Liighter dinosaurs than ever before? Giraffititan at 23 Tonnes

[SBell]

http://www.manchester.ac.uk/research/news/display/?id=8354

It's interesting that this is so opposite of the recent mega-estimates of dinosaur mass.

[ZoPteryx]

Interesting technique for calculating mass, it could explain how dinosaurs managed to get so big.

Perhaps I'm missing something, but it sounds like they didn't take into account the weight of the muscle or organs.

[SBell]

Interesting technique for calculating mass, it could explain how dinosaurs managed to get so big.

Perhaps I'm missing something, but it sounds like they didn't take into account the weight of the muscle or organs.

It's an estimate of mass, not weight, and as far as I can tell they used modern analogues to come to their numbers.  There is a lot of computer modeling going on right now, so we'll see which version plays out best.

[stoneage]

Interesting, but even though I've always suspected Dinosaurs were't as big and heavy as often quoted, I'm a little skeptical of using modern mammals to determine the weight of Dinosaurs.  Why not use something there more directly related too?

[amargasaurus cazaui]

I see another far more serious issue with the study. The Berlin Mount is considered to be made from as many five individuals, and certainly at least three. There is known to be size variance in the animals used. I am unsure what using such a mount for measuring could return for accuracy but to me at least it somewhat destablizes the entire study

[SBell]

I see another far more serious issue with the study. The Berlin Mount is considered to be made from as many five individuals, and certainly at least three. There is known to be size variance in the animals used. I am unsure what using such a mount for measuring could return for accuracy but to me at least it somewhat destablizes the entire study

It's the same issue I had with the other study, claiming that T.rex should be closer to 9 tonnes.  It too was based on mounted skeletons, which are of course very rarely 100% complete--and coupled with limits involved in actual mounting (as well as modifications that may be oncorporated due to poses or spatial reasons) the skeletons may not be correct reflections of the animals.

But maybe this work can be seen as 'jumping off points' for future research--like finding more appropriate modern/testable models and see how it plays out.

[amargasaurus cazaui]

I see another far more serious issue with the study. The Berlin Mount is considered to be made from as many five individuals, and certainly at least three. There is known to be size variance in the animals used. I am unsure what using such a mount for measuring could return for accuracy but to me at least it somewhat destablizes the entire study

It's the same issue I had with the other study, claiming that T.rex should be closer to 9 tonnes.  It too was based on mounted skeletons, which are of course very rarely 100% complete--and coupled with limits involved in actual mounting (as well as modifications that may be oncorporated due to poses or spatial reasons) the skeletons may not be correct reflections of the animals.

But maybe this work can be seen as 'jumping off points' for future research--like finding more appropriate modern/testable models and see how it plays out.

I quite agree. It is a rather amazing jumping off point so to speak. I just hope they are careful not to try and take it too seriously until or unless they have a very complete mount to work with that can be determined as quite accurate in context of pose as well as completeness, and restoration.Still a fascinating study. Thanks for sharing

[Sharptooth]

http://www.manchester.ac.uk/research/news/display/?id=8354

It's interesting that this is so opposite of the recent mega-estimates of dinosaur mass.

... Just to show how "serious" are some paleontological studies and why paleo-fans shouldn't always take'em for granted 

[Eriorguez]

Or how mass estimates half of the time are utter bull.

Half of the studies forget to take air sacs into account, or the fact that mammals tend to be built like bricks in the case of the larger species.

Use birds and crocs dammit.

[Horridus]

Half of the studies forget to take air sacs into account...

Yeah, this has been a major problem in the past, particularly with regard to sauropods.

[DC]

Roughly animals tend to wieght about the same as the volume of water they would displace.  The air sacs - bone density shoud average out.  Dinosaur Science project 101:  put your solid model into a bucket filled to the top.  Calculate the volume of water displaced and weigh it.   There is a formula for scaling it up.  Baseline the experiment using a scale model on an elephant.

