Dinosaurs Survived 700,000 Years Past KT Event

I would go a lot further that this.  I suspect that a population of dinosaurs livedinto the Ice Age in the Australian New Guinea Sub continent called the Sahul.  This was a mostly vast rain forest in theNorthern reaches and likely around fifteen degrees further south if we acceptthe Pleistocene Nonconformity as ending the Ice Age.

The fauna is largely unlike theold world fauna and it is reasonable that a number of dinosaur species couldwell have held out here.  Besides, this acomplexly opposite the Yucatanwhich we recognize as the impact zone for the KT event.  It should have been the least affected placeon Earth and only came under serious pressure with the advent of the suddencollapse of the Ice Age which inundated the rain forest in particular.

We have also learned that a subgroup of dinosaurs were adapted to swamplands and had excellent chances ofsurviving anything as did the crocodiles and many other reptiles there.  I suspect that our most famous reptile knownas Tyrannosaurus Rex was aquatic and hunted crocs.  Certainly we have evidence of such a remnantpopulation in the remnants of the Sahul that is surely aquatic. (google thisblog for Burrunjor)

Thus it comes as no surprise thatsurvivors made it through even in the old world mostly depending on theirability to retreat to swamps.  Highlands and forest would have been covered with ash anddust throughout the Northern Hemisphere at least and geology suggests that justabout everywhere had a ash problem.

Thus outside of swamps, survivalwas scant.  Afterward the tide againstthe dinosaurs became overwhelming in the old world also in the Sahul.

What ended was the use of large eggsas a method of raising the next generation. Two separate strategies evolved butthose reptiles dependent on protecting large eggs died out.  It obviously remains in use for birds butattempts by large birds to survive have generally been too difficult.  We like to blame humanity for theseextinctions but any aggressive mammal can do it as rats on many islands haveshown.

In the event the dinosaurssurvived but massively decimated in numbers from which it appears that theynever recovered.

Dinosaurs survived for at least 700,000 years after meteorite collision

http://www.telegraph.co.uk/science/dinosaurs/8288863/Dinosaurs-survived-for-at-least-700000-years-after-meteorite-collision.html

Dinosaurs survived for more than 700,000 years after the earth was hitby a massive meteorite originally believed to have caused their extinction,according to new research.

28 Jan 2011

Many palaeontologists believe that all non-avian dinosaurs disappearedalmost 66 million years ago - after debris from the meteorite blocked out thesun and caused extreme climate conditions, killing vegetation worldwide.

But new tests on a fossilised bone of a plant eating dinosaurdiscovered in New Mexicofound that it was only 64.8 million years old - meaning that it was alive about700,000 years after it was thought to have died.

A team at the University of Alberta, Canada, used a new"direct-dating" method called U-Pb (uranium lead) dating to establishthe age of a hadrosaur's thigh bone much more accurately.

A laser beam removes minute particles of the fossil, which then undergoradioactive dating - which allows the age of the fossil bone to be determinedand can even tell what type of food the dinosaur ate.

Living bone contains very low levels of uranium, but duringfossilisation (typically less than 1000 years after death), this levelincreases.

The uranium atoms in bone decay spontaneously to lead over time and,once fossilisation is complete, the uranium-lead "clock" startsticking.

By measuring the radioactive decay it is possible to establishaccurately the age of the hadrosaur, a giant plant eating dinosaur with aplatypus-like bill.

Currently, palaeontologists date dinosaur fossils using a technique called'relative chronology' which means establishing the age of sedimentary rocksabove and below the layer in which the fossil is found.

But a potential weakness for this approach is that over millions ofyears geologic and environmental forces may cause erosion of the fossil-bearinglayer causing it to move from its original position in relation to other rocklayers.

Led by Larry Heaman from the Department of Earth and AtmosphericSciences, the team say there could be several reasons why the New Mexico hadrosaurcame from a line of dinosaurs that survived the great mass extinction of thelate Cretaceous period (KT extinction period).

Dr. Heaman said it is possible that in some areas the vegetation wasn'twiped out and a number of hadrosaur species survived.

The researchers added that the potential survival of dinosaur eggsduring extreme climatic conditions also needed to be explored.

They believe if their new uranium-lead dating technique bears out onmore fossil samples then the KT extinction paradigm and the end of thedinosaurs will have to be revised.