http://www.physorg.com/news108218928.html

How did they figure that a 160 MYA asteroid belt event would cause a major impact on the Earth 65 MYA?

The whole timing scheme seems a bit far fetched.

There is no dispute currently concerning the occurrence of the big asteroid strike in the Yucatan Peninsula area about 65 Ma, but the latest research currently published already in the geological journals is that the impact was actually 300,000 years before the KT boundary and had no significant effect on global ecosystems at the time of impact. Extinction of the dinosaurs was not caused by a meteor impact! The actual 3 cm thick horizon that identifies the meteor impact, when studied for example 1,000 miles away from the impact area shows fossil sequences passing up to and past the impact debris layer. Above this, physically perhaps about 1.5 metres, is the extinction horizon. So the latest (and very carefully researched) view of eminent American researchers, is that the main extinction in fact matches all the other main extinction events recorded through geological time, which all have no connection with an asteroid strike. Incidentally, the KT extinction was by no means the worst one recorded - one earlier extinction wiped out 95% of all species on the planet. The important thing - the very important thing - to be recognised is that an asteroid impact has been shown to not be catastrophic globally at all. Thus, it will wipe out everything over a limited radius, clearly, but the world will be safe. How about that!
Nevertheless the interesting - and vital - question remains: if asteroids didn't cause these major life extinctions, then what did?
Peter Rankilor BSc MSc PhD CEng CGeol FICE FIMMM FIGeol FGS.

CactusCritter -- When the Baptistina parent body broke up, the fragments didn't fly in a straight line towards Earth. Rather, they had their own orbits that changed very slowly over time. It apparently took 52 My (give or take 20 My) for one piece to drift to impact the Moon (producing Tycho), and it took a bit longer for another to finally impact Earth. This does indicate the need for more detailed analysis of main-belt asteroidal orbits, to estimate the likelihood of similar collisions in the future. Admittedly, we'd have tens of millions of years before the results of such a collision would become a danger down on Earth, but the other debris could become a danger to anything outside in space. The smaller the pieces of debris, the faster I'd expect them to reach the Solar system's inner orbits, so sand-sized fragments could easily endanger interplanetary probes, Lunar colonies and even satellites, without posing any threat whatsoever to anyone living under an atmosphere.

It appears that most of the "cratering" on the moon occurred over a very short period of time, probably only a few "earth months" of time. This is obvious because at the present time we are not observing new cratering formation on the moon. Also consider the "cratering activity" that has occurred on most of the asteroids themselves, those craters were almost undoubtedly created in the same time period as those on our moon, & the ones on Mars. The past "impact forces" we observe on just the asteriods themselves speak of a one time violent event that undoubtedly altered the entire solar system.

How could an asteriod large enough to punch a 180km crater in the the Earth's surface have "no significant effect on global ecosystems at the time of impact"?

Abusing double negatives, it can't not have an effect.
This person falsely posing as Peter Rankilor person is talking out of their arse.

i am with guest_lan....please explain

Everybody knows another Earth, it's twin, that comes around every zillion years or so, came so close to the planet Earth that it causes big problems, like, um, unusual weather, dying dinosaurs, etc. It's clearly written in the, ah Runes, man!

whoa

There is no dispute currently concerning the occurrence of the big asteroid strike in the Yucatan Peninsula area about 65mya. There were a lot of impacts on the Earth. One of these impacts was maybe 160mya. Although the scientific community's current view is that the K/T boundary was created by a meteorite impact, it is still under debate. The K/T layer has very high amounts of iridium, which is hard to explain by other means than an extraterrestrial origin. This gives us at least two possibilities, namely an isolated major impact or a large meteor shower which would affect the climate in the same way as a single large asteroid. There are a number of anthropomorphic ideas trying to explain dinosaur extinction: Epidemic disease, Acid rains, Giant tsunami, Other proposed causes are climatic change (especially cooling and drying), change in sea levels, chemical poisoning of ocean waters, changes in atmospheric chemistry, rocks falling out of the sky, cosmic radiation, and global volcanic activity. All versions are true. They were together reason dinosaurs’ extinction and additional factors too: Only Modern Cosmogeological Theory can explain everything. www.cosmogeology.ge
Billions of years ago in the Solar system were collapsed 5-th planet (Ceres' Titanic mother body), one of the Saturn's and Neptune's moon. 65 million years ago one of the remains of this catastrophes, one of the destroyed geosphere huge chunk (10 km in diameter) was crushed to the Earth on the north-west part ancient Africa-south American (without west Andes) continent. There were created giant cracks on the ancient Tethys Ocean bad and on the inner and outer margins of ancient Africa-south American continent. There were destroyed everything and everybody around centre of explosion. There were submerged almost all north-west part of ancient continent by this time. Only high mountains were not submerged and now they are as the islands and parts of American continents around Caribbean sea. Giant meteorite's explosion caused not only shock-shaking all over the Earth, impact destroyed balance of huge geoforces between inner geospheres... Started EB geotransfer (huge geocatastrophe)...... C and D geosphere of mantle are under influence huge geoforces. Into outer nucleus is huge pressure. Reason is defect of volume into E geosphere. C and D geosphere are under huge pressure of asthenosphere and crust too.
I don't have any doubt of many scientists investigations about Chicxulub Crater . Caribbean sea's floor proves that, impact was huge... but it can not explain how did the reptiles and fishes die into all seas and all oceans.... how could create Caucasus, west part of northern Cordilleras and Andes, all same age mountain chains very far from impact. This crater was not center of huge K/T geocatastrophe, it was only DETONATOR of huge K/T geocatastrophe. Impact theory could not explain destroy huge Tethys ocean, formation of Atlantic Ocean, etc. Clue is into EB geotransfer... (Rapid movement outer nucleus masses into asthenosphere). Inner balance of Earth inner geological forces between mantle and outer nucleus was destroyed by this giant impact, and was began EB geotransfer... It has another name, HUGE GEOCATASTROPHE..... (K/T event) now we can explain everything.....

The Yucatan Peninsula impact site is an interesting observation point. There are several tectonic plates recognized in that small region: the Caribbean, North American, Cocos, and South American Plates. The Caribbean, Cocos, and South American Plates are confronting each other in such a way as to appear to have their respective forces in a clockwise rotation (a very slow clockwise motion). The North American Plate would appear to be nudging the Caribbean Plate into the other two the Caribbean Plate is adjacent too.

In some ways, that area is a very busy intersection in a geologic frame of reference. I’ve speculated that the “big rock” that impacted Yucatan may have triggered a lasting effect which shuffled the other plates while they were in motion causing a cascade event on a geologic time scale. Yucatan resides at the 10 o’clock position in reference to those three plates going round. It’s made me wonder if the Isthmus of Panama will, someday, look like Drake’s Passage between South America and Antarctica or whether it once was and is now a land mass separating two oceans.

There is still quite a bit of research and exploration to be had, but I’m hoping that orbital imaging refinements and enhanced techniques are just around the technology corner.