onceforgivennowfree

[Isotelus]

Greetings,

Interesting study and implications:

Researchers declassify dinosaurs as being the great-great-grandparents of birds

Kindest regards,

James

It's so bad that it doesn't have any implications; at least none that would effect the current consensus on bird evolution. You've probably heard enough about Feduccia to know he's a well-known BANDit who has published on similar topics in the past; none which have been supported by other analyses. Czerkas is a dinosaur enthusiast but does not have a degree. You might also recognize his name from elsewhere (hint: Archaeoraptor). Of course, none of this ought to have any bearing on the accuracy of the paper, so I gave it a quick read. They conclude that their observations of Scansoriopteryx validates their view that birds are a separate branch within Archosauria, but I don't see any form results or phylogenetic tests to support this. They indicate full-blown feather impressions in slightly-too-small and in some cases rather unclear images of the fossil, but I can't see what they're talking about; at least not to the extent they claim. There's also some rehashed claims that were shown to be incorrect a while ago, such as a certain aspect with the dinosaur hip joint. It's actually reminiscent of what's happened earlier on this very thread. I may read it again later, but there are blogs popping up condemning this paper for similar reasons.

Edit: Haven't forgotten your other prior post. I'll respond to it when I have more time.

Que creationists saying once again science got it wrong in 3, 2, 1...

http://www.uncommondescent.com/evolution/birds-not-descended-from-dinosaurs-but-from-common-ancestor-with-them/

It's not even a remotely compelling article.

 

[Dragan Glas]

Greetings,

Greetings,

Interesting study and implications:

Researchers declassify dinosaurs as being the great-great-grandparents of birds

Kindest regards,

James

It's so bad that it doesn't have any implications; at least none that would effect the current consensus on bird evolution. You've probably heard enough about Feduccia to know he's a well-known BANDit who has published on similar topics in the past; none which have been supported by other analyses. Czerkas is a dinosaur enthusiast but does not have a degree. You might also recognize his name from elsewhere (hint: Archaeoraptor). Of course, none of this ought to have any bearing on the accuracy of the paper, so I gave it a quick read. They conclude that their observations of Scansoriopteryx validates their view that birds are a separate branch within Archosauria, but I don't see any form results or phylogenetic tests to support this. They indicate full-blown feather impressions in slightly-too-small and in some cases rather unclear images of the fossil, but I can't see what they're talking about; at least not to the extent they claim. There's also some rehashed claims that were shown to be incorrect a while ago, such as a certain aspect with the dinosaur hip joint. It's actually reminiscent of what's happened earlier on this very thread. I may read it again later, but there are blogs popping up condemning this paper for similar reasons.

Edit: Haven't forgotten your other prior post. I'll respond to it when I have more time.

Que creationists saying once again science got it wrong in 3, 2, 1...

http://www.uncommondescent.com/evolution/birds-not-descended-from-dinosaurs-but-from-common-ancestor-with-them/

It's not even a remotely compelling article.

I confess I hadn't heard of either of them and assumed they were bona fide - however, if they're not, and/or have done this sort of thing before... :|

Was the other paper - regarding gizzards versus teeth - of any interest/value to our discussion, Isotelus?

Kindest regards,

James

 

[Isotelus]

I confess I hadn't heard of either of them and assumed they were bona fide - however, if they're not, and/or have done this sort of thing before... :|

When I first read the title of the paper as per the news article, I seriously thought to myself: "oh boy, who is it this time? Rueben or Feduccia? I hope it's not Czerkas." They've definitely done this sort of thing before, and every time something is published, facepalms ring throughout the biology and palentology world. Feduccia actually is a paleontologist, but I'm putting it lightly to say his position has fallen out of favor with the rest of the scientific community.

Was the other paper - regarding gizzards versus teeth - of any interest/value to our discussion, Isotelus?

Uh-huh! See my edit from my last post.

 

[Mugnuts]

[sarcasm]Wow, that article really put some doubt in my faith of Evolutionism.[/sarcasm]

And the B.A.N.D. played on...

