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  1. I was very pleasantly surprised (actually more thrilled to be honest) when I heard about the discovery of the northern tyrannosaurid dinosaur Nanuqusaurus hoglundi from the Cretaceous Prince Creek Formation dating 70.6-69.1 Million Years ago in what is now the U.S. State of Alaska. Image Credit and Source: https://www.researchgate.net/publication/260757717_A_Diminutive_New_Tyrannosaur_from_the_Top_of_the_World At first thought to be only 5-6 meters (16-20 feet) in length based on the currently catalogued specimens, it's now believed based on currently undescribed remains to be 8-9 meters (26-30 feet) in length fully grown (compared to the 12.3-12.4 meters (40.4-40.7 feet) in length it's cousin Tyrannosaurus rex could reach fully grown). Image Credit: Artist Nathan Rogers Image Source: https://www.artstation.com/artwork/Z5w900 Fiorillo, A. R., & Tykoski, R. S., 2014. A diminutive new tyrannosaur from the top of the world. PloS one, 9(3), e91287. https://doi.org/10.1371/journal.pone.0091287 Druckenmiller, P. S., Erickson, G. M., Brinkman, D., Brown, C. M., & Eberle, J. J. (2021). Nesting at extreme polar latitudes by non-avian dinosaurs. Current biology : CB, 31(16), 3469–3478.e5. https://doi.org/10.1016/j.cub.2021.05.041 https://www.cell.com/current-biology/fulltext/S0960-9822(21)00739-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982221007399%3Fshowall%3Dtrue The Tyrannosaurid Nanuqusaurus is also unique as the northern most tyrannosaur known from Western North America (at the time the continent of Laramidia). Adapted to the colder climates of the region, it shared its habitat with a vast diversity of plants, small mammals, and other non-avian dinosaurs including hadrosaurs such as Edmontosaurus, the pachycephalosaur Alaskacephale, the Ceratopsian Pachyrhinosaurus, and a large currently unnamed genus of troodontidae. But it's confirmed geologic range is only during the early Maastrichtian (70.6-69.1 Million Years ago) of the Cretaceous period. Images Credits and Sources: https://www.researchgate.net/publication/260757717_A_Diminutive_New_Tyrannosaur_from_the_Top_of_the_World Fiorillo, A. R., and Gangloff, R. A., 2001. Theropod teeth from the Prince Creek Formation (Cretaceous) of northern Alaska, with speculations on Arctic dinosaur paleoecology. Journal of Vertebrate Paleontology. 20(4):675-682 Image Credit: Artist Nathan Rogers Image Source: https://www.artstation.com/artwork/Z5w900 The question I have is why this is? Did anything major happen to the habitat of the Prince Creek Formation between the Early-Late Maastrichtian? Did Nanuqusaurus live up to 66 Million Years ago to the latest Maastrichtian of the Cretaceous period?
  2. ThePhysicist

