# Could the Eath's gravity have increased since the dinosaurs? **URL:** \ **Category:** Factual Questions\ **Created:** [August 15, 2006, 11:36pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889 "2006-08-15T23:36:23Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Valteron](https://avatars.discourse-cdn.com/v4/letter/v/f17d59/32.png) [@Valteron](https://boards.straightdope.com/u/Valteron)\ **Post date:** [August 15, 2006, 11:36pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/1 "2006-08-15T23:36:23Z")
Something has just occurred to me and I wonder if anyone has citations or info on this hypothesis. A lot of people have wondered how the really huge dinosaurs that existed 200 million years ago could have gotten around. I mean, Brachiosauraus weighed 78 tonnes or more. It used to be thought that they spent most of their time in the water to support their weight, but most scientists no longer believe that, as far as I can see. But is it possible that the Earth’s gravity was less 200 million years ago? I have just learned from a google search that “Every year Earth is bombarded with about 40,000 tons of extraterrestrial material. This includes microscopic cosmic dust particles shed by comets and asteroids in outer space, meteorites, as well as large comets and asteroids that have led to catastrophic events in the geologic past.” Now then, I cannot prove what the accumulation rates have been over the past 200 million years, but assuming they were on average 40,000 tonnes a year, that means that our old Earth took on 8,000,000,000,000 tonnes of extra weight in 200 million years. What is 8 followed by 12 zeros anyhow? Trillions?? I realize that this is still a small proporotion of the Earth’s mass, but it must count for something. In fact, my assumption that the acculuation rate was the same over the past 200 million years may be wrong. After all, we are told that the rocky planets in the inner solar system were formed by larger lumps of orbiting matter attracting other lumps. So if anything, the amount of matter that the Earth could vacuum up in its orbit is likely to have been GREATER, not less, 200 million years ago. I am not a scientist, so if my hypothesis makes no sense, please do not laugh at me. Has anyone ever heard this idea discussed by a real scientist? ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [August 16, 2006, 12:17am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/2 "2006-08-16T00:17:14Z")
> [@Valteron](#): > > Now then, I cannot prove what the accumulation rates have been over the past 200 million years, but assuming they were on average 40,000 tonnes a year, that means that our old Earth took on 8,000,000,000,000 tonnes of extra weight in 200 million years. What is 8 followed by 12 zeros anyhow? Trillions?? The mass of the earth is about 6,000,000,000,000,000,000,000 metric tons. That 8 trillion tons is only \ 0.000000133% of the earth’s mass, a very small increase. And even if we extend it back all the way to 4.5 billion years ago, that’s only 180,000,000,000,000 metric tons, still a mere 0.000003% of the earth’s mass. It wouldn’t significantly affect the earth’s gravity. (My decimal points may be slightly off, but I think I got them right.) Besides, everybody who’s read Robert J. Sawyer’s book [_End of an Era_](http://www.amazon.com/gp/product/0312876939/sr=1-1/qid=1155687189/ref=pd_bbs_1/104-7530769-9165522?ie=UTF8&s=books) knows why the gravity was REALLY lower. 😉 ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 16, 2006, 1:01am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/3 "2006-08-16T01:01:27Z")
Well, in dino-days, all the continents were squished together; modern geography is a result of a billion years of continental drift. I suppose all that mass on one side of the planet might’ve increased the local gravity. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [August 16, 2006, 1:29am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/4 "2006-08-16T01:29:10Z")
Well, we have astronomical evidence of gravitational bending of light from stars. If any of the objects bending the light are 200 million light light years from here that would tell us because I believe the observed bending is in accord with the gravitational effect present today. ---
**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\ **Post date:** [August 16, 2006, 1:29am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/5 "2006-08-16T01:29:55Z")
The master speaks: [[http://www.straightdope.com/classics/a940408a.html](http://www.straightdope.com/classics/a940408a.html)]Why were dinosaurs big? This addressess the question of whether low gravity could have been a factor … ---
**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\ **Post date:** [August 16, 2006, 1:31am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/6 "2006-08-16T01:31:39Z")
> [@Arjuna34](#): > > The master speaks: > > [[http://www.straightdope.com/classics/a940408a.html](http://www.straightdope.com/classics/a940408a.html)]Why were dinosaurs big? > > This addressess the question of whether low gravity could have been a factor … Arghh - make that [Why were dinosaurs big?](http://www.straightdope.com/classics/a940408a.html) ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [August 16, 2006, 1:32am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/7 "2006-08-16T01:32:35Z")
A Wiki link to the subject of huge dinosaurs: [Bruhathkayosaurus - Wikipedia](http://en.wikipedia.org/wiki/Bruhathkayosaurus) ---
**Author:** ![Beware\_of\_Doug](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)\ **Post date:** [August 16, 2006, 2:00am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/8 "2006-08-16T02:00:35Z")
> [@chorpler](#): > > The mass of the earth is about 6,000,000,000,000,000,000,000 metric tons. Never mind the earth. We’re talking about the _Eath_. It’s about 20 feet tall and located in a vacant lot in Canton, Ohio. They think it might be papier-maché, but the stray cats don’t let anybody in close enough to check. 😃 ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [August 16, 2006, 7:32am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/9 "2006-08-16T07:32:23Z")