 

[Dragan Glas]

Greetings,

I confess I hadn't heard of either of them and assumed they were bona fide - however, if they're not, and/or have done this sort of thing before... :|

When I first read the title of the paper as per the news article, I seriously thought to myself: "oh boy, who is it this time? Rueben or Feduccia? I hope it's not Czerkas." They've definitely done this sort of thing before, and every time something is published, facepalms ring throughout the biology and palentology world. Feduccia actually is a paleontologist, but I'm putting it lightly to say his position has fallen out of favor with the rest of the scientific community.

I remember the Archaeoraptor kerfuffle at the time, but had forgotten Czerkas' name. Must look out for those names next time.

I'm more aware of fringe scientists in other fields than in yours - like Sheldrake, and - of course - Dembski with regard to information theory.

It would be interesting if it were true, though, as "trees-down" would makes more sense than "ground-up", since gliding is a natural precursor to flapping-flight.

It's a pity that their reputations damage any veracity in their claims. Like the "Archaeoraptor fossil" that turned out to be a mish-mash of various parts of other fossils - including some which were unknown at the time, and part of which remains so today. Had the farmer(s) responsible for putting it together just presented the new fossils, they'd have been famous - which would have brought them wealth and fame in the first place. :facepalm: :roll:

Was the other paper - regarding gizzards versus teeth - of any interest/value to our discussion, Isotelus?

Uh-huh! See my edit from my last post.

Good to know - something, hopefully, to make up for wasting your time.

Kindest regards,

James

 

[Dragan Glas]

Greetings,

Four-winged dinosaur is 'biggest ever'

As a correction to the Czerkas-related article above:

C. yangi is a new species of microraptorine, a group related to early avians.

These ancient creatures offer clues to the origin of flight - and the transition from feathered dinosaurs to birds.

Palaeontologists once thought that four-winged gliders were a stepping stone in the path to two-winged flight.

But recent fossil discoveries suggest that microraptorines were an evolutionary side-branch.

Flight probably evolved many times in different feathered species - not only the lineage which ultimately became birds.

Kindest regards,

James

 

[Isotelus]

* Makes note to self: don't type before reading. *)

A good piece of advice for the creationists who come on this form.

At the time, I was thinking that what was really needed was a phylogeny of the digestive system, from mouth to anus, to identify who had what, and - hopefully - why?

I found a interesting paper - Gizzards versus Teeth - that touches on a lot of what we've been discussing, including your cryptic metabolism comment. It also included a simple "tree" of the relationship between gizzards, teeth, etc, and references two other papers with more detailed "trees" - here and here. Their review of the possible reasons for one or the other being present is particularly fascinating: perhaps the most interesting being the fact that the gizzard is ideal for flight as it places digestion nearest the centre of gravity, whereas teeth mean a large head (strong jawbones and masticatory muscles for chewing), which would make flight awkward. Hence, gizzards favour flight - which explains why all birds have them.

A interesting corollary to this is that most birds fly with their head out-front, including tall birds. Cranes, for example, do this. In contrast, shoe-billed storks (aka, "whale-heads"), which have large heads/bills, fly with their head resting back between their wings. A interesting exception to the long-necked birds flying with their heads out-front are larger herons and egrets - like the (Great Blue/Grey) heron and large egret - which also fly with their heads back between their wings - it's the key identifier to distinguishing between cranes and these particular birds in flight. (Also, divers tend to fly with their heads at a lower level than the plane of their bodies.)

This would appear to suggest that the heron's head is heavier relative to that of cranes and/or the length/strength of the neck's ability to support it out-front during flight. (Perhaps divers' heads are relatively heavy too but not so heavy that they require the heron's adaptation!?)

I'm sure there's a study/paper on birds to be written, by a under-graduate who's lost for an idea for their degree, on the relationship between the centre of gravity, the weight of the head, the head's distance from the centre-of-gravity and the length/strength of the neck.

That paper definitely touches on what I was getting at with my comment about metabolism. The efficient breaking down of food is necessary to sustain a higher metabolism, which is required for flight, and coupled with the presence of feathers implies at least some level of endothermy. Gizzards can make more energy available by grinding food particles to smaller sizes, and hence supply said high metabolism. Of course it's so high that some birds can grow many times faster from an egg to an adult than even a small mammal can.

