Dinosaur hunt: how many more are there left to find?Alamy

Thanks to movies such as Steven Spielberg's Jurassic Park and visits to natural history museums, 'dinosaur hunter' is one scientific job that schoolchildren aspire to. And according to a study of dinosaur diversity, these budding palaeontologists will have plenty to do: researchers estimate that more than 1,000 new groups of dinosaur species remain to be discovered.

"It's a safe bet that a child born today could expect a very fruitful career in dinosaur palaeontology," says Peter Dodson, an author of the estimate and a palaeontologist at the University of Pennsylvania in Philadelphia.

So far, 527 dinosaur genera — the plural of genus, a group of species that share similar characteristics — have been identified from fossils. But the rate of discovery is growing, with scientists now finding about 20 genera per year (see tab/060904-2T1.html">Dinosaur count), raising the question of how many more species remain to be discovered.

Dodson attacked the problem by teaming up with Steve Wang, a statistician at Swarthmore College in Pennsylvania. They combed through the fossil record to see how often new finds dropped into existing genera, and how often they necessitated the naming of a new one. A lot of instances of the former would indicate that the range of dinosaurs has already been well sampled, whereas a lot of the latter would suggest that scientists are still just scratching the surface of dinosaur diversity.

After trawling the 2004 edition of The Dinosauria, a book co-authored by Dodson that lists known dinosaur species, together with more recent additions described in scientific papers, Wang and Dodson conclude that more than 1,300 new species groups remain to be discovered.

Counting up

The actual number of dinosaur types that lived is probably higher than that, Dodson says, but some will probably remain undiscoverable for various reasons — perhaps because the bones have not been preserved, for example, or are only to be found in inaccessible locations.

The estimate, published in the Proceedings of the National Academy of Sciences¹, is higher than the researchers had previously thought. In 1990, when 285 genera were known, Dodson estimated that there were some 900 to 1,200 new genera left to find.

The increase is in part due to new scientists entering the field and unearthing fossils from previously unexplored parts of the world, says Dodson. Most dinosaur taxonomy has been the purview of the western world, he says, but, "with the recent explosion of dinosaur palaeontology in places like China, Mongolia and South America, that is clearly no longer the case".

The result is good news for dinosaur hunters, but some note that the estimates need to be treated with caution. David Weishampel, a palaeontologist at Johns Hopkins University in Baltimore, Maryland, says he is glad to know that "I'm going to live out my life with plenty to find". But he also points out that the error bars on Dodson's successive estimates are getting bigger. This suggests that the methods used to create the estimate are subject to a great deal of uncertainty.

So the true amount of dinosaur diversity remains unknown; but it is certain that discoveries will inevitably one day peter out. Dodson says that although today's children have plenty to unearth, their children's grandchildren will see the rate of new discoveries start to decline in the early twenty-second century.

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John Hopkins University, Baltimore.

• References

  1. WangS. C., DodsonP. et al. P. Proc. Natl Acad. Sci., 103. 13601 - 13605 (2006).