The Evolution of the Wubbanub

A few days ago, my friend Michael Sims came to me with a paleontological quandary. The question centered on a cute little dinosaur. Michael’s young son is currently enamored with a rattle and pacifier modeled after a horned dinosaur, but, Michael wanted to know, which dinosaur? What’s the exact genus of the Wubbanub?

The answer is simple enough. The “Okey Dokey Dino” has a frill and three horns – one over each eye, and one on the nose. That’s classic Triceratops. And, appropriately enough, the plush dinosaur seems to be a juvenile Triceratops.

In 2006, paleontologists Jack Horner and Mark Goodwin published a landmark paper on how dramatically the appearance of Triceratops changed as the dinosaur grew up. Indeed, contrary to the idea that baby dinosaurs were effectively tiny versions of adults that only got larger, Horner and Goodwin assembled a picture of dramatic change for Triceratops throughout the ceratopsid’s life.

As a baby, Triceratops was awkwardly adorable. The horns of the youngsters were small nubs, and their short frills were decorated by rounded ornaments called epiossifications. From there, the dinosaur took on a spikier appearance. Adolescent Triceratops had longer, backward-curving brow horns and sharper, arrow-shaped epiossifications set around an expanded frill. Then, as the herbivore approached adulthood, the brow horns remodeled to point forward, and those frill decorations flattened out. (Whether or not Triceratops continued to change after this point – taking on the form of the dinosaur traditionally called Torosaurus – remains a matter of investigation and debate.)

Within the bounds of Triceratops transformation, the fuzzy Wubbanub looks quite a bit like a juvenile. The toy’s horns are rounded little cones, and the brow stubs seem to curve ever-so-slightly backwards. So the Wubbanub might not be equivalent to the youngest Triceratops yet found, but the toy is pretty close to that infant – just old enough to see the subtle curve of horn that marks juvenile Triceratops.

Of course, this is assuming that the Wubbanub truly is a Triceratops. What if the toy is a unique dinosaurian genus, descended from the familiar Triceratops? (We’re 66 million years removed from the very last of the great horned dinosaurs, after all.) In that case, Wubbanub could be a case of neoteny – when on organism’s growth is slowed in such a way that adult animals retain juvenile traits. In fact, such a trend can be seen along the transition from non-avian dinosaurs to modern birds.

From Triceratops to the long-necked oddity Massospondylus and the ferocious Tyrannosaurus, many dinosaurs changed dramatically during their lives. But among birds – avian dinosaurs – babies look very much like adults and don’t undergo the same kinds of sweeping anatomical changes. As biologist Bhart-Anjan Bhullar and colleagues proposed in a paper published just last year, this may be because of a kind of neoteny that caused adult birds to retain traits seen in the juveniles of their non-avian dinosaur forerunners. Unfortunately, I don’t think I could actually publish a paper on “Neoteny in Wubbanubia” as Michael suggested, but the dinosaur pacifier inadvertently got one thing right – baby dinosaurs were adorable, big-eyed little critters that you didn’t have to be a mother Triceratops to love.

References:

Bhullar, B., Marugán-Lobón, J., Racimo, F., Bever, G., Rowe, T., Norell, M., & Abzhanov, A. (2012). Birds have paedomorphic dinosaur skulls. Nature. 487: 223-226

Horner, J., Goodwin, M. 2006. Major cranial changes during Triceratops ontogenyMajor cranial changes during Triceratops ontogenyMajor cranial changes during Triceratops ontogeny. Proceedings of the Royal Society B. 273, 1602: 2757-2761