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Topic: Fukn enantiornitheans: how do they work? (Read 162 times) previous topic - next topic

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  • osmanthus
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Fukn enantiornitheans: how do they work?
I'm curious about these particular dead birds. How the fuck did they end up with a major ball-and-socket joint being arse about?

That's a pretty significant change, or seems like it anyway. Does anyone have an idea how and when this happened?
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Re: Fukn enantiornitheans: how do they work?
Reply #1
I'm curious about these particular dead birds. How the fuck did they end up with a major ball-and-socket joint being arse about?

That's a pretty significant change, or seems like it anyway. Does anyone have an idea how and when this happened?

It involved Rule 34 and it happened early on a Tuesday.
Are we there yet?

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Re: Fukn enantiornitheans: how do they work?
Reply #2
well, joint formation is pretty plastic, but what specific feature are you talking about?

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Re: Fukn enantiornitheans: how do they work?
Reply #3
The enantiornitheans were aliens
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
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Re: Fukn enantiornitheans: how do they work?
Reply #4
If you're referring to the hip joint, it's not that ball-sockety in birds I think, more like a cylinder. I suppose turning the concave cartillage on the distal end to convex would not be that significant a change? Do bear in mind though that I'm just speculating here and also I know preciously little about non-mammalian anatomy which means I shouldn't have made this post in the first place n/m

Who even made the rule that we cannot group ducks and fish together for the simple reason that they are both aquatic? If I want to group them that way and it serves my purpose then I can jolly well do it however I want to and it is still a nested hierarchy and you can't tell me that it's not.

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Re: Fukn enantiornitheans: how do they work?
Reply #5
Well for a start, this bit:

Quote from: Wiki
This refers to an anatomical feature - the articulation of the shoulder bones - which has a concave-convex socket joint that is the reverse of that of modern birds. Specifically, in enantiornitheans, the facet where the scapula (shoulder blade) meets the coracoid (the primary bone of the shoulder girdle in vertebrates other than mammals) is a convex knob and the corresponding point on the shoulder blade is concave and dish-shaped. In modern birds, the way the joint articulates is reversed.
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Re: Fukn enantiornitheans: how do they work?
Reply #6
Oh that *is* a significant change. It has clear biomechanical implications because it shifts the center of rotation towards the midline, and on the more stable aspect of the joint. That makes the action of the abductors and rotators more focused and stable. I bet the whole kinematics of the joint were improved.

Fun fact: Many modern shoulder arthroplasties apply the same trick to make a more stable and functional construct, especially when the muscles and ligaments stabilizing and mobilizing the joint are damaged. Some orthopods view that as improving on a natural construct; turns out that nature was way ahead of us- At least for enantiornithines.
Who even made the rule that we cannot group ducks and fish together for the simple reason that they are both aquatic? If I want to group them that way and it serves my purpose then I can jolly well do it however I want to and it is still a nested hierarchy and you can't tell me that it's not.

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Re: Fukn enantiornitheans: how do they work?
Reply #7
Who even made the rule that we cannot group ducks and fish together for the simple reason that they are both aquatic? If I want to group them that way and it serves my purpose then I can jolly well do it however I want to and it is still a nested hierarchy and you can't tell me that it's not.

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Re: Fukn enantiornitheans: how do they work?
Reply #8
Cool. Learn something every day.

According to Wiki (yeah, I know) a lot of these critters are thought to have been quite weak fliers, so I don't know what's going on there. It mentions they used a different motion to fly, but doesn't give details.

What got me into this is New Scientist has just put up an article about them, but I don't have a subscription so I can't read it. It just jogged my memory about them since I had idly wondered sometimes.
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Re: Fukn enantiornitheans: how do they work?
Reply #9
Maybe they relied more on their deltoids to fly, and the change made the muscle more efficient in abducting the arm. I think a study had shown that confuciusornithidae used their deltoids as well[1], which could have been the basal state, so maybe that was the way enantiornitheans managed to raise their wings more efficiently. Neornithes modified the supracoracoid to get more strength in arm elevation, and perhaps that proved even more efficient? Again, just speculating.
'Socrates' threads did have an educating aspect as well as an entertaining one.
  • Last Edit: March 07, 2017, 01:16:02 PM by Faid
Who even made the rule that we cannot group ducks and fish together for the simple reason that they are both aquatic? If I want to group them that way and it serves my purpose then I can jolly well do it however I want to and it is still a nested hierarchy and you can't tell me that it's not.

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Re: Fukn enantiornitheans: how do they work?
Reply #10
http://www.clevelandshoulder.com/pdf/reverseShoulder.pdf


(In case anyone's interested)
A quick google doesn't  find any enantiornithines with a humeral head that looks like that. The coracoid is a bone that fits between the furcula (clavicle) and the scapula, about where the coracoid process is, but much bigger, and technically not homologous.

Enantiornithines don't have a reversed shoulder girdle. That would be completely bizarre. They're talking about the joint between bones that make up the shoulder girdle, not the joint between that and the humerus.
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Re: Fukn enantiornitheans: how do they work?
Reply #11
:sadcheer:

Yeah, I totally goofed there. I somehow misread that as the glenoid joint. It doesn't help that all those bones are completely joined and ossified in the human scapula and the glenohumeral joint is the basic point of movement.

Oh well. Got my dose of unfounded childish excitement for the month.
Who even made the rule that we cannot group ducks and fish together for the simple reason that they are both aquatic? If I want to group them that way and it serves my purpose then I can jolly well do it however I want to and it is still a nested hierarchy and you can't tell me that it's not.

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Re: Fukn enantiornitheans: how do they work?
Reply #12
http://www.clevelandshoulder.com/pdf/reverseShoulder.pdf


(In case anyone's interested)
A quick google doesn't  find any enantiornithines with a humeral head that looks like that. The coracoid is a bone that fits between the furcula (clavicle) and the scapula, about where the coracoid process is, but much bigger, and technically not homologous.

Enantiornithines don't have a reversed shoulder girdle. That would be completely bizarre. They're talking about the joint between bones that make up the shoulder girdle, not the joint between that and the humerus.
So what's the story here then? Are these arse about birds arse about or not?
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Re: Fukn enantiornitheans: how do they work?
Reply #13
Not particularly. Not in the way faid though at least.
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Re: Fukn enantiornitheans: how do they work?
Reply #14
So how then?
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Re: Fukn enantiornitheans: how do they work?
Reply #15
Its not the ball and socket joint that's arse about face. Its the connection between the scapula and the coracoid. The shoulder joint where the humerus goes is still a standard ball and socket same as in everything else I'm aware of.
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Re: Fukn enantiornitheans: how do they work?
Reply #16
Know of any pix?
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Re: Fukn enantiornitheans: how do they work?
Reply #17
Not off the top of my head.
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