# If that meteor strike hadn’t killed off the dinosaurs, how would life be different for the human rac **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [October 17, 2013, 4:24pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494 "2013-10-17T16:24:35Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![sweeperpan](https://avatars.discourse-cdn.com/v4/letter/s/e274bd/32.png) [@sweeperpan](https://boards.straightdope.com/u/sweeperpan)\ **Post date:** [October 17, 2013, 4:24pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/1 "2013-10-17T16:24:35Z")
I’d like a reference for dinosaurs being cold blooded, which is alluded to in the answer. Also, the emergence of man was never a foregone conclusion and even the smallest change or event could have resulted in our evolutionary lineage having never existed. I don’t think it would be unreasonable to say that if the extinction event that did away with the dinosaurs hadn’t happened, humans would not exist. ---
**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:** [October 18, 2013, 2:26am UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/2 "2013-10-18T02:26:49Z")
Welcome to the Straight Dope Message Boards, **sweeperpan** , we’re glad you found us. For future ref, when you start a thread based on one of Cecil’s columns, it’s helpful to other readers to provide a link to the column in question. In this case: [If that meteor strike hadn’t killed off the dinosaurs, how would life be different for the human race? - The Straight Dope](http://www.straightdope.com/columns/read/3126/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-race) No biggie, you’ll know for next time, and (as I say) welcome! … and I’ll let someone knowledgable respond to your questions. ---
**Author:** ![TonySinclair](https://avatars.discourse-cdn.com/v4/letter/t/49beb7/32.png) [@TonySinclair](https://boards.straightdope.com/u/TonySinclair)\ **Post date:** [October 19, 2013, 3:09am UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/3 "2013-10-19T03:09:29Z")
I have no info for you, but you might try asking in this thread: > **[If that meteor hadn’t killed off the dinosaurs...](https://boards.straightdope.com/sdmb/showthread.php?t=702190)** > > My understanding is that there is mounting evidence that dinosaurs were actually warm-blooded. Cold-Blooded Dinosaur Theory Put on Ice Not saying the evidence is definitive, but still thought it odd to see this stated in today’s column so... ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [October 28, 2013, 4:43pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/4 "2013-10-28T16:43:13Z")
I just adore the way the title cuts off abruptly, like the snap of a _T. Rex’s_ jaws. Latest suggestion I’ve seen is that dinosaurs may have been _lukewarm_-blooded, so to speak, rather than warm- or cold-blooded. In theory, they would have the advantages of both approaches to body heat, such as the ability to move muscles rapidly even when it’s cook outside while retaining the (relatively) lower food requirements of cold-blooded creatures. [Some citations](https://www.google.com/#q=dinosaurs+lukewarm-blooded) ---
**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:** [October 28, 2013, 7:24pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/5 "2013-10-28T19:24:02Z")
As might be expected for any group spanning 165+ million years, there was likely a diversity of metabolic types over time and across different lineages. It’s unlikely that dinosaurs, as a group, were all “warm-blooded” or all “cold-blooded” or all whatever-blooded. Birds - the living descendants of what most folks consider to be “the dinosaurs” - are endothermic, and they likely inherited that trait from their pre-avian dinosaurian ancestors. The first dinosaurs, way back in the Late Triassic, were probably similar to crocodiles in their metabolism. In between, metabolsms were likely as diverse as the various lineages themselves were. What worked for an _Argentinosaurus_ probably would not have worked for a \*Zuolong/i]. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [October 29, 2013, 5:49pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/6 "2013-10-29T17:49:05Z")
> [@Darwins\_Finch](#): > > As might be expected for any group spanning 165+ million years, there was likely a diversity of metabolic types over time and across different lineages. It’s unlikely that dinosaurs, as a group, were all “warm-blooded” or all “cold-blooded” or all whatever-blooded. OK, my turn to be surprised. Are any other groups of animals that, uh, “heterothermic,” to coin a term? I always thought all mammals were warm-blooded, all birds warm-blooded, all amphibians cold-blooded, and so forth. Would metabolic rates really be likely to have varied so wildly within dinosauria? ---
**Author:** ![qazwart](https://avatars.discourse-cdn.com/v4/letter/q/5fc32e/32.png) [@qazwart](https://boards.straightdope.com/u/qazwart)\ **Post date:** [October 29, 2013, 8:39pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/7 "2013-10-29T20:39:50Z")
> [@Sailboat](#): > > OK, my turn to be surprised. Are any other groups of animals that, uh, “heterothermic,” to coin a term? I always thought all mammals were warm-blooded, all birds warm-blooded, all amphibians cold-blooded, and so forth. Would metabolic rates really be likely to have varied so wildly within dinosauria? Actually, the naked mole rat is _cold blooded_ in the fact it cannot regulate its temperature the way mammals and birds do. They depend upon their environment being a more or less constant temperature and will huddle and shiver to help stay warm. This allows the naked mole rat to have a very low metabolic rate and probably contributes to their reletive longevity. It can live almost 30 years – compared to a mouse or rat which only lives for 3 or 4 years at the most. ---
**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:** [October 29, 2013, 11:50pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/8 "2013-10-29T23:50:47Z")
Keep in mind that dinosaurs represent a transition between “cold-blooded” crocodilian reptiles and warm-blooded birds. In the Saurischia alone, we have the evolution of feathers (which likely evolved primarily as a means of thermoregulation) in the Theropods, and possible “mass homeothermy” (i.e., able to generate internal heat simply on account of their size) in the form of the large sauropods. Some large herbivores might have relied on gut fermentation for thermoregulation, as well. Also, see [here](http://books.google.com/books?id=pX_l24sDARwC&pg=PA873&dq=%22The+Complete+Dinosaur%22+%22intermediate+dinosaurs%22&hl=en&sa=X&ei=g0lwUo7vH4TtigKCt4CAAQ&ved=0CC8Q6AEwAA#v=onepage&q=%22The%20Complete%20Dinosaur%22%20%22intermediate%20dinosaurs%22&f=false). ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [October 30, 2013, 4:35pm UTC](https://boards.straightdope.com/t/if-that-meteor-strike-hadn-t-killed-off-the-dinosaurs-how-would-life-be-different-for-the-human-rac/671494/9 "2013-10-30T16:35:53Z")
> [@Sailboat](#): > > OK, my turn to be surprised. Are any other groups of animals that, uh, “heterothermic,” to coin a term? Well, how about chordates (animals with backbones) or tetrapods (animals with four limbs; i.e. mammals, birds, reptiles, amphibians, and ancestors of such). Yes, these are larger groups than ‘birds’ but the point is that ‘Dinosaurs’ is also a much larger group than ‘birds’.