Tuesday, December 12, 2006

Emu dissection

Not much time to chat now, just posting pictures of an emu dissection for the edification of colleagues. Full description to follow.

This is what you start with: 100 pounds of dead bird.

Should mention that I did this in the anthro anatomy lab at UC Santa Cruz a couple of years ago. Richard (above left) runs the lab and was kind enough to let me scrub in.

First step: pluck the bird. Here I'm stuck with the butt end.

Here's what a peeled ratite looks like. The amount of fat and gore is impressive. The birds carry big fat pads on their backs.

We saved all the fat and weighed it. Eighteen pounds of adipose. On a bird that weighed just over 100 lbs. Suddenly I don't feel so bad.

Rewind a sec. Here's the inflatable throat pounch from the outside...

...and again from the inside. Here we've cut along the dorsal side of the trachea and I'm holding it open. That gap is the opening of throat pouch. Several of the cartilage rings that support the trachea are incomplete. I'd seen drawings of this in books, but the real thing was much cooler (as is usually the case).

Yep, that's a hand claw on a living theropod. Pretty darn cool.

Same thing sans skin. I had thought that only male ratites have claws, but this bird was a female. Seasoned Vectorites will recognize this as the starting point of my planet-making tutorial.

Unfortunately, I couldn't stick around for the whole show. These were the totals when I left.

More to come on big dead birds very soon.

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Anonymous Anonymous said...

This claws are really interesting, I really didn´t know that they own such structures. It reminds me a bit on this tasty roasted duck I ate some time ago, because it had also small claws on its fingers. But it seems that claws on bird´s wings are not as rare as normally assumed, making hoatzin a bit lesser special than they actually are, especially if you keep in mind that we have also in our "boring" european avian fauna a bird who uses its clawed fingers to climb and when it´s still a hatchling. I´m still waiting to find somewhere a realistic reconstruction of the hands and fingers of Titanis, and this one gives at least a vague idea.

10:47 AM  
Blogger amit said...

hello der thnx 4 the review of ur postmorteum.....i was really confused about this tracheal cleft thing and tracheal slit openin into the pouch....thnx a million 4 this...im a vet student studyin in bombay vet colege...if u waana mail me more such pms here is my id.....arcner123@gmail.com or .......@yahoo.com or ..........@hotmail.com

5:21 AM  
Blogger T. rex guy said...

Hello, I am a grad. student at Kansas State University and am completing my thesis on the forelimb function of T. rex. I just dissected an emu and was very puzzled by the slit in the trachea, thanks for the clarification. Do you have any good sources/papers on emu anatomy, especially neural anatomy, ie.. the brachial plexus? I would appreciate your help.

Thanks again,

John Myers

6:05 PM  
Blogger Dr. Vector said...

Sorry, I don't know anything about neural anatomy in emus. My first instinct is to check Google Scholar (for everything, these days), but you probably did that already. Sorry to not be more help.

1:45 AM  
Anonymous Anonymous said...

I am wondering if this wing claw is fully functional, vestigial or atavistic, can you enlighten me?

10:25 PM  
Blogger Dr. Vector said...

That's a darn good question.

Functional--presumably, but for what? I had heard about wing claws in male ratites, and if they are sexually dimorphic then some kind of intraspecific combat function is a possibility. Big wrench in that hypothesis: the individual shown here is female!

Vestigial or atavistic--I assume by 'vestigial' you mean 'inherited from their dinosaurian ancestors', and by 'atavistic' you mean 're-evolved within ratites'. I honestly don't know which is correct, but my guess is the former. I will bug the omni-knowledgeable Darren and see what he knows.

7:53 PM  
Blogger Matt Kuchta said...

Interesting detail about the weight of the feathers:

With this emu, they make up only about 7.5% of the body weight. In some flying birds, feathers can be upwards of 20% the total weight.

10:20 AM  
Blogger Dr. Vector said...

Hi Pascal,

Good point! I assume you know about Brodkorb (1955), which listed the masses of the body components of a bald eagle. I believe in that individual the feathers accounted for something like 15-20% of the body mass, but the skeleton only accounted for ~7-10%. So the feathers weigh twice as much as the skeleton. Pretty darned interesting.

Thanks for stopping by.

10:28 AM  
Blogger Monado said...

Wot nothing about the feathers? Emu feathers are the model for Dr. Seuss feathers: dual feather from one base, flopping in all directions. Obviously not aerodynamic.

The claws could be for grooming the mat of feathers and removing parasites.

You might be interested to know that when an emu sits down, there's an audible thump as the adipose hits the ground.

8:24 AM  
Anonymous Anonymous said...

Do ratites have tongues? We're having a debate here, and since you dissected one, I thought you'd know. Thanks! :)

8:41 AM  
Anonymous Anonymous said...

Hi, I am a veterinarian at national institute of animal health, Bankok, Thailand.Today I perform a necropsy of an emu. And I am totally surprised that I find a slit which is located at trechea.It is completely amazing to me. If you like to get those pictures,please sent an e-mail to jrattha@gmail.com

1:00 AM  

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