How the T-Rex Lost Its Arms

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  • Published on:  Tuesday, June 26, 2018
  • Support us on Patreon! rex was big, Tyrannosaurus rex was vicious, and Tyrannosaurus rex had tiny arms. The story of how T-Rex lost its arms is, itself, pretty simple. But the story of why it kept those little limbs, and how it used them? Well, that’s a little more complicated.Thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart: in collaboration with PBS Digital Studios: special thanks to the following Patreon patrons for helping make Eons possible:Aldo Espinosa Zúñiga, Svetlana Pylaeva, Colin Sylvester, Philip Slingerland, John Vanek, Jose Garcia, Noah offitzer, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Wilco Verweij, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Addison Baker, Michael McClellan, Elysha Nygård, Jeff Graham, Maria Humphrey, Southpoint, Connor Jensen, Ehit Dinesh Agarwal, Sapjes, Dave, Daisuke Goto, Zachary Winkler, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Mario Morales, Tsee Lee, Sarah Fritts, phil parker, Ruben Winter, Ron Harvey Jr, Joshua Mitchell, Johnny Li, Katie Fichtner, Budjarn Lambeth, Jacob Gerke, Katie M Vasilescu, Brandon Burke, Alex Yan, Jordon SokollWant to follow Eons elsewhere on the internet?Facebook - - -, Matthew G., David B. Norman, and Paul M. Barrett. "A new hypothesis of dinosaur relationships and early dinosaur evolution." Nature 543.7646 (2017): 501. Bates, Karl T., and Peter L. Falkingham. "Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics." Biology Letters (2012): rsbl20120056.Brusatte, Stephen L., and Thomas D. Carr. "The phylogeny and evolutionary history of tyrannosauroid dinosaurs." Scientific Reports 6 (2016): 20252.Burch, Sara. Osteological, Myological, and Phylogenetic Trends of Forelimb Reduction in Nonavian Theropod Dinosaurs. Diss. The Graduate School, Stony Brook University: Stony Brook, NY., 2015.Carpenter, Kenneth. "Forelimb biomechanics of nonavian theropod dinosaurs in predation." Senckenbergiana lethaea 82.1 (2002): 59-75.Erickson, Gregory M., et al. "Bite-force estimation for Tyrannosaurus rex from tooth-marked bones." Nature 382.6593 (1996): 706.Fowler, Denver W., et al. "Reanalysis of “Raptorex kriegsteini”: a juvenile tyrannosaurid dinosaur from Mongolia." PLoS One 6.6 (2011): e21376. Gillingham, James C., and Jeffrey A. Chambers. "Courtship and pelvic spur use in the Burmese python, Python molurus bivittatus." Copeia 1982.1 (1982): 193-196. Gould, Stephen Jay, and Richard C. Lewontin. "The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme." Proc. R. Soc. Lond. B 205.1161 (1979): 581-598.Hutchinson, John R., and Stephen M. Gatesy. "Dinosaur locomotion: beyond the bones." Nature 440.7082 (2006): 292. Makovicky, Peter J. "A new small theropod from the Morrison Formation of Como Bluff, Wyoming." Journal of Vertebrate Paleontology 17.4 (1997): 755-757.MIDDLETON, KEVIN M., and STEPHEN M. GATESY. "Theropod forelimb design and evolution." Zoological Journal of the Linnean Society 128.2 (2000): 149-187.Personal communication, Amy Atwater & Dr. John Scanella, Museum of the RockiesPontzer, Herman, et al. "Control and function of arm swing in human walking and running." Journal of Experimental Biology 212.4 (2009): 523-534.Ruiz, Javier, et al. "The hand structure of Carnotaurus sastrei (Theropoda, Abelisauridae): implications for hand diversity and evolution in abelisaurids." Palaeontology 54.6 (2011): 1271-1277.Sellers, William I., et al. "Investigating the running abilities of Tyrannosaurus rex using stress-constrained multibody dynamic analysis." PeerJ 5 (2017): e3420.Sereno, Paul C., et al. "Tyrannosaurid skeletal design first evolved at small body size." Science 326.5951 (2009): 418-422.Stanley, Steven M. “Evidence that the Arms of Tyrannosaurus rex were not functionless but adapted for vicious slashing.” Geological Society of America Annual Meeting 2017. Sullivan, Corwin, et al. "The asymmetry of the carpal joint and the evolution of wing folding in maniraptoran theropod dinosaurs." Proceedings of the Royal Society of London B: Biological Sciences (2010): rspb20092281.Therrien, François, and Donald M. Henderson. "My theropod is bigger than yours… or not: estimating body size from skull length in theropods." Journal of Vertebrate Paleontology 27.1 (2007): 108-115. [108:MTIBTY]2.0.CO;2USAMI, Yoshiyuki, and Ryuta KINUGASA. "A Possibility of Fast Running of TYRANNOSAURUS." DEStech Transactions on Engineering and Technology Research amma (2017).Xu, Xing, et al. "A basal tyrannosauroid dinosaur from the Late Jurassic of China." Nature 439.7077 (2006): 715.


  • doctorsmoothlove
    doctorsmoothlove  7 months ago +1733

    No joke. I live in the USA and went to a Christian school in the early 90s. My science teacher said that T Rex used its little arms to hold onto trees while eating fruit in the garden of eden. It's teeth were cantaloupe slicers! I thought it was funny and told my parents who withdrew me from the school.

  • Lee YAHwehson
    Lee YAHwehson  10 months ago +567

    The T-rex arms were used for the slap chest mannerism "me T-rex come at me bro".

  • nebulaunfolding
    nebulaunfolding  a years ago +579

    Over millions of years they developed a high level of intelligence. The small 2 fingered arms were used for writing. In this way they could teach their young hunting strategies like a coach would a football team.

  • Frank Tiemens
    Frank Tiemens  28 days ago +260

    ᵉˣᶜᵉᵖᵗ ᶠᵒʳ ᵐʸ ˡᶦᵗᵗˡᵉ ʰᵃⁿᵈˢᵎ

  • Qt_Pieee
    Qt_Pieee  a years ago +715

    The actual reason a t-rex cant give a high five is just because they only had 2 fingers on each hand

  • Timothy Drake x Coffee
    Timothy Drake x Coffee  7 months ago +84

    "T rex what happened to your arms?"
    "I skipped arm day bro....For Like a billion years"

  • Sheila Armenti
    Sheila Armenti  8 months ago +518

    T Rex: grab my hand Son!
    Baby Rex: I can’t reach!
    T rex: NOOOOO!
    Baby Rex: HELPPPP!

  • Elena Lenkova
    Elena Lenkova  5 months ago +146

    I adore the (anatomically correct) t-Rex impersonation 😂👍

  • Biru Merah
    Biru Merah  a years ago +205

    Carnatorus : hold my beer

  • AlternateHistoryHub
    AlternateHistoryHub  a years ago +4487

    They didnt lift

  • SilverFoxUchiha
    SilverFoxUchiha  6 months ago +102

    “Legs and Teeth. THATS ALL WE NEED!”
    Taken from the Memoirs of a T Rex.

  • Beowulf Macbethson
    Beowulf Macbethson  5 months ago +72

    The reason the T Rex had small arms was so that no one could see its hands move when it used the force.

  • Zhivko Vasilev
    Zhivko Vasilev  yesterday +1

    he used his hands to tear the victim's cervical artery

  • thetruthimpart
    thetruthimpart  yesterday +1

    Maybe they are vestigial organs, like in whales, oops, on the wrong end or maybe, like they transformed, into wings, then to birds, where the eater, now can be eaten by everybody, very nice adaption:)This Guy said it went extinct, before it evolved, yet they teach; Every bird living today is a distant relative of Tyrannosaurus rex, the fearsome "king of the dinosaurs"

  • Upcycle Electronics
    Upcycle Electronics  a years ago +1403

    No silly. T-Rex was a cyclist.

  • Armando Durazo Hoyos
    Armando Durazo Hoyos  5 months ago +32

    Me: Hey T-rex, give me a high five.
    T-rex: How about a high two.
    Me: that'll do.

  • suskirk
    suskirk  7 months ago +42

    I love that you use meters and kg. !!!! Subscribed 👍😊

  • cnnrmcllstrnovowels
    cnnrmcllstrnovowels  12 hours ago

    If I woke up one morning in the Cretaceous period and I saw a T-Rex, I wouldn’t be making jokes about his arms lol

  • thetruthimpart
    thetruthimpart  yesterday +1

    Ha Ha! In which none of this is or ever will be, though they will make some fiction about It, i.e. Jurassic park! scientific method - systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses and maybe they will get their method right, in billions of years?

  • ObjectManiacLewis 27
    ObjectManiacLewis 27  7 months ago +38

    Is anyone going to comment about how Hank Green presented this?