In terms of herons, storks, and cranes, I would say it's less to do with the weight of the head and more to do with the weight of the neck. Both shoebills and herons are piscivorous and feed in a similar manner, i.e., by forcefully striking at their prey. This type of strong and coordinated movement requires a number of muscles in the neck that would need to be retracted closer to the bird's center of gravity to balance out the weight. Loons (or divers, as you Europeans call them ) don't use their necks in the same way when hunting, as they're propelled mostly by their feet, ergo, their necks probably aren't as heavy and can remain extended in flight. I don't know if there's a specific reason that they hang they're heads comparatively lower when flying; in fact there might not be. One thing that we should always be aware of is that characteristics are not required to be adaptive. Loons are surprisingly heavy birds, and it may simply be a function of their mass.

I did look for some more information regarding gastroliths in crocodiles to clarify this but all I could find was a Google Books reference (pages 36-39 regarding "Digestion")

I can't recall where I saw it. All I remember is that it was a paper.

If the main purpose of crops is storage (for later digestion), owls might not need it due to less likelihood of being disturbed - at least, nocturnal species, since there are diurnal owls.

Diurnal birds-of-prey would face stiffer competition and likelihood of disturbance on kills, hence the need for crops.

However, it appears that - genetically - owls are more related to nightjars and their allies than falconiformes, which may be a more relevant factor.

Button quails though...?

Description[/url]"]The buttonquails are a group of small terrestrial birds. The smallest species is the quail-plover, the only species in the genus Ortyxelos, which is 10 cm (3.9 in) in length and weighs only 20 g (0.71 oz). The buttonquails in the genus Turnix range from 12–23 cm (4.7–9.1 in) in length and weigh between 30–130 g (1.1–4.6 oz). They superficially resemble the true quails of the genus Coturnix, but differ from them in lacking a hind toe and a crop. The females of this family also possess a unique vocal organ created by an enlarged trachea and inflatable bulb in the oesophagus, which they use to produce a booming call.

This would appear to suggest that not all button quails are without crops - just the Turnix genus: and it's possible that, in the latter case, it was sacrificed for the enlarged trachea and inflatable oesophagus for mating calls!? (On a side-note, songbirds appear to have only a small dilation of the oesophagus where the crop would be.)

As for ducks and geese, this may be more related to their being "weeders" - preferring grasses - rather than (broad) leaves and/or seeds.

Gulls and penguins don't appear to have crops either, though this could be due to their diet being almost exclusively piscine in nature.

Geese in particular are also heavy birds and digest their food comparatively quickly; storing grass and what have you (a readily availably food source) would add unnecessary weight.

As for gulls and penguins, the former I would say are not almost exclusively piscivorous, but rather omnivorous. It would also depend on the species. I worked at a landfill one summer doing gull control. Those buggers ate whatever they could find. As for why they don't have crops...I don't know and I've never found an explanation as to why. Same with penguins. I can think of many other piscivorous birds that have crops, so perhaps we could guess that it may instead have something to do with their rather unique lifestyle. It's always difficult to study an animal that lacks a certain feature, for the simple reason that you can't study it directly, and so you have to resort to drawing comparisons .

So it appears that they may well have had crops - just that the fossilized evidence is sparse.

Correct.

As a child, my mother encouraged an interest in Nature - birds, animals, flowers, trees, and astronomy.

I am a member of Birdwatch Ireland, Irish Wildlife Trust and Astronomy Ireland (in the UK, I was a member of the RSPB).

Birdwatching is increasing in popularity, which is a good thing for the most part. Do you do bird photography? I do! https://www.flickr.com/photos/rhodephotos/with/9302762542/

Ichthyornis appears to have been a piscivore rather than a omnivore - although that's not the reason for its name, as you'll be aware! - thus may have been more prone to an extinction event where the sea-level dropped by over 150m.

It should not be surprising that the extinction of omnivores was a case of hit-or-miss depending on where and how the flora/fauna were affected by the change in climate at the time.

As you note, metabolism.

