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Re: Floatin' Ankylosaurs

Alrighty:

Jaime Headden said: 
  Now, given the anatomy of ankylosaurs, I suggested
that 1) the wide, flattened bellies formed perfect
floating platforms (here's to the crocs in _Frogger_)
that would have reduced yaw very nicely, like an
outrigger, in the abscence of a keel; 2) the extensive
gut and amble lungs of the ankylosaurs, as evidenced
by their ribcages and pelves, would have produced
ample bouyancy to counteract the negative bouyancy of
their more solid bones and especially (or possibly)
the armor ...

Hey, first off, I don't want you to think I'm pickin' on you. Now, here's an idea to test your hypothesis, although I'm not saying it's easy. Have you ever heard of a product called Sculpey? It's like a plastic modelling clay that turns into solid plastic when heated to about 300 degrees in a regular oven. I've used it to model forelimbs in sauropods with quite good success.

Why not make some different Sculpey models of different basic ankylosaur body types, leaving hollows for lung and gut space. How to determine gut space? Well, that will take a bit of reading and dissecting, but you may be able to come up with something somewhat realistic (restoring internal anatomy in very dead reptiles is very difficult and has nothing to do with your knowledge or artistic abilities). In any case, if you could get measurements of the various ankylosaur thoracic cavities and come up with a way to generate a standard gut and lung space, that might be all you need.

In any case, make these as simple or complex as you want, and see which float better and which don't. Maybe put them in a fish tank with a pump to simulate moving water? See if your yaw notion works. Do they float? -- now, of course, Sculpey does not have the same buoyancy as flesh and bone. I know wood has a Young's modulus (a measurement of the amount of bending a material can take before deforming and then breaking) close to that of bone, but I'm not sure about the buoyancy or density. You could look into that too. Run several trials altering different things each time? Time floatation and then run statistical tests to see if there are differences between body types and the time it takes for them to sink? The possibilities are limitless -- well, almost. =)

The trouble is, figuring these things out is tough crackers. Maybe if you computer modeled something ... ? There is a new program available for about $150 called Amorphium in which you "sculpt" three-dimensional objects in real time. I'm playing with it right now, but like anything it takes practice and time.

You said:
3) the fore- and hindfeet of ankies, while

not elongate in the form of the digits as in other
aquatic forms such as hippos, water-dwelling crocs,
etc., were nonetheless broad, and could have aided the
animals in swimming enterprises.

Well, sure, even elephants and horses swim when they have to, but it doesn't mean they normally do it on a regular basis. Take a look at the manus and pes of ankylosaurs again, and really compare it to 'gators and hippos -- there is a difference. The feet of ankies are similar in many respects to stegosaurs and ceratopsians. Would you, by the same token, suggest that they swam too? What about theropods, who have excellent feet for swimming (as far as long toes)? Did T. rex or 'raptors swim off in search of prey?

All I'm getting at is that, as with any paleobiological thing with dinos, it's not easy, which is why these sorts of studies are rarely undertaken or why most functional and locomotor stuff is generalized. Manipulating fossil material from big, heavy reptiles with poor joint articular surfaces and a tendancy to break when looked at wrong is a good reason why we are all still so ignorant about these issues.

I encourage you to investigate this further. Be skeptical of every idea you have as well as those of others! Ask yourself, are you looking for data to support your notion, or are you looking for data that would destroy your hypothesis? You should be doing the second one a lot. Maybe you're right -- maybe ankies did make a habit of being semi-aquatic. But if you want to get at the meat of this, try out some of these suggestions or come up with your own tests. Otherwise, we are both doomed to argue endlessly in circles about speculative matters -- leave that for the philosophers! =) As for me, I would join in you in this pursuit if I wasn't already banging my head against the humeurs of a sauropod!

Matt Bonnan



From: "Jaime A. Headden" <qilongia@yahoo.com>
Reply-To: qilongia@yahoo.com
To: dinosaur@usc.edu
Subject: Floatin' Ankylosaurs
Date: Mon, 2 Aug 1999 14:37:28 -0700 (PDT)

  I see I goofed somewhere along the line. let's try
this again. The prescence of ankylosaurids in Judith
River Wedge sediments, which are depositional in
nature and indivate an estuarine/deltaic environment,
shows that most likely, the fossils of
*Euoplocephalus* et al., were laid down after being
washed out in the surf, as it were, either from
elsewhere in the delta, or upstream.

  Now, given the anatomy of ankylosaurs, I suggested
that 1) the wide, flattened bellies formed perfect
floating platforms (here's to the crocs in _Frogger_)
that would have reduced yaw very nicely, like an
outrigger, in the abscence of a keel; 2) the extensive
gut and amble lungs of the ankylosaurs, as evidenced
by their ribcages and pelves, would have produced
ample bouyancy to counteract the negative bouyancy of
their more solid bones and especially (or possibly)
the armor; 3) the fore- and hindfeet of ankies, while
not elongate in the form of the digits as in other
aquatic forms such as hippos, water-dwelling crocs,
etc., were nonetheless broad, and could have aided the
animals in swimming enterprises.

  And this was all I suggested, or intended to,
anyway: ankylosaurs could swim, float along, etc.
rather than be confined to the land, especially in an
environment even _near_ a deltaic setting; sandy or
muddy substrate would still be a conflict to an animal
with the bearing of an ankylosaur, unless the animal
had a means of overcoming this problem, and that would
we swim across a channel, instead of flounder through
the muck. Getting through the muck to the water could
be problematic, but I merely suggest the capability.

  The broader ankylosaurids (as opposed to rounder
shamosaurids or nodosaurids) are found quite
prolifigately in these wetter environs. Now, as to the
mechanic capability of ankylosaurs swimming, this is
not so clear.

  Just to make sure, references for these comments and
assumptions are from Farlow and Brett-Surman (1997;
various chapters), Carpenter (1997), Coombs and
Maryanska (1990), Molnar (1980), and Maryanska (1977).

===
Jaime A. Headden

"May I lure us, ere the mote ends us?"

Qilong, the we---is temporarily out of service.
Please check back when the phone lines are no
longer busy.
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