Chicxulub crater may be result of binary impact

["Richard W. Travsky" <rtravsky@uwyo.edu>]

http://www.newscientist.com/article/dn23126-dinosaurkilling-asteroid-was-a-twin-terror.html
[...]
The dino-killing asteroid is usually thought of as a single rock with a 
diameter of 7 to 10 kilometres, but it may really have been two widely 
separated rocks with that combined diameter.

The surprise conclusion comes from a re-evaluation of the proportion of 
asteroid craters on Earth that were formed from binary impacts. It could 
also spell bad news for those hoping to protect our world from 
catastrophic collisions in future.
[...]
"It's been known for 15 years that about 15 per cent of near-Earth 
asteroids are binary," says Katarina Miljkovic' at the Institute of Earth 
Physics in Paris, France. All else being equal, 15 per cent of Earth's 
impact craters should be the result of twin impacts. Why does the real 
figure appear so much lower?

Miljkovic' and her colleagues have found an explanation. They ran computer 
simulations of binary asteroids hitting Earth and found that they often 
form a single crater.
[...]
The simulations also suggest that it is possible to identify which of 
Earth's single craters had binary origins. These craters should be subtly 
asymmetrical, and that makes the crater near Chicxulub in Mexico  thought 
to be the result of an asteroid impact 65.5 million years ago that wiped 
out the dinosaurs  a strong candidate.

"The Chicxulub crater shows some important asymmetries," says Miljkovic'. 
"It is worth considering that it was formed by a binary asteroid."
[...]

http://www.sciencedirect.com/science/article/pii/S0012821X12007194
Morphology and population of binary asteroid impact craters