Does anyone else here ever wonder if some of these "new" dinosaurs are really just re-discoveries of known dinosaurs? The article even mentions that the skeletal remains are incomplete. What if a number of these sauropods are really all the same species, albeit at different stages of their life? Is size alone enough to create a new classification? Perhaps growth continued throughout the life of a sauropod, and the largest ones were just the oldest?
I don't think species are classified solely on size. I'm pretty sure juvenile specimens have been discovered and identified as being the same species as the adult specimens. Yes, mistakes have been made, but my impression is that the bone shapes play a substantial and important role, perhaps moreso than just the size.
The idea that you can determine the size of an animal from a single bone comes from Cuvier and was an early development in paleontology. I don't know how much progress there has been on the task of putting it on a firm scientific footing. http://en.wikipedia.org/wiki/Georges_Cuvier#Principle_of_the...
Lower leg bones are likely to directly relate to body weight where say teeth on the other extreme have little to so with it. Overall, it's note quite BS because it can be somewhat true.
The scientists that study this kind of thing try to check for similarities and classify them as the same or different when appropriate.
They probably classify them as different if the time they lived (based on the surrounding rock they were found in) or their bone structures is sufficiently different from anything previously discovered.
It's also a lot easier to merge two classifications rather than split a group into two.
So the problem is - the very concept of a species is not particularly well defined, and loses a large degree of meaning in paleontology amidst lack of fossil-record data (both extreme scarcity and geographical patchiness) and the additional dimension of time.
A species is a particular genetic type which does not routinely interbreed with other related types it encounters, and retains some physiological differences from them, as a forked, internally consistent genetic branch.
We're a hundred million years late to demonstrate that the sauropods were or weren't interbreeding. We don't have that behavior to observe. We don't have any DNA, a fairly accurate way of demonstrating breeding pools, to work with. We only have the occasional left third rib, and equations derived from the most similar complete skeletons we know of. Even when we do find a complete skeleton, we can only date it to a certain degree of precision, and while understanding that there is an evolutionary tree that is constantly sprouting and changing branches, we have nothing to really demarcate when one species "becomes" another - we are speculating about two specimens' reproductive compatibility with millions of years between them.
Could you breed with a proto-human? Would you? How far back? Would the kids come out alright? Would you call them a new subspecies or pick one of the parents' taxonomy? On top of that, to represent the last several millions of years of subtle changes, new branches, & trimmed branches in hominid genetics, what if you only have 6 specimens closer than chimpanzees, mostly age/sex-indeterminate, only one of which is a complete skeleton? How do you draw an org chart of the hominids then?
There are size variations corresponding to age and gender, heritable variations within a breeding pool, variations corresponding to differential nutrition & the good times vs the bad times for a population, variations corresponding to individual sickness and injury, variations corresponding to the entire population getting steadily larger or smaller for a thousand or thirty thousand or a million years, variations corresponding to sudden changes in habit associated with adaptations to rapid changes in environment, variations corresponding to drift from a parent population associated with permanent reproductive incompatibility as well as reversible reproductive isolation.
The historical paleontological record is thousands of times richer in micro-scale detail than we have the data to describe, even if we did have good words to describe it with that the popular media could understand. But they want to talk in terms of species, because that's what people are familiar with.
So what's their secret? How did they manage to feed themselves? Were they living sparsely? Was bioshpere denser then? Were they capable of eating just about anything?
And how was such massive size selected for? Is it just a matter of warmer climate and a feedback loop with larger and larger predators?
The short answer for why dinosaurs got so large is because they could. That might seem a flippant answer but they had much less constraints than most animals left living today:
Air sacs not only allowed more efficient breathing but were also within skeletal structure, allowing for light weight strength. They also laid lots of small eggs so less reproductive investment per chick. Small heads on long necks with a sturdy body allowed long range eating without moving. With small heads and no chewing the disadvantages of long necks are well handled. For much more depth I encourage reading:
<speculative As a non-expert my own guess would be some kind of food-weight advantage feedback cycle. The larger ones were not just more protected from predation but with longer reach came wider access to edible plant material. However, the larger sauropod size, coupled with no chewing and low grade of food (and probably not stones users) required larger and larger (fermenting?) stomachs to get enough energy to support their size. (not directly related but, reasoning from whales they might have even been cancer resistant. And if you consider that their size strongly suggests a 'cold blooded' like metabolism, then given their size, sauropods could well have lived a couple hundred years) />
Nothing was different. The "Giant of Castelnau", even if he/she was actually as tall as the discoverer conjectured, wasn't wildly outwith the recorded range of human height - Robert Wadlow was 8'11" (2.72m) when he died, and was only 22. It's completely plausible to me that someone afflicted by the same disorder as Wadlow could've reached 3.5m just by being lucky enough to live longer, and it's also completely plausible to me that it could've happened more than once in the vast, vast swathe of human history about which we know next to nothing.
Scant evidence that a human was once very large certainly isn't evidence that "humans were bigger", and that in turn wouldn't be much evidence that a difference in the environment was causing it.
>It's completely plausible to me that someone afflicted by the same disorder as Wadlow could've reached 3.5m just by being lucky enough to live longer,
That's not plausible at all. Robert Wadlow as at the very limits of human height. He already numerous medical problems caused by his height and needed leg braces just to walk.
There is no way a bronze age man with access to bronze age medical care was able to live long enough to grow nearly 3 feet taller than Wadlow.
Since weight doesn't scale linearly with height, a 12' tall man would be enormous. Robert wadlow weighed nearly 500 pounds. A 12' tall man would weigh much much more than that.
I think there are only 2 real possibilities to explain the giant. Either he wasn't really as tall as the discoverer thought, or something was different to allow him to get that tall.
I know little about the subject, but I'm sure there are differences between the limits of human height and the limits of biped primate height. If the giant of Castelnau were, as claimed, part of a "race of giants," it is not unreasonable to think this group explored the limits of biped height more profoundly, as a group, given that they could eliminate some (but not all) of the problems that height suggested.
On the latter point:
"There is no way a bronze age man with access to bronze age medical care was able to live long enough to grow nearly 3 feet taller than Wadlow."
You don't know that. Even in antiquity, with Iron Age medical care, men commonly lived to 100 years, with the absolute limit, as placed by the Etruscans, at 110 years, thus defining the Etruscan century at this number. Now, perhaps if the man in question was a giant there would be intrinsic difficulties in being gigantic, but natural selection within his tall genetic group could, as a group, overcome many of them. This is a very different situation that Robert Wadlow's, who did not come from exceptionally tall parents. If a group has selective pressure to become tall, it's an entirely different matter from an individual accidentally becoming tall.
Keep in mind there have been around 60 billion Homo Sapiens Sapiens, most of them outside historical record, and in prehistory, very isolated. This can commonly lead to vast phenotype differences. I would have to see stronger evidence to rule out that an adapted giant biped cannot reach 15 feet.
>I would have to see stronger evidence to rule out that an adapted giant biped cannot reach 15 feet.
I didn't say an adapted biped can't reach 15 feet, but a modern human with a pituitary tumor cannot. Which is what the OP suggested. There are too many health problems associated with 9' giants of Wadlow's type for bronze age medicine to overcome, much less 12' or 15' giants.
>You don't know that. Even in antiquity, with Iron Age medical care, men commonly lived to 100 years, with the absolute limit, as placed by the Etruscans, at 110 years
I'm not talking about the lifespan of a normal human who happens not to develop any terminal illnesses, I'm talking about the lifespan of a giant with a pituitary tumor. At the extremes they have too many medical problems to live anywhere near a normal lifespan. Wadlow could barely walk, he couldn't feel his legs so he constantly developed blisters (this is what eventually killed him by the way), and like all extreme giants he had heart problems because his heart was enlarged and couldn't handle his pumping blood throughout his enormous frame.
Keep in mind these are the problems with a 9' giant. Now imagine the medical problems of a 12' giant. He would be a third taller and probably at least 2 times heavier. There is no way someone like that is going to survive in the bronze age, unless he is either of a subspecies that is adapted to growing that tall, or conditions were somehow different.
> At the extremes they have too many medical problems to live anywhere near a normal lifespan.
Absolutely, yes - and, given that the normal lifespan has been three score and ten for about as far back as we can see, and given that Wadlow managed only one score and two, what're the odds that nobody with Wadlow's afflictions ever managed longer?
My point is, Wadlow's death was effectively a matter of poor luck - a blister popped up and went septic that he didn't notice soon enough, but others had previously been spotted and dealt with. Who's to say that no Iron Age 20 year old could possibly do better?
>My point is, Wadlow's death was effectively a matter of poor luck - a blister popped up and went septic that he didn't notice soon enough, but others had previously been spotted and dealt with.
It wasn't a matter of luck, it was because of his condition that he couldn't feel his feet and thus developed blisters.