While it's true that Icthyornis ate fish, we have to consider other ornithurines too. It would make sense initially that the one major physical character setting ornithurines apart from modern birds (teeth), may have some connection as to why they didn't make it. There was in fact a possible ornithurine fossil found that dated to the Paleocene, but it was too fragmented to make any firm diagnosis. That's the annoying thing about birds and their evolution. Their bones are too darn small and fragile.

From your other post:

It would be interesting if it were true, though, as "trees-down" would makes more sense than "ground-up", since gliding is a natural precursor to flapping-flight.

Intuitively, yes. Of course it's still an unknown, and we can't forget WAIR.That being said, there was a study that looked at the amount of energy and work done/needed for taking off in modern birds. Incidentally, most of the force exerted at the moment of take-off comes from the legs. Sometimes when reading studies on this, you get the feeling that it's an either/or type of thing, when in reality, there's no reason that there can't be a combination of these hypotheses.

It's a pity that their reputations damage any veracity in their claims.

Indeed, and they kind of did that to themselves. They've been writing those types of papers for some time now, so as soon as a new one comes out, you can almost know for sure what types of things they're going to say. At least they're consistent?

 

[Dave B.]

Do you do bird photography? I do!

Absolutely amazing photo collection. Thank you so much for sharing this with us.

 

[Isotelus]

Many are probably aware of this already, but this is very pertinent to the current discussion: http://www.sciencemag.org/content/345/6195/451. It's been suspected that feathers or feather-like structures were not exclusive to theropods and may have been widespread amongst dinosaurs as a whole, and a new fossil ornithischian, Kulindadromaeus, seems to support this notion. Three types of scales and three types of avian-like filaments were found, including bristly monofilaments, down-like feathers, and ribbon structures so far unique to Kulindadromaeus. The scales and filaments are fossilized as carbonaceous sheets (just in case any claims of mushy soft-tissue preservation pop up). The structures may very well be homologous to the protofeathers found in theropods, but regardless it indicates that filaments in general are likely a basal trait at least in Dinosauria, and could quite possibly be a character shared amongst archosaurs as a whole.

Do you do bird photography? I do!

Absolutely amazing photo collection. Thank you so much for sharing this with us.

Thank you! I haven't updated it in months, though. I'm heading off to Hawaii for a week and a bit, and I'll be hauling my camera around for sure.

 

[Inferno]

Jerry Coyne has a wonderful post about this:
A new feathered dinosaur suggests that most dinosaurs had feathers

 

[Dragan Glas]

Greetings,

A interesting new study on dinosaurs' evolution into birds:

Shrinking dinosaurs evolved into flying birds (w/ Video)

By the way, Isotelus, I haven't forgotten/abandoned answering your last post!

Kindest regarding,

James

 

[Isotelus]

By the way, Isotelus, I haven't forgotten/abandoned answering your last post!

James

Said Dragan Glas forever-ago! I cries.

 

[Dragan Glas]

Greetings,

By the way, Isotelus, I haven't forgotten/abandoned answering your last post!

James

Said Dragan Glas forever-ago! I cries.
]

Has it really been a whole month??

"Haven't handed in your paper yet, have you?!" *she asked archly*

I'm sorry, Isotelus - it's been rather busy in a few other threads in which I'm involved that also required quite a bit of reading - on our "kissing cousins", and Neanderthals in particular.

I will - I pwwwwwomise! :lol:

Kindest regards,

James

 

[Dragan Glas]

Greetings,

Well, seeing as it's nearly a year since I "pwomised" to reply, I thought I'd best do so before I'm "sent down"!

* Makes note to self: don't type before reading. *)

A good piece of advice for the creationists who come on this form.

Indeed.

At the time, I was thinking that what was really needed was a phylogeny of the digestive system, from mouth to anus, to identify who had what, and - hopefully - why?

I found a interesting paper - Gizzards versus Teeth - that touches on a lot of what we've been discussing, including your cryptic metabolism comment. It also included a simple "tree" of the relationship between gizzards, teeth, etc, and references two other papers with more detailed "trees" - here and here. Their review of the possible reasons for one or the other being present is particularly fascinating: perhaps the most interesting being the fact that the gizzard is ideal for flight as it places digestion nearest the centre of gravity, whereas teeth mean a large head (strong jawbones and masticatory muscles for chewing), which would make flight awkward. Hence, gizzards favour flight - which explains why all birds have them.

