p. 1876 Table 1 and p. 1877) (Erickson et al., 2006, Supplementary Materials, p. 13). Based on the femur and tibia lengths being basically identical, I'm placing MOR 009 in the juvenile age range (10-15 years old). 


Links:
Persons IV et al., (2019):
https://onlinelibrary.wiley.com/doi/epdf/10.1002/ar.24118?tracking_action=preview_click&r3_referer=wol&show_checkout=1
Link 2:
https://www.gbif.org/species/159236947
Abstract:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/ar.24118
Padian and Horner (2004) (P. 1876 Table 1):

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.515.6451&rep=rep1&type=pdf
Link 2:

https://www.researchgate.net/publication/8364874_Age_and_growth_dynamics_of_Tyrannosaurus_rex

Erickson et al., (2006) (Supplementary Materials) (P. 13):

7. "Tinker":
"Tinker's" skull (Christies):

"Tinker's" Dentary (photo belongs to Dalman) (Measuring tape is presumably in inches):

Age: 14 (Juvenile) (Erickson et al., 2006, Supplementary Materials, p. 13).
Dentary: 82.6 cm (32.5 inches) (at best) (Measured on 11/21/21).

Observations:
Maxilla:
1. Maxillary fenestra is large and on the maxillary strut instead of near the antorbital fenestra.
2. Maxillary strut is circular, and straight, in the beginning. This is near the front of the maxilla.
Dentary:
3. 12 teeth.

Size estimation:
"Jane":
Dentary: 
-Length: 57 cm (Measured in Brusatte et al., 2010 on 8/28/21).
-Tooth row length: 31.5 cm (Measured on 2/12/22).
-Tooth count: 12 (visible).
Skull: 77.7 cm (Measured in Brusatte et al., 2010 on 8/28/21).

Body Length: 22 feet (6.7 meters).


Dentary:
82.6 - 57 = 25.6.
25.6/57*100 = 44.9% increase.
6.7 m + 44.9% = 9.7 meters.

BHI 6439:
Dentary:
-Length: 54.5 cm.
-Tooth row length: 31.5 cm.
Skull: 81.4 cm.
Body length: 23 feet (7.0 meters).


82.6 - 54.5 = 28.1.
28.1/54.5*100 = 51.6% increase.
7.0 m + 51.6% = 35 feet (10.6 meters).
81.4 cm + 38.4% = 123.4 cm for the Skull.

"Tinker's" Stats:
Body length: 35 feet (10.6 meters).
Dentary length: 82.6 cm (32.5 inches) (at best).
Skull length: 123.4 cm.


Links:

Erickson et al., (2006) (Supplementary Materials) (P. 13):

Sebastian Dalman (pers. comm.).

Christies:

https://www.christies.com/lot/lot-5989561


8. RSM P.2990.1:

RSM P.2990.1's lacrimal (Holtz's Twitter page):

Age: 10-15 (Juvenile) (Dalman, pers. comm) (Carr, 2020).

Observations:
Characteristics of the lacrimal:
1. Shape is identical to Tarbosaurus specimen MCP-107/7's lacrimal (Tsuihiji et al., 2011, p. 10 Figure 8 F).
2. Lacrimal horn (or cornual process) may be present. Juvenile Tarbosaurus specimen GIN 100/66 has lacrimal horns (Currie, 2003, p. 200) (Yun, 2015, p. 4).

(?)3. No multiple pneumatopores (holes) are present except for the typical one seen in other tyrannosauroids, but the specimen could just be old enough not to have them.
4. One small pneumatopore inside the lacrimal, as in the juvenile Tarbosaurus specimen MCP-107/7. Nanotyrannus, Appalachiosaurus, and Gorgosaurus have large pneumatopores in their lacrimals.
5. Lacrimal is not covered in rugosities, as in Nanotyrannus and Appalachiosaurus (called a "ridge" in Carr et al., 2005).

RSM's lacrimal is basically identical to Tarbosaurus specimen MCP-107/14's lacrimal (Tsuihiji et al., 2011, p. 10 Figure 8 F):

9. TMM 41436-1:

TMM 41436-1's maxilla (Wick, 2014, Figure 1) (Scale bar is 10 cm):

Age: 10-15 (Juvenile), since the size of the maxilla is rather small (about 35-45 cm; 39 cm in Lawson, 1976, p. 159). Granted, it is incomplete at the end, but the tooth row is rather small (22.8cm in Lawson, 1976, p. 160).
-Other ages given: Subadult (Wick, 2014, Brief history and referral, para. 2) (Carr, 2020, pp. 59 and 93).