It was just a matter of time until one of his blisters or other feet injuries got infected. And in the bronze age with no knowledge of germ theory, much less antibiotics, these infections would likely prove lethal.
Robert Wadlow wouldn't have lived very long in a tribe in ancient France with a condition that caused chronic blisters and foot wounds. Furthermore gigantism causes extremely high blood pressure leading to varicose ulcers in the legs and again, infection.
However, the blister alone wasn't what killed him, he had an autoimmune problem caused by his disorder that contributed to his death, and he had an enlarged heart and was generally unhealthy.
>Who's to say that no Iron Age 20 year old could possibly do better?
It's not do better, it's significantly better with vastly inferior medicine. Even if his growth rate remained at the rate it was during the last few years of his life he would have to have lived almost 20 more years to grow another 3 feet. In addition his growth rate most likely would have slowed or stopped eventually.
If he had continued growing the strain on his skeleton and circulatory system would have killed him way before he got to 12'. This kind of gigantism is a disorder that causes immense strain on the body, humans just aren't build to handle that level of growth hormone.
Have you noticed that there are only 3 people in all of recorded history who reached 8.5' tall. The reason is because that is basically the upper limit of what is survivable.
Even if it were possible for a 12' tall man to live, given a population 10 times larger (all the people who ever lived compared to all those born in the 20th century) what's the chance that this population produced a man 3 feet taller than the tallest in recorded history--Keeping in mind that people with this disorder would have been likely to die even earlier than the giants of the modern era due to the lack of any semblance of modern medicine.
> "Even in antiquity, with Iron Age medical care, men commonly lived to 100 years,"
But that's not remotely comparable to someone growing 3.5 meters tall. Nowadays there are also plenty of people who live more than 100 years, and not all of them need extensive medical care.
Growing to 3.5 m is more comparable to finding someone who lived to 200 years.
I don't mean to suggest credibility for the antediluvian weirdness in Genesis, or Greek stories about titans for that matter, but this kind of stuff certainly makes you think.
From the BBC article:
Weighing in at 77 tonnes, it was as heavy as 14 African elephants, and seven tonnes heavier than the previous record holder, Argentinosaurus.
According to the Wikipedia page about Dinosaur size[1], the biggest (and longest) dinosaur is Amphicoelias fragillimus (at 122 tons), not Argentinosaurus. So, won't this new dinosaur be the second heaviest?
Keep reading. There was only one fossil found and described in the 19th century, then lost. The results can't be verified and the size estimate may be completely wrong.
Sea creatures don't need to support their own weight.
Though I'm anything but expert on the topic, my understanding is that many dinosaurs were surprisingly light-weight for their size, and masses of many dinosaurs have been revised downward. As ancestors of birds, whose own bodies are generally of very low mass, and incorporate interesting features (hollow bones and internal air sacs) this isn't entirely surprising.
I'm really fascinated by the possibilities of paleontological discoveries. We have excavated such a minuscule portion of our planet (you might just round it down to 0%) that there absolutely must be an enormous amount of fantastic things out there waiting to be discovered.
I hope we can develop things like clear underground imaging from aircraft, and start finding more and more of these incredible types of discoveries.
FYI, my comment was a nebulous reference to "Steel Beach" by John Varley, about a future space civilization where dinosaurs had been cloned and were raised as game meat.
No sense of humor around here, looks like. The fact is, if we could revive dinosaurs, they would become game meat. What other purpose would they serve? To strip a forest in a day? To hunt and kill all the mammals?
As for the fundamental question of whether we should revive ancient species, the answer is "Of course!" To clone an animal using fully sequenced DNA would be an amazing achievement, and the programmed behavior in the DNA would be fascinating to study.
Of course, it's much more likely and scientifically feasible that we could clone more recent species such as Neanderthals which according to at least one scientist might be achievable today, or in the very near future. But dinosaurs are what capture people's imagination, and the bigger, the better.
Hmmm, judging by the number of down-votes on my "it'll taste like chicken" comment I have the feeling I need to remind some of the evolutionary grandparents of the humble chicken. Remember that chickens, being birds, most likely are descended from small carnivorous dinosaurs. While the mentioned dinosaur is a vegetarian sauropod, both share a common ancestor.
I think diet may have a far bigger impact on taste than genetic similarity. Cows and pigs are far more closely related than chickens and sauropods, yet they taste very differently. Also, plenty of birds don't taste all that much like chicken.