So the differences would be in reconstruction.  Thick verses thin legs and neck, how deep is the torso the tail.  The other issue is convention of using max size as the size metric rather than average size.  Average size isn't pracitcal for many dinosaurs because only a few a reknow from multiple aticulated skeletons.   Max size is proably misleading as it represents the outlier.       

[amargasaurus cazaui]

I also wonder just how accurate the model of an animal can determine its mass and weight if you do not know how that animal actually looked. For instance it used to be common practice to place the verts from hadrosaurs close together when reconstructed however the x-rays taken for Dakota suggest spacing between each. With larger animals it is also possible they have body parts which do not fossilize, similar to a mammoths trunk. These are all things that have to influence the weight to some degree.

[DC]

I also wonder just how accurate the model of an animal can determine its mass and weight if you do not know how that animal actually looked. For instance it used to be common practice to place the verts from hadrosaurs close together when reconstructed however the x-rays taken for Dakota suggest spacing between each. With larger animals it is also possible they have body parts which do not fossilize, similar to a mammoths trunk. These are all things that have to influence the weight to some degree.

The Dakota mummy was a big surprise for reconstructions.  So error could be high.I would average the weight of several different reconstructions.

[Harry_the_Fox]

Or how mass estimates half of the time are utter bull.

Half of the studies forget to take air sacs into account, or the fact that mammals tend to be built like bricks in the case of the larger species.

Use birds and crocs dammit.

Yep- that's the answer I'd imagine.

Interestingly, the guy who published that claim that Azdarkids were too heavy to fly actually used BIRDS as his yardstick for weigh measurements- the problem with this is that birds are actually very heavy for their size compared to other flying creatures like bats, as their feathers actually added quite a lot of weight. In this case bats would have been better as both these animals had membranous wings.

Of course, many size estimates I'd wager were based on even less than direct comparison anyway (to put it nicely); as African Bush Elephants- which are actually much larger than most theropods as well as being much more heavily built, only weigh between 5 and 8 tonnes. With that in mind, an animal like T-Rex would be hard-pressed to beat that weight- only its huge tail would make any substantial difference (offset by the fact that it is sleeker and built to be light on its feet.

Scaling this up to the extreme end- a Blue whale, whose entire 30m length is solid bulk, is estimated between 90-200 tonnes (the most extreme side). Assuming it's 200, there is no chance that any sauropod could reach even half of that- as a 40m sauropod is mostly comparatively skinny neck and tail, with a vastly smaller body too.

At the worst end of the scale are people who saw "Walking with Dinosaurs" and assume Leopleurodon really weighs 120 tonnes- ignoring the fact that the largest specimen is about the same size as an Orca bull

[Simon]

Harry - Agree completely, would only add that if you take the "Liopleurodon" from WWD as a generic representation of a pliosaur, then "Predator X" would be the high end at maybe 50-60 feet in length - but still well under the ludicrous 120 tonne estimate.  Maybe 30 tonnes.

Your other points are spot-on as well - for too many decades dinosaurs suffered from the mistaken belief that the mammals that survived them were somehow better in the evolutionary sense - while the exact opposite is actually true - mammals are inferior to dinosaurs in just about every evolutionary way and are only here because the dinosaurs' very success made them too large to survive the freak impact of the K/T boundary.

I remember reading Bakker's "Dinosaur Heresies" in the late 1980s and having my eyes opened - look at a Triceratops for example - the legs of the animal are just so much more MASSIVE than those of rhinos or elephants - we can hardly imagine how much stronger - and more agile these critters were from the nearest-sized mammals of today.

Or how about a plodding TRex because of course, based on mammalian physiology, the legs would just HAVE to be 3x larger for the animal to run at 20MPH or so?  Then, they figured out the bones had air sacs, and more recently that the tails of the theropods were MASSIVE right behind the hips because THAT WAS WHERE THE DARNED POWERHOUSE MUSCLES WERE THAT PROPELLED THE CRITTERS FORWARD!

*LOL*

[Harry_the_Fox]

Exactly Simon;
It would be a safe wager that a dinosaur would have superior strength and stamina, and relative lightness, compared to a mammal of similar proportions;
And we already know this by looking at birds- who despite having the most extremely gracile physiology as far as 'therapoid-oids' go, are still quite strong and durable, and tend to weigh half as much as any mammal of comparable size, but enough strength and often speed to handle themselves. Certainly you could weigh up stronger birds like Ostriches and Cassowaries and use them as a potential model for measuring a dinosaur's output, factoring in only a few errors of physiological differences (eg body and leg proportions, bone and muscular density, and the added weights of forelimbs, a tail, and a heavier neck and head).

That aside, there could be opportunities for more potent mammals to wriggle through with the right physiology, such as thicker musculature, or the reduced relative weight of lacking a long head/neck and counterbalancing tail. But that would only just tip the balance, most likely.

Agree on T-Rexes running musculature. It is amazing that people would assume that an animal with that much thigh power noticeable in its pelvic bones would somehow not be able to run- especially that we now know slightly more gracile therapods that DID hunt actually exceed its size, but have slightly more slender thigh muscles.

[tyrantqueen]

Your other points are spot-on as well - for too many decades dinosaurs suffered from the mistaken belief that the mammals that survived them were somehow better in the evolutionary sense - while the exact opposite is actually true - mammals are inferior to dinosaurs in just about every evolutionary way and are only here because the dinosaurs' very success made them too large to survive the freak impact of the K/T boundary.

I dunno, I haven't seen dinosaurs put rockets into outer space, paint the mona lisa, or cure smallpox.

[Harry_the_Fox]

Your other points are spot-on as well - for too many decades dinosaurs suffered from the mistaken belief that the mammals that survived them were somehow better in the evolutionary sense - while the exact opposite is actually true - mammals are inferior to dinosaurs in just about every evolutionary way and are only here because the dinosaurs' very success made them too large to survive the freak impact of the K/T boundary.

I dunno, I haven't seen dinosaurs put rockets into outer space, paint the mona lisa, or cure smallpox.

Or did they?
Bear with me, I think I've figured it all out!
-Aliens are really dinosaurs visiting their old homeworld
-Dinosaurs were simply so awesome that smallpox simply failed to be an issue?
-A dinosaur painted the Mono Lisa and Da Vinci took credit for it, and everyone was too scared to question him because he would send his army of robotic party lions to eat them (you heard me!)

Take THAT history channel!

[tyrantqueen]

Your other points are spot-on as well - for too many decades dinosaurs suffered from the mistaken belief that the mammals that survived them were somehow better in the evolutionary sense - while the exact opposite is actually true - mammals are inferior to dinosaurs in just about every evolutionary way and are only here because the dinosaurs' very success made them too large to survive the freak impact of the K/T boundary.

I dunno, I haven't seen dinosaurs put rockets into outer space, paint the mona lisa, or cure smallpox.

Or did they?
Bear with me, I think I've figured it all out!
-Aliens are really dinosaurs visiting their old homeworld
-Dinosaurs were simply so awesome that smallpox simply failed to be an issue?
-A dinosaur painted the Mono Lisa and Da Vinci took credit for it, and everyone was too scared to question him because he would send his army of robotic party lions to eat them (you heard me!)

Take THAT history channel!

Nooooo, everyone knows the dinosaurs evolved into spaceshifting reptilian Illuminati overlords who secretly control most of the Earth's government

Open your EYES people

[Harry_the_Fox]

Nooooo, everyone knows the dinosaurs evolved into spaceshifting reptilian Illuminati overlords who secretly control most of the Earth's government

Open your EYES people

Exactly- only when you free your mind can you look at the dollar bill with open eyes, and realize that the so called 'eye-and-pyramid thingie' is in fact a dinosaur's eye inside a volcano- a cryptic clue that the reptile people came from the center of the earth (because you know, reptiles are 'cold blooded'- which means that they can somehow NOT burst into flames from being near the same heat that is powerful enough to liquidize metals and stones.)