How fat is an elephant?

May 29, 2013

We jumped the gun a bit in asking How fat was Camarasaurus? a couple of years ago, or indeed How fat was Brontosaurus? last year. As always, we should have started with extant taxa, to get a sense of how to relate bones to live animals — as we did with neck posture.

So here we go. I give you a herd of Indian elephants, Elephas maximus (from here):

056-Elephant-c-Gehan-de-Silva-Wijeyeratne-Minneriya-2004-07-27-165-Gathering

You will notice, from this conveniently-close-to-anterior view, that their torsos bulge out sideways, much further than the limbs.

Now let’s take a look at the skeleton of the same animal in the Oxford University Museum of Natural History (downloaded from here but for some reason the photo has now gone away):

4795746797_575d1f0ce6_b

The rib-cage is tiny. It doesn’t even extend as far laterally as the position of the limb bones.

(And lest you think this is an oddity, do go and look at any mounted elephant skeleton of your choice, Indian or African. They’re all like this.)

What’s going on here?

Is Oxford’s elephant skeleton mounted incorrectly? More to the point, are all museums mounting their elephants incorrectly? Do elephants’ ribs project much more laterally in life?

Do elephants have a lot of body mass superficial to the rib-cage? If so, what is that mass? It’s hard to imagine they need a huge amount of muscle mass there, and it can’t be guts. Photos like this one, from the RVC’s televised elephant dissection on Inside Nature’s Giants, suggest the ribs are very close to the body surface:

01020162576700

I’m really not sure how to account for the discrepancy.

Were sauropods similarly much fatter than their mounted skeletons suggest? Either because we’re mounting their skeletons wrongly with the ribs too vertical, or because they had a lot of superficial body mass?

Consider this mounted Camarasaurus skeleton in the Dinosaur Hall at the Arizona Museum of Natural History (photo by N. Neenan Photography, CC-BY-SA):

Camarasaurus_skeleton

Compare the breadth of its ribcage with that of the elephant above, and then think about how much body bulk should be added.

This should encourage palaeoartists involved in the All Yesterdays movement to dramatically bulk up at least some of their sauropod restorations.

It should also make us think twice about our mass estimates.

About these ads

9 Responses to “How fat is an elephant?”

  1. Dean Says:

    Perhaps 20% of torso mass could be missing? Although most non-titanosaurian sauropods are thought to be more narrow bodied than elephants, right?

  2. Matt Wedel Says:

    This should encourage palaeoartists involved in the All Yesterdays movement to dramatically bulk up at least some of their sauropod restorations.

    Should it? You seem to be jumping to this conclusion without solving what’s going on in elephants first.

    I think most museum elephants are just mounted incorrectly. As you point out, dissections show the ribs to be pretty close to the body surface, as I’d expect them to be in any non-blubbery mammal. Maybe John of the Freezers will drop by to confirm or deny.

    But barrel-chested elephants don’t tell us much about sauropods because the rib shapes are so different. Look at the mounted elephant above–the ribs are so rounded they could be segments of circles. Now compare to the MUCH straighter ribs on the mounted camarasaur. If this seems like a familiar observation, it’s because I wrote a whole post on it a while back. ;-)

    If anything, I think a lot of paleoartists make their sauropods too mammalian. I won’t name names, but I have seen some recent skeletal skeletal recons that in dorsal view are just as round as elephants, in complete contravention to what the bones show.


  3. A very interesting photo, but I should point out not all elephants look like this in anterior (or posterior) view. For instance: http://image.shutterstock.com/display_pic_with_logo/148102/148102,1270893864,3/stock-photo-a-tall-elephant-towers-above-the-photographer-50598679.jpg (anterior view of Loxodonta)

    http://www.johnlund.com/images/Elephant-Walking-Journey-Road.jpg (posterior view of Elephas)

    http://www.travelblog.org/Photos/343735 (Elephas charging)

    So I don’t think it is a clear cut case. Clearly some elephants have rib-cages that are much more portly, while others conform more to the way the skeleton above is mounted.

