Causes of mass extinctions – with special reference to vanishing of dinosaurs

Abstract

The causes of mass extinctions have been currently reviewed with state-of-the-art information on new hypotheses dealing with the disappearance of creatures as a result of sudden (catastrophic) and/or gradual changes in environments. A special reference to vanishing of dinosaurs is detailed.

Full text

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ISSN: 2276-7851
Causes of Mass
Extinctions - With
Special Reference to
Vanishing Of Dinosaurs
By
Ashraf M. T. Elewa

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Research Article
Causes of Mass Extinctions - With Special Reference
to Vanishing Of Dinosaurs
Ashraf M. T. Elewa
Professor of Micropaleontology and Paleoecology, Geology Department, Faculty of Science, Minia University, Egypt.
Email: ashraf.aleiwa@mu.edu.eg; aelewa@link.net
ABSTRACT
The causes of mass extinctions have been currently reviewed with state-of-the-art information on new hypotheses
dealing with the disappearance of creatures as a result of sudden (catastrophic) and/or gradual changes in
environments. A special reference to vanishing of dinosaurs is detailed.
Keywords: Mass extinctions; impact; volcanism; dinosaurs; current mass extinction; avoiding mass extinction.
Safety of planet Earth is our responsibility (the pale blue dot; as described by Sagan (1995)); so minimizing
dangerous effects resulting from catastrophes related to natural processes such as earthquakes and volcanoes, and
artificial processes made by man himself should be on the top of our strategy. Surprisingly, however, we accelerate
extinction of organisms in our world (Elewa, 2008h).
It is common that there are at least five major mass extinctions (Raup and Sepkoski, 1982), adding to
frequent minor extinctions, occurred throughout the history of life on Earth. These extinctions arranged from older to
younger as follows:
1. Ordovician-Silurian mass extinction
2. Late Devonian mass extinction
3. Permian-Triassic mass extinction
4. Triassic-Jurassic mass extinction
5. Cretaceous-Paleogene mass extinction (e.g. K/Pg mass extinction).
Nevertheless, some geologists believe in additional major mass extinction that occurred, according to their belief, at
the end of Cambrian (Late Cambrian mass extinction).
Interestingly, Prothero (1998) mentioned that if 5 to 50 billion species have lived on this planet, but only
about fifty million are alive today, then 99.9% of all species that have ever lived are now extinct!! He added that
statistically this percent might indicate, at first approximation, that all species are extinct!!
Erwin (2001) indicated that mass extinctions seem to account for the disappearance of less than 5% of all
extinct species; even though, the evolutionary opportunities they have created have had a disproportionate effect on
the history of life.
Elewa and Joseph (2009) discussed the history, origins, and causes of mass extinctions, from the creation of
our planet to modern times. Their detailed review included mass extinctions during the Ordovician, Devonian,
Permian, Triassic, and Cretaceous, and prior to and during the Cambrian Explosion, as well as the ongoing sixth
mass extinction.
Noort and Elewa (2011) introduced a new theory based on the celestial factor to explain and to estimate the
size and frequency of all extinctions over the entire period of the fossil record.
In this review I am introducing a complete review on mass extinctions with coverage of important hypotheses
on the subject, as well as new ideas, and finally my own terminology to avoid current mass extinction.
1. MOST WIDELY SUPPORTED HYPOTHESES
In the following, a brief focus on the most widely supported causes has been shown to define how each of them is
assumed to cause more than one of the major mass extinctions of the fossil record, and to which extent these
causes are complicated.

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In fact, still, the causes of these mass extinctions are subject to several disputable opinions (Elewa, 2008a, b, c, d, e,
f, g, h). If we summarized the most acceptable causes of these extinctions we will find that they are applicable,
according to many authors, to the majority of mass extinctions of the fossil record. These causes, without any
particular order, are mainly:
1. Global cooling
2. Major glaciation
3. Sea level drop
4. Global anoxia
5. Volcanic eruptions
6. Asteroid, or extraterrestrial bolide, impacts
- Global cooling
This reason is mentioned by many authors to cause or, at least, control some other reasons leading to all major
mass extinctions; from the Late Ordovician through the Late Devonian, Late Permian, and Late Triassic to the Late
Cretaceous. These authors suppose that global cooling triggered glaciation and significant lowering of the sea level,
therefore deep marine organisms as well as organisms favoring warm conditions died. McAnena et al. (2013)
mentioned that most of the marine biotic crises of the Mesozoic era have been associated with occasions of great
warmth. They added that others may have taken place during cooler intervals that disrupted Cretaceous greenhouse
warmth.
- Major glaciation
Glaciation itself is considered as a dependent factor, in which it is controlled by global cooling. Sheehan (2001)
confirmed that the cause of Ordovician mass extinction was a brief glacial interval that produced two pulses of
extinction. Matthew (2009) argued that volcanic weathering led to draw down pCO
2
and resulted in a cooling episode,
which produced the well known End-Ordovician (Hirnantian) glaciation. It is remarkable that both rapid warming and
glaciation might be occurred during the Permian; as stated by several authors.
- Sea level drop
Sea level drop means decreasing of sea level; in other words, it refers to sea level fall. Resembling glaciation, the
sea level drop is based on global cooling, in which global cooling leads to lowering of sea level; in contrast, global
warming causes sea level rise. Therefore, creatures that cannot acclimatize with global changes in climate and/or
environmental conditions die. On the other hand, Lantzy et al. (1977) applied the catastrophe theory
to the Permian
extinction of marine invertebrates, and concluded that a reduction in oceanic salinity was a
more significant factor in
the extinction of marine invertebrates
than was a reduction in the area of shallow seas.
Pálfy
et al.
(2000) declared that the end-Triassic biotic
crisis on land appears to have preceded that in the
sea
by at least several hundred thousand years. This notice needs more research to know the exact reasons for that
situation!! If reduction in oceanic salinity was significant in the extinction of marine invertebrates at the end of
Permian, then, supposing accuracy of the used age dating techniques, what are the significant reasons that led to
accelