# Why did T-Rex have such teeny arms? **URL:** \ **Category:** Factual Questions\ **Created:** [May 16, 2012, 3:15am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058 "2012-05-16T03:15:46Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [May 17, 2012, 5:41pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/61 "2012-05-17T17:41:36Z")
> [@Scumpup](#): > > Would _you_ be willing to arm wrestle with a T-Rex? I didn’t think so. [Already been done](http://www.tyrannosaurfaire.com/). Here comes the science: [Could a Human Beat a T. Rex In Arm Wrestling?](http://www.popsci.com/science/article/2009-10/could-stallone-beat-t-rex-arm-wrestling) ---
**Author:** ![Scumpup](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Scumpup](https://boards.straightdope.com/u/Scumpup)\ **Post date:** [May 17, 2012, 5:45pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/62 "2012-05-17T17:45:41Z")
You’re forgetting something important: T-Rex cheats at arm wrestling and gay chicken. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [May 17, 2012, 6:15pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/63 "2012-05-17T18:15:58Z")
> [@Polycarp](#): > > This is what T. rex was faced with, and he couldn’t bang a gong for help. > [@TriPolar](#): > > A counter-position to **Chronos’** assertion that they used the short arms to get it on. > [@Ludovic](#): > > I see even other species have problems with all their young dudes. Now that’s a series of possibly under-appreciated brilliance. [T. Rex](http://en.wikipedia.org/wiki/T._Rex_%28band%29) [Bang a Gong (Get It On)](http://en.wikipedia.org/wiki/Get_It_On_%28T._Rex_song%29), a song by T. Rex [Mott the Hoople](http://en.wikipedia.org/wiki/Mott_the_Hoople) sang [All the Young Dudes](http://en.wikipedia.org/wiki/All_the_Young_Dudes_%28song%29) which references T. Rex in their lyrics [“Man, I needed TV when I got T. Rex”](http://www.elyrics.net/read/d/david-bowie-lyrics/all-the-young-dudes-lyrics.html) Fucking brilliant. I’d link to the songs on Youtube, but I don’t have sound here and can’t tell if I’d be linking to a dead video. But definitely worth checking out. ---
**Author:** ![Ksnook](https://avatars.discourse-cdn.com/v4/letter/k/ce7236/32.png) [@Ksnook](https://boards.straightdope.com/u/Ksnook)\ **Post date:** [May 18, 2012, 11:46am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/64 "2012-05-18T11:46:56Z")
Right, then. I’m off to The Hundred Acre Wood to ask Kanga, who always has the answers. ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [May 18, 2012, 12:50pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/65 "2012-05-18T12:50:28Z")
> [@njtt](#): > > When I Googled it, the plural was _[Reges](http://www.cyberlatin.net/3rd%20declension%20masculine,%20rex.htm)_. > > If we are considering it to be a word fully adopted into English, rather than Latin, then surely it would be _rexes_. I prefer T’s-Rex, sort of like mothers-in-law. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 18, 2012, 1:05pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/66 "2012-05-18T13:05:18Z")
> [@C\_K\_Dexter\_Haven](#): > > I prefer T’s-Rex, sort of like mothers-in-law. Or attorneys general. ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [May 18, 2012, 2:56pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/67 "2012-05-18T14:56:24Z")
If a T-rex had a grip on prey with it’s mouth, could the arms be used to inflict further damage? Like a cat can rake/claw with it’s legs while holding it’s prey with a bite. I grant that the damage comparison between a cat’s bit and it’s legs make them a bunch more equal than a T-rex bite compared to a T-rex arm gouge, but still… ---
**Author:** ![Corcaigh](https://avatars.discourse-cdn.com/v4/letter/c/eb8c5e/32.png) [@Corcaigh](https://boards.straightdope.com/u/Corcaigh)\ **Post date:** [May 18, 2012, 7:51pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/68 "2012-05-18T19:51:02Z")
> [@Scumpup](#): > > Would _you_ be willing to arm wrestle with a T-Rex? I didn’t think so. Well not me personally, no. I have very weak wrists being a gurl an all! > [@mlees](#): > > If a T-rex had a grip on prey with it’s mouth, could the arms be used to inflict further damage? Or hold live prey still while he chowed down…? ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [May 18, 2012, 10:40pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/69 "2012-05-18T22:40:04Z")
[quote=Son of a Rich;15070621\*what’s the plural of T-rex?[/quote] RUN!!! ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [May 18, 2012, 10:55pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/70 "2012-05-18T22:55:46Z")
> [@drachillix](#): > > RUN!!! I don’t have to run faster than a Tyrannosaur, drachillix. I just have to run faster than you. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [May 18, 2012, 11:54pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/71 "2012-05-18T23:54:19Z")
