Giant theropods: North vs South

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Ok, wading into the always contentious issue of who was the biggest (which on 'teh internetz' seems to loosely translate into "who was more awesome?") I'm presenting my analysis of the always popular Tyrannosaurus vs Giganotosaurus issue.

A few things worth noting:

1) It appears that the type specimen of Giganotosaurus is essentially the same size as Sue despite having a somewhat longer femur. This is sort of surprising, since T. rex is generally thought of as having longer legs (in reality Sue simply has a proportionately longer lower leg relative to her upper leg, not longer legs overall).

2) We really don't know which of the two was longer, as there is enough of a margin of error in restoring tail lengths that the margin of error could allow either one to eek out a "who's the longest" win here (we're ignoring other theropods for the time being). A good discussion on this topic can be found here: [link]

3) Sue almost certainly had a higher mass than the Giganotosaurus type specimen, as tyrannosaurs seem to have broader torsos for their size.

4) So...that large isolated Giganotosaurus jaw? It's not really clear how much bigger that individual is, because there isn't perfect linear scaling between it and the type specimen (the isolated jaw is proportionately a bit deeper). My "best fit" version appears above, and indicates an animal about 6.5% longer than the type. THat would result in an animal over 13 meters in length, and also one that would be heavier than Sue.

5) Yes, I know there are also fragments of even larger T. rex specimens. Unfortunately things like toe bones are even harder to try and scale up reliably, so I haven't attempted it (also I really would want to see the things first hand before I tried it).

6) So in conclusion, between the specimens that are well enough known to estimate reliably, Tyrannosaurus and Giganotosaurus are about the same length, and T. rex was probably a bit heavier. The big jawed Giganotosaurus appears to be from a larger animal, but the nature of fragmentary specimens being what it is you simply aren't going to get to know which species was "truly the biggest". 

Sorry, the data just doesn't allow this sort of thing to be done conclusively at this point in time, no matter how much we wish it were otherwise.

 

Ornithomimus had wings...as an adult

Just a quick note, because today we got one of the cooler new papers on dinosaurs to have been published in quite a while, describing not one but three specimens of Ornithomimus with feathers.

And not only are there three specimens, but they are of different ages, and it turns out the feathers change as Ornithomimus grows up. In particular, the adults seem to have large wings with branching feathers on them, while the juveniles are covered only with the dinofuzz that we have become familiar with in the Chinese dinosaurs we have come to know and love.

This also pulls protowings further down the family tree - prior to this we only had definite wings in those wacky oviraptorids, deinonychosaurs (the various "raptor" dinosaurs), and those critters on the main bird line.

So for those of you who illustrate the fleet-footed ornithomimids, you may need to alter some of the images. It also brings up some interesting questions regarding what the feather condition is in alverasaurs (which may have been ant-eaters) and the bizarre therizinosaurs. Specimens of the basal therizinosaur Beipiaosaurus have been found covered in dinofuzz and non-branching plumes, but not with true branching feathers, so it was assumed that the origin of wing-like structures must have happened closer to birds. Now it appears that was wrong, and we will have to try and figure out whether therizinosaurs lost them at some point during their evolution, or if perhaps the Beipiaosaurus specimen might have been too young to have developed them.

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There will also be questions about what those feathers were doing in such animals, which clearly did not fly or live in trees (and equally clearly did not evolve from flying or tree-dwelling ancestors); alas that will have to be another post. In the mean time, there are a couple other fun implications to consider from this paper:

1) The Ornithomimus specimens are from fluvial deposits; for those non-geologists out there all you need to know is that most dinosaur deposits around the world are fluvial, so this discover means we will have a lot more museums taking a closer look at their specimens, rather than assuming that feathers can't be preserve outside of a few special depositional settings. In other words, there are going to be a lot more discoveries in the coming years now that more people know what to look for.

2) Along those lines, not all of the feathered dinosaurs are from China anymore. Having been to China and seen many of the specimens personally this never was a big deal to me, but for the couple of stragglers that simply didn't want to believe in feathered dinosaurs, this should end any sort of conspiracy theory.

3) Looking at the already-decided debate about whether birds are dinosaurs, I can't really say that this is the final nail in the coffin - realistically all of the nails were pounded into that coffin years ago. But this discovery makes sure there is a large concrete memorial placed on top of the coffin preventing it from ever being dug up again, and for those of you who lived through the original birds are dinosaurs wars that has to be comforting.

If you have any thoughts or questions be sure to leave them below. And for the paleoartists out there, go forth and illustrated winged adult ornithomimids. Here is a skeletal to get you started:

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Zelenitsky, D., Therrien, F., Erickson, G., DeBuhr, C., Kobayashi, Y., Eberth, D., Hadfield, F. 2012. Feathered non-avian dinosaurs from North American provide insight into wing origins. Science. 338, 510-514

Terrible Claw!

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I haven't been posting much lately, so I thought I'd at least put up this skeletal I finished over the weekend...

It's Deinonychus antirrhopus, the quintessential "bird-like" dinosaur that John Ostrom discovered in the 1960s. More than any other discovery. it is responsible for sparking the Dinosaur Renaissance of the 1960s and '70s. Bob Bakker's illustration of Deinonychus for Ostrom's monograph is probably the single most famous piece of paleo art ever produced (although it looks awfully cold in its featherless nudity!).