A interesting corollary to this is that most birds fly with their head out-front, including tall birds. Cranes, for example, do this. In contrast, shoe-billed storks (aka, "whale-heads"), which have large heads/bills, fly with their head resting back between their wings. A interesting exception to the long-necked birds flying with their heads out-front are larger herons and egrets - like the (Great Blue/Grey) heron and large egret - which also fly with their heads back between their wings - it's the key identifier to distinguishing between cranes and these particular birds in flight. (Also, divers tend to fly with their heads at a lower level than the plane of their bodies.)

This would appear to suggest that the heron's head is heavier relative to that of cranes and/or the length/strength of the neck's ability to support it out-front during flight. (Perhaps divers' heads are relatively heavy too but not so heavy that they require the heron's adaptation!?)

I'm sure there's a study/paper on birds to be written, by a under-graduate who's lost for an idea for their degree, on the relationship between the centre of gravity, the weight of the head, the head's distance from the centre-of-gravity and the length/strength of the neck.

That paper definitely touches on what I was getting at with my comment about metabolism. The efficient breaking down of food is necessary to sustain a higher metabolism, which is required for flight, and coupled with the presence of feathers implies at least some level of endothermy. Gizzards can make more energy available by grinding food particles to smaller sizes, and hence supply said high metabolism. Of course it's so high that some birds can grow many times faster from an egg to an adult than even a small mammal can.

In terms of herons, storks, and cranes, I would say it's less to do with the weight of the head and more to do with the weight of the neck. Both shoebills and herons are piscivorous and feed in a similar manner, i.e., by forcefully striking at their prey. This type of strong and coordinated movement requires a number of muscles in the neck that would need to be retracted closer to the bird's center of gravity to balance out the weight. Loons (or divers, as you Europeans call them ) don't use their necks in the same way when hunting, as they're propelled mostly by their feet, ergo, their necks probably aren't as heavy and can remain extended in flight. I don't know if there's a specific reason that they hang they're heads comparatively lower when flying; in fact there might not be. One thing that we should always be aware of is that characteristics are not required to be adaptive. Loons are surprisingly heavy birds, and it may simply be a function of their mass.

I'd argue against your explanation for the great blue/grey heron flying with its head on its shoulders - the shoe-billed stork is obviously dealing with a large and heavy head - if only because other herons also strike but carry their heads out front when flying. This is why I was thinking of the size difference - and, thus, the length of the neck in combination with the weight of the head - being the key factor.

As for the divers (or loons, as you Americans call them ), I've since been wondering, is there a aerodynamic factor involved? The head and neck held low helping to create air-flow over the body per se, thus adding "lift", making the body lighter in the air and reducing the amount of energy needed to fly!? [They also tend to fly low over the water using the air trapped between wings and waves to increase "lift", and reduce energy for flight.]

Just an hypothesis!

I did look for some more information regarding gastroliths in crocodiles to clarify this but all I could find was a Google Books reference (pages 36-39 regarding "Digestion")

I can't recall where I saw it. All I remember is that it was a paper.

Well, I have found a article by Oliver Wings, though I have a feeling it's already been mentioned elsewhere, where he discusses gastroliths in crocodiles.

If the main purpose of crops is storage (for later digestion), owls might not need it due to less likelihood of being disturbed - at least, nocturnal species, since there are diurnal owls.

Diurnal birds-of-prey would face stiffer competition and likelihood of disturbance on kills, hence the need for crops.

However, it appears that - genetically - owls are more related to nightjars and their allies than falconiformes, which may be a more relevant factor.

Button quails though...?

[...]

This would appear to suggest that not all button quails are without crops - just the Turnix genus: and it's possible that, in the latter case, it was sacrificed for the enlarged trachea and inflatable oesophagus for mating calls!? (On a side-note, songbirds appear to have only a small dilation of the oesophagus where the crop would be.)

As for ducks and geese, this may be more related to their being "weeders" - preferring grasses - rather than (broad) leaves and/or seeds.

