Western University of Health Sciences

Matt Wedel

A bunch of stuff, loosely organized by theme.

## Media

First up, I need to thank Brian Switek, who invited me to comment on
*Patagotitan* for his [piece at
Smithsonian](http://www.smithsonianmag.com/science-nature/did-scientists-just-unveil-biggest-dinosaur-all-time-180964443/).
I think he did a great job on that, arguably the best of any of the
first-day major media outlet pieces. And it didn't go unnoticed -- his
article was referenced at both the [Washington
Post](https://www.washingtonpost.com/amphtml/news/speaking-of-science/wp/2017/08/09/which-dinosaur-is-the-biggest-theres-a-new-contender-and-its-alarmingly-large/)
and
[NPR](http://www.npr.org/sections/thetwo-way/2017/08/09/542396807/this-could-be-the-biggest-dinosaur-ever-found-and-its-finally-got-a-name)
(and possibly other outlets, those are the two I know of right now). I
don't think my quotes got around because they're particularly eloquent,
BTW, but rather because reporters tend to like point-counterpoint, and I
was apparently the most visible counterpoint. They probably would have
done the same if I'd been talking complete nonsense (which, to be fair,
some people may think I was).

## Paleobiology vs Records

The most commonly reproduced quote of mine is this one, originally from
Brian's piece:

> I think it would be more accurate to say
> that *Argentinosaurus,* *Puertasaurus* and *Patagotitan* are so
> similar in size that it is impossible for now to say which one was the
> largest.

That may seem at odds with the, "Well, actually...\[pushes glasses up
nose\]...*Argentinosaurus* was still biggest" tack I've taken both in
[my post
yesterday](https://svpow.com/2017/08/09/dont-believe-the-hype-patagotitan-was-not-bigger-than-argentinosaurus/)
and on Facebook. So let me elaborate a little.

There is a minor, boring point, which is that when I gave Brian that
quote, I'd seen the *Patagotitan* paper, but not the Electronic
Supplementary Materials (ESM), so I knew that *Patagotitan* was about
the same size as the other two (and [had known for a
while](https://svpow.com/2014/05/19/the-new-argentine-titanosaur-was-about-the-same-size-as-the-biggest-argentinosaurus/)),
but I hadn't had a chance to actually run the numbers.

The much more interesting point is that the size differences between
*Argentinosaurus*, *Puertasaurus*, and *Patagotitan* are astonishingly
small. The difference between a 2.5m femur and a 2.4m one is negligible,
ditto for vertebrae with centra 59cm and 60cm in diameter. OMNH 1331,
the [biggest
centrum](https://svpow.com/2013/03/24/omnh-1331-is-my-new-hero/) bit
from the giant Oklahoma apatosaur, had an intact max diameter of 49cm,
making it 26% larger in linear terms than the next-largest apatosaur.
The centra of these giant South American titanosaurs are more than 20%
bigger yet than OMNH 1331, just in linear terms. That's crazy.

It's also crazy that these three in particular -- *Argentinosaurus*,
*Puertasaurus*, and *Patagotitan* -- are so similar in size. Dinosaur
developmental programs were 'messy' compared to those of mammals, both
in having [weird
timings](https://svpow.com/2016/02/18/dinosaur-life-histories-are-plicomcated/)
for things like onset of reproduction, and in [varying a
lot](https://svpow.com/2013/03/15/our-neural-spine-bifurcation-paper-is-out/) among
closely related taxa. Furthermore, sauropod population dynamics should
have been [highly
skewed](https://svpow.com/2016/02/27/giant-oklahoma-apatosaurus-mount-from-above/){target="_blank"
rel="noopener"} toward juveniles and subadults. So is the near-equality
in size among *Argentinosaurus*, *Puertasaurus*, and *Patagotitan* just
a coincidence, or does it mean that something weird was going on?
There's really no third option. I mean, even if some kind of internal
(biomechanical or physiological) or external (ecological, food or
predation) constraint forced those three to the same adult body size,
it's weird then that we're finding only or at least mostly near-max-size
adults. (If the available specimens of these three aren't near-max-size,
then any hypothesis that they're forced to the same size by constraints
is out the window, and we're back to coincidence.)

BUT

With all that said, the title of "world's largest dinosaur" is not
handed out for effort expended, number of specimens collected, skeletal
completeness, [ontogenetic
speculation](https://svpow.com/2014/09/05/brief-thoughts-on-dreadnoughtus/),
or anything other than "the dinosaur with the largest measured
elements". And that is currently *Argentinosaurus*. So although for any
kind of paleobiological consideration we can currently consider
*Argentinosaurus*, *Puertasaurus*, and *Patagotitan* to all be about the
same size -- and *Alamosaurus*, *Paralititan*, *Notocolossus*, and
probably others I've forgotten should be in this conversation -- anyone
wanting to dethrone *Argentinosaurus* needs to actually show up with
bigger elements.

So, if you're interested in paleobiology, it's fascinating and frankly
kind of unnerving that so many of these giant titanosaurs were within a
hand-span of each other in terms of size. *Patagotitan* is one more on
the pile -- and, as I said yesterday, exciting because it's so complete.

But if you want to know who holds the crown, it's still
*Argentinosaurus*.

## Humeri

In a
[comment](https://svpow.com/2017/08/09/dont-believe-the-hype-patagotitan-was-not-bigger-than-argentinosaurus/#comment-154962)
on the last post, Andrea Cau made an excellent point that I am just
going to copy here entire:

> Even *Paralititan stromeri* humerus is apparently larger than
> *Patagotitan* humerus (169 cm vs 167.5 cm). I know humerus length
> alone is bad proxy of body size, but at least this shows that even in
> that bone *Patagotitan* is just another big titanosaur among a well
> known gang of titans, not a supersized one.

That made me want to start a list of the longest sauropod humeri. Here
goes -- if I missed anyone or put down a figure incorrectly, I'm sure
you'll let me know in the comments.

- *Giraffatitan*: 213cm
- *Brachiosaurus*: 203cm
- *Ruyangosaurus*: 190cm (estimated from 135cm partial)
- *Turiasaurus*: 179cm
- *Notocolossus*: 176cm
- *Paralititan*: 169cm
- *Patagotitan*: 167.5cm
- *Dreadnoughtus*: 160cm
- *Futlognkosaurus*: 156cm

Admittedly the *Patagotitan* humerus is from a paratype and not from the
largest individual, but that is true for some others on the list,
including *Giraffatitan*. And we have no humeri from *Argentinosaurus*,
*Puertasaurus*, and some other giants.

## Dorsal Vertebrae

A couple of further thoughts on how the dorsal vertebrae of
*Patagotitan* compare to those of *Argentinosaurus*. First, now that
I've had some time to think about it, I have a hard time seeing how the
dorsal polygon method used by Carballido et al. in the *Patagotitan*
paper has any biological meaning. In their example figure, the polygon
around the *Puertasaurus* vertebra is mostly full of bone, and the one
around *Patagotitan* has a lot of empty space. It's easy to imagine an
alternative metric, like "area of the minimum polygon actually filled by
bone", that would lead to a different 'winner'. But that wouldn't mean
much, either.

Something that probably does have a real and important biomechanical
meaning is the surface area of the articular face of the centrum,
because that's the area of bone that has to bear the compressive load,
which is directly related to the animal's mass. The biggest
*Patagotitan* centrum is that of MPEF-PV 3400/5, which is at least a
local maximum since has smaller centra both ahead and behind. The
posterior face measures 59cm wide by 42.5cm tall. Abstracted as an
ellipse, which may not be perfectly accurate, those measurements give a
surface area of (pi)(29.5)(21.25)=1970 cm\^2. For *Argentinosaurus*, the
largest complete centrum has a posterior face measuring 60cm wide by
47cm tall (Bonaparte and Coria 1993: p. 5), giving an elliptical surface
area of (pi)(30)(23.5)=2210 cm\^2. (I'd use hi-res images of the centra
to measure the actual surface areas if I could, but AFAIK those images
either don't exist or at least have not yet been made public, for either
taxon.) So although the *Argentinosaurus* dorsal seems like it is only a
bit bigger in linear terms, it's 12% larger in surface area, and that
might actually be a meaningful difference.

## Cervical Vertebrae

One thing I haven't commented on yet -- *Patagotitan* is the newest
member of the "world's longest vertebrae" club. The longest
*Patagotitan* cervical, MPEF-PV 3400/3, is listed in the ESM as having a
centrum length of 120cm, but it's also listed as incomplete. In the
skeletal recon in the paper, the centrum is colored in as present, but
the neural spine is missing. So is the centrum complete in terms of
length? I don't think it's clear right now.

Anyway, here's the current rundown of the longest cervical centra of
sauropods (and therefore, the longest vertebrae among animals):

- BYU 9024, possibly referable to *Supersaurus* or *Barosaurus*: 137cm
- Price River 2 titanosauriform: 129cm
- OMNH 53062, *Sauroposeidon* holotype: 125cm
- KLR1508-77-2, *Ruyangosaurus giganteus* referred specimen: 124cm
- MPEF-PV 3400/3, *Patagotitan* holotype: 120cm (+?)
- MPM 10002, *Puertasaurus* holotype: 118cm

You may be surprised to see the Price River 2 cervical in there. It was
reported in an SVP abstract a few years ago (I'll dig up that ref and
update this post), and Mike and I saw it last year on the
[Sauropocalypse](https://svpow.com/category/travel/sauropocalypse-2016/).
We measured the centrum at 129cm, making it just a bit longer than the
longest centrum of *Sauroposeidon*, and therefore the second-longest
vertebra of anything ever.

Aside -- I'm probably getting a reputation as a big ole meanie when it
comes to debunking "world's largest dinosaur" claims. If I'm willing to
take the lead in kicking *my own dinosaur* down the ladder, don't expect
me to be kind to yours. I follow where the numbers lead.

Now, here's an interesting thing -- now that *Sauroposeidon* is coming
out as a basal titanosaur, rather than a brachiosaur, it might not have
been a [skinny
freak](https://svpow.com/2009/08/07/how-tallweird-was-sauroposeidon/).
The 120cm cervical of *Patagotitan* makes the 125cm cervical of
*Sauroposeidon* and the 129cm cervical from Price River 2 look even more
tantalizing. Maybe it's super-giant sauropods all the way down.


A bunch of stuff, loosely organized by theme. Media   First up, I need to thank Brian Switek, who invited me to comment on
<em>
 Patagotitan
</em>
for his piece at Smithsonian. I think he did a great job on that, arguably the best of any of the first-day major media outlet pieces.

Some further thoughts on <i>Patagotitan</i>

This will be all too short, but I can’t let the publication of a new giant sauropod pass unremarked.

Fowler_20100105.vp

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Rogue Scholar Beiträge

Some further thoughts on Patagotitan

Notocolossus is a beast