New Dinosaur Species were Evolving when the Asteroid Struck!

Many palaeontologists believe that dinosaurs were on the way out when the asteroid struck at the end of the Cretaceous and the impact was the straw which broke the camels back. (Apologies for the metaphor.)

But THIS ARTICLE contends that new species were continuing to evolve. The perceived decrease in diversity is caused by the difficulty in identifying new species. 

 They illustrate this by describing how museum specimens described as being a juvenile specimen of a recognised species was actually a completely new species which evolved at the relevant time.

And they do this by looking at the spacing of growth rings in the animals bones. If it was a juvenile the rings would be wide - rapid growth. But this animal has closely spaced growth rings indicating it was an adult. 

It had been classified as a juvenile "chicken from hell" Eoneophron anzu. (I think that is the official name of the larger beastie - the article is not very clear on this.) It has been given the name Eoneophron infernalis. 

So new species were evolving right up to the time of the impact.

Teal markers point to lines of arrested growth on the cross-section of fossilized bone. Toward the outside of the bone, the lines are much closer together, reflecting less growth per year. Researchers counted exactly six lines, meaning this animal was between 6 and 7 years old when it died. Holly Woodward

And here is a picture of the animal itself.

Birdlike dinosaur Eoneophron infernalis was about the size of an adult human. Zubin Erik Dutta