Intense Heat in Earth’s Atmosphere Led to Global Forest Fires

There has been much discussion in recent weeks regarding the extraterrestrial impact that occurred approximately 66 million years ago, a probable causal factor in the demise of the dinosaurs, their ultimate extinction and the loss of something like seventy-five percent of all land based organisms.  A new study by a team of scientists based at Colorado University – Boulder has concluded that one of the immediate consequences of the impact of an object from outer space on planet Earth, was a global fire-storm.

Chicxulub Impact

Fires would have devastated all the terrestrial vegetation, the smoke and ash from such an immense conflagration would have contributed to a contamination of the Earth’s atmosphere and probably blocked out the sun’s light for a very long period.  Any plants that were not burnt to a crisp, or any seeds that germinated after the initial fires would have had very little light with which to photosynthesis.   The collapse of the land-based food chains would have followed, once there were no plants, the plant-eaters including herbivorous dinosaurs were doomed.

After a brief period of bounty where the surviving predators could feast on the carcasses of the dead, the meat-eaters too would all be ultimately doomed.

Extinction of the Dinosaurs

Such an apocalyptic picture is presented by researchers from the Co-operative Institute for Research in Environmental Sciences (CIRES) who used sophisticated computer modelling techniques to synthesise the amount of debris that would have been ejected into the atmosphere after the extraterrestrial impact.  Scientists remain uncertain as to what exactly collided with the Earth and led to the extinction of the dinosaurs.

In a recent paper, published by a team of researchers from New Hampshire (United States), it was suggested that the actual object that smacked into the Yucatan peninsula of Mexico was a comet and not an asteroid/meteor at all.

To read more about the “Dinosaur Comet Theory”: American Researchers Suggest the Chicxulub Impact Caused by Comet.

Douglas Robertson (CIRES), and his co-authors propose that the ejected material that would have been blown up into and almost beyond the atmosphere by the impact blast would have been heated in the upper atmosphere as it re-entered.  The skies would have glowed red for many hours after the impact at temperatures possibly exceeding 2,700 degrees Fahrenheit – cooking any organism that was not able to seek shelter underground.  Vegetation would have spontaneously combusted and a global fire-storm resulted.

One of the drawbacks proposed previously for the extensive forest fires theory was the lack of charcoal to be found at the famous K-T boundary, the geological feature that marks the end of the Cretaceous and the beginning of the Palaeogene.  If there had been such a fiery inferno created, the vegetation consumed by the flames would have left extensive geological deposits of ash and charcoal.  The Colorado University team corrected their data to take into account changing sedimentation rates and when the charcoal data from the K-T boundary was adjusted to take into account these same changing sedimentation rates, the figures showed an excess of charcoal not a deficiency.

A “Smoking Gun”

In essence, this new assessment of the charcoal evidence, sometimes referred to as the “smoking gun” in relation to forest fires, supports the theory of a global fire-storm rather than detracting from it.

Speaking about the scientific paper, which has just been published in the American academic journal the “Journal of Geophysical Research-Biogeosciences”, Douglas Robertson stated:

“Our data show the conditions back then are consistent with widespread fires across the planet.  Those conditions resulted in 100 percent extinction rates for about 80 percent of all life on Earth.”

Studies of the 170 kilometre wide Chicxulub crater on the Yucatan peninsula of Mexico have led the majority of scientists to believe that this global catastrophe had an enormous impact on the fauna and flora around at the time.  Along with the dinosaurs, marine reptiles, flying reptiles, ammonites, as well as many types of marine plankton, brachiopods, bivalves and sea-urchins became extinct.  In terms of plant life, the angiosperms (flowering plants) as a group suffered also but most of the species affected and ultimately caused to become extinct were associated with land masses to be found in the northern hemisphere.

Recently, an analysis of the geophysical evidence at the Yucatan site enabled scientists to come up with the most accurate date yet for the extraterrestrial impact.  A team of international researchers, including scientists from Holland, the United States and Great Britain established the date of the impact event to be around 66,038,000 years ago, plus or minus 11,000 years for a margin of error.

Immediately following the impact, the explosion would have sent up millions of tonnes of vaporised rock.  This would then have condensed into sand-grain-sized spheres as they rose up into the upper atmosphere.  As the ejected material began to fall back down to Earth under the influence of gravity, enough heat energy was retained in the atmosphere to create an infrared “heat pulse”, so hot that the sky would have glowed red for many hours, not that there was much alive bigger than a small dog on the land to see it.

Radiated Heat Energy

Part of the radiated heat energy would have been blocked, firstly by the falling material in the atmosphere and secondly from the ash and smoke that would have been ascending from the fires.  Even with some of the “heat pulse” effectively being blocked out and not reaching the surface of the Earth, there was enough heat energy getting to ground level to cause dry materials such as leaves and pine needles to explode into flames.

To read more about the latest impact dating research: Most Accurate Date for Extraterrestrial Impact.

The American team then set out to calculate  just how much energy would have been generated by the infrared radiation.  They calculate that the total amount of infrared heat was equal to a one megaton hydrogen bomb exploding every four miles over the entire surface of the planet.  A one megaton hydrogen bomb has the explosive power of about eighty Hiroshima-type nuclear devices.  The scientists postulated that the extraterrestrial impact generated about one hundred million megatons of energy.

The layer of soot, which can be found at the K-T boundary (the geological feature that marks the end of the Cretaceous), is thought by some scientists, to be evidence of the actual impact.  However, this new research paper suggests that the sooty layer is too deep to have been created solely by the impact event.  The thickness of the sooty layer, according to the researchers, is consistent with great fires that would have engulfed much of the Earth in the aftermath of the collision.

For models and figures of Late Cretaceous dinosaurs and pterosaurs, take a look at the models section of Everything Dinosaur’s award-winning website: Dinosaur, Pterosaur and Prehistoric Animal Models.

Keen-eyed Pupil Spots Tiny Dinosaur Bone

A Japanese schoolboy on an outing with his family to a mining museum has discovered the toe-bone of a dinosaur, most likely a member of the theropod group of dinosaurs and the bone may represent a species that is new to science.  The tiny fossil, it measures just three centimetres in length, was found by Takato Sasaki, who was on a visit to the Kuji Amber Museum in Kuji, Iwate Prefecture, the north-eastern part of Honshu island (Japan).

Kuji Amber Museum

The Kuji Amber Museum is the only museum of its kind in Japan, amber can be collected in this area, the fossilised tree resin dates from approximately fifty million years ago (Palaeogene geological period) to as old as approximately one hundred million years ago (Cretaceous geological period).  The fossil, although very small and representing just a single toe bone has been tentatively dated to around eighty-five million years ago (Santonian faunal stage of the Late Cretaceous).  The fossil was found last May, it has been identified as a pedal phalange, a toe bone from a bipedal, fast-running dinosaur that may have been between one and two metres tall.  The height of the dinosaur can be estimated by comparing the size of this toe bone with the pedal phalanges of more complete specimens of bipedal dinosaur where more of the skeleton has been excavated.

Dinosaur Toe Bone

Researchers such as Professor Ren Hirayama (Waseda University), have stated that the bone came from the left hind foot of a member of the Coelurosauria dinosaur family.  The Coelurosauria clade of dinosaurs is an exceptionally diverse group of theropod dinosaurs. It includes the ornithomimids, the tyrannosaurs, Compsognathidae and the raptors such as the dromaeosaurs.  Dinosaur fossils are extremely rare in Japan.  Those that are found tend to be very fragmentary, for example, a distinctive, tooth root found earlier this year suggests evidence of horned dinosaurs living on the land mass that we now know as Japan in the Late Cretaceous.

To read more about the fossil evidence suggesting horned dinosaurs once lived on the land we now know as Japan: Japan’s First Horned Dinosaur.

A couple of years ago, Japanese scientists found a huge thigh bone (femur) of a dinosaur.  This suggests that there may have been dinosaurs very similar to titanosaurs living in this part of the world back in the latter stages of the Mesozoic.

To read an article on the discovery of the huge femur: Huge Femur Fossil Found in Japan.

Professor Ren Hirahama commented:

“It is uncommon that a toe bone, which is easily worn away, was found in such good condition.”

The bone is not much bigger than the schoolboy’s little finger, it measures just three centimetres in length and just about one centimetre in diameter at its widest part.  Given that the scientists have only a single bone to study, they can’t say much more about this dinosaur, it is not possible to identify the genus, but it does show that there were fleet-footed relatives of Tyrannosaurus rex living in Japan during the Late Cretaceous.

Eroded Out of Older Sediments

The bone may have been re-deposited having been eroded out of older sediments and become mixed up with the amber bearing strata, although if it had been transported a significant distance, the palaeontologists would have expected the tiny fossil bone to show more signs of erosion than it actually does.

High school student Takato Saski, is said to be very excited about his discovery, the tiny specimen was found at an amber mine site on the museum’s premises.  Describing the moment when he first saw the object, Takato stated:

“At first I thought it was just a small branch, but it was more amazing than that”.