Gulls and penguins don't appear to have crops either, though this could be due to their diet being almost exclusively piscine in nature.

Geese in particular are also heavy birds and digest their food comparatively quickly; storing grass and what have you (a readily availably food source) would add unnecessary weight.

As for gulls and penguins, the former I would say are not almost exclusively piscivorous, but rather omnivorous. It would also depend on the species. I worked at a landfill one summer doing gull control. Those buggers ate whatever they could find. As for why they don't have crops...I don't know and I've never found an explanation as to why. Same with penguins. I can think of many other piscivorous birds that have crops, so perhaps we could guess that it may instead have something to do with their rather unique lifestyle. It's always difficult to study an animal that lacks a certain feature, for the simple reason that you can't study it directly, and so you have to resort to drawing comparisons .

As you noted, gulls and penguins - as well as ratites (ostriches and emus) - don't have crops. Having said that, I've since discovered that there are gulls with crops! If those with and without crops could be clearly identified, it may be possible to compare diets/life-styles to identify why some do and some don't!? (Apparently, insects, earthworms, some gastropods and leeches also have them. Bees carry nectar back to the hive, for instance.)

Again. as an alternative, I've been wondering since if its possible that they evolved from dinosaurs that, for whatever reason, had already lost or never had crops in the first place!?

If palaeontologists could identify from which branch they'd evolved and what their ancestors' diet had been, perhaps this conundrum might be resolved!?

So it appears that they may well have had crops - just that the fossilized evidence is sparse.

Correct.

As a child, my mother encouraged an interest in Nature - birds, animals, flowers, trees, and astronomy.

I am a member of Birdwatch Ireland, Irish Wildlife Trust and Astronomy Ireland (in the UK, I was a member of the RSPB).

Birdwatching is increasing in popularity, which is a good thing for the most part. Do you do bird photography? I do! https://www.flickr.com/photos/rhodephotos/with/9302762542/

Some nice photos there, Isotelus.

I note that the frigate birds also appear to fly with their heads pulled back towards the body - perhaps another one for consideration regarding weight of head/neck versus neck length versus strength of muscles.

Ichthyornis appears to have been a piscivore rather than a omnivore - although that's not the reason for its name, as you'll be aware! - thus may have been more prone to an extinction event where the sea-level dropped by over 150m.

It should not be surprising that the extinction of omnivores was a case of hit-or-miss depending on where and how the flora/fauna were affected by the change in climate at the time.

As you note, metabolism.

While it's true that Icthyornis ate fish, we have to consider other ornithurines too. It would make sense initially that the one major physical character setting ornithurines apart from modern birds (teeth), may have some connection as to why they didn't make it. There was in fact a possible ornithurine fossil found that dated to the Paleocene, but it was too fragmented to make any firm diagnosis. That's the annoying thing about birds and their evolution. Their bones are too darn small and fragile.

Yes, it's a pity that the smaller birds, at least, don't fossilise that well - unlike the largest ones (moas, etc). Perhaps further fossil-finds in China may help.

From your other post:

It would be interesting if it were true, though, as "trees-down" would makes more sense than "ground-up", since gliding is a natural precursor to flapping-flight.

Intuitively, yes. Of course it's still an unknown, and we can't forget WAIR.That being said, there was a study that looked at the amount of energy and work done/needed for taking off in modern birds. Incidentally, most of the force exerted at the moment of take-off comes from the legs. Sometimes when reading studies on this, you get the feeling that it's an either/or type of thing, when in reality, there's no reason that there can't be a combination of these hypotheses.

Agreed - as the discussion for the latest Know Your Bones topic shows.

It's a pity that their reputations damage any veracity in their claims.

Indeed, and they kind of did that to themselves. They've been writing those types of papers for some time now, so as soon as a new one comes out, you can almost know for sure what types of things they're going to say. At least they're consistent?

Is it their apparent inability to give up their biases that's resulted in their being marginalised?

Kindest regards,

James

 

[Isotelus]

Greetings,

Well, seeing as it's nearly a year since I "pwomised" to reply, I thought I'd best do so before I'm "sent down"!

