Pages

Thursday, April 11, 2019

A Beautiful New Dunkleosteus model from Mojo


Review: Mojo Dunkleosteus
By Matt Bille



As founder of the coolest site on FaceBook and a fanatical Dunkleosteus terrelli fan, I am pleased to report the newest Dunk on the market is a beautiful model.  At under 8 inches long, it’s about the same size as the Safari dunk but smaller (and less expensive) than the CollectA Dunk I consider the gold standard for mass-produced models.  It has no articulated parts but is done in a swimming pose that, added to careful detailing, gives it a lifelike appearance.  As with the CollectA fish, this is clearly an organic living creature, unlike some Dunk illustrations we’ve all seen that look like an armored head with the boring parts sort of stuck on. 
I need to start with the usual disclaimer: I’m not an ichthyologist, paleontologist, or (God knows) an artist. So my comments are thoughts and suggestions, not a hard-science critique. I have messaged the maker twice to ask questions and never heard back, so let’s go. 
The handsome green and yellow body with some countershading, a little reminiscent of a speckled trout, is plausible and looks great. It resembles Charles R. Knight’s classic painting of the critter.  As in most Dunk models, the artist set the rounded dorsal fin well back on the body.  The mouth is open, as is the law for all Dunk models (why make them if you don’t show off God’s own staple remover)?  The biting plates and head look great, although the sclerotic rings might have been set half-a-millimeter deeper.
There comes a point in any Dunk modeler’s life where he or she must make judgement calls, and some of the ones on display here are especially interesting.  The striations or folds on the body, indicating the allowance for movement by the skin, are carried considerably further back (all the way to the region of the anal fin), than in most Dunks. Indeed, most models either show these only at the cephalic joint (as with the with CollectA) or not at all.  No one has enough information to say “this is what Dunk skin looks like," so let's accept it as a maybe. The striations are sculpted, as every bit of this model (such as the fin rays) is, with precision. This Dunk has none of the pebbly-osteoderm-laden appearance of the CollectA or Schleich types, and no hint of the very large scutes on the Schleich model (the online information for a seller of that Dunk says, "authenticated model by the paleontologists of the Museum of Natural History," but I really would like to ask that artist about the scutes). 
The paired fins show the “wrists” reaching out further from the body than in all the other models I have.  There are illustrations of D. terrelli showing it this way, but they are definitely in the minority. However, we don’t have a Dunk fin, nor the cartiliginous skeleton of one, nor the outline of one, and some articles describe the pectoral fins as stenobasal (narrow based), so again the choice is reasonable. The pectoral fins are set a bit further back than the CollectA artist chose to place them.
On the tail, I do have strong opinions. I’ve never liked the symmetrical or almost-symmetrical eel-like tail idea: it just doesn’t seem to have enough surface area for the speed and maneuverability this heavily armored predator needed to catch prey like sharks. The most recent paper on this plumped for a more heteroceral tail, which I think more likely to be correct.  But we don’t KNOW this for sure, and some specialists still think this type of model is accurate. You could say the tail here is eel-like with just enough asymmetry to hint Dunk evolution might have started on the path to a more prominent upper lobe when the Frasnian-Famennian extinction event punched the arthrodires in their armored noses and the Hangenberg event left them on the bone heap of history.  I am also not a hydrodynamicist, but I know something of aerodynamics, so I’m big on control surfaces, given that the fins and tail had to propel/maneuver a head and forebody that by itself could weigh a ton.
The bottom line is that I don’t think anything, except perhaps the tail, is wrong with this Dunk, and again it’s just gorgeous.  Artists and scientists have many different interpretations of the species’ body plan and appearance, and unless we find impression fossils of something closer to the Dunk than its ubiquitously-cited little cousin Coccosteus, it’s going to stay that way. You might say it's now my favorite small model: the Safari Dunk is lovely, too, but this has more texture, and I think the dorsal armor on the Safari goes a little too far back, to where it might impede vertical movement.)  This is a great toy and display model, and, selling at only $11.95 on Amazon, a major addition to anyone’s lineup.


Photos by Matt Bille, Mojo and CollectA Dunkleosteus
(use of Steve Brusatte's superb book on dinosaurs is meant as a homage and is not an endorsement)






References: 


Lauren Cole Sallana and Michael I. Coatesa,”End-Devonian extinction and a bottleneck in the early evolution of modern jawed vertebrates,”  PNAS, https://www.pnas.org/content/107/22/10131

Neil Shubin, et. al., “The pectoral fin of Tiktaalik roseae and the origin of the tetrapod limb,” 2006, Nature volume 440, pages 764–771

Zerina Johanson, “Vascularization of the osteostracan and antiarch (Placodermi) pectoral fin: similarities, and implications for placoderm relationships,” Lethaia, 02 January 2007, https://doi.org/10.1111/j.1502-3931.2002.tb00077

"Dunkleosteus Schleich Dinosaur Scale Model," https://www.dinosaurcorporation.com/dunkleosteus2.html

G. C.Yioung, “The relationships of placoderm fishes,” September 1986, Zoological Journal of the Linnaean Society,  https://doi.org/10.1111/j.1096-3642.1986.tb00876 

No comments:

Post a Comment