Deinonychus was my favorite dinosaur for a lengthy portion of my childhood, so it was a lot of fun working on this skeletal - the closest thing that technical illustration has to a stroll down memory lane (for me at least).

There are a couple of unpublished specimens floating around, but this skeletal is based almost entirely on the Yale Peabody Museum and AMNH specimens that compromised Ostrom's original papers. Happily there is enough overlap that I don't anticipate any large changes.

The two biggest questions I see are how retroverted the pubis is - I did not restore the pelvis with the more extreme Velociraptor-like backsweep seen in some reconstructions, but until an articulated pelvis is published we won't know the exact angle. Also, I'm not entirely sure whether the curve on the ventral margin of the jugal of YPM 5210 is natural, or due to being a bit squished.

Hopefully new specimens will clear those points up soon. The good news is those are fairly minor changes to make if necessary. In the mean time, I'm off to work on more skeletals, as well as preparing for my upcoming course on advanced creature design, which is now officially open to registration.

I'm teaching an online course on anatomy

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So it turns out I haven't vanished (and actually have a lot of new content to share) but I've been swamped working on several projects of late. One of them I'd like to share, for those of you who really like dinosaurs but actually have different job aspirations:

I'll be teaching a course for Visualarium, one of the leading educational resources for visual effects artists (and artists in training) that use Pixologic ZBrush. The class is Advanced Creature Anatomy, and rather than being on dinosaurs (although you'll see some of them!) it centers on learning enough comparative anatomy from living and extinct animals to develop your own mental toolkit of concepts you can apply when to design more plausible speculative anatomy for fictional creature design.

I'll do my best to keep it fun, so if ZBrush and 3D art is your thing, I invite you to check it out; we'll be conducting a free webinar this Thursday so people can get a taste of what the course will be like.

Yup, the OK Apatosaurus is freakin' huge!

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How big did Apatosaurus get? Well, that gray silhouette that is being dwarfed in terms of bulk there is Supersaurus vivianae. So yeah, that's one big honk'in sauropod...

The genesis of this post comes courtesy of a Matt Wedel post over at the excellent SV-POW! blog, where he was taking a look at the size of the partial Apatosaurus specimen preserved in Oklahoma, specimen OMNH 1670. Matt took a measuring tape to the OMNH specimen himself, and it measures up at a whopping 135 cm (for those of you who don't know the metric system, 135 centimeters is equal to one really big vertebra...).

But Matt really caught my attention when he stated:

...so the big Oklahoma Apatosaurus was probably in Supersaurus territory, mass-wise, and may have rivaled some of the big titanosaurs.

 

A younger me carving a pedal ungal. Look at that hair - what a hippy!

A younger me carving a pedal ungal. Look at that hair - what a hippy!

Supersaurus is an animal near and dear to my heart - it's an animal I've literally shed blood over. Yes really. In addition to working with my coauthors on a description of the second specimen of Supersaurusj and a reassessment of diplodocid phylogeny, we also had to produce a full mount of the animal under exceedingly tight time constraints. As with many small museums this meant we all had to pitch in, and that included learning how to sculpt missing bones. Near the very end of the project, while getting by on little more than 2 hours of sleep and coffee doses that would kill a small horse, I had a very small boo-boo with a carving knife (see photographic evidence at right). No stitches were necessary, and thankfully no sauropods where injured in the process.

The end result of our work was a mount that received top billing in a temporary exhibit in Japan in summer 2006. While the estimated length of 34 meters and mass estimate of 36-40 tonnes is smaller than some of the more sensational numbers that have been floated in popular books (and of course the internet), we suggested in our paper that many of those estimates were, shall we say... extravagant. Supersaurus appears to be close to the longest animal whose length can be reliably estimated (read: not counting Amphiceolias fragilimus), though it was lighter than the giant titanosaurs.

Given my personal stake here I wasn't about to take Matt's vicious maligning of Supersaurus  on faith. But - and this is the darndest thing about science - the facts are on his side. After scaling the fourth dorsal of Apatosaurus louisae up to the appropriate size, it turns out that the thing definitely is bulkier than Supersaurus.

 And if you try it with the other species of Apatosaurus (to whit: A. ajax and A. excelsus), it turns out just as bad - or worse in the case of A. ajax, who seems to have a proportionately shorter D4, which in turn leads to a larger animal when it's scaled to 135 cm.

Of course Supersaurus still looks to be longer by a fair amount, in large part due to the highly elongate neck. But when it comes to moving the dial on a scale, it's clear that Apatosaurus is just more sauropod than Supersaurus. Oh well Jimbo, we'll always have Japan...

Fishing at Dawn

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Unenlagia comahuensis looking for fish at dawn.

What can I say, it's been over a year since I tried my hand at something more artistic than a muscle or skeletal reconstruction. I did the sketch over a year ago, and had it ready to go (it's a digital painting in Photoshop), so I decided to give it a crack and it fell into place a lot faster than I'd expected (most of the time was spent painting water detail).

I've reconstructed Unenlagia as somewhat less ecologically specialized than it's relatives Buitreraptor and Austroraptor, but fishing nonetheless. I don't really have a lot more to say about it - we'll get back to more hard core skeletal stuff soon, I promise! If you have any questions about the process I used I'll do my best to answer in the comments section.