    Juvenile T. rex

    From the album: Hell Creek / Lance Formations

    Tyrannosaurus rex Hell Creek Fm., Garfield Co., MT, USA This is from the right maxilla of a juvenile individual (note the lingual wear). Art by RJ Palmer
  3. Perhaps one of the most exciting scientific papers in a while about the genetic diversity of the Tyrannosaurid genus Tyrannosarus itself (the genus that includes the famous and well documented T-rex) was just announced and published (or at least the abstract of it)!!! Image Credit: Dalman et al. 2023 (abstract) and the Society for Vertebrate Paleontology (SVP). https://vertpaleo.org/wp-content/uploads/2023/10/2023_SVP_Program-Final-10032023.pdf At the Society for Vertebrate Paleontology's annual meeting for 2023, Paleontologists Dr. Sebastian Dalman, Dr. Philip J. Currie, and seven other experienced Paleontologists and experts on the Tyrannosaurid theropod dinosaurs published an abstract on October 21, 2023 about a new species of Tyrannosaurus (Tyrannosaurus mcraensis) from the Hall Lake Formation dating 72 Million Years ago to the Campanian-Maastrichtian Cretaceous of what is now New Mexico!!! This not only gives insights on the origins of the genus Tyrannosaurus, but validates previous hypothesis over the years (at least since 2013) that a unique giant Tyrannosaur from southern Larmidia (now Western North America) that lived during the Campanian-Maastrichtian Cretaceous!!! Names given to this animal over the years include Alamotyrannus brinkmani and Tyrannosaurus brinkmani. A Digital Reconstruction of the Tyrannosaurus species Tyrannosaurus mcraensis and it's size compared to an average Human, April 2022. Image Credit: Artist LancianIdolatry https://twitter.com/LancianIdolatry/status/1511016414252978182 This is especially true given for how long the debate has been raging on the Validity ofThe species Tyrannosaurus mcraensis was when fully grown the same size of the averaged size adults of the later Tyrannosaurus rex from the later Maastrichtian Cretaceous. By the look of things with the Paper and the experienced paleontologists and Tyrannosaur experts who authored it, it seems just by looking at its abstract it will be be far more through and accurate than the recent Gregory S. Paul Paper from 2022 and maybe even prove the validity of the debate Tyrannosaur species Tyrannosaurus vannus from the 70-66 Million Years ago dated Javelina Formation of what is now Texas. But I'm wondering if anyone has more information on this study and the potential of it's results?
  4. Jonathan Raymond

    My T-rex tooth

    Here's my young T-rex tooth. Species : Tyrannosaurus rex Formation : Hell Creek Place : Powder River County , Montana Age : 66 million years Tooth size: 1,05 inches
  5. dongmin

    ankylosaurus fossil

    This fossil is called an Ankylosaurus scoot scute armor plate discovered in the Hell Creek Formation. I don't know which part of Ankylosaurus this fossil refers to, but I would appreciate it if you could tell me which part of Ankylosaurus it refers to! I'm sorry I posted it wrong before so I'm uploading it again.
  6. Fellow members, I am considering purchasing this tooth which is advertised as being a T. rex tooth from the HCF of Carter Co., MT. The seller isn’t able to provide the nearest town. The enamel isn’t perfect but I am guessing that much of the value will be in the length. I am told that there is no repair nor restoration - can anyone see any evidence that might suggest otherwise? The description also states that there is some partial root present. From research, it seems to be an average specimen as is typically found. Or perhaps somewhat above average given that most teeth found are in a worse state. Might members agree that this is a nice 2” T. rex tooth (albeit with some enamel missing) at this price point. There are better out there but those perfect examples will be well north of much more, one suspects. Thankyou in advance.
  7. Frightmares

    Tyrannosaurus rex tooth

    From the album: Dinosaur Teeth

    Tyrannosaurus rex tooth from Hell Creek Formation, South Dakota.
  8. Frightmares

    IMG_6630.jpeg

    From the album: Dinosaur Teeth

  9. Tyrannosaurus rex (Osborn, 1905) Late Cretaceous, c. 67 Ma Hell Creek Formation, Isabel, Dewey Co., South Dakota, USA. It has been a dream since childhood to own a Tyrannosaurus rex tooth and my dream came true with this recent acquisition of a gorgeous T. rex 1.5” dentary tooth.
  10. ThePhysicist

