There’s a trope in media whereby using a famous figure for advertisement, viewers have a tendency to associate that figure instead of anything the advertisement might actually contain. Celebrity sells. In American comics, for example, this is called “Wolverine Publicity,” when Wolverine (famous character from the X-Men series) has appeared in advertisements or on the covers of issues in which he is not actually present. Tyrannosaurus rex (or as a proxy, tyrannosaurids) is paleontology’s own Wolverine. In fact, it is responsible enough for media advertisement and dinosaur-based publicity that we can call this “Tyrannosaurus Publicity.”
Recently, I myself bowed to this level of publicity by stating “While the news is abuzz about new things in the paleontological circles (a new South American tyrannosaurine [which has yet to be published]” for which I was promptly (and rightly) chastised by Dr. Tom Holtz. At this time, the animal in question (now published as Bicentenaria argentina) was undescribed. No, Bicentenaria argentina is not a tyrannosaurine, or even a tyrannosauroid; it could be something cooler.
But the problem is further promoted by the use of “Tyrannosaurus rex” or “Velociraptor” to bring some level of pop-cultural reference to the casual reader. Not only is this practice common, it can be pretty egregious.
“You don’t need to look further than the headlines to see that the great Cretaceous predator has become the standard by which almost all of prehistory is judged. Dunkleosteus – a Devonian armoured fish – ‘had [a] bite stronger than a T. rex‘; the invertebrate Hurdia was heralded as the ‘T. rex of the Cambrian period‘; and, despite having a different shape, Colombia’s fossil snake Titanoboa was said to be ‘as big as T. rex‘.
I’m almost convinced that there is a journalism guide that advises: ‘If a catchy headline doesn’t readily present itself for a new fossil discovery, a reference to T. rex will do at a pinch.'”
In some of these cases, it is because the press-release that accompanies the release of the paper in which these studies come from end up using Tyrannosaurus on their own. It is a way for the public to both grasp the quality of the animal being talked about — and sometimes, that’s the only way to talk abotu a fossil comprised of a partial foot, or a fragment of hand, or a small piece of the skull — and become more excited and spread the concept of dinosaurs as more and more accessible. Not the province of white lab-coated geeks whose eyeglasses are tapped up and who go nowhere without a clipboard. The film Jurassic Park did much to help romanticize the actual experience of field work, which is often sustained in harsh, unyielding and unpleasant conditions. Paleontologists have had to become more media savvy and work to shuck the concept that they are always lab-coated nerds.
Granted, paleontologists do wear lab coats sometimes, but for the most part it’s denim and plaid — and instead of a clipboard, it’s a cold beer at the end of a nice 14-hour field-scouring, dig and jacketing session.
Bicentenaria argentina was recently described by Fernando Novas and a host of colleagues [n1], and I am fortunate to now have a copy of the paper, which firmly disavows the suggestion of some media that this was in any way a “close relative” of anything. Instead, lead-author Dr. Fernando Novas’ press release, which stated “Scientists in Buenos Aires have unveiled a new species of dinosaur related to the giant Tyrannosaurus, the smaller Velociraptor and existing birds[,]” is quite correct:
Here, note that Bicentenaria is not, in fact, directly ancestral to either group, but rather to both. Novas, it turns out, is quite correct. But then, he knows his stuff (he was one of the pioneers who worked to bring standard phylogenetic analysis of dinosaurian species to the mainstream, following in Jacques Gauthier’s footsteps). It should be noted that this phylogeny is limited: it is not as complete as some other recent phylogenies presented seeking to resolve the coelurosaurian tree, but it helps demonstrate the work Novas and others had available from which they could then say things like it is “a new species of dinosaur related to the giant Tyrannosaurus, the smaller Velociraptor and existing birds.” Quite correct, if a little vague.
Yet, still … we rely too heavily on using Tyrannosaurus rex as though it were a yardstick. As Brian says, “our reliance on the tyrant becomes more problematic in stories about its dinosaurian kin. Upon making its debut last January, the early dinosaur Eodromaeus was dubbed the ‘earliest knownT. rexrelative‘, and, a few weeks later, the bizarre dinosaur Linhenykus was presented as a ‘one-fingered T. rex relative‘.”
As we discover more animals like Juravenator starki, Sciurumimus albersdoerferi, Bicentenaria argentina, Zuolong salleei, messing around with what taxa are at the base of Tyrannosauroidea or are “compsognath”-grade taxa (my little despots and peons, if you will. Bicentenaria argentina comes in in the “peon” rank for basal coelurosaurs, the “if it looks like a compsognath, it can go anywhere” rank. This allows it much shifting about on the base of the coelurosaur family tree. It doesn’t help, sadly, that the material is so brief, but we have a remarkable quality of what’s there, including a larger section of skull than is typical for small theropods from the Cretaceous of Argentina.
Before I close, let me note on one particular aspect of this animal. Several skeletons are known, with the holotype (MACN 865) comprising only the posterior half of the skull, as seen above. The paratype (MACN 866) is comprised of at least four individuals and suggested by three large left femora and one small right femur, and several of these elements may belong to the individual which provided the rear of the skull.
Limb material is valuable, as this material helps up determine how the animal may have walked, run, or simply held its body. Certainly, with the advent of research from workers like Denver Fowler, it will also help us figure out some factors about how the animal hunted or preyed. In particular, the distal tibia is interesting because it has special evocations for taxa that have, in the recent literature, been pointed at oviraptorosaurian relationship.
Expecially, note the slender distal tibia, and the distinct medial expansion which forms the medial malleolus (im, above); a relatively shallow astragalar fossa on the cranial surface of the tibia; and the overall broad distal end. The astragalus is very circular in lateral and medial views, with a distinct cranially-offset condylar morphology, but rather than a broad, maniraptoriform-like ascending process instead the astragalus has a very narrow process. Moreover, the astragalus has an intricate set of cranial fossae and grooves between the condyles and at the base of the ascending process.