Lol! Lucky I picked today to see what was going on in the forums otherwise this would have been buried!

I'd argue against your explanation for the great blue/grey heron flying with its head on its shoulders - the shoe-billed stork is obviously dealing with a large and heavy head - if only because other herons also strike but carry their heads out front when flying. This is why I was thinking of the size difference - and, thus, the length of the neck in combination with the weight of the head - being the key factor.

I'm a tad confused with what you mean? All herons fly with their heads tucked in, including the shoe bill. Storks and cranes typically don't, and the shoebill is a stork that happens to feed like a heron. I don't know if I clarified anything or made it worse :lol:

As for the divers (or loons, as you Americans call them ), I've since been wondering, is there a aerodynamic factor involved? The head and neck held low helping to create air-flow over the body per se, thus adding "lift", making the body lighter in the air and reducing the amount of energy needed to fly!? [They also tend to fly low over the water using the air trapped between wings and waves to increase "lift", and reduce energy for flight.]

Could be? On the other hand the loons here don't really fly with their heads that much lower in comparison to other birds. That being said, it could also in part be a function of the skeleton; they're basically torpedos in shape.
Also. Canadian

As you noted, gulls and penguins - as well as ratites (ostriches and emus) - don't have crops. Having said that, I've since discovered that there are gulls with crops! If those with and without crops could be clearly identified, it may be possible to compare diets/life-styles to identify why some do and some don't!? (Apparently, insects, earthworms, some gastropods and leeches also have them. Bees carry nectar back to the hive, for instance.)

Again. as an alternative, I've been wondering since if its possible that they evolved from dinosaurs that, for whatever reason, had already lost or never had crops in the first place!?

If palaeontologists could identify from which branch they'd evolved and what their ancestors' diet had been, perhaps this conundrum might be resolved!?

I'm not sure if anyone has done any rigorous study on why some birds do or don't have crops, at least in how it pertains to gulls and such. It almost certaintly has to do with diet and life style. for example, how far do the parents have to travel to find food, bring it back, then feed the chick? Perhaps one species needs to fly for miles and is hunting for a constantly moving and changeable resource. It would need to shove in as much food as possible, and a crop might come in real handy in that instance!

Birds have tended to group outside of dromaeosaurs and troodontids; although some recent work shows them being much closer to troodontids. Did they have crops? No idea, no way of knowing yet.

Yes, it's a pity that the smaller birds, at least, don't fossilise that well - unlike the largest ones (moas, etc). Perhaps further fossil-finds in China may help.

Tell me about it. I wish often that fossil birds were hadrosaur sized.

Agreed - as the discussion for the latest Know Your Bones topic shows.

I'll take a looksee!

Is it their apparent inability to give up their biases that's resulted in their being marginalised?

[/quote]

That's the root of the problem, yes. That inability or whatever you want to call it means they keep on publishing things that are just plain wrong.

 

[Dragan Glas]

Greetings,

Greetings,

Well, seeing as it's nearly a year since I "pwomised" to reply, I thought I'd best do so before I'm "sent down"!

Lol! Lucky I picked today to see what was going on in the forums otherwise this would have been buried!

I'd argue against your explanation for the great blue/grey heron flying with its head on its shoulders - the shoe-billed stork is obviously dealing with a large and heavy head - if only because other herons also strike but carry their heads out front when flying. This is why I was thinking of the size difference - and, thus, the length of the neck in combination with the weight of the head - being the key factor.

I'm a tad confused with what you mean? All herons fly with their heads tucked in, including the shoe bill. Storks and cranes typically don't, and the shoebill is a stork that happens to feed like a heron. I don't know if I clarified anything or made it worse :lol:

No, you didn't - I'd been dealing with Bernhard the other day, and took a break - though it appears my feeling "punchy" carried over to this post, hence the less-than-sensible reply ...

I confess I was confusing herons, egrets, cranes and storks in flight.

It's been some years since I've been out-and-about bird-watching and am forgetting the distinguishing features or "field marks". I had to look in one of my field guides - Collins' 4[sup]th[/sup] edition (1983), from when I was "active" (must check out the most recent edition sometime, as well as the RSPB's recent edition) - to refresh my memory ( :facepalm: ):

Herons (including bitterns and egrets) fly with their necks tucked back to their shoulders. Cranes and all other large long-legged marsh-birds fly with their necks extended.