Observations:
Characteristics of the maxilla:
1. Maxillary strut is deep.
2. Maxillary strut is circular, and straight, in the beginning. This is near the front of the maxilla.
3. Maxillary fenestra is huge, and right on the maxillary strut instead of the antorbital fossa.
4. 11 teeth fit inside.

Links:
Lawson (1976) (PP. 159-161): 
https://zenodo.org/record/3675277#.YOs7KBNKh-U

Wick (2014) (Brief history and referral, para. 2):
Figure 1:
https://images.app.goo.gl/5s863Z7Q9niWnQsC7
Paper:
https://www.sciencedirect.com/science/article/abs/pii/S0195667114000500
Carr (2020) (pp. 59 and 93):
https://peerj.com/articles/9192/


10. LACM 23845:
LACM 23845's preserved skull bones drawing (Olshevsky, 1995, p. 3):

Age: 14 (Juvenile) (Based on femur and tibia being the same length, as seen in "Baby Bob") (14-16 in total is based on Erickson et al., 2004, p. 774 Table 1, and Carr, 2020).


Note: Skull, femur, tibia, and fibula lengths come from multiple different sources, so I'll have to measure the fibula to get an accurate skull length estimate.


My Measurements:
Fibula: 88 cm (at best) (Measured on 11/21/21 in Molnar, 1980, p. 106) (Molnar, 1980, p. 107 says that the skull is the same size as the fibula).

LACM 23845's fibula (Molnar, 1980, p. 106). Scale bar is 10 cm:

Other measurements given:
Femur: 98.9 cm (Erickson et al., 2004, p. 774 Table 1).
Tibia: 98.9 cm (Erickson et al., 2004, p. 774 Table 1).
Note: The femur and tibia are the same size (Persons and Currie, 2016, p. 6 Table 2).
Skull: 90 cm (Paul, 1988, pp. 333-334).
Femur:
-98.9 cm (Erickson et al., 2004, p. 774 Table 1).
-82.5 cm (Persons and Currie, 2016, p. 6 Table 2).
Tibia: 82.5 cm (with a 82.5-cm femur) (Persons and Currie, 2016, p. 6 Table 2).

Size estimate:
Fibula:
Daspletosaurus torosus TMP.2001.036.0001:
Femur: 98.7 cm.
Length: 30 feet (9.2 meters).

98.9 - 98.7 = 0.2.
0.2/98.7 * 100 = 0.2% increase.
9.2 m + 0.2% = 30 feet (9.2 meters).

Allosaurus USNM 4734:
Fibula: 62.3 cm. 
Body length: 7.9 meters.

88 - 62.3 = 25.7.
25.7/62.3*100 = 41.3% increase.
7.9 m + 41.3% = 11.1 meters.

T. rex specimen "Sue":
Fibula Length: 110.0 cm.
Body Length: 13.6 meters.

110 - 88 = 22.
22/110*100 = 20% decrease.
13.6 m - 20% = 36 feet (10.9 meters).
143 cm - 20% = 114.4 cm for femur and tibia.


T. rex specimen TCM 2001.90.1 (originally ICM) ("Bucky"):
Femur: 116.8 cm.
Body: 10.8 meters.


116.8 - 114.4 = 2.4.

2.4/116.8*100 = 2.1% decrease.

10.8 m - 2.1% = 35 feet (10.6 meters).


Skull:

T. rex specimen "Duffy":

Skull: 117 cm.
Body: 9.7 m.


117 cm - 88 cm = 29.
29/117*100 = 24.8% decrease.
9.7 m - 24.8% = 24 feet (7.3 meters).


LACM 23845's Stats:
Age: 14.
Skull and Fibula: 88 cm.
Body Length: 24 feet (7.3 meters).


Longrich and Saitta (2023) (preprint) said that LACM's skull was "about 12% larger" than the skull of the "Nanotyrannus" (cf. Dryptosaurus) specimen "Jane." They said its skull length was 80 cm (p. 26). This fits well with the 88-cm length I've obtained for it. The authors also stated that the specimen also comparable in size to the larger "Nanotyrannus" (cf. Dryptosaurus) specimens (I'm assuming they mean "Jane" and "Petey") (p. 28).


Observations:
Characteristics of the nasal:
1. The nasal has few and lower-sized rugosities (Molnar, 1980, p. 103) unlike the younger 
Nanotyrannus ("Zuri" at 13-years of age) and Alioramus specimens (both 9 years old).

Characteristics of the lacrimal:
2. No lacrimal horn/cornual process is present (Molnar, 1980, p. 103) (Carr and Williamson, 2004, p. 497). The horn/process seems to have left by the time T. rex turned 14.
3. Top of the lacrimal is similar in morphology to RSM P.2990.1's and other adults, and is smooth unlike Nanotyrannus', Appalachiosaurus', and Gorgosaurus'.
(?)4. No multiple pneumatopores (holes) are present, but the specimen could just be old enough not to have them.
Characteristics of the maxilla:
5. The maxillary fenestra touches the margin of the maxillary strut (Olshevsky, 1995, p. 3) (Molnar says it's the antorbital fossa [p. 103]).

Characteristics of the maxillary strut:
6. Maxillary strut is circular, and straight, in the beginning. This is near the front of the maxilla.
Characteristics of the skull:
7. Skull is the same length as the fibula (Molnar, 1980, p. 107). It's smaller than the femur, which is also seen in "Baby Bob." This may suggest an age of 14 instead of 16.
Characteristics of the arms:
8. Arms are small (Paul, 1988, pp. 334 and 336) (Olshevsky, 1995, p. 4), or match the proportions of Albertosaurus (probably meaning Gorgosaurus) (Molnar, 1980, p. 106). Nanotyrannus, Dryptosaurus, and Megaraptor, had long arms.
Characteristics of the femur and tibia lengths:
9. Femur and tibia are the same length, just like "Baby Bob" (Persons and Currie, 2016, p. 6 Table 2). This helps to reaffirm an age of 14 instead of 16. Subadults have larger skulls compared to their femurs, not juveniles.


Links:
Molnar (1980):
https://www.jstor.org/stable/1304167
Paul (1988) (pp. 333 and 334):
https://archive.org/details/g.s.paul1988predatorydinosaursoftheworld/page/n338/mode/1up
Olshevsky (1995):
https://zenodo.org/record/1038228#.YT875SUpCEe
Erickson et al., (2004) (P. 774):
http://webpages.math.luc.edu/~ebalderama/bayes_resources/mt/nature02699.pdf
Persons and Currie (2016):
https://www.researchgate.net/publication/292188989_An_approach_to_scoring_cursorial_limb_proportions_in_carnivorous_dinosaurs_and_an_attempt_to_account_for_allometry

Carr (2020):
https://peerj.com/articles/9192/
Longrich and Saitta (2023) (Preprint):

https://osf.io/preprints/paleorxiv/nc6tk/?fbclid=IwAR3_YkPSpKBQXk5Aiff0sJRKsl59dIqqO5DXveSjV-tx24Vs6ZLuRZdcaHs


11. USNM 6183:
Specimen's femur and tibia lengths (Gilmore, 1920, p. 122):

Age: 17 (Subadult) (Erickson et al., 2006, Supplementary Materials, p. 13).
Femur: 104.0 cm.
Tibia: 91 cm.

LACM 23845:
Femur: 98.9 cm.
Body: 30 feet (9.2 meters).

Size estimation:
104.0 - 98.9 = 5.1.
5.1/98.9*100 = 5.2% increase.
9.2 m + 5.2% = 32 feet (9.7 meters).

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

107.5 - 104 = 3.5.
3.5/107.5*100 = 3.3% decrease.
10.0 m - 3.3% = 32 feet (9.7 meters).

Observations:
Characteristics of the femur and tibia:
1. Femur is larger than the tibia. Given that it's 17 years old, this is a characteristic of a subadult T. rex.


Link:
Gilmore (1920) (P. 122):

https://www.biodiversitylibrary.org/item/125786#page/140/mode/1up

Erickson et al., (2006):

https://www.researchgate.net/publication/6944402_Tyrannosaur_Life_Tables_An_Example_of_Nonavian_Dinosaur_Population_Biology

Supplementary Materials (P. 13):

https://science.sciencemag.org/content/sci/suppl/2006/07/11/313.5784.213.DC1/Erickson.SOM.pdf


12. TCM 2001.90.1 (originally ICM) ("Bucky"):
Age: 16 (Subadult) (Erickson et al., 2004, p. 774 Table 1).
Femur: 116.8 cm (estimated) (Erickson et al., 2004, p. 774 Table 1).
Manual phalanx 1-1: 9.2 cm (at best) (Measured on 4/8/22).


