Now, the further question is were the Pterosaurs cold blooded. They were reptiles. Their range was approximately a latitude of 50 degrees north and south. There are fossil indications of a form of skin covering; quasi fur? Did they have to warm up on a cliff before fishing. Their body mass was too small for inertial homeothermy.

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(By the way, I hate it that so many papers in the areas of planetary science and geology are not easily available to the dreaded "non-subscribers". It is like they are screaming at me: "YOU CAN'T HANDLE THE TRUTH". Good, I feel better now.)

"Quaerendo inventis"

Ok, so my explanation for big size was inertial homeothermy without knowing the term.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

Now see, you should have played it off all cool.
I just thought you knew but put it in simple words.

I was thinking, "Garsh! That HenrikOlsen sure is a Smart Fella!"

Now I know better.

You can still think that, since I reasoned it out instead of reading what someone else had thought.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

Just a couple of days ago I saw a flock of vultures in a field on the way to work, shortly after sunrise. They were standing facing the sun with wigs extended wide. I assume that even a homeotherm doesn't mind a free boost now and then.

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If they can get you asking the wrong questions, they don't have to worry about the answers.

(emphasis added) I know it's a typo and you don't make them often, but I like the image of wig-wearing vultures facing the sun.

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

Darren Naish and Mark Witton had recent papers on pterosaur anatomy and function, and they determined (pretty thoroughly, I think) that the big end-Cretaceous pterosaurs (azhdarchids, technically - the group that includes Quetzalcoatlus) were powerful walker/flyers similar to marabou storks or cranes. They could take off from flat ground by running; apparently their land speed was fairly decent.

Another thought about why things got so big: we had a very recent extinction event (about 10,000 years ago) that killed most of our biggest animals. Of all the dinosaurs, only the sauropods clearly exceeded the size of the largest mammoths (some of them could reach 15 ft. at the shoulder; the record African elephants are around 12'6" or 13', and we have a much bigger sample of African elephants than mammoths). There are a few hadrosaurs that have been estimated at 20+ tons, but that's about it for 15+ ton non-sauropods. So the real question is, "why did sauropods get so big"?

Any chance that paper isn't behind a paywall?

Most of the sauropods were during the Jurassic before flowering plants had evolved. They ate cycads and conifer plants, very tuff vegetation. But, they got very big; Seismosaurus for example. One vertebra was a 1 meter cube.

__________________
(By the way, I hate it that so many papers in the areas of planetary science and geology are not easily available to the dreaded "non-subscribers". It is like they are screaming at me: "YOU CAN'T HANDLE THE TRUTH". Good, I feel better now.)

"Quaerendo inventis"

Hippos are large heriferous mammals that can out muscle crocs. If crocs were bigger, I'll bet hippos woud be bigger.

Perhaps sauropods evolved a size based protection mrchanism.

When a land mass becomes an island (or animals swim/raft there) the mammals get smaller, and the reptiles get bigger. The low level of food affects the mammals evolution, while not becoming food for your cannibalistic relatives affects the reptiles.

Did you mean herbivorous?

Not only can they out muscle crocs, they've even been observed to drive bull crocs away from their kills so they could munch on them themselves.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

Thought they were veggie?! Sorry, this is a science forum..herbivorous.

Apparently they sometimes eat meat, although they are mostly herbivorous. Sometimes herbivores will surprise you by eating meat. For example, pandas will sometimes eat meat if they can get it, but I've never heard of them taking a bite out of someone.

I thought, now I've got time, I'd annotate the reference list Robinson offered from Nick Lane's book, for anyone interested. I've colour-coded Robinson's original text:Red are spurious, duplicates of other references but with copying errors in the journal names; blue are previous works by Berner, precursors to his GEOCARBSULF (770kB pdf) model which I referenced; green relate to the high oyxgen levels of the Paleozoic, the time of the giant dragonflies; orange relate to the hypothesized global wildfire at the end of the Cretaceous; purple relate to wildfires as a potential limiting factor on atmospheric oxygen. The remaining reference deals with polar gigantism, an observation about the increasing size of some marine life with higher latitudes, which may or may not be related to oxygen availability.
So there's nothing there that challenges Berner's model of low oxygen pressures at the time of the pterosaurs. The most recent paper on the list is one of Berner's, from 2000; the oldest is thirty years old, a Lovelock classic.