This evokes the morphology seen in animals that have been ascribed to Oviraptorosauria by some authors, such as the problematic tibia NHM R186 (e.g., Lydekker, 1891; but see Naish et al., 2001 and Galton & Molnar, 2005) which had been moved around a tad before settling into … confusion. Or, Kakuru kujani (which I mentioned here), described by Molnar & Pledge (1981) with positive resemblances to Avimimus portentosus (now considered an oviraptorosaur), but which recently has received a less than stellar — and somewhat dismissive — “nomen dubium” label by both Agnolin et al. (2010) and Barrett et al. (2010). Yet, the distal tibial morphology as seen in Bicentenaria argentina seems to consistently find itself in basal coelurosaurs, or “generalized” tetanurans, which I am beginning to suspect are the same thing when it comes to where this morphology develops (that is, coelurosaurs less derived than the tyrannosaur, ornithomimosaur and oviraptorosaur-dromaeosaurid-troodontid-bird groups, and this likely basal within each of those lineages.
Now, I’m going to go out on a limb here and even make the questionable presumption that we’re going to find a lot more basal coelurosaurs in the “Peon” category that are going to have rather birdy-ankles. These will include basal ornithomimosaurs, basal oviraptorosaurs, basal paravians (that’s dromaeosaurs, troodontids and birds), basal tyrannosaurs, basal therizinosauroids, and so forth. All will have some large measure of combinations of the following features of the ankle:
1. Tibia with narrow diaphysis, broad epiphysis (that’s a slender shaft, but a significantly broader distal end where the astragalus articulates);
2. Tibia has a distinct medial malleolus with a sharp proximal “shoulder”;
3. Tibia with a shallow triangular distal aspect, maybe even a slightly turned “shoulder” when viewed distally, but not narrowly rectangular and not broadly triangular.
4. Tibia with a very shallow, almost definition-less facet for the astragalus. This should not indicate that there is no ascending process, but that there is not distinct fossa, or notch, or the astragalus’ ascending process.
5. Astragalaus with narrow, rather than broad, ascending process, meaning there will be either a) medial offset, so that the ascending process apex is medially situated and the medial marging of the ascending process is vertical but not slanted; b) a lateral offset, in which there is a slot between the fibula (if present), the lateral margin of the tibia, and the lateral margin of the ascending process; or both.
6. Astragalus with a cranial surface “ornamented” with grooves and fossae; specifically, a fossae occupies the craniodorsal “corner” between the top of the condyles and the ascending process, and a groove or more crossing transversely between and above the medial and lateral condyles.
7. Astragalus condyles are cranially offset, and thus rather than ventrally placed or cranioventrally placed, they are almost exclusively cranially placed.
I find that the morphology seems remarkably similar to the ankles of alvarezsaurians, even derived ones, but also to the other taxa I’ve already mentioned, and thus may be a hint that other theropod dinosaur ankles may be more coelurosaurian than previously considered. Thus, also that radical or strange relationships for some fragmentary specimens may not be required, whatever the similarities, and instead that the generalized anatomy may indicate merely that one has a generalized small coelurosaurian theropod. It also may suggest that the ankle may be less diagnostic of taxonomy than has been implied before.
[n1] I possess what is apparently a draft copy of the print publication for Novas et al., but it is marked as “impresso” (in press), though pagination and dating on the paper is secure. I do not know the precisely date of publication, but am publishing this post in the vain hope that this publication is “out,” and thus the name is not a nomen nudum. There is little fear of reprisal, as the journal that publishes this is not embargoed, but more certainly, this is provided courtesy of (but not directly from) the authors.
Agnolin, F. L., Ezcurra, M. D., Pais, D. F. & Salisbury, S. W. 2010. A reappraisal of the Cretaceous non-avian dinosaur faunas from Australia and New Zealand: evidence for their Gondwanan affinities. Journal of Systematic Palaeontology 8(2):257-300.
Barrett, P. M., Kear, B. P. & Benson, R. B. J. 2010. Opalised archosaur remains from the Lower Cretaceous of South Australia. Alcheringa 34:293-301.
Galton, P. M. & Molnar, R. E. 2005. Tibiae of small theropod dinosaurs from Southern England. pp3-22 in Carpenter (ed.) The Carnivorous Dinosaurs. Indiana University Press (Bloomington & Indianapolis).
Lydekker, R. 1891. On certain ornithosauria and dinosaurian remains. Quarterly Journal of the Geological Society of London 47:43-44.
Molnar, R. E. & Pledge, N. S. 1980. A new theropod dinosaur from South Australia. Alcheringa 4:281-287.
Naish, D., Hutt, S. & Martill, D. M. 2001. Saurischian dinosaurs 2: Theropods. pp242-309 in Martill and Naish (eds.) Dinosaurs of the Isle of Wight. Palaeontological Association Field Guides to Fossils, 10. Palaeontological Association (London).
Novas, F. E., Ezcurra, M. D., Agnolin, F. L., Pol, D. & Ortíz, R. 2012. New Patagonian Cretaceous theropod sheds light about the early radiation of Coelurosauria. Revista del Museo Argentino de Ciencias Naturales 14(1):57-81.
Perle A., Norell, M. A., Chiappe, L. M. & Clark, J. M. 1993. Flightless bird from the Cretaceous of Mongolia. Nature 362:623-626.
Perle A., Chiappe, L. M., Rinchen B., Clark, J. M. & Norell, M. A. 1994. Skeletal morphology of Mononykus olecranus (Theropoda: Avialae) from the Late Cretaceous of Mongolia. American Museum Novitates 3105:1-29.