Left to right: manual phalanx 1-1 bones of Gorgosaurus, Nanotyrannus BHI 6437, T. rex specimens MOR 980, and TCM 2001.90.1 (Peter Larson's Twitter post):
"Bucky's" phalanx is black. A poster from BHIGR shows that "Bucky's" phalanx was discovered with the skeleton.

Size estimate:

Acrocanthosaurus Holotype OMNH 10143:

Femur: 115.3 cm.
Body Length: 35 feet (10.7 meters).


116.8 - 115.3 = 1.5.

1.5/115.3*100 = 1.3% increase.

10.7 m + 1.3% = 35 feet (10.8 meters).


Observations:
Characteristics in the manual phalanx 1-1 bone:
1. Smaller than Nanotyrannus' (2nd one, white), despite the Nanotyrannus specimen BHI 6437 also being a subadult (Tyrannosauroidea central, Tyrannoethics: The naturalist T. rex and the and the T. rex list of shame, updated). It's also smaller than the adult T. rex specimen MOR 980's (brown) right next to it. This, and UCRC-PV1's manual 1-1 phalanx, seems to indicate that T. rex's manual 1-1 phalanx grew instead of shrunk during ontogeny. BHIGR showed that "Bucky's" manual phalanx 1-1 was indeed preserved. 

Nanotyrannus BHI 6437's age:
Carr, Thomas. Tyrannosauroidea central. Tyrannoethics: The naturalist T. rex and the and the T. rex list of shame, updated. 2015:

https://tyrannosauroideacentral.blogspot.com/2015/02/tyrannoethics-4-naturalis-t-rex-t-rex.html


13. BHI 3033 ("Stan"):

BHI 3033's ("Stan's") dentary (Dalman and Lucas, 2016, p. 25):

Note: Interior groove covers the first two alveoli/teeth.


Age: 18 (Subadult) (Erickson et al., 2006, Supplementary Materials, p. 13).

Skull: 147 cm. 
Maxilla:
-Length: 76 cm. 
-Tooth count: 11.
Dentary: 
-Length: 91 cm. 
-Tooth count: 13.
Femur: 130.0 cm. 
Tibia: 109.6 cm.
Body: 12.2 meters. 

Observations:
Characteristics of the maxilla:
1. 11 teeth are present.
Characteristics of the dentary:
2. Lingual bar covers the first two teeth.
3. 13 teeth are present.
Characteristics in the skull and femur lengths:
4. The skull is longer than the femur, unlike in the baby and juvenile specimens "Baby Bob" and LACM 23845.
Characteristics of the femur and tibia:
5. Femur is larger than the tibia, just like USNM 6183. This seems to back up my hypothesis of this being a subadult characteristic.


Link:

Erickson et al., (2006) (Supplementary Materials) (P. 13):

Hendrickx and Mateus (2014) (Figure 2):
https://www.researchgate.net/figure/Left-maxillae-of-Tyrannosaurus-rex-in-A-B-lateral-view-CMNH-9380-reversed-and-C_fig2_260561984 
Dalman and Lucas (2016) (P. 25): 

https://www.dinosaur.pref.fukui.jp/archive/memoir/memoir016-017.pdf

Larson (2013) (p. 37):

https://www.geokniga.org/bookfiles/geokniga-tyrannosaurid-paleobiology.pdf


14.  CM 79057 ("Samson") and PARC-TD-11-094/FDM-xx?:

 CM 79057 ("Samson") dentary and tooth count (Deak and McKenzie, 2016, slide 9) (from Horner, 2011):

PARC-TD-11-094/FDM-xx? dentary (Stein, 2021, p. 37, Figure 16):

Note: First two alveoli are covered by the interior groove (A).

Stein's statement on the dentary having 14-15 tooth positions (Stein, 2021, p. 36):

Ages:
-"Samson": 23 (Adult) (Erickson et al., 2006, Supplementary Materials, p. 13).

-PARC-TD-11-094/FDM-xx?: Unknown, but compared to "Stan," it's probably a subadult (based on the length of the dentary given by Stein, 2021, p. 36).

