# 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:** 5
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [February 9, 2013, 1:19am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/81 "2013-02-09T01:19:43Z")
T-Rexes used their forelimbs to go Bolan. 😛 ---
**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:** [February 9, 2013, 1:48am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/82 "2013-02-09T01:48:16Z")
> [@maconlists](#): > > Isn’t it more likely that they didn’t evolve smaller arms but actually evolved smaller WINGS (as now seen on flightless birds). No. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [February 9, 2013, 2:11am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/83 "2013-02-09T02:11:10Z")
> [@Elmer\_J.Fudd](#): > > Not _tyrannosauri rex_? Not in English, at least according to the editors at Merriam-Webster. “Tyrannosauruses” or “T. rexes.” ---
**Author:** ![auntlohimein](https://avatars.discourse-cdn.com/v4/letter/a/74df32/32.png) [@auntlohimein](https://boards.straightdope.com/u/auntlohimein)\ **Post date:** [February 9, 2013, 2:12am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/84 "2013-02-09T02:12:06Z")
- Bearded dragons [small lizards from australia], the female ‘waves’ one of her upper legs [arms i guess] to show submission to males! SO- ---
**Author:** ![auntlohimein](https://avatars.discourse-cdn.com/v4/letter/a/74df32/32.png) [@auntlohimein](https://boards.straightdope.com/u/auntlohimein)\ **Post date:** [February 9, 2013, 2:52am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/85 "2013-02-09T02:52:59Z")
to add- - pythons and boa’s have vestigial hips/legs and, external “claws”, i have many times, watched males “stimulating,” scratching females they are trying to mate with, its sometimes hard to believe how far a range of motion these little claws move! Its generally though, but i could be wrong, that the males have larger spurs. So could T-rex “caress” his mates neck? ---
**Author:** ![Grendel\_s\_Father](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grendel\_s\_Father](https://boards.straightdope.com/u/Grendel_s_Father)\ **Post date:** [February 9, 2013, 12:53pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/86 "2013-02-09T12:53:13Z")
> [@Darwins\_Finch](#): > > No. Why not? It’s now known that wings go back at least as far in the dino family tree as ornithomimids, which are only one or two branch up from tyrannosaurs. > **[Ornithomimus had wings...as an adult](http://skeletaldrawing.blogspot.com/2012/10/ornithomimus-had-wingsas-adult.html)** > > A blog about the science and art of reconstructing dinosaurs. If the arms of large tyrannosaurids bore display feathers of some kind, this could partially explain the paradoxical small size plus heavy musculature (perhaps employed in some kind of flapping display?). ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [February 9, 2013, 1:08pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/87 "2013-02-09T13:08:32Z")
> [@tdn](#): > > They were used to play the ukulele. _**The ukulele? THE UKULELE? REALLY?!?**_ Everybody knows T-Rex played the Bassoon. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [February 9, 2013, 2:52pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/88 "2013-02-09T14:52:48Z")
> [@tdn](#): > > They were used to play the ukulele. > [@Bosda\_Di\_Chi\_of\_Tricor](#): > > _**The ukulele? > THE UKULELE? REALLY?!?**_ > Everybody knows T-Rex played the Bassoon. [You’re both wrong!](http://www.youtube.com/watch?v=TVEhDrJzM8E)😃 ---
**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:** [February 9, 2013, 7:44pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/89 "2013-02-09T19:44:24Z")
> [@Grendel\_s\_Father](#): > > Why not? It’s now known that wings go back at least as far in the dino family tree as ornithomimids, which are only one or two branch up from tyrannosaurs. > > [Skeletal Drawing: Ornithomimus had wings...as an adult](http://skeletaldrawing.blogspot.com/2012/10/ornithomimus-had-wingsas-adult.html) > > If the arms of large tyrannosaurids bore display feathers of some kind, this could partially explain the paradoxical small size plus heavy musculature (perhaps employed in some kind of flapping display?). Couple of reasons: 1. The post to which I gave my terse response asked “isn’t it more likely that they…actually evolved smaller WINGS?” That would require wings to already have been present among coelurosaurs, prior to Tyrannosauridae. Possible? Perhaps. But not “more likely”, given our current knowledge of these groups. 2. Feathered forearms do not a wing make, any more than feathers alone make a bird. The time of feathers being a diagnostic character for birds is long gone. Similarly, the definition of “wing” ought to be further refined (note that even the cladogram in the linked Skeletal Drawings blog notes that actual wings don’t appear until about the Paraves clade; Ornithomimids actually had a pennibrachium). Thus, if tyrannosaurs were found to have had feathered forelimbs, they could be also said to have a pennebrachium (contingent on the actual arrangement of these hypothetical feathers), but I wouldn’t say they had actual _wings_. ---
**Author:** ![madsircool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/madsircool/32/3432_2.png) [@madsircool](https://boards.straightdope.com/u/madsircool)\ **Post date:** [February 9, 2013, 8:37pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/90 "2013-02-09T20:37:13Z")
> [@Exapno\_Mapcase](#): > > Would you want to face a T. Rex? If the answer is no, then it doesn’t really matter what its arms were like. They were just fine. I would rather face a T Rex than a mammal predator for the reason that IIRC T Rex had no meylin sheathing on their neurons and their brains were far slower than ours. It would be easy to hide from one. ---