    Juvenile Tyrannosaurus rex Tooth

    Identification Though smaller than many imagine T. rex teeth to be, this is indisputably one. It is characteristically robust, and has chisel-shaped denticles with similar denticle densities on each carina.1 Those qualities support its identification as a Tyrannosaurid, and with the locality information confirming it originated from the Hell Creek formation, this must be T. rex. Comments Like most isolated theropod teeth, this is a shed tooth, likely lost during feeding.2 This specimen has exquisite preservation with the enamel texture sharply retained as in life. It however has minor weathering with possible feeding wear at the tip, light root etching, and the base of the tooth has been lightly smoothed possibly by tumbling in an ancient river (enamel is harder so it wouldn't have weathered as much as other portions of the tooth). References 1. Smith, Joshua B. “Heterodonty in Tyrannosaurus Rex: Implications for the Taxonomic and Systematic Utility of Theropod Dentitions.” Journal of Vertebrate Paleontology, vol. 25, no. 4, 2005, pp. 865–87. JSTOR, http://www.jstor.org/stable/4524513. 2. Fiorillo, Anthony R., and Philip J. Currie. “Theropod Teeth from the Judith River Formation (Upper Cretaceous) of South-Central Montana.” Journal of Vertebrate Paleontology, vol. 14, no. 1, 1994, pp. 74–80. JSTOR, http://www.jstor.org/stable/4523546.
  11. Hi TFF friends, how are you? After reading, Caleb M. Brown, Philip J. Currie, and Francois Therrien, Intraspecific facial bite marks in tyrannosaurids provide insight into sexual maturity and evolution of bird-like intersexual display I decided to see if our Tyrannosaurus rex replicas (MOR 555) had any visible facial bite marks. I noticed it had 2 big scars, one on the maxilla and one on the dentary. Does anyone know if they are actually Intraspecific bite marks (MOR 555 is not cited among the Tyrannosaurus rex studied for the previously cited study)? Thank you ?
  12. As a freshmen in College, I did a little extra credit report for my geology class about a controversial topic - Tyrannosauroidea diversity in the Southern Hemisphere during the Jurassic-Early Late Cretaceous periods. I was quite surprised at the amount of specimens I found. This diversity likely was the result of an early spread of the early tyrannosaur group Pantyrannosauria into Africa, Eurasia, and North America during the Jurassic and diversified once the land connecting these continents spread out more. Most of these species lived during the Early Cretaceous, though one or two exceptions might have lasted into the Early Late Cretaceous. I've created a list of known of the species and specimens which I would like to share on the forum (let me if there are any examples I'm missing or should add): South America Santanaraptor (Romualdo Member of the Santana Formation) (Early Albian, Cretaceous period 112.6-109.0 million years ago) Specimen: MN 4802-V (partial skeleton) http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&collection_no=67712 Tyrannosauroidea indet. (Rio do Peixe Group of the Sousa Formation) (Berriasian to the Berriasian, Cretaceous period 145.5-130.0 million years ago) Specimen: NA http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&collection_no=58791 https://www.researchgate.net/publication/309717524_As_localidades_com_rastros_fosseis_de_Tetrapodes_na_America_Latina Tyrannosauroidea indet. (Serra da Galga Member of Marília Formation) (Late Maastrichtian, Cretaceous Period, 70.0-66.0 million years ago) Specimen: CPP 449 (partial tooth) https://www.researchgate.net/publication/270524259_Theropod_teeth_from_the_Marilia_Formation_late_Maastrichtian_at_the_paleontological_site_of_Peiropolis_in_Minas_Gerais_State_Brazil (above paper initially described specimen, identification as possible Tyrannosauroidea in science direct paper) https://www.sciencedirect.com/science/article/abs/pii/S0031018220303151 Africa (Madagascar) Tyrannosauroidea indet. (Isalo Illb Formation) (Bathonian, Jurassic period 167.7-164.7 million years ago) Specimen: MSNM V5819 (partial tooth) http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&collection_no=55391 https://www.researchgate.net/publication/257651210_First_description_of_theropod_remains_from_the_Middle_Jurassic_Bathonian_of_Madagascar Australia Timimus hermani (Otway Group of Eumeralla Formation) (Late Aptian, Cretaceous period 122.5-109.0 million years ago) Specimens: NMV P186303 (limb: left femur), NMV P186323 (limb: left femur of juvenile individual), QM F34621 (Pedal phalanx III-1) http://www.paleofile.com/Dinosaurs/Theropods/Timimus.asp http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=57099 Tyrannosauroidea indet. (Otway Group of Eumeralla Formation) (Late Aptian, Cretaceous period 110.0 million years ago) Specimen: NMV P186069 (Pubis bone) Possible Specimen: ?NMV P186046 (Pubis bone) https://www.researchgate.net/publication/42589187_A_Southern_Tyrant_Reptile https://www.sciencedaily.com/releases/2010/03/100325143045.htm
  13. Tyrannosauridae Dinosaur diversity was unique in the Western and Eastern areas of the North American Continent during the Late Cretaceous era around 95-66 Million Years ago) as a result of a seaway the cut the continent in two (creating the continents of Laramidia (now Western North America) and Appalachia (now Eastern North America)). By the Maastrichtian stage of the Cretaceous 68 Million Years ago, the seaway decreased in size and a land bride formed between Laramidia and Appalachia. https://deeptimemaps.com/western-interior-seaway/ This is around the same time Tyrannosaurus rex emerged in Laramida and other Tyrannosauridae including the smaller Dryptosaurus lived in Appalachia. Map of the currently known Tyrannosaurus rex fossil discovery sites Maps of the currently known Maastricthian Tyrannosauridae fossil discovery sites in Eastern North America (not shown on the maps here are Late Cretaceous Tyrannosauridae fossil sites in South Carolina and North Carolina) https://paleobiodb.org/navigator/ What I'm wondering is even with this land bridge formed, what prevented Tyrannosaurus from colonizing the Eastern portion of North America during the Maastricthian Cretaceous? If it didn't prevent this, has there been any fossils found in the Eastern portion of North America that belong to the Tyrannosauridae genus Tyrannosaurus?
  14. The_bro87

