The alvarez hypothesis as the reason for the extinction of dinosaurs from the earth

Impactor comparisons[ edit ] "For comparison, the Martian moon Deimos is 12 km".

The alvarez hypothesis as the reason for the extinction of dinosaurs from the earth

O—S The blue graph shows the apparent percentage not the absolute number of marine animal genera becoming extinct during any given time interval. It does not represent all marine species, just those that are readily fossilized. The labels of the traditional "Big Five" extinction events and the more recently recognised End-Capitanian extinction event are clickable hyperlinks; see Extinction event for more details.

Non-avian dinosaurs, for example, are known from the Maastrichtian of North America, Europe, Asia, Africa, South America, and Antarctica, [30] but are unknown from the Cenozoic anywhere in the world. Similarly, fossil pollen shows devastation of the plant communities in areas as far apart as New Mexico, Alaska, China, and New Zealand.

Species that depended on photosynthesis declined or became extinct as atmospheric particles blocked sunlight and reduced the solar energy reaching the ground. This plant extinction caused a major reshuffling of the dominant plant groups.

No purely herbivorous or carnivorous mammals seem to have survived. Rather, the surviving mammals and birds fed on insectswormsand snails, which in turn fed on detritus dead plant and animal matter.

Extinction was more severe among animals living in the water column than among animals living on or in the sea floor. Animals in the water column are almost entirely dependent on primary production from living phytoplankton, while animals on the ocean floor always or sometimes feed on detritus.

For example, it is thought that ammonites were the principal food of mosasaursa group of giant marine reptiles that became extinct at the boundary. Modern crocodilians can live as scavengers and survive for months without food, and their young are small, grow slowly, and feed largely on invertebrates and dead organisms for their first few years.

These characteristics have been linked to crocodilian survival at the end of the Cretaceous. There is no evidence of mass extinction of these organisms, and there is support for high productivity of these species in southern high latitudes as a result of cooling temperatures in the early Paleocene.

As the marine microbiota recovered, however, it is thought that increased speciation of benthic foraminifera resulted from the increase in food sources. Ultimate recovery of the benthic populations occurred over several stages lasting several hundred thousand years into the early Paleocene.

Many Theories, No Proof

The apparent rate is influenced by a lack of fossil records, rather than extinctions. A review of these fossils shows that ostracod diversity was lower in the Paleocene than any other time in the Cenozoic.


Current research cannot ascertain, however, whether the extinctions occurred prior to, or during, the boundary interval. The solitary corals, which generally do not form reefs and inhabit colder and deeper below the photic zone areas of the ocean were less impacted by the K—Pg boundary.

Colonial coral species rely upon symbiosis with photosynthetic algaewhich collapsed due to the events surrounding the K—Pg boundary, [45] [46] however, the use of data from coral fossils to support K—Pg extinction and subsequent Paleocene recovery, must be weighed against the changes that occurred in coral ecosystems through the K—Pg boundary.

These included the ecologically significant belemnoidsas well as the ammonoidsa group of highly diverse, numerous, and widely distributed shelled cephalopods. Researchers have pointed out that the reproductive strategy of the surviving nautiloids, which rely upon few and larger eggs, played a role in outsurviving their ammonoid counterparts through the extinction event.

The ammonoids utilized a planktonic strategy of reproduction numerous eggs and planktonic larvaewhich would have been devastated by the K—Pg extinction event.

Dinosaur extinction is still a major enigma of earth history. In this review article, extinctions in the geological record will be briefly mentioned. This event changed the planet’s climate and is widely believed to have triggered a mass extinction of species — including the end of the dinosaurs. clay Fine-grained particles of soil that stick together and can be molded when wet. The Alvarez Hypothesis: The original hypothesis is the basis for several subsequent variations on the theme that a large extraterrestrial object collided with the Earth, its impact throwing up enough dust to cause the climatic change. The iridium layer is what prompted the Alvarez team to blame an asteroid impact for the extinction.

Additional research has shown that subsequent to this elimination of ammonoids from the global biota, nautiloids began an evolutionary radiation into shell shapes and complexities theretofore known only from ammonoids.

Mid-latitude, deep-water echinoderms were much less affected at the K—Pg boundary. The pattern of extinction points to habitat loss, specifically the drowning of carbonate platformsthe shallow-water reefs in existence at that time, by the extinction event. The specific problem is: The paragraph on sharks and survival through the K-T event simply does not make sense.

It contradicts the article on sharks, and self-contradicts. It also requires some language cleanup. March There are substantial fossil records of jawed fishes across the K—Pg boundary, which provide good evidence of extinction patterns of these classes of marine vertebrates.

While the deep sea realm was able to remain seemingly unaffected, there was an equal loss between the open marine apex predators and the durophagous demersal feeders on the continental shelf.

Researchers found that Cretaceous sites, prior to the extinction event, had rich plant and insect-feeding diversity. During the early Paleocene, however, flora were relatively diverse with little predation from insects, even 1. In high southern hemisphere latitudes, such as New Zealand and Antarctica, the mass die-off of flora caused no significant turnover in species, but dramatic and short-term changes in the relative abundance of plant groups.

The dominance of fungal species lasted only a few years while the atmosphere cleared and plenty of organic matter to feed on was present. Once the atmosphere cleared, photosynthetic organisms, initially ferns and other ground-level plants, returned. A study of fossil vertebrates across the K—Pg boundary in Montana concluded that no species of amphibian became extinct.

These include the frog Theatonius lancensis [68] and the albanerpetontid Albanerpeton galaktion; [69] therefore, some amphibians do seem to have become extinct at the boundary. The relatively low levels of extinction seen among amphibians probably reflect the low extinction rates seen in freshwater animals.

Choristodere[ edit ] The choristoderes semi-aquatic archosauromorphs survived across the K—Pg boundary [28] but would die out in the early Miocene.Sep 25,  · The sun, at billion years old, predates all the other bodies in our solar system.

But it turns out that much of the water we swim in and drink here on Earth . This event changed the planet’s climate and is widely believed to have triggered a mass extinction of species — including the end of the dinosaurs.

clay Fine-grained particles of soil that stick together and can be molded when wet. At the same time, in , geologist Walter Alvarez and his father, Nobel Prize-winning scientist Luis Walter Alvarez, put forth his hypothesis that a large extraterrestrial body had struck Earth.

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In , unaware of Penfield's discovery, University of Arizona graduate student Alan R. Hildebrand and faculty adviser William V.

The alvarez hypothesis as the reason for the extinction of dinosaurs from the earth

Boynton published a draft Earth . is and in to a was not you i of it the be he his but for are this that by on at they with which she or from had we will have an what been one if would who has her. The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction, was a sudden mass extinction of some three-quarters of the plant and animal species on Earth, approximately 66 million years ago.

With the exception of some ectothermic species such as the leatherback sea turtle and . A researcher whose work was sponsored by the National Science Foundation explains how his mathematical paper was not merely rejected post-publication, but intentionally vanished by the New York Journal of Mathematics Our paper underwent several further revisions until, on April 3, , our manuscript was officially accepted for publication.

Dinosaur Extinction