[Comic book artist Neal Adams thinks that at one point and time gravity was less.](http://www.nealadams.com/enceladus/earthinfo.html) > [@](#): > > Relative to the “growing earth” theory, write-ins have asked for a clarification on this subject… that if the Earth were smaller… that in the dinosauric past wouldn’t all the waters in the present oceans cover all the land in the past…. Or if there were shallow seas ONLY in the past… how then is there so much water that it now fills the oceans of this much bigger earth. > > The answer of course is that if the Earth grew, the whole Earth, all elements were created in the same proportions as now (inside the Earth.) > > If you “get” or understand the basic concept that Earth had to make mass (stuff) to get to THIS present size you have to ask what “STUFF” was made. Sensibly all the same stuff that “was made” to give us the earlier smaller Earth is the same stuff, solids and gasses that gives us the mass for this now bigger Earth. > > The same proportion of iron, oxygen, hydrogen, copper, tin, silicate rock, basalts, and so on. > > Imagine an Earth’s core like you see in a geode. (You know, those round stones that when you cut them in half and look inside you see beautiful crystals seemingly growing inward.) in the very middle, it’s empty, because the crystals are, in reality, growing and pushing outward! No, I _don’t_ know what he’s been smoking. ---
**Author:** ![DanBlather](https://avatars.discourse-cdn.com/v4/letter/d/f4b2a3/32.png) [@DanBlather](https://boards.straightdope.com/u/DanBlather)\ **Post date:** [August 16, 2006, 7:46am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/10 "2006-08-16T07:46:57Z")
> [@Bryan Ekers](#): > > Well, in dino-days, all the continents were squished together; modern geography is a result of a billion years of continental drift. I suppose all that mass on one side of the planet might’ve increased the local gravity. Are you having us on? ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [August 16, 2006, 9:19am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/11 "2006-08-16T09:19:16Z")
> [@Beware of Doug](#): > > Never mind the earth. We’re talking about the _Eath_. It’s about 20 feet tall and located in a vacant lot in Canton, Ohio. They think it might be papier-maché, but the stray cats don’t let anybody in close enough to check. > > 😃 Oh, man, do I feel like an idiot for having totally gone off on an irrelevant tangent! :smack: ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [August 16, 2006, 10:44am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/12 "2006-08-16T10:44:32Z")
> [@DanBlather](#): > > Are you having us on? It’s not always easy to distinguish feigned ignorance from the real thing, but I’d prefer to give the boy Ekers the benefit of the doubt, since you’d have to be a real tool to think either [list=a]squishing all the continents together into Pangaea would have had any worthwhile effect on the planet’s surface gravity, or[_]Pangaea still existed when the dinosaurs were kicking around, instead of having split into Laurasia and Gondwanaland or whatever it’s called, or[_]anything like a billion years have passed since the Cretaceous era.[/list] ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [August 16, 2006, 11:15am UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/13 "2006-08-16T11:15:06Z")
This is a subject that posed a question I wonder about. How much more of our gravitational attraction was nutralized by the faster rotation of the earth during the age of dinosaurs? What was the rotational period of the Earth at that time? This all became a question when reading claims that dinosaurs couldn’t have lived on the Earth, if the gravity hadn’t been less. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 16, 2006, 12:03pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/14 "2006-08-16T12:03:16Z")
> [@DanBlather](#): > > Are you having us on? Quite. ---
**Author:** ![Hoopy\_Frood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hoopy_frood/32/8452_2.png) [@Hoopy\_Frood](https://boards.straightdope.com/u/Hoopy_Frood)\ **Post date:** [August 16, 2006, 3:25pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/15 "2006-08-16T15:25:03Z")
> [@Bryan Ekers](#): > > Well, in dino-days, all the continents were squished together; modern geography is a result of a billion years of continental drift. I suppose all that mass on one side of the planet might’ve increased the local gravity. Yeah, but what happens when all those dinos on the same side of the planet stand on chairs and jump off at the same time? ---
**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\ **Post date:** [August 16, 2006, 3:28pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/16 "2006-08-16T15:28:18Z")
> [@Hoopy Frood](#): > > Yeah, but what happens when all those dinos on the same side of the planet stand on chairs and jump off at the same time? Fortunately, dinosaurs had not invented chairs. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [August 16, 2006, 3:34pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/17 "2006-08-16T15:34:54Z")
How _could_ they have invented chairs? They wouldn’t even be able to use them! They had tails and stuff. They’d have to invent stools. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [August 16, 2006, 3:47pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/18 "2006-08-16T15:47:45Z")
> [@Zsofia](#): > > They’d have to invent stools. It’s not widely known that they’d more or less perfected stools and were hard at work upon a type of very sturdy stepladder. It was all part of a very forward-looking scheme to develop the technology to cope with a possible comet impact. Sadly, funding was inadequate and the comet came a bit too early. In the aftermath of the impact there were, of course, bitter recriminations among the few survivors. One popular theory was that a relatively insignificant order of furry animals had somehow conspired to sabotage the program, believing that they stood to profit from such a catastrophe. ---
**Author:** ![Hoopy\_Frood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hoopy_frood/32/8452_2.png) [@Hoopy\_Frood](https://boards.straightdope.com/u/Hoopy_Frood)\ **Post date:** [August 16, 2006, 3:47pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/19 "2006-08-16T15:47:45Z")
> [@Zsofia](#): > > How _could_ they have invented chairs? They wouldn’t even be able to use them! They had tails and stuff. They’d have to invent stools. Maybe they used open-backed chairs. ---
**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:** [August 16, 2006, 4:08pm UTC](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889/20 "2006-08-16T16:08:04Z")
While Bryan might have been joking, he’s not as far off as one might think. We know that different concentrations of minerals can affect the gravitiational force you detect at different points on the earth’s surface. A subterranean deposit of heavy matter increases local gravity, light matter decreases it. Of course this is only a very slight variation, only detectable with sophisticated instruments. But the effect is likely to be much larger than the affect of increased gravity due to accumulation of dust and meteorites. I’m not sure how many orders of magnitude these density gravitional variations have, but I suspect they might overwhelm the 0.000000133% from extraterrestrial matter. [Next page](https://boards.straightdope.com/t/could-the-eaths-gravity-have-increased-since-the-dinosaurs/368889.md?page=2)