Young people have two major advantages when it comes to finding fossils.  Firstly, they tend to be shorter than adults, this means that they are closer to ground and since fossils tend to be found on the ground, they are closer to where the action is – from a palaeontological perspective.  In addition, their young eyes generally tend to be more acute and a better sense of vision can help young people spot small objects, even tiny dinosaur toe bones.

For further information about fossil hunting and dinosaurs: Contact Everything Dinosaur.

Scientists are hopeful that news about this rare find will encourage more sharp-eyed visitors to the museum.  Perhaps more fossilised fragments will come to light and these fossils can help palaeontologists to understand the diversity of the Dinosauria in this part of the world towards the end of the Cretaceous.

Factor in Extinction of the Dinosaurs – Potentially a Comet Impact

A team of scientists based in the eastern part of the United States have published details of a paper that suggests that the extraterrestrial object that struck the Earth and marked the end of the dinosaurs may have been a comet.  The New Hampshire based research team outlined their theory at the forty-fourth Lunar and Planetary Science Conference which was being held in Texas.

Chicxulub Impact

It was father and son team Luis and Walter Alvarez and their study of the iridium-rich clay layer that marked the Cretaceous/Tertiary geological boundary across so many parts of the world, that first led to the theory that there had been a meteorite or asteroid object collision that had led to the deposition of iridium – a rare Earth element.

It was the discovery of the almost 190 kilometre wide Chicxulub crater in the Yucatan peninsula of Mexico that provided the “smoking gun” evidence that there had been an extraterrestrial impact some 65 million years ago that led to the demise of the Dinosauria and around seventy percent of all terrestrial life.  The theory that such a catastrophic event might have been a causal factor in the mass extinction that followed has now been largely accepted by the majority of the scientific community.

The actual date of the impact has even been calculated to around 66 million years ago, plus or minus either way a few thousands of years for margin of error.

To read more about the dating evidence: Dating the Cretaceous Mass Extinction.

Cretaceous Comet

However, this new paper proposes that a smaller, faster travelling comet collided with our planet and the culprit was not a larger, slower moving asteroid or meteorite.  The New Hampshire team (from Dartmouth College), studied the sediments and rock strata at the Yucatan site and concluded that the crater might have been caused by the impact of a much smaller object, but one that was travelling at immense speed.

The smaller mass of the colliding object would have reduced the kinetic energy released but the devastation caused could have been amplified by the much greater speed that a body like a comet would be travelling compared to a rocky meteorite or asteroid.

In an analysis of a second rare Earth element deposited  – osmium the team were able to hypothesise that the impact object deposited much less debris than previously thought.

Higher Levels of Iridium

The research team also concluded that the widely reported higher levels of iridium had been previously overstated.  This data was then examined in conjunction with the known geo-physical nature of the Chicxulub impact crater and the team deduced that to deposit on Earth that much iridium and osmium a meteor or asteroid of over five kilometres wide would be needed, but if a rocky object of that size smacked into the geology of the Gulf of Mexico a much larger crater would have resulted.

To read more about scientific studies of the Chicxulub crater: Getting to the Bottom of the Chicxulub crater.

The End of the Dinosauria

For a smaller object to have created the Chicxulub crater on impact it would have had to have had a greater terminal velocity and the research team point to a long-period comet as being  a more likely candidate for the harbinger of dinosaur doom.  Long period comets are believed to be remnants left over from the formation of our solar system.  They consist of rocks, dust and ice and they orbit the sun, often in very eccentric trajectories, with some comets taking millions of years to complete one circuit.  Other comets such as the famous Halley’s comet are known as a short-period comets – having an orbit of less than 200 years.

Other scientists challenge the Cretaceous comet impact idea, suggesting that a lot of debris may have been ejected up into and beyond our atmosphere.  If a lot of the impact object material was ejected into space and left our atmosphere then the evidence tips in favour of a larger rocky object such as an asteroid.

Whatever it was, the devastation caused was certainly terrific with earthquakes, fire storms, enormous tidal waves and acid rain.  It is likely that much of the light and heat from the sun was obscured by dust in the atmosphere, shrouding the Earth in what has been termed a “nuclear winter”.

Dinosaurs, marine reptiles, the last of the pterosaurs along with many types of invertebrate, plants and marine plankton became extinct.  Flowering plants including the hardwood trees, along with mammals also suffered but it was from the end of the Age of Reptiles that flowering plants and mammals rapidly diversified becoming the dominant and most prominent floras and faunas in most ecosystems today.

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