    Dromeosaur or Tyrannosaur tooth?

    Hello! I’ve had this tooth for a while now and always labeled it as nannotyrannus, since that’s what I bought it as. It’s about .8” long, supposed to be from the Hell Creek formation but no other locality was listed, so I understand an ID might not be 100%. I was just wondering broadly if it was a tryannosaur or dromeosaur tooth. At first I thought tyrannosaur because it’s kind of thick for its size and has large serrations. It also looks like it has “pinching” on only the right side in the base picture which made me think it was a nanno tooth specifically. Then I saw a picture posted on the forum of a similar sized tooth with the same profile listed as dromeosaur. Any help would be appreciated thanks!
  15. Recently acquired this beautiful T. rex tooth, just over 5cm / 2” length. Such teeth are typically dark brown / mahogany coloured but this specimen appears to have escaped the usual staining. The location of find (Hell Creek Fmn, nr. Mosby, Garfield Co., Montana, USA), basal rectangular cross section and thicker enamel supports identification that this is a Tyrannosaurus rex maxillary tooth. The fact that the whitish / pale colouration is consistent throughout, absence of pitting / “dried out” appearance / absence of splintering would seem to preclude sun-bleaching.
  16. Jonathan Raymond

    T-rex tooth or Nanotyrannus tooth ?

    Hello everyone ! I bought this Tyrannosaur tooth and the seller told me it was either a Tyrannosaurus rex or a Nanotyrannus. Can you tell me if it's a T-rex or a Nanotyrannus ? It's a premaxillary tooth. It comes from Hell Creek formation in South Dakota.
  17. I've recently found a, how do I say...quite unusual Theropod dinosaur tooth from the Late Cretaceous Hell Creek Formation (67-66.0 Million Years ago). The paper, titled The occurrences of vertebrate fossils in the Deadhorse Coulee Member of the Milk River Formation and their implications for provincialism and evolution in the Santonian (Late Cretaceous) of North America by Derek Williams Larson, is a record of theropod teeth from various Late Cretaceous formations in Western North America, and buried on page 244 of the report an apparent megalosauridae tooth (UCMP120305) from the Hell Creek Formation (67-66.0 Million Years ago). https://era.library.ualberta.ca/items/54e305be-de2a-4529-adc9-4e6b038ae699/view/28ba15f8-8131-44be-b48f-e4e9648db26e/Larson_Derek_Fall_2010.pdf This for me is pretty unusual as Megalosauridae (as far as we know) lived only between the Middle-Late Jurassic (170-145 Million Years ago), millions of years before the Maastrichtian Cretaceous. I know in the past many theropod dinosaurs were described as species of "Megalosaurus", but that was more around the 1800-early 1900s and the citation for the tooth lists its apparent phylogenetic description as recently as 2008. There was also another less confusing but fascinating description of a Dromaeosauridae tooth (UALVP48462) from the Milk River Formation, which apparently has a tooth crown height of 17.3mm. But besides the pretty fascinating Milk River Dromeosauridae tooth, I'm puzzled about the UCMP120305 specimen! I really skeptical this tooth specimen belongs to megalosauridae. But if it's not, then where could the classification of the specimen have come from? What do you guys think?
  18. Along with an interest in Pennsylvanian fish diversity, I've also had an interest (like many others studying Paleontology) in the diversity of Dinosaur genera during the Cretaceous era (particularly the Theropod diversity in North America during the Maastrichtian period 72.1-66 Million years ago). Compared to the preceding Campanian period (83.6-72.1 Million years ago), I've noticed there is a slightly less number of known Tyannosauridae genera in Western North America (at the time a separate continent known as Laramidia). I've come up with a list of confirmed known and possible Tyrannosauridae genera during the Maastrichtian period in Western North America and Eastern North America. Eastern North America (at the time a separate continent known as Appalachia) Dryptosaurus Donoho Creek Formation Tyrannosauridae genera (possibly Appalachiosaurus) https://palaeo-electronica.org/content/2018/2123-appalachia-biogeography Chronister well (Ripley Formation) Tyrannosauridae genera http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=38606&max_interval=Cretaceous&country=United States&state=Missouri&is_real_user=1&basic=yes&type=view&match_subgenera=1 Western North America (Laramidia) Tyrannosaurus Rex Nanuqsaurus (Prince Creek Formation) Albertosaurus (more early Maastrichtian to around 68 Million Years ago) ?"Alamotyrannus" (could also be a species of Tyrannosaurus - ?Tyrannosaurus brinkmani) ?"Daspletosaurus sp. (Horseshoe Canyon Formation) (specimen CMN 11315) (more early Maastrichtian to around 68 Million Years ago) https://cdnsciencepub.com/doi/10.1139/cjes-2014-0072 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7079176/ I'm wondering if this is an accurate list, why is there a dip in Tyrannosauridae diversity in Eastern and Western North America after the Campanian (was it a result of the Deccan Volcanic eruptions in India around the same time, at least for Western North America (if this theory is current) the Native Western North American Tyrannosaur genera being outcompeted by the Eurasian ancestors of Tyrannosaurus Rex arriving in North America via a land bridge during the late Campanian Early Maastrichtian, or both), the status on the taxonomic validity of Alamotyrannus, was Nanuqusaurus present during the later part of the Maastrichtian, and did Albertosaurus and Tyrannosaurus Rex ever come into direct contact with one another?
  19. Something that has been baffling me for a while is the fate of the European genera of Tyrannosauridae after the Mid Cretaceous. Multiple Tyrannosauridae genera including Proceratosaurus (Tyrannosauridae, England, Great Britain, Middle Jurassic (166 Million Years ago): ironically one of the earliest known Tyrannosauridae from the fossil record currently known), Eotyrannus (Tyrannosauridae, Wessex Formation, Isle of Wight, Early Cretaceous (136.4-125.45 Million Years ago)) and an unnamed Tyrannosauridae genera from Germany (Early Cretaceous (130.0-122.5 Million Years ago)) are known from Mesozoic deposits in Europe dating from the Middle Jurassic up to the Early Cretaceous. Holtz, Thomas (December 1998). "A new phylogeny of the carnivorous dinosaurs". Gaia. 15: 5–61. https://www.geol.umd.edu/~tholtz/gaiaphyl.pdf Hutt, Stephen & Naish, Darren & Martill, David & Barker, Michael & Newbery, Penny. (2001). A preliminary account of a new tyrannosauroid theropod from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research. 22. 227-242. 10.1006/cres.2001.0252. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=242e6d5f962a143900f3c8d2ff5eb20d6fe7482b K.-P. Lanser and U. Heinhofer. (2015). Evidence of theropod dinosaurs from a Lower Cretaceous karst filling in the northern Sauerland (Rhenish Massif, Germany). Palaeontologische Zeitschrift 89:79-94 https://www.semanticscholar.org/paper/Evidence-of-theropod-dinosaurs-from-a-Lower-karst-Lanser-Heimhofer/94860c34dedf8ac6d65759af9725ae76402eef59 But by the Late Cretaceous around 70-66 Million Years ago, they are absent from the fossil record in the region. Instead, the top predators of the region at the time seem to be Abelisaurs and large pterosaurs. Isasmendi, Erik & Torices, Angelica & Canudo, José & Currie, Philip & Pereda Suberbiola, Xabier. (2022). Upper Cretaceous European theropod palaeobiodiversity, palaeobiogeography and the intra‐Maastrichtian faunal turnover: new contributions from the Iberian fossil site of Laño. Papers in Palaeontology. 8. 10.1002/spp2.1419. https://onlinelibrary.wiley.com/doi/full/10.1002/spp2.1419 I’m curious on what could have caused this faunal turnover (especially since that between the Ealy Cretaceous (at the time of the known records of Tyrannosauridae from Europe) and the Late Cretaceous, Europe was basically a series of islands) or if they were still present in Europe during the Late Cretaceous and specimens have yet to be found or properly categorized? What do you guys think?
  20. The two most prominent hypothesizes on the direct evolutionary origin of perhaps the most famous Theropod Dinosaur from the fossil record, Tyrannosaurus Rex (Tyrannosauridae, Late Cretaceous (68-66 Million Years ago)) are what I call the Laramidia and Asian Origins. The Laramidia origin (named after the region of the Western North America which was a separate Continent during most of the Late Cretaceous and home to a vast amount of dinosaurs including Tyrannosaurus rex) hypothesizes that Tyrannosaurus rex is the direct descendent of and evolved from slightly older North American Tyrannosaurids like Daspletosaurus (Tyrannosauridae, Late Cretaceous (79.5-74 Million Years ago)). Warshaw, Elías & Fowler, Denver. (2022). A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana. PeerJ. 10. e14461. 10.7717/peerj.14461. https://www.researchgate.net/publication/365746599_A_transitional_species_of_Daspletosaurus_Russell_1970_from_the_Judith_River_Formation_of_eastern_Montana The Asian origin hypothesizes that Tyrannosaurus’s direct ancestor was a Tyrannosaurid from Asia. This supported by how closely related the Asian Tyrannosaurid Tarbosaurus (Tyrannosauridae, Late Cretaceous (70 Million Years ago)). This hypothesis further elaborates that a that the Asian Tyrannosaurids arrived in Western North America via a land bridge between what is now Eastern Russia and Alaska around 73-72 Million Years ago. On arrival, theses Asian Tyrannosaurids outcompeted and caused the extinction of most of the Native Tyrannosaur species of Laramidia (including Albertosaurus (Tyrannosaurid, Late Cretaceous (71-68 Million Years ago)), creating conditions allowing for the emergence of the genus Tyrannosaurus. Brusatte, Stephen & Carr, Thomas. (2016). The phylogeny and evolutionary history of tyrannosauroid dinosaurs. Scientific Reports. 6. 20252. 10.1038/srep20252. https://www.nature.com/articles/srep20252 Takasaki R, Fiorillo AR, Tykoski RS, Kobayashi Y (2020) Re-examination of the cranial osteology of the Arctic Alaskan hadrosaurine with implications for its taxonomic status. PLoS ONE 15(5): e0232410. https://doi.org/10.1371/journal.pone.0232410 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0232410 Both hypotheses have points that are supported by the fossil record, but still don’t fill all the gaps in answering the question of the direct origin of the genus Tyrannosaurus. There is however another hypothesis I have pondered over for at least the past few months which could fill in some (if not all) the gaps to this question. It is the Hybrid Speciation Origin hypothesis. The Hybrid Speciation Origin hypothesis basically states that after a land bridge formed between Eurasia and Laramidia during the Late Campanian stage of the Cretaceous (73-72 Million Years ago) and the Asian Tyrannosaurids arrived in Laramidia, certain individuals of a Asian Tyrannosaurid genus breed with a species of a genus of Native Laramidia Tyrannosaurid (likely a direct descendent of Daspletosaurus). Enough of these inter-genus breeding events occurred that a new Tyrannosaurid genus distinct from its parent species (and genuses) emerged around 68 Million Years ago, Tyrannosaurus. I will admit this would be extremely difficult to prove, but I do believe it could be a valid hypothesis. It corroborates the many similarities in skeletal structure Tyrannosaurus shares (and how closely related it is phylogenetically) with the Asian Tyrannosaurid Tarbosaurus and the skeletal structure similarities and general body shape it shares with Daspletosaurus. Image Credit: https://www.nature.com/articles/srep20252 Brusatte, Stephen & Carr, Thomas. (2016). The phylogeny and evolutionary history of tyrannosauroid dinosaurs. Scientific Reports. 6. 20252. 10.1038/srep20252. https://www.nature.com/articles/srep20252 Warshaw, Elías & Fowler, Denver. (2022). A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana. PeerJ. 10. e14461. 10.7717/peerj.14461. https://www.researchgate.net/publication/365746599_A_transitional_species_of_Daspletosaurus_Russell_1970_from_the_Judith_River_Formation_of_eastern_Montana Stein, Walter W.; Triebold, Michael (2013). "Preliminary Analysis of a Sub-adult Tyrannosaurid Skeleton from the Judith River Formation of Petroleum County, Montana". In J. Michael Parrish; Ralph E. Molnar; Philip J. Currie; Eva B. Koppelhus (eds.). Tyrannosaurid Paleobiology. Bloomington: Indiana University Press. pp. 55–77. Currie, P.J. (2003). Cranial anatomy of tyrannosaurid dinosaurs from the Late Cretaceous of Alberta, Canada. Acta Palaeontologica Polonica 48 (2): pp. 191–226. https://www.app.pan.pl/archive/published/app48/app48-191.pdf I am interested in how the tyrannosaurid species Nanuqusaurus (Tyrannosaurid, Late Cretaceous (70-68 (likely also to 66) Million years ago), the Daspletosaur Tyrannosaurid specimen RMDRC 2002.MT-001 “Sir William”, and the Tyrannosaurid specimen CM 9401 could factor into the validity of the hybrid speciation hypothesis. I hold no illusions in thinking this hypothesis is not going to be controversial. But I do think it could be semi plausible. What do you guys think?
  21. ThePhysicist

    Juvenile T. rex tooth

    From the album: Hell Creek / Lance Formations

    Interesting blue color near the base, and some feeding wear at the tip of this immature Tyrannosaurid tooth.
  22. Hello, I was doing a study on the T. rex and Nanotyrannus teeth specimens I had, and I wanted to compare them against a list of known T. rex teeth with measurement. The paper: Dental Morphology and Variation in Theropod Dinosaurs: Implications for the Taxonomic Identification of Isolated Teeth (JOSHUA B. SMITH, DAVID R. VANN, AND PETER DODSON) contains a list of 115 T. rex teeth. To make it easier to compare and read the data, I combined the measurements into a single chart, added colors and lines for ease of reading, and added the size and names of the T. rex used in the study Feel free to refer to the below chart for T. rex teeth measurements. I had to split the chart into 2 due to size limitations, but if you want the full-sized PDF version (25 MB), please message me so I can send it to you by email. If you have any suggestions to improve readability, or have your own data to add, go ahead and post it here! I will be posting pics and measurements of my various T. rex and Nanotyrannus teeth here @Troodon
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