Another question about small T-rex arms

[Sight Reader]

OK, I thought I’d sneak this question in before time runs out for this group!

I can’t remember where I heard this - I don’t think I heard it directly - but somebody was speculating that selection pressure to keep increasing both size and power of the head and neck of T-rex, abelisauroids and other big theropods required such extensive musculature that they simply ran out of room to attach significant arm muscles.

Does that even make sense? Would that imply that the shoulder girdle would be getting devoted more and more to attachment sites for neck (or even head) muscles rather than those for arms?

Thanks!

[jillery]

I recall someone suggesting that reducing the weight of the arms
helped to balance their massive heads. OTOH I also recall a lecture
by Robert Bakker who pointed out that the arms' musculature is well
developed, despite its relatively short size.

And then I recall a joke about a triceratops mocking a T.rex by
challenging it to a push-up contest.

[erik simpson]

The Carcharodontosauridae (see Wiki) all had reduced arms, with the more
highly derived carnivores resembling Tyrannosaurids. They aren't
closely related, both in space and time. As far as is known they were
restricted to the southern hemisphere. The short (but muscular) arms
are an example of convergence, but the evolutionary advantages are still
controversial (perhaps used in mating?).

[Sight Reader]

Hey everyone, thanks for responding!

The well-muscled nature of what small arms remain is one of the reasons this theory gives me pause for thought.

I would suppose that, due to the formidable size of the many of the prey animals (not to mention competing carnivores), reducing the head and neck size in predators like T-rex and abelisaurids was not an option.

I would also suppose that, given the tremendous size and strength of potential prey, having powerful jaws capable of securing such large animals, then having the head and neck power needed to wrench around such a powerful animal around no matter how much it might struggle, might prove to be a decisive advantage to these predators.

Now, I believe that the weight of the head and neck (and thus, I would think, momentum) grows by the CUBE of size, while muscle power only grows by the square of size (that is, the cross section of the muscle). So, as these heads and necks got bigger and bigger, proportionately way more musculature was needed to get the same kind of acceleration possible with in smaller theropods.

So, I would see the argument going something like this: it’s not that the arms are “not important” (the well-muscled nature of what arms exist would be testament to this). Instead, it’s that the arms are somehow competing for the same attachment space (on the shoulder girdle) as neck muscles, and the pressure to get a stronger head and neck muscles is so vital for survival that it’s worth sacrificing the arms that are kinda “in the way” of space needed for neck muscles.

What I don’t know is if the shoulder girdle and even be used in this way? Do head and neck muscles actually attach to the shoulder girdle at all? Is it even possible to increase head and neck power by reducing arm musculature - or do the muscles that power heads and necks attach at completely different locations than those powering arms?

[erik simpson]

Recall that juvenile T-rex was very different from Daddy, both in size
and structure of the head and mode of hunting. They were cursorial, and
chased after much smaller game. If, as has been suggested, T-rex had
pack behavior, they probably didn't eat the big game unless is were
already dead. The juveniles also had short arms; maybe it just wasn't
important to their attack mode anyway.

[erik simpson]

On 12/18/23 10:43 PM, Sight Reader wrote:

[erik simpson]

On 12/18/23 10:43 PM, Sight Reader wrote:

Sorry for the duplicates. Eternal September betrayed me. Using solani now.

[Trolidan7]

I guess this is a time to review usenet.

aioe no longer works, right?

Is it still possible to use Netscape Navigator
for usenet?

[erik simpson]

I don't know anything about aloe, or Netscape Navigator (nn?), but
Thunderbird and solani are doing fine for me. I put together a cheat
sheet so I can do it again if I have to. Here it is:
If you don't have Thunderbird installed, do that. Go to "Account
settings" and make sure the news server is "Google Mail - smtp.gmail.com
(Default)"

Register with "news.solani.org" (newsgroup client). Again, there are
others. Eternal September didn't word as well for me.

Back on Thunderbird, go to Account Setting, then "Account Actions".
Click on "Add Newsgroup Account", and register your account identifiying
"news.solani.org".

On exiting the "account wizard", you will have an account named
"news.solani.org". You can rename it anything you like, such as
"GoogleGroups".

Under "File" on Thunderbird, select "Subscribe", and the list of news
groups will appear. Pick the ones you want to subscribe to and you're
ready to go.

It's very easy on Thunderbird to set up killfiles (they're called
'Filters"). To use a non-controversial example, Mark varhaegen and his
aquarboreal apes (or me, for that matter). Just click on the message,
and left click on the name. One of the options is "Filter". Select it,
and he's gone. Under "Tools" in Thunderbird is the filter options and
you can modify the consequences of the filter, such as putting the
offender in "junk" or "spam". You can run the filter manually on the
whole directory and get rid of everything he's ever said.

Good luck! Feel free to email me with questions and problems.

[erik simpson]

On 12/18/23 10:43 PM, Sight Reader wrote:

I inadvertently deleted your post about missing us, but here's what to
do to continue:Thunderbird and solani are doing fine for me. I put

together a cheat sheet so I can do it again if I have to. Here it is:

If you don't have a gmail account, get one.

[Kerr-Mudd, John]

On Thu, 21 Dec 2023 14:05:24 -0800
erik simpson <eastsi...@gmail.com> wrote:

> On 12/18/23 10:43 PM, Sight Reader wrote:
> > On Monday, December 18, 2023 at 9:31:59 AM UTC-7, erik simpson wrote:
> >> On 12/18/23 4:57 AM, jillery wrote:
> >>> On Sat, 16 Dec 2023 19:46:48 -0800 (PST), Sight Reader
> >>> <thesigh...@gmail.com> wrote:
> >>>
> >>>> OK, I thought I’d sneak this question in before time runs out for this group!
> >>>>


[]

> I inadvertently deleted your post about missing us, but here's what to
> do to continue:Thunderbird and solani are doing fine for me. I put
> together a cheat sheet so I can do it again if I have to. Here it is:
>
> If you don't have a gmail account, get one.
>

I strongly suggest you ditch google as they're ditching us.
E-S is free, only registration is required (to discourage spammers and
trolls).

> If you don't have Thunderbird installed, do that. Go to "Account
> settings" and make sure the news server is "Google Mail - smtp.gmail.com
> (Default)"

mail isn't required, just nntp.

>
> Register with "news.solani.org" (newsgroup client). Again, there are
> others. Eternal September didn't word as well for me.
>
> Back on Thunderbird, go to Account Setting, then "Account Actions".
> Click on "Add Newsgroup Account", and register your account identifiying
> "news.solani.org".
>
> On exiting the "account wizard", you will have an account named
> "news.solani.org". You can rename it anything you like, such as
> "GoogleGroups".
>
> Under "File" on Thunderbird, select "Subscribe", and the list of news
> groups will appear. Pick the ones you want to subscribe to and you're
> ready to go.
>
> It's very easy on Thunderbird to set up killfiles (they're called
> 'Filters"). To use a non-controversial example, Mark varhaegen and his
> aquarboreal apes (or me, for that matter). Just click on the message,
> and left click on the name. One of the options is "Filter". Select it,
> and he's gone. Under "Tools" in Thunderbird is the filter options and
> you can modify the consequences of the filter, such as putting the
> offender in "junk" or "spam". You can run the filter manually on the
> whole directory and get rid of everything he's ever said.
>
> Good luck! Feel free to email me with questions and problems.
>
>
>
>

--
Bah, and indeed Humbug.

[erik simpson]

On 12/22/23 4:52 AM, Kerr-Mudd, John wrote:
> On Thu, 21 Dec 2023 14:05:24 -0800
> erik simpson <eastsi...@gmail.com> wrote:
>
>> On 12/18/23 10:43 PM, Sight Reader wrote:
>>> On Monday, December 18, 2023 at 9:31:59 AM UTC-7, erik simpson wrote:
>>>> On 12/18/23 4:57 AM, jillery wrote:
>>>>> On Sat, 16 Dec 2023 19:46:48 -0800 (PST), Sight Reader
>>>>> <thesigh...@gmail.com> wrote:
>>>>>
>>>>>> OK, I thought I’d sneak this question in before time runs out for this group!
>>>>>>
>
>
> []
>
>> I inadvertently deleted your post about missing us, but here's what to
>> do to continue:Thunderbird and solani are doing fine for me. I put
>> together a cheat sheet so I can do it again if I have to. Here it is:
>>
>> If you don't have a gmail account, get one.
>>
>
> I strongly suggest you ditch google as they're ditching us.
> E-S is free, only registration is required (to discourage spammers and
> trolls).

Eternal September gave me some problems, so I'm using solani. So far
it's worked. Whatever works, don't change it.

>
>> If you don't have Thunderbird installed, do that. Go to "Account
>> settings" and make sure the news server is "Google Mail - smtp.gmail.com
>> (Default)"
>
> mail isn't required, just nntp.

Thanks for the correction.

[Ruben Safir]

Trolidan7 <trol...@go.com> wrote:
> On 12/19/23 13:36, erik simpson wrote:
>> On 12/18/23 10:43 PM, Sight Reader wrote:

>>> On Monday, December 18, 2023 at 9:31:59???AM UTC-7, erik simpson wrote:
>>>> On 12/18/23 4:57 AM, jillery wrote:
>>>>> On Sat, 16 Dec 2023 19:46:48 -0800 (PST), Sight Reader
>>>>> <thesigh...@gmail.com> wrote:
>>>>>

>>>>>> OK, I thought I???d sneak this question in before time runs out for
>>>>>> this group!
>>>>>>
>>>>>> I can???t remember where I heard this - I don???t think I heard it

>>>>>> directly - but somebody was speculating that selection pressure to
>>>>>> keep increasing both size and power of the head and neck of T-rex,
>>>>>> abelisauroids and other big theropods required such extensive
>>>>>> musculature that they simply ran out of room to attach significant
>>>>>> arm muscles.
>>>>>>

the obvious advantage of small arms is to keep them away from head first
combat, and being bitten off.

>>> So, I would see the argument going something like this: it???s not that
>>> the arms are ???not important??? (the well-muscled nature of what arms
>>> exist would be testament to this).?? Instead, it???s that the arms are

>>> somehow competing for the same attachment space (on the shoulder
>>> girdle) as neck muscles, and the pressure to get a stronger head and

>>> neck muscles is so vital for survival that it???s worth sacrificing the
>>> arms that are kinda ???in the way??? of space needed for neck muscles.
>>>
>>> What I don???t know is if the shoulder girdle and even be used in this

>>> way? Do head and neck muscles actually attach to the shoulder girdle

>>> at all??? Is it even possible to increase head and neck power by

>>> reducing arm musculature - or do the muscles that power heads and
>>> necks attach at completely different locations than those powering arms?

>> Sorry for the duplicates.?? Eternal September betrayed me.?? Using solani