It could be that _T. rex_’s arms were of more use to juveniles, and of little to no use for adults. Tyrannosaur body proportions changed as they aged, as happens with many animals, and it is suspected that juveniles were, among other traits, more athletic than were the adults. For example, the tyrannosaurus specimen nicknamed [“Jane”](http://en.wikipedia.org/wiki/File:Jane_TRex_Burpee.jpg) is thought to be a juvenile. Note that the arms, while still small, aren’t quite as _comparatively_ tiny as they are in adult rexes. This could explain why the forelimbs appear so useless in adults, but were nevertheless retained. ---
**Author:** ![Lukeinva](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lukeinva/32/17872_2.png) [@Lukeinva](https://boards.straightdope.com/u/Lukeinva)\ **Post date:** [May 19, 2012, 12:01am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/72 "2012-05-19T00:01:59Z")
Perhaps to help care for baby Rex? Such as digging out a nest, etc. ---
**Author:** ![Memoe](https://avatars.discourse-cdn.com/v4/letter/m/6bbea6/32.png) [@Memoe](https://boards.straightdope.com/u/Memoe)\ **Post date:** [May 22, 2012, 4:04am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/73 "2012-05-22T04:04:54Z")
Could they have actually been Caresses, some birds are born with claws on their 1st and 2nd digits today. If they were located farther out on a wing it would make sense as to why the bones are usually found several feet from the actual body. It would explain the shape of the shoulder blade and many other discrepancies in the archeological records. ---
**Author:** ![Autolycus](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@Autolycus](https://boards.straightdope.com/u/Autolycus)\ **Post date:** [May 23, 2012, 1:36am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/74 "2012-05-23T01:36:35Z")
Well duh, how else are they going to pilot the F-14s? ---
**Author:** ![Evil\_Captor](https://avatars.discourse-cdn.com/v4/letter/e/f17d59/32.png) [@Evil\_Captor](https://boards.straightdope.com/u/Evil_Captor)\ **Post date:** [May 26, 2012, 8:08pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/75 "2012-05-26T20:08:00Z")
Actually you guys came VERY CLOSE with your theory that they used their tiny claws to pick their teeth. Tyrannosaurs actually used their tiny forelimbs to pick OTHER dinosaurs’ teeth. They were the cleaner wrasses of the Jurassic ecosystem, according to science1. They would stand in a clearing and all the other dinosaurs would line up to have their teeth cleaned. Scientists theorize2 that the large size and teeth of tyrannosaurs was to terrify other dinosaurs into holding still while their teeth were being cleaned. 1. Bruckner and Feldspar, “Look At The Cool Theory We Just Made Up,” Journal of Irreproducible Results, 2006. 2. Made you look! ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [May 27, 2012, 1:52am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/76 "2012-05-27T01:52:09Z")
Then you have vestigial organs that are selected against and persist without known function. The human appendix has no know function, and until recently those with appendicitis had a great chance of dying, and this often occurred before the age of reproduction. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 27, 2012, 4:54am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/77 "2012-05-27T04:54:11Z")
> [@dauerbach](#): > > Then you have vestigial organs that are selected against and persist without known function. The human appendix has no know function, and until recently those with appendicitis had a great chance of dying, and this often occurred before the age of reproduction. Actually, recent research has found that the appendix does have a[function in the immune system.](http://www.scientificamerican.com/article.cfm?id=what-is-the-function-of-t) It may also serve as a reservoir for beneficial intestinal bacteria. ---
**Author:** ![maconlists](https://avatars.discourse-cdn.com/v4/letter/m/f0a364/32.png) [@maconlists](https://boards.straightdope.com/u/maconlists)\ **Post date:** [February 8, 2013, 11:05pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/78 "2013-02-08T23:05:01Z")
All of the above noted functions for the forelimbs would be better if the forelimbs were bigger. The issue of balance seems unlikely compared to the possibility of having a slightly longer or thicker tail. It has been noted that the trend started in T. Rex smaller feathered ancestral species. Isn’t it more likely that they didn’t evolve smaller arms but actually evolved smaller WINGS (as now seen on flightless birds). I’m sure an ostrich would love to have functional arms if given the choice but you can’t go back. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [February 8, 2013, 11:25pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/79 "2013-02-08T23:25:59Z")
zombie or no it was a sausage eater. ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [February 8, 2013, 11:49pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/80 "2013-02-08T23:49:04Z")
> [@njtt](#): > > When I Googled it, the plural was _[Reges](http://www.cyberlatin.net/3rd%20declension%20masculine,%20rex.htm)_. > > If we are considering it to be a word fully adopted into English, rather than Latin, then surely it would be _rexes_. Not _tyrannosauri rex_? [Previous page](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058.md?page=3) [Next page](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058.md?page=5)