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Counting dinosaurs: how many kinds were there?
1Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104-6045.
Summary
Dinosaur taxonomy is unreliable, but a critical review confirms 285 valid genera and 336 species. Despite fossil record biases, dinosaur diversity peaked near their extinction.
Area of Science:
- Paleontology
- Evolutionary Biology
- Stratigraphy
Background:
- Dinosaur studies are hindered by outdated taxonomy, imprecise biostratigraphy, and poor fossil preservation.
- Understanding dinosaur diversity is crucial for mass extinction and evolutionary analyses.
Purpose of the Study:
- To critically evaluate dinosaur taxonomy and diversity.
- To estimate the completeness of the dinosaur fossil record.
- To model dinosaur evolution and extinction patterns.
Main Methods:
- Taxonomic validation of dinosaur genera and species.
- Analysis of fossil preservation and distribution.
- Application of logistic and bottleneck models for diversity estimation.
Main Results:
- 285 dinosaur genera and 336 species are considered valid.
- The fossil record is estimated to be only 25% complete.
- Dinosaur diversity peaked in the latest Cretaceous (Maastrichtian) before extinction.
- Estimated genus duration is 7.7 million years; global diversity was ~100 genera per stage.
Conclusions:
- Dinosaur taxonomy requires critical revision to accurately assess diversity.
- Despite biases, models suggest dinosaurs evolved rapidly and peaked in diversity before their extinction.
- Future discoveries are anticipated from Argentina and China.