# Were Tyrannosaurus Rex's forearms useless? **URL:** \ **Category:** Factual Questions\ **Created:** [April 7, 2015, 4:22am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020 "2015-04-07T04:22:29Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Tron](https://avatars.discourse-cdn.com/v4/letter/t/3da27b/32.png) [@Tron](https://boards.straightdope.com/u/Tron)\ **Post date:** [April 7, 2015, 4:22am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/1 "2015-04-07T04:22:29Z")
It seems this question must have been asked before but I can find no reference to it. Were Tyrannosaurus Rex’s forearms useless? I’ve seen reports running the gamut from useless to useful for holding up dinner. What’s the consensus? ---
**Author:** ![Lanzy](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@Lanzy](https://boards.straightdope.com/u/Lanzy)\ **Post date:** [April 7, 2015, 5:04am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/2 "2015-04-07T05:04:56Z")
They were small relative to its body but overall not so small. I just thought they would have to lean way over to pick something up. ---
**Author:** ![jimbuff314](https://avatars.discourse-cdn.com/v4/letter/j/c57346/32.png) [@jimbuff314](https://boards.straightdope.com/u/jimbuff314)\ **Post date:** [April 7, 2015, 6:15am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/3 "2015-04-07T06:15:30Z")
From the [Wiki](http://en.wikipedia.org/wiki/Tyrannosaurus#Arms) : > [@](#): > > Tyrannosaurus rex arms are very small relative to overall body size, measuring only 1 metre (3.3 ft) long, and some scholars have labelled them as vestigial. However, the bones show large areas for muscle attachment, indicating considerable strength. This was recognized as early as 1906 by Osborn, who speculated that the forelimbs may have been used to grasp a mate during copulation.[70] It has also been suggested that the forelimbs were used to assist the animal in rising from a prone position.[63] > […] > Another possibility is that the forelimbs held struggling prey while it was killed by the tyrannosaur’s enormous jaws. This hypothesis may be supported by biomechanical analysis. Tyrannosaurus rex forelimb bones exhibit extremely thick cortical bone, which have been interpreted as evidence that they were developed to withstand heavy loads. The biceps brachii muscle of a full-grown Tyrannosaurus rex was capable of lifting 199 kilograms (439 lb) by itself; other muscles such as the brachialis would work along with the biceps to make elbow flexion even more powerful. The M. biceps muscle of T. rex was 3.5 times as powerful as the human equivalent. A Tyrannosaurus rex forearm had a limited range of motion, with the shoulder and elbow joints allowing only 40 and 45 degrees of motion, respectively. In contrast, the same two joints in Deinonychus allow up to 88 and 130 degrees of motion, respectively, while a human arm can rotate 360 degrees at the shoulder and move through 165 degrees at the elbow. The heavy build of the arm bones, strength of the muscles, and limited range of motion may indicate a system evolved to hold fast despite the stresses of a struggling prey animal. So, used in getting up, getting on and getting fed. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [April 7, 2015, 8:52am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/4 "2015-04-07T08:52:53Z")
> [@jimbuff314](#): > > From the [Wiki](http://en.wikipedia.org/wiki/Tyrannosaurus#Arms) : > > So, used in getting up, getting on and getting fed. How can we eat, why do we eat, where shall we have lunch? ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [April 7, 2015, 1:00pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/5 "2015-04-07T13:00:04Z")
> [@jimbuff314](#): > > From the [Wiki](http://en.wikipedia.org/wiki/Tyrannosaurus#Arms) : > > So, used in getting up, getting on and getting fed. I had a brainwave where I speculated that juvenile T rexes had a longer relative arm length, and caught prey actively, whereas the adults mostly took prey from every carnivore, including smaller rexes. Not borne out by facts, though. ☹ I have to say, I still feel that all these large theropods look alike to me, and all seem to have small forelimbs. T Rex doesn’t stand out as SO unusual, to me. This last statement is also apparently untrue, according to dinosaurologists on SDMB. ☹ Two strikes, but still at bat. Anyone want to weigh in on what percentage of a large T rex’s diet was found already dead? Without denying the capbaility of a large top predator to catch and kill prey, I still think it would be easier just to take what you want, when no-one could deny you. ---
**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:** [April 7, 2015, 1:02pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/6 "2015-04-07T13:02:42Z")
I have no idea how plausible this is, but [here](http://www.livescience.com/24293-tyrannosaurus-eat-triceratops.html) is how some speculate T. Rex ate Triceratops. (And it ain’t pretty.) ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [April 7, 2015, 3:58pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/7 "2015-04-07T15:58:36Z")
> [@jimbuff314](#): > > From the [Wiki](http://en.wikipedia.org/wiki/Tyrannosaurus#Arms) : > > So, used in getting up, getting on and getting fed. They were terrible bowlers though. ---
