It doesn't let me actually "quote" immediately in the next post, only reply.
"how" is beyond my ability
"how" is beyond my ability
Estimating the mass of a dinosaur involves scaling up the volume of a model of that dinosaur and then multipying that scaled up volume by an estimate of the dinosaur's body density (mass = volume x density).
There lies the problem, just what is the density of a dinosaur?
Obviously, if that density figure is overestimated, we will obtain an overestimated figure for its mass.
Recent studies suggest that sauropod dinosaurs had a reduced bone density, allowing a lightweight but mechanically strong skeletal structure.
This would result in a lower density of the animal, meaning it may not have been as massive as previously thought.
There is a still a great deal of uncertainty in our knowledge of dinosaurs. Most of what we know about them is based on just a handful of bones!
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You only need to click the multi quote button before reply. How can that be beyond your ability? 😀
I have no options except reply until one other post is in between. I used to be able to but it changed a while ago.
I also don't have a multi-quote option
I also don't have a multi-quote option
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They've dug these things up and MRI's them. After 100 million yrs or more in the ground, they have calcified and the voids in the bone have filled up with sand etc. But when you image them, you still get an accurate picture of their bone density and structure.
There was a very good BBC show a few yrs ago about the biggest land dwelling dinosaur ever unearthed. It was in Argentina and it weighted in at a whopping 80 tons. IIRC the tibia was about 7 foot long and c. 3 feet in diameter.
The hypotheses is that these animals lived in shallow waters where their body mass would have been partially supported in the water.
There has been a recent change to the system designed to prevent members quoting the last post in the list in its entirety, which clogs up the thread.
Press the 'Multi-Quote' button to the right of the 'Reply' button before pressing the Reply button (the 'Multi-Quote' button will turn red).
Clever repurposing of my statement there.🙂
So you're suggesting their musculature was far less massive than previously thought? That doesn't align with a proportionally correct ratio, though.
So they never came out of the water even though they had fully formed massive legs to do so with? I might believe that if there was no dry land at all during that period.
They've dug up whole sauropods?
I believe the shallow water hypothesis no longer holds sway.
There is still much to learn about dinosaurs and they represent a challenge to evolutionary biologists trying to understand body size evolution.
Sorry, I just assume muscle density would be lower with diminished bone density.
Anyway, there must be some kind of gravitational component to the explanation.
Anyway, there must be some kind of gravitational component to the explanation.
The question is: "How can biology explain how sauropods managed to evolve in a gravitational field of strength 9.81N/kg?"
That is a 'hot' question that evolutionary biologists are still struggling to answer.
And the sauropods did it very quickly to boot! Very large body masses evolved in sauropods very rapidly (within a few million years after their origin). This makes sauropods appear unique among dinosaurs because most other major dinosaur lineages show a gradual body size increase over tens of millions of years.
Sauropoda - Wikipedia
More from my research:
Gravity certainly limits body size, and the current gravitational field has been proposed to limit body size to 20 t, based on a mass estimate for the largest land mammal ever, Paraceratherium. Paraceratherium - Wikipedia
However, sauropods were much heavier than the largest land mammals, and it has been suggested by some that the upper limit for terrestrial organisms due to gravitational forces may be at least 75 t. Similarly. it has been calculated by others that bone strength and muscle forces only become limiting to terrestrial animal size at masses in excess of 100 t.
See what I mean about it being a 'hot' question?
Honestly, I don't know how I come up with these silly notions, they just enter my head from nowhere. 😱
An interesting point that makes me think of this.
Birds are considered remnant creatures from the dinosaurs. Obviously, birds have less body density.
In this theory not only mammals survived the meteorite disaster but small dinosaurs that evolved as the birds of now days.
Adaptation creeps in there in addition to evolution..that is if those 'wild' conjectures are believable. 🙂
Density aside, undomesticated birds that fly meaningful distances have quite low relative body mass. Once they're domesticated, it's clear their structures are capable of handling far more weight than they've adapted to allow flight.
Density aside, undomesticated birds that fly meaningful distances have quite low relative body mass. Once they're domesticated, it's clear their structures are capable of handling far more weight than they've adapted to allow flight.
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