The link to a sample chapter is handy, because it shows that Lane referenced some of Berner's earlier modelling (penultimate paragraph), and we can again see Berner's prediction of very low oxygen levels in the early Mesozoic:Grant Hutchison

Look up the face transplant guy from China Ron. Pandas, like other bears, are fond of eating peoples scalps and faces, often while they are still alive. That wasn't the first time a panda did that either.

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In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales

Pandas are not bears.
They are oversized racoons.

Nope, red pandas are, DNA says pandas are sunbears

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In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales

You're right. I just looked it up.

Well, everything wasn't. We just hear about the big stuff because it's exciting. But almost all life, always, has been considerably smaller than a human.

True. Think: IIRC, there are about 10,000 known species of bird. In the U.S. alone, birds outnumber people. If, as seems likely, the number of extinct bird species is considerably greater than the total number of extant ones, then there should be a smorgasbord of bird fossils out there. Yet, I'd be surprised if the entire list of known extinct (pre-Holocene) birds wouldn't fit on a handful of index cards. Don't even get me started on insects.

In short, the fossil record--especially the terrestrial record--is strongly biased toward robust-boned vertebrates. I can't help but wonder how many small pterosaurs that lived more or less birdlike lives inland have either been erased from the fossil record, or were never preserved in the first place.

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"Call me old-fashioned, but I think fire is magic. And it scares me a lot."

--The State

Romanus,

you must be aware that the process of fossilization is not the usual way of things, as it takes the organism out of the carbon cycle.

And it favors not so much robust boned creatures but creatures who's bodies are likely to fall into an alkaline/low oxygen enviroment. So things that live in rain forests, upland conifer forests and grassy plains are very unlikely to fossilize.

In a book on pterosaurs I read they point out that almost nothing is known of upland pterosaurs.

__________________
In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales

^
True, but having strong bones (as opposed to the fragile bones of birds, bats, and pterosaurs) definitely helps.

__________________
"Call me old-fashioned, but I think fire is magic. And it scares me a lot."

--The State

While pterosaurs are not dinosaurs, much less sauropods, Sankar Chatterjee, and R. J. Templin make the case in Posture, Locomotion, and Paleoecology of Pterosaurs that it was the oxygen rich atmosphere that enabled them to become so large, as well as fly.

By the late Cretaceous oxygen levels were back up to 28, maybe 30%, which is when the giant pterosaurs evolved/lived.

Before that they were mostly small creatures. Like birds.

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smile, and the Universe smiles with you

Nick Lane makes the case that Giantism is directly related to oxygen levels. His books are well worth reading. The giant dragonflies, insects and dinosaurs, are only a small part of the story.

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smile, and the Universe smiles with you

Now I have heard about them taking a bite out of someone. (I knew all that cuteness must be covering up something!)

The late Cretaceous "peak" in oxygen likely comes from Bergman's 2004 COPSE model, which uses more assumptions and less isotopic data than Berner's more recent work. There's a brief critique in Berner's 2006 GEOCARBSULF paper (770kB pdf).

Previous claims for high oxygen levels during the Cretaceous came from studies during the 1980s of gas trapped in amber, by Berner and others. These have since been discredited, and Berner has subsequently abandoned the amber results.

Grant Hutchison

True, true, I won't argue with that!

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In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales

yes

My laptop keyboard has died and I'm using the onscreen keyboard.
Sometimes it doesnt register a selected letter. I try to proof read my posts but that one slipped by.

I find it interesting that pterosaurs are usually found in former offshore deposits. why would they die offshore? Was there not enough lift for them to get back? Perhaps they flew too far away from the cliffs and without the strong thermals they couldnt stay airborne.

Did they have webbed feet? Birds that can launch from water usually have webbed feet.

Certainly some of them did, from trackway evidence. See here, for example.

Grant Hutchison

Bravo! First rate link Mr. Hutchinson.

(C'mon, what's a star but too much gas in one spot, these are pterodactyls man!)

__________________
In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales

Glad you like it.
It's a nice review, isn't it?

Grant Hutchison

Because (if the analogy holds true) most true sea birds only spend 1/20 of their lives on or over land. Where would you have them die? In bed?

But mainly its an artifact of how things fossilize. Hard to find conditions inland that are condusive to fossilization.

__________________
In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales