[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

FW: The ground-nowhere hypothesis on the origin of bird flight (joke)

Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0

The birds I mentioned do pounce from trees. Sure. Their hunting
range has greatly expanded because of their highly evolved modern
capabilities. They can also fly after their prey.
Any proavis as you would point out would have a fraction of that=20
range but doesn't make it any less viable. Predators like to stick
around where the prey collects particularly if their range is restricted. W=
aterhole anyone?? --dale (not a joke)

> Date: Mon=2C 12 Oct 2009 10:12:42 -0700
> From: erikboehm07@yahoo.com
> Subject: Re: FW: The ground-nowhere hypothesis on the origin of bird flig=
ht (joke)
> To: dinosaur@usc.edu=3B wdm1949@hotmail.com
> The birds you mention do not pounce from a tree.
> They sit in an elevated position=2C on the lookout.
> The tree serves as a lookout tower=2C from which they can see prey easier=
> Once they spot the prey=2C they go chase after it.
> In a humans case=2C once the prey is spotted=2C a projectile is launched =
at it.
> Raptors sitting in a tree will attack prey much farther away than what th=
ey could get to by gliding (especially if that glide has to be fast to catc=
h the prey unaware/in time).
> Like a human in a tree=2C a raptor sitting in a tree has a huge hunting a=
> Some primitive glider incapable of powered flight sitting in a tree would=
 have a tiny hunting area.
> Several orders of magnitude less in fact.
> At half the "predation radius" (the radius from the perch at which prey c=
an be hunted from the perch)=2C the hunting area is reduced to 1/4.
> The early "bird's" glide ratio was clearly less than half that of a hawk/=
eagle/buzzard=2C and the inability to undergo powered flight (since we are =
hypothesizing a precursor to powered flight)=2C lead me to guess the radius=
 from the perch it could go after prey is less than 1/4 that of the radius =
for a raptor.
> Thus their hunting area would be less than 1/16th that of modern raptors=
=2C and we can't conclude that because its a viable strategy for modern rap=
tors=2C that it was a viable transition form.
> --- On Mon=2C 10/12/09=2C dale mcinnes wrote:
>> From: dale mcinnes=20
>> Subject: FW: The ground-nowhere hypothesis on the origin of bird flight =
>> To: "DML"=20
>> Date: Monday=2C October 12=2C 2009=2C 9:21 AM
>> <140054.33837.qm@web50812.mail.re2.yahoo.com>
>> Content-Type: text/plain=3B charset=3D"iso-8859-1"
>> Content-Transfer-Encoding: quoted-printable
>> MIME-Version: 1.0
>> Whooooa.
>> =3D20
>> Mammals need to eat way too often to be able to just sit in
>> a tree=3D20
>> and wait for something to walk underneath them? Really??
>> This may
>> not be the preferred method of mammals but they can do it.
>> They
>> don't just pick any old tree. They pick a tree that's
>> reasonably
>> secure for them to sleep in=3D2C drag food up=3D2C and in the
>> case of=3D20
>> hunting=3D2C pick a nice shady spot around a waterhole and
>> wait. Yes.
>> Wait. All day if necessary. If not longer. Burns fewer
>> calories.=3D20
>> Much fewer calories. And meat is reasonably assured here.
>> =3D20
>> But raptors do this. Especially eagles. Hunting fish.
>> Hunting birds.
>> Hunting mammals. Doesn't matter. It probably all leads back
>> to that
>> proavis hunting strategy around a water hole. Think Archie.
>> Am I
>> close here? --dale
>> ----------------------------------------
>>> Date: Mon=3D2C 12 Oct 2009 07:29:29 -0700
>>> From: d_ohmes@yahoo.com
>>> To: dinosaur@usc.edu
>>> Subject: Re: FW: The ground-nowhere hypothesis on the
>> origin of bird flig=3D
>> ht (joke)
>>> Hmmm. Perhaps the drop-bear is attracted to camera
>> straps?
>>> More seriously -- mammals need to eat way too often to
>> be able to just si=3D
>> t in a tree and wait for something to happen to walk
>> underneath them. There=3D
>> is another factor too=3D3B most prey is alert enough that
>> missing your initi=3D
>> al pounce is likely=3D2C and if a prey species are slow
>> movers=3D2C then active=3D
>> ly searching works better than waiting anyway. All in
>> all=3D2C I think pounci=3D
>> ng is highly over-rated=3D2C at least in today's world.
>>> The local anoles seem to use it w/ success on
>> insects=3D2C though=3D2C so I t=3D
>> hink it still plays in flight evolution cartoons.
>>> Humans hunt deer from trees of course=3D2C w/ good
>> success=3D2C but use proje=3D
>> ctile weapons to greatly increase their killing range as
>> well as various ba=3D
>> its=3D2C scents=3D2C and calls. I once calculated the cost of
>> licensing=3D2C spec=3D
>> ial clothes=3D2C weapons=3D2C trucks=3D2C refrigeration and other
>> accessories and=3D
>> came up w/ a total cost 250$US/lb for venison (although
>> assuming 2 deer/ye=3D
>> ar for 10 years=3D2C and 10 years per truck it gets closer to
>> 15$US).
>>> --- On Mon=3D2C 10/12/09=3D2C Tim Williams wrote:
>>>> From: Tim Williams=3D20
>>>> Subject: Re: FW: The ground-nowhere hypothesis on
>> the origin of bird fli=3D
>> ght (joke)
>>>> To: dinosaur@usc.edu
>>>> Date: Monday=3D2C October 12=3D2C 2009=3D2C 12:11 AM
>>>> Dann Pigdon=3D20
>>>> wrote:
>>>>> I've seen lots of leopard hunting footage over
>> the
>>>> years=3D2C
>>>>> but I've never seen a leopard leap onto
>>>>> prey from above.
>>>> I'm sure there are other examples=3D2C but the only
>> mammal I
>>>> can think of that leaps out trees to attack prey
>> on the
>>>> ground is the drop-bear of Australia. British and
>>>> Japanese tourists are its preferred prey.
>>>> http://en.wikipedia.org/wiki/Drop_bear
>>>> Cheers
>>>> Tim
>> =3D0A=3D
>> _________________________________________________________________=3D0A=
>> New! Get to Messenger faster: Sign-in here now!=3D0A=3D
>> http://go.microsoft.com/?linkid=3D3D9677407=3D
>                                         =0A=
Click less=2C chat more: Messenger on MSN.ca=0A=