Tuesday, August 12, 2014


If not Sue, then which Tyrannosaurus rex specimen is the most important to science? That title goes to the type (name-bearing) specimen that in biology serves as the comparative point of reference for a species. For T. rex that distinction is held by CM (Carnegie Museum) 9380, an incomplete skull and skeleton of an adult. Image modified from Osborn (1906).

The tagline for the film Dinosaur 13 hits an all-time low note with the outrageous claim that the T. rex specimen nicknamed ‘Sue’ is “one of the greatest discoveries in history”.  The complete lack of irony or humor in this comical declaration is intended to give leaden gravitas to the fulcrum of its moral fable. This exaggeration has to be put in perspective.

Historically, Sue doesn’t rate the most important T. rex ever found – that title goes to the type (name bearing) specimen, CM (Carnegie Museum) 9380, the defining specimen for the species. That specimen is represented an incomplete skull and skeleton of a very mature adult, and it is the subject of a series of articles penned in the early twentieth century by Henry Fairfield Osborn, the paleontologist who coined the name T. rex and who first defined and described the species.

In comparison with CM 9380, and the slew of T. rex specimens collected since 1906, Sue is a run of the mill, relatively young adult T. rex, with a badly crushed skull. Sue’s scientific importance comes from the fact that it is relatively complete, which helps to capture the osteology of the species and sort out signal from noise. Signal is nonrandom variation that is informative with regard to evolution and growth, whereas noise is random variation that is minimally informative. However, signal cannot be identified in isolation, and even spectacular specimens like Sue are virtually meaningless without comparison with other examples of the species.

The potential of Sue's importance was realized by the publication of Chris Brochu’s excellent monographic description (2003) of the skull and skeleton, which transformed Sue into a reference specimen for the species that supplements the incompleteness of the type. Without that treatment, Sue would be no better than a toothsome (and very expensive) adornment to Stanley Field Hall. Sue’s importance comes from its documented information content; but that was an artifact of the vagaries of history - there are plenty of other T. rex specimens that could have received the close documentation that Sue did

The bottom line, really, is that all T. rex specimens are equally important since each of them brings to light unique sets of information that collectively capture the biology of the species. Even without the descriptive treatment that Sue received, all T. rex specimens are vital to science. The fossils are analogous to frames of film that capture aspects of a continuum only understood when taken together, in contrast to individually definitive snapshots.

In this view, it is easy to see that the tagline is absurdly grandiose; it seems to say that this slightly better than average T. rex specimen is shoulder to shoulder with, say, the laws of gravity and superposition, or with the theories of relativity and evolution by means of common descent. If not any of those, it also implies Sue is toe-to-toe with the discovery of the Americas, the wheel, the red shift of distant galaxies, or the constancy of radioisotopic decay.
Regardless, it is a claim that will not snow the historians of the future who, with untarnished clarity, upon watching this screed upon a mote on the legal landscape, they will discover the thinnest of smokescreens intended to obscure the real issue that plagued vertebrate paleontology from the late Twentieth Century to the early Twenty-first Century, namely the sale of fossils by amateurs out of the hands of science. In that light, the overreach of the tagline is sufficient to impart a rose tint to the jadest cheek, present or future.

References cited

Brochu, C.A. 2003. Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Society of Vertebrate Paleontology Memoir 7: 1-138.

Osborn, H.F.  1906.  Tyrannosaurus, Upper Cretaceous carnivorous dinosaur (second communication). Bulletin of the American Museum of Natural History, 22:281-296.