**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:** [February 9, 2013, 11:19pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/91 "2013-02-09T23:19:54Z")
> [@madsircool](#): > > I would rather face a T Rex than a mammal predator for the reason that IIRC T Rex had no meylin sheathing on their neurons and their brains were far slower than ours. It would be easy to hide from one. You mean like we don’t have to worry about snakes and crocodiles and other reptiles, because they are so slow and stupid? Or you could give me a cite that the T Rex had no meylin sheathing on its neurons. ---
**Author:** ![madsircool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/madsircool/32/3432_2.png) [@madsircool](https://boards.straightdope.com/u/madsircool)\ **Post date:** [February 10, 2013, 1:40am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/92 "2013-02-10T01:40:11Z")
> [@Exapno\_Mapcase](#): > > You mean like we don’t have to worry about snakes and crocodiles and other reptiles, because they are so slow and stupid? > > Or you could give me a cite that the T Rex had no meylin sheathing on its neurons. Investigate the work of Nicolai Bernstein ---
**Author:** ![TSBG](https://avatars.discourse-cdn.com/v4/letter/t/77aa72/32.png) [@TSBG](https://boards.straightdope.com/u/TSBG)\ **Post date:** [February 10, 2013, 1:48am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/93 "2013-02-10T01:48:06Z")
That’s not a cite, which is annoying, but in a generous mood I went so far as look at the Wiki for Bernstein. Nothing on T. Rex, or myelin. You need to do better. ---
**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:** [February 10, 2013, 3:44am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/94 "2013-02-10T03:44:47Z")
> [@TSBG](#): > > That’s not a cite, which is annoying, but in a generous mood I went so far as look at the Wiki for Bernstein. Nothing on T. Rex, or myelin. You need to do better. If it’s the same one who comes up first in Google, he died in 1966. And that means I can guarantee you that the sum total of his knowledge of myelin sheathing in T. Rex was exactly equal to that of madsircool. ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [February 10, 2013, 3:53am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/95 "2013-02-10T03:53:32Z")
> [@Palo\_Verde](#): > > Why did T-Rex have such teeny arms? First rule of T-Rex… Don’t talk about the T-Bone. ---
**Author:** ![monkeytail](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@monkeytail](https://boards.straightdope.com/u/monkeytail)\ **Post date:** [February 11, 2013, 6:50am UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/96 "2013-02-11T06:50:01Z")
I think it’s all about utility. I.e: Bigger doesn’t necessarily mean better. The reason T Rex arms were muscular were because the required them strong. The reason they were small were because (Speculative): 1. The center of gravity would’ve shifted forward if they hands were big. 2. They would’ve used their hands to claw and latch prey down rather than feed itself like most creatures do (I mean the nails were pretty big…) 3. (The really embarrassing bit) (Fe)male T Rexs liked small hands… Like how peacocks with large and colourful plumage are mostly chosen over less attractive and smaller ones. In retrospection: They need big a jaw to crunch bones and tear flesh… big legs to run fast and big tail to balance… (Nature gave it to them) But since they were bipeds and the hands weren’t used to handle tools or do other energy demanding jobs… they probably became reduced over time… yet remaining strong enough to ensure that they could be used as a hunting devices for pinning, clawing or tearing… ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 11, 2013, 2:25pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/97 "2013-02-11T14:25:11Z")
[This current thread](http://boards.straightdope.com/sdmb/showthread.php?t=681922) might be relevant. 😛 ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [February 11, 2013, 2:32pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/98 "2013-02-11T14:32:59Z")
> [@Chronos](#): > > One hypothesis I’ve heard is that they used them to hold onto each other for mating. Probably why they were so cranky. It’s hard to cuddle properly with such tiny arms.☹ ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [February 11, 2013, 2:37pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/99 "2013-02-11T14:37:46Z")
> [@madsircool](#): > > I would rather face a T Rex than a mammal predator for the reason that IIRC T Rex had no meylin sheathing on their neurons and their brains were far slower than ours. It would be easy to hide from one. Did the T-Rex challenge it’s prey to a game of Scrabble or something? Who cares how smart it was. I’d rather face a predator that’s not as tall as a building. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 11, 2013, 2:38pm UTC](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058/100 "2013-02-11T14:38:47Z")
> [@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_. > [@C\_K\_Dexter\_Haven](#): > > I prefer T’s-Rex, sort of like mothers-in-law. > [@Elmer\_J.Fudd](#): > > Not _tyrannosauri rex_? So you are thinking of _Rex_ as functioning like an adjective, modifying _tyrannosaurus_? Well, OK, but if (again) we are doing Latin, adjectives need to agree in number (and case) with the nouns they modify - so still _Reges_. 😉 [Previous page](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058.md?page=4) [Next page](https://boards.straightdope.com/t/why-did-t-rex-have-such-teeny-arms/622058.md?page=6)