(Emphasis in original. There's even helpful silhouettes of a crane and heron in flight showing the difference.)

Serves me right for not checking before posting - failed my earlier "note to self" ... again. :facepalm:

So, it would appear I stand corrected - sorry, Doctor (Professor!?): on this, it would appear that the neck weight is the deciding factor based on extra muscle for striking.

Biologist - 1, Just Some Guy - 0.

("Although..." - *slap!* - "... but ..." - *slap!* - ".... not even? ..." - *slap!* - "... ohhhh ..." - *slap!* "... ..." )

:lol:

As for the divers (or loons, as you Americans call them ), I've since been wondering, is there a aerodynamic factor involved? The head and neck held low helping to create air-flow over the body per se, thus adding "lift", making the body lighter in the air and reducing the amount of energy needed to fly!? [They also tend to fly low over the water using the air trapped between wings and waves to increase "lift", and reduce energy for flight.]

Could be? On the other hand the loons here don't really fly with their heads that much lower in comparison to other birds. That being said, it could also in part be a function of the skeleton; they're basically torpedos in shape.

It appears more pronounced in some than others - for example, the Red-throated Diver (Loon) has a distinctive "hunch-backed" appearance in flight. Not sure whether this is due to skeletal, shape/weight or habitat (colder air in more northerly latitudes being countered by the "aerodynamic" posture in flight...!?)

More opportunity for research grants.

Also. Canadian

Is this a "cultural thing"? Because they migrate(?!) from Canada, rather than being native, they're "loons"? So much for PC!

As you noted, gulls and penguins - as well as ratites (ostriches and emus) - don't have crops. Having said that, I've since discovered that there are gulls with crops! If those with and without crops could be clearly identified, it may be possible to compare diets/life-styles to identify why some do and some don't!? (Apparently, insects, earthworms, some gastropods and leeches also have them. Bees carry nectar back to the hive, for instance.)

Again. as an alternative, I've been wondering since if its possible that they evolved from dinosaurs that, for whatever reason, had already lost or never had crops in the first place!?

If palaeontologists could identify from which branch they'd evolved and what their ancestors' diet had been, perhaps this conundrum might be resolved!?

I'm not sure if anyone has done any rigorous study on why some birds do or don't have crops, at least in how it pertains to gulls and such. It almost certaintly has to do with diet and life style. for example, how far do the parents have to travel to find food, bring it back, then feed the chick? Perhaps one species needs to fly for miles and is hunting for a constantly moving and changeable resource. It would need to shove in as much food as possible, and a crop might come in real handy in that instance!

Birds have tended to group outside of dromaeosaurs and troodontids; although some recent work shows them being much closer to troodontids. Did they have crops? No idea, no way of knowing yet.

If gulls could be separated into those with and without crops, then compare their diets and distance needed to feed/return to fledglings, it might help with other species - crops might indicate longer distances for feeding!?

Yes, it's a pity that the smaller birds, at least, don't fossilise that well - unlike the largest ones (moas, etc). Perhaps further fossil-finds in China may help.

Tell me about it. I wish often that fossil birds were hadrosaur sized.

Perhaps someone could work out under what circumstances such fragile specimens might best be preserved and then go look for them - like Shubin's Tiktaalik and/or Schweitzer's "soft tissue".

Agreed - as the discussion for the latest Know Your Bones topic shows.

I'll take a looksee!

Is it their apparent inability to give up their biases that's resulted in their being marginalised?

That's the root of the problem, yes. That inability or whatever you want to call it means they keep on publishing things that are just plain wrong.

The dangers of not rigorously following the scientific method.

Kindest regards,

James

 

[he_who_is_nobody]

Also. Canadian

Is this a "cultural thing"? Because they migrate(?!) from Canada, rather than being native, they're "loons"? So much for PC!

[sarcasm]Well, it is quite easy for someone from Eurasia to confuse America Jr. for America.[/sarcasm]