Theropod envy?

When giving conference or public presentations, I often use the opportunity to take a swipe a theropods: after all, most of my career has been spent working on dinosaur herbivores, which often end up in the capacious guts of their carnivorous relatives. However, it's not because I genuinely hate theropods per se - some are amazing animals, and even though Tyrannosaurus is, without doubt, over-exposed and over-rated it is still a neat animal. I've even found myself working on theropods from time-to-time, though admittedly I still have a strong preference for the more diverse and disparate herbivores. The main reason I feel I have to insult theropods (and by extension theropod workers) is simply the hyperbole that surrounds these animals. A mouthful of sharp teeth, claws, and endless speculations over dino-celebrity death matches seems to get people weak at the knees, clouding all sensible judgement regarding new claims about their palaeobiology. Who really cares if one giant theropod was 50 cm longer than another? Such trivia has no real effect on our knowledge of theropod biology and evolution. Although the media might be blamed for fanning the flames of theropod adoration, this would be unfair - they simply give people what they want and there are plenty of people out there, both professionals and public, who idolize theropods in ways analogous to 'A'-list celebrities. This manifests every year at Society of Vertebrate Paleontology meetings, for example: theropod talks are often packed to the rafters (thanks mainly to work on feeding and behaviour: big fluffy killer death lizard syndrome), whereas the room feels distinctly emptier when similar talks start on herbivorous dinosaurs.

A cast of Giganotosaurus in the Museo "Carmen Funes" Plaza Huicul, Argentina

More seriously, this idolatry extends to scientific publication too. I'm frequently teased by colleagues in other disciplines about how easy it must be to get dinosaur papers into top journals like Nature and Science - after all, dinosaur papers appear in both venues regularly, despite the fact that dinosaur workers represent only a tiny fraction of scientists worldwide. However, while vertebrate palaeontology clearly punches above its weight in this regard, there is a bias - almost all dinosaur papers in these journals are on theropods, while the other two-thirds of dinosaur diversity do far less well (and analytical papers dealing with dinosaurs as a whole are exceptionally rare). These theropod papers generally fall into two categories - announcements of new dinosaurs with feathers, or some other aspect of the dinosaur/bird link - or discoveries of non-feathered theropods with potentially interesting palaeobiological features or geographical/temporal range extensions.

This is perhaps exemplified by the new paper in Science published last week on the iconic North African theropod Spinosaurus (Ibrahim et al., 2014). In this widely reported paper, the authors describe a new articulated skeleton of this animal and use it to update various aspects of the animal's anatomy. The hook for the paper was that Spinosaurus might have been a largely aquatic animal - and when not aquatic might have been quadrupedal - an unusual (and potentially interesting) adaptation for a theropod. This news flashed around the world on the media, Facebook and Twitter, with few critical voices. However, the hype generated by the release (in no small measure due to the heavy involvement of National Geographic) overlooks some important details.

Importantly, most dinosaur workers had already accepted that spinosaurs were probably unusual dinosaurs that did spend a lot of time in water. This was based on numerous lines of evidence:
1. Snout and tooth morphology: convergently looking like a crocodile and potentially engaged in croc-like feeding behaviour. Those teeth aren't for slashing, but could have been good at holding slippery prey;
2. Weird forelimbs: the big claws have long been suggested as tools for gaffing fish from the water, and it has even been suggested that the robust humerus might have been associated with quadrupedality;
3. Gut contents: the British spinosaur Baryonyx has fish remains in its gut contents (the only gut content known for a spinosaurid);
4. Oxygen isotopes: these suggest that spinosaurs ate far more aquatic prey than other dinosaurs and may have spent more time in/near water as a result;
5. Palaeoenvironments: the North African localities yielding Spinosaurus have long been though to be very wet - with wide meandering channels, which, coincidentally are full of big tasty fish.

This work was all done previously by palaeontologists going back to Strömer, most notably by Angela Milner, Alan Charig, Andrew Cuff, Emily Rayfield and colleagues in their work on Baryonyx and Spinosaurus (Charig & Milner, 1986, 1997; Cuff & Rayfield, 2013) and by the isotopic work of Romain Amiot and colleagues on Spinosaurus (Amiot et al., 2010), as well as numerous other less detailed accounts. Although these papers are cited in the recent Science contribution, they are not given due credit for establishing the idea of aquatic spinosaurs – the new observations made on the additional material are really only the icing on the cake for the story of spinosaur habitat preference. Moreover, doubts have emerged over the proportions of the new skeleton (see the excellent blog entry by Scott Hartman) and given the vagaries associated with the collection of the material (which was  collected by professional fossil dealers who did not  keep or provide detailed field notes to corroborate the association of the skeleton) additional assurances are needed to support the claims of the authors in the Science article. If the new specimen is genuinely associated and the problems noted thus far can be accounted for this would be a neat discovery (even if it is a theropod): a new, good specimen of an animal known otherwise from published images and isolated material. However, extraordinary claims merit extraordinary levels of evidence.


Given the foregoing I'm left wondering why the editors thought that this might be suitable for Science - a journal that wants to publish transformative research. Is it a new taxon? No. Does it tell us something distinctive about evolution or dinosaurs that we didn't know before? No. This is really a specialist paper, updating our knowledge of a single taxon that was named nearly a century ago, although one with an interesting history. My theory? It's a big scary theropod ... I doubt very much that anyone working on a new sauropod or ornithischian skeleton belonging to a named taxon would stand much chance of getting similar papers published. That's why I'm envious of theropods ...

References:

Amiot, R. et al. (2010). Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods. Geology 38: 139–142 doi:10.1130/G30402.1.
Charig, A. J. & Milner, A. C. 1986. Baryonyx, a remarkable new theropod dinosaur. Nature 324: 359–361.
Charig, A. J. & Milner, A. C. (1997). Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey. Bulletin of the Natural History Museum London 53: 11–70.
Cuff, A. R. & Rayfield, E. J. (2013). Feeding mechanics in spinosaurid theropods and extant crocodilians. PLoS ONE 8(5): e65295. doi:10.1371/journal.pone.0065295.
Ibrahim, N. et al. (2014). Semiaquatic adaptations in a giant predatory dinosaur. Science DOI: 10.1126/science.1258750.