**Author:** ![velomont](https://avatars.discourse-cdn.com/v4/letter/v/8491ac/32.png) [@velomont](https://boards.straightdope.com/u/velomont)\ **Post date:** [April 7, 2015, 5:57pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/8 "2015-04-07T17:57:03Z")
The tragic irony about the whole thing is that their arms could have been much more developed had T-Rexes had the self-discipline to do push-ups on a regular basis; but sadly, their snouts were too big to allow it and they went extinct as a result:) ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [April 7, 2015, 7:10pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/9 "2015-04-07T19:10:00Z")
> [@velomont](#): > > The tragic irony about the whole thing is that their arms could have been much more developed had T-Rexes had the self-discipline to do push-ups on a regular basis; but sadly, their snouts were too big to allow it and they went extinct as a result:) This is not nearly as ironic as the sabre-tooth tiger issue, where their teeth grew too large to permit them to eat. 🙂 ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [April 7, 2015, 7:25pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/10 "2015-04-07T19:25:16Z")
Or the sailback dinosaur, whose sails grew too big and the kept being blown over in a stiff wind. ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [April 7, 2015, 7:27pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/11 "2015-04-07T19:27:08Z")
> [@Blue\_Blistering\_Barnacle](#): > > This is not nearly as ironic as the sabre-tooth tiger issue, where their teeth grew too large to permit them to eat. 🙂 Also ironic - the way human beings became so distrusting of variations in others of the same species, e.g. darker ones, those that had different languages, etc., that they warred against each other and became extinct, too. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [April 7, 2015, 8:15pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/12 "2015-04-07T20:15:31Z")
T. Rex could have used those diminutive appendages for finely detailed work such as assembling watch crystals, leading to further cognitive development and eventually becoming the intellectual powerhouses and master species of the planet. But no, they chose instead to use their raw brute force to make a living, crudely chomping on anyone else they felt like eating, and look where that got them. Let that be a moral for the children! ---
**Author:** ![Nonsuch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nonsuch/32/2922_2.png) [@Nonsuch](https://boards.straightdope.com/u/Nonsuch)\ **Post date:** [April 7, 2015, 8:29pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/13 "2015-04-07T20:29:15Z")
A long time ago, David Letterman did a week where he had a T. Rex skull (on loan from a museum) as part of his set. On the last night of the week, they allowed the skull to do a “monologue” in voice over, and one of the things it said was, “That business about my front arms being useless is a load of crap!” ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 7, 2015, 8:38pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/14 "2015-04-07T20:38:42Z")
Hi **Tron**. Welcome to SD. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 7, 2015, 8:42pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/15 "2015-04-07T20:42:16Z")
This is as good a place as any to spread the news that the Brontosaurus is back. _Yo, bitch, never left._ If only I could go back in the past and tell off my oh-so-smart 10 year old nephews to go stuff it with their oh-so-smart corrections to my adult wisdom. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [April 7, 2015, 8:50pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/16 "2015-04-07T20:50:20Z")
> [@CC](#): > > Also ironic - the way human beings became so distrusting of variations in others of the same species, e.g. darker ones, those that had different languages, etc., that they warred against each other and became extinct, too. NOT FUNNY! NOT IRONIC! COMPLETLY DIFFERENT! > **[Saturday Morning Breakfast Cereal - Meaning](https://www.smbc-comics.com/index.php?id=3491)** > > Saturday Morning Breakfast Cereal - Meaning ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [April 7, 2015, 8:58pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/17 "2015-04-07T20:58:08Z")
> [@velomont](#): > > The tragic irony about the whole thing is that their arms could have been much more developed had T-Rexes had the self-discipline to do push-ups on a regular basis; but sadly, their snouts were too big to allow it and they went extinct as a result:) _tap_ _tap_ Look up, ain’t no arms gonna save you from that. ---
**Author:** ![Roderick\_Femm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/roderick_femm/32/14875_2.png) [@Roderick\_Femm](https://boards.straightdope.com/u/Roderick_Femm)\ **Post date:** [April 7, 2015, 10:50pm UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/18 "2015-04-07T22:50:12Z")
Obligatory [clip](https://www.youtube.com/watch?v=3LVXjB_VUfk). ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [April 8, 2015, 12:02am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/19 "2015-04-08T00:02:38Z")
> [@Blue\_Blistering\_Barnacle](#): > > NOT FUNNY! NOT IRONIC! COMPLETLY DIFFERENT! > > [Saturday Morning Breakfast Cereal - Meaning](http://www.smbc-comics.com/index.php?id=3491) I wonder what you are trying to say. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [April 8, 2015, 12:11am UTC](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020/20 "2015-04-08T00:11:08Z")
> [@CC](#): > > I wonder what you are trying to say. Merely trying to be funny. Never mind. [Next page](https://boards.straightdope.com/t/were-tyrannosaurus-rexs-forearms-useless/717020.md?page=2)