Asks Jon Tennant at Paleo Community: Further to the dinosaur document dump (a fair bit of news and views recently, about the late and the great):
Why are there so many bird species around today, when we have relatively so few dinosaurs in the fossil record? This disparity is even more extreme when you consider that while non-avian dinosaurs were around for about 170 million years, there were only ever about 800 or so species of dinosaur, based on current records. The actual number fluctuates through time, as new species are discovered, and others are shown to be invalid through research broadly known as ‘taxonomy’.
One problem is with the difference between what existed and what gets preserved and another is the tendency to look where one already expects to find something.
Many think the true number much larger, for example:
Steve Brusatte of the University of Edinburgh is sceptical though: “I would take these numbers with an ocean full of salt”, he said. “There are over 10,000 species of birds – living dinosaurs – around today. So saying there were only a few thousand dinosaur species that lived during 150+ million years of the Mesozoic doesn’t pass the sniff test.
One of two things: Either there weren’t very many dinosaur species, compared to bird species, and the reason would doubtless be instructive. Or there were, and new finds might change much that we think we know.