Maxilla:
-"Samson": 13 (Carr et al., 2011, p. 5, Discussion).

-PARC: Unknown.
Dentary:

-"Samson": Length is unknown.
-PARC: 92 cm.
-Tooth count (both): 15 (Carr et al., 2011, p. 5, Discussion) (Stein, 2021, p. 36).


Observations:
Characteristics of the maxilla:
1. "Samson" had 13 teeth in its maxilla.
Characteristics of the dentaries:
2. Lingual bar covers the first two alveoli in PARC-TD-11-094/FDM-xx?'s dentary. "Samson" more than likely had this as well.
3. 15 teeth in the dentaries for both specimen.


Links:

Erickson et al., (2006) (Supplementary Materials) (P. 13):
Deak and McKenzie (2016) (slide 13):
https://www.researchgate.net/publication/309340780_HYPOTHETICAL_DIVERGENT_EVOLUTION_OF_TWO_APEX_PREDATORS_FROM_THE_HELL_CREEK_FORMATION_NANOTYRANNUS_LANCENSIS_AND_TYRANNOSAURUS_REX
Stein (2021) (P. 36):
http://www.thefossilforum.com/applications/core/interface/file/attachment.php?id=755388

15. BHI 2033/FMNH 2081 ("Sue"):
Age: 28-33 (Adult) (Erickson et al., 2004, p. 773 Figure 1 C) (Cullen et al., 2020).
Length: 13.6 meters.
Right Maxilla: 86 cm.
Right Dentary: 101.0 cm. 
Humerus: 39.0 cm.
Right Femur: 143 cm (at best).
Right Tibia: 124 cm.
Right Fibula: 110 cm. 

Characteristics of femur and tibia:
1. Femur is larger than the tibia.
Characteristics of age:
2. EFS found in "Sue" states that T. rex stopped growing around the age of 19 (Erickson et al., 2004, p. 773 Figure 1 C).

Links:
Erickson et al., (2004) (P. 773 Figure 1 C):
http://webpages.math.luc.edu/~ebalderama/bayes_resources/mt/nature02699.pdf
Cullen et al., (2020):
"Abstract":

Summary of Characteristics listed:
1. T. rex doesn't show any signs of increasing, and then decreasing, in tooth count during ontogeny. In fact, it shows the opposite. T. rex's tooth count seems to have stayed the same, or even increased. For example: "Stan" had 11 teeth in its maxilla and 13 teeth in its dentary, but "Samson" had 13 teeth in its maxilla and 15 teeth in its dentary. "Stan" is 18 years old, while "Samson" is 23. The small fluctuations in tooth counts is a result of individual variation, and variation is not too vast from specimen to specimen. 

2. The nasals had very few, and small, rugosities on it, even when the individual was 14 years old. This is seen in LACM 23845. The rugosities seem to have grown larger, and increased in number, when the individual grew to be a subadult. This is seen in "Stan."

3. T. rex's maxilla had a wide maxillary fenesta (hole) in its antorbital fossa throughout its lifetime. It did not change shape during ontogeny.

4. The maxillary strut grew from being weak during a young age to being very prominent and deep in adulthood, and the maxillary fenestra was closer in position to the strut rather than the antorbital fenestra. It did not change position during ontogeny.

5. Maxillary strut is circular, and straight, in the beginning. This is near the front of the maxilla, and doesn't change during ontogeny. The strut is so straight at the beginning that a straight line could be drawn through it, cutting it in half.

6. The first maxillary tooth is probably slightly incisiform when the species was a baby, but it is still serrated and they are located on the lateral/side views of the tooth, unlike in Nanotyrannus', Dryptosaurus', and Gorgosaurus'. Nanotyrannus' is either unserrated, or very lightly serrated, and there are ridges on the lateral/side views of the tooth. These ridges are not on T. rex's first maxillary tooth, and this is evident in baby specimens. Tarbosaurus' was the same. Gorgosaurus' first maxillary tooth was identical to Nanotyrannus'.

7. The lingual bar in the interior/medial side of the dentary covered the first two alveoli/teeth throughout its lifetime.

8. The teeth were always wide without any sign of changing shape (extremely blade-like to extremely thick) during ontogeny. 

9. T. rex's lacrimal horn, or cornual process, was probably, or not, present when it was 4, as seen in "Baby Bob." However, it may have appeared around the animal's juvenile stage, as seen in RSM P.2990.1. When the animal turned 14, the lacrimal horn disappeared. This is seen in LACM 23845.

10. The arms started out small and grew during ontogeny. They didn't start out large and then shrink. This is seen in the juvenile specimens LACM 23845 and UCRC-PV 1.

11. The manual phalanx 1-1 started small and skinny during ontogeny, as seen in UCRC-PV 1, "Bucky," and , and MOR 980. It was similar to Albertosaurus' and Daspletosaurus'. Over time, the bone grew to be thicker but not that much taller, as seen in the adult specimen MOR 980. The largest manual phalanx 1-1 is about 10 cm long, and it belongs to "Scotty" (Persons IV et al., 2019, p. 669).

12. The manual unguals (hand claws) were small but thick throughout T. rex's lifetime, contrary to Nanotyrannus' which were longer.

13. T. rex's femur and the tibia were either about the same lengths, or the tibia was slightly longer, when it was a baby and a juvenile, as demonstrated by "Baby Bob," LACM 23845, and MOR 009. At best, the tibia was barely and longer than the femur during this time in its life.

14. The skull was shorter than the femur for baby-juvenile specimens, as seen in "Baby Bob" and LACM 23845.

15. The skull grew larger than the femur when the animal became a subadult, as seen in "Stan"

16. The femur grew larger than the tibia when T. rex became a subadult, as seen in USNM 6183 and "Stan."

17. T. rex reached maturity (stopped growing) at the age of 19, as indicated by an EFS marker in "Sue" (Erickson et al., 2004, p. 773 Figure 1 C).

*Work in Progress*
Growth Charts:
Here's my four growth charts for T. rex's and juvenile Dryptosaurus' ("Nanotyrannus") femur and tibia lengths:
As you can see, three out of four of the charts state that the juvenile Dryptosaurus specimens ("Nanotyrannus") are either outside, or way below, T. rex's growth in terms of femur and tibia lengths. All trendlines are linear. The growth trendline (R^2) for the first chart is 0.941 for T. rex's femur, and 0.777 for the tibia. Dryptosaurus' is 0.998 for the femur, but 1 for the tibia. The second chart shows 0.888 for T. rex's femur, and 0.648 for the tibia. Dryptosaurus' femur is 0.998 again, but 1 for the tibia. The third chart shows 0.932 for T. rex's femur, and 0.8 for its tibia. Dryptosaurus' femur is 0.893, and its tibia is 0.887. A more positive result this time. For the fourth and final chart, T. rex's femur is 0.888, and the tibia is 0.648. Dryptosaurus' femur is 0.883, and its tibia is 0.887. 

This is not good if the juvenile Dryptosaurus specimens ("Nanotyrannus") were juvenile T. rexes.

Dryptosaurus (Blue) vs. T. rex (Red) Ontogeny Chart:
Note: In the Dryptosaurus chart, the 7.3-meter specimen is the actual Dryptosaurus holotype. No age has been assigned to this specimen, but it has been stated as being an adult in Brusatte et al., (2011). 

The trendline (linear) (R^2) for Dryptosaurus is 0.775. The trendline for T. rex is 0.962. A 7-year old Dryptosaurus (CMNH 7541) was 1.4 meters shorter than a 4-year old T. rex ("Baby Bob"). I obtained a length of 7.0 meters for BHI 6439, which would place this specimen in between a 4-14-year old individual. However, this specimen would probably have been only slightly older than "Baby Bob," since I got a length of 6.0 meters for that specimen. So, a baby T. rex would have been the same size as a juvenile Dryptosaurus. An adult Dryptosaurus (the actual holotype of Dryptosaurus), at 7.3 meters in length, is completely dwarfed by two 14-year old T. rex specimens ('Tinker" and LACM 23845). This leads me to conclude that an actual juvenile T. rex would be two, or more, meters longer than an adult Dryptosaurus.  

Update (3/5/22):
Chart 3 (Featuring all the T. rex specimens listed here):
Note: T. rex specimen BHI 6439's age is unknown, so it is left blank. This is still the same for the Dryptosaurus holotype.

The trendline (linear) (R^2) for Dryptosaurus is still 0.775, but the trendline for T. rex is down to 0.908. Still a large difference between the two species, and the results from my first ontogeny chart still ring true.
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