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Tuesday, April 19, 2011

Everybody loves Tyrannosaurus

Guardian.co.uk: Notes & Theories, Dispatches from the Science Desk: Everybody loves Tyrannosaurus
wonder if Henry Fairfield Osborn created a self-fulfilling prophecy when he named Tyrannosaurus rex. The tyrant king is the most beloved and celebrated of all dinosaurs, and when the first specimen was put on display in 1906 – nothing more than the hips and legs – The New York Times declared Tyrannosaurus to be the "prize fighter of antiquity". It has held onto that top spot ever since.

But our love for Tyrannosaurus can be unhealthy. 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."

Granted, such references to Tyrannosaurus are quick and easy ways to invoke the ferocity of extinct organisms, but 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 known T. rex relative", and, a few weeks later, the bizarre dinosaur Linhenykus was presented as a "one-fingered T. rex relative". Then, just last month, the dinosaur Zhuchengtyrannus was announced to be "T. rex's new cousin".

The phrases "T. rex relative" and "T. rex cousin" are thrown around so often that they have nearly lost their meaning. Citing the news of Zhuchengtyrannus as a "T. rex cousin", NPR blogger Bill Chappell wrote "It's exciting news, but doesn't it seem like we've heard something similar recently?" He wondered why both Linhenykus and the small tyrannosaur Raptorex had been given the same honorary title.

Dinosaurs have become victims of their own success. The pace of dinosaur discoveries is so rapid – and requires so much context – that journalists simply can't keep up. Only the truly exceptional, eye-grabbing stories make it to press, and when they do the stories are typically along the lines of "New dinosaur discovered. Cousin of [famous dinosaur]. Ooooh."

The tyrannosaurs themselves provide perfect examples. For decades Tyrannosaurus, Albertosaurus, Daspletosaurus, and other tyrants were considered to be "Carnosaurs" – a grab-bag group of giant predators that also included Allosaurus, Spinosaurus, and others. Palaeontologists have since split up this dinosaurian mish-mash into a branching tree of theropod dinosaurs.

As is now understood, tyrannosaurs fit inside a highly diverse theropod subgroup called coelurosaurs, which also encompass small, sickle-clawed hunters (Velociraptor); long-necked herbivores with Freddy Krueger claws (Therizinosaurus); ostrich-mimics (Gallimimus); and birds, among others. Even better, within the past 10 years palaeontologists have found a wealth of tyrannosaurs that document the group's evolution from small, feather-covered creatures to some of the largest predators of all time. Zhuchengtyrannus is only the latest tyrannosaur to be welcomed into the family.

Both Eodromaeus and Linhenykus were only distant relatives of Tyrannosaurus. Eodromaeus preceded tyrannosaurs by over 165m years, and was about as closely related to the tyrants as to any other giant, badass theropod you care to name. Linhenykus, on the other claw, belonged to a coelurosaur lineage called alvarezsaurs which were not notably close to the tyrants.

The true "T. rex cousins" were found among the tyrannosauroids – a group that included everything from the pint-sized, fuzzy-feathered Dilong to large, deep-snouted apex predators such as Tyrannosaurus and the recently described Teratophoneus.

In a review of tyrannosaurs published last September, a team of theropod experts noted that at least six new tyrants had been named within a year of their paper's debut, and two more have been named since then. (More are on the way – attendees at last year's Society for Vertebrate Paleontology meeting in Pittsburgh got a preview of a new, as-yet-unnamed tyrant.)

Yet the flock of new tyrants does not give us a complete explanation for the confusion about these dinosaurs. Tyrannosaurus – along with Triceratops, Stegosaurus, Apatosaurus and Edmontosaurus – represents one of the primary dinosaur archetypes that have been popularised for over a century. They are THE dinosaurs, and their long shadows obscure recently discovered species that have led palaeontologists to revise our understanding of dinosaur evolution and relationships.

Take Linhenykus, for example. Who – other than palaeontologists – knows what an alvarezsaur is? From a writer's perspective, it is easier to play up its tenuous connection to Tyrannosaurus than spend a paragraph explaining the dinosaur's unique nature. It doesn't fit in the already established set of familiar dinosaur shapes, so a well-known dinosaur is used to make the introduction.

As science writers, we face the difficult task of condensing technical details into compelling, easily accessible stories that will hopefully catch the eyes of readers before they click over to another webpage. That doesn't mean that we should shrink from accuracy. We are not doing our jobs if we simply refer every sharp-toothed dinosaur to the tyrant family because Tyrannosaurus provides a solid hook. If we fall victim to this trope, we perpetuate a cycle in which no one will understand what an alvarezsaur is because we never explain it and we never explain it because we don't think anyone will understand.

There will always be more dinosaur discoveries than available media space to disseminate their details. That is true of any scientific discipline, and it is why context has become so vital. Our reliance on Tyrannosaurus as an attention-grabbing anchor is just one symptom of a more pervasive affliction in which brevity and page views are valued over placing news in context.

Palaeontologists are not exempt, either. Too often – from grant applications to press releases – we have relied upon the cultural cachet of Tyrannosaurus to get attention.

There is more to palaeontology than Tyrannosaurus rex. Just as the tyrant king was just one member of a rich and diverse dinosaurian family, so are new scientific discoveries intimately connected to the ongoing interrogation of nature. We would do well to remember that.

Brian Switek is the author of Written in Stone: Evolution, the Fossil Record, and Our Place in Nature. He writes for the WIRED Science blog Laelaps and Smithsonian magazine's Dinosaur Tracking

References
Brusatte, SL et al (2010). Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms. Science (New York, N.Y.); 329 (5998): 1481-1485. DOI: 10.1126/science.1193304
Hone, D et al (2011). A new tyrannosaurine theropod, Zhuchengtyrannus magnus is named based on a maxilla and dentary. Cretaceous Research (in press). DOI: 10.1016/j.cretres.2011.03.005
Martinez, R et al (2011). A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea. Science; 331 (6014): 206-210. DOI: 10.1126/science.1198467
Nesbitt, S et al (2011). A small alvarezsaurid from the eastern Gobi Desert offers insight into evolutionary patterns in the Alvarezsauroidea. Journal of Vertebrate Paleontology; 31 (1): 144-153. DOI: 10.1080/02724634.2011.540053

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