    However, what I have noticed in large herbivores is that generally-speaking, the widest part of the rib cage is usually no wider than the widest breadth of the ilia. See this top view image of elephants here for an example: http://www.elephantswithoutborders.org/images/tracking_view_from_the_top.jpg

    This is also how sauropods skeletons are generally restored (the widest part of the ribcage is generally on point with the widest part of the ilia). This appears to be true in the Camarasaurus mount as well as the ROM Futalognkosaurus mount as well.

    My rule of thumb when restoring sauropod rib-cages in top view is to make the ribcage about as wide as the ilia (more specifically, the preacetabular lobe).

    Also, like Matt said, sauropods are not elephants. I’d like to see a thoracic vertebra of an elephant compared it to a sauropod to see how similar the processes that articulate to the ribs are.

  4. Mark Robinson Says:

    Going to be a pedant and say that I think that the depicted elephants are actually Sri Lankan elephants, Elephas maximus maximus not Indian, E. maximus indicus. If you’re just talking about E. maximus, I think Asian/Asiatic is the preferred name.

    I agree that we should always look at extant animals for clues about extinct ones as long as we don’t get caught up with thinking that any of them are necessarily perfect analogues. Matt’s already mentioned how s’pod’s ribs (shape and articulation) are very different from large extant mammals so I’m not convinced that there is a lot more flesh/mass to add, as long as we’re not starting from a shrink-wrapped position.

    Still, I wouldn’t object if someone depicted a late cretaceous titanosaur larded-up on a seasonal feast of fruit and seeds (and perhaps drunk from fructose fermentation and belligerently taking on a carcharodontosaur).


  5. Elephant ribs definitely are close(ish) to the surface of an animal (i.e. the external rib surface on the side of the abdomen is no more than a couple centimeters deep). Look closer at that skeleton and the photo – the part that looks “fat” to you in front of the leg is actually not overlapping the ribs (remember that the ribs shorten dramatically going posterior into the lumbar region). As noted above, not all elephants look quite that well fed (e.g. http://images5.fanpop.com/image/photos/28700000/Elephant-elephants-28788754-1024-768.jpg ) so I’d guess that just like people elephants put on extra weight more quickly in the lower abdominal area that doesn’t directly overlap the rib cage.

    Even if sauropods did this it wouldn’t look exactly the same, as they lack a true lumbar region and generally have quite long ribs. On the other hand, almost all dinosaur mounts horribly mangle the ribs (usually mounting them like overgrown mammal rib cages) and in macronarians it does seem like when properly articulated the ribs do protrude out quite a bit – I oversaw the mounting of a Camarasaurus at the WDC which had the ribs mounted in this manner (the mount is now in Lyon, France I believe).

    Caution should probably be used when apply this to a group as broad as sauropods though – I’ve seen a lot of diplodocid ribs (and mounted my share) and they really seem to be more slab-sided; even within macronaria there is plenty of room for variation in other features (e.g. neck length and tail morph) so I’d hesitate to paint their ribs with a single brush.

  6. Heteromeles Says:

    Here’s a dumbass question: in the picture, are we seeing the rib-cage as the widest part of the body, or is it the belly and intestines behind the foreshortened ribcage? From the head-on angle of the photo, I can’t tell.

  7. brian engh Says:

    I don’t think there is an easy answer to the question of ‘how should we paleo-artists pose sauropod ribs?’ …especially if we don’t define what we are aiming to show with the reconstruction. Are we trying to show a resting, gently breathing animal? An inhaling sauropod with a full belly of gassily fermenting vegetation? A reared up sauropod reaching for a tasty morsel? As can be seen in the various elephant pictures all of these different scenarios and behaviors would affect rib posture, and it would seem to me that without being able to actually see the cartilage in the joints or how their lungs and guts were working in different situations, we can’t really be too sure (outside of really extreme joint-breaking posing, of course).

  8. Bryan Riolo Says:

    As is normal for you guys, great stuff! Looks to me, from my viewpoint, that the elephants’ ribs are close to the surface and that the museum mounts are correct. Maybe the gut area is bulging?

  9. Bryan Riolo Says:

    Been studying a bit. The gut is bulging past the ribcage and the limb elements. You can see the rib area and it does nothing to contradict either the skeleton mounts nor the dissection photo.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 421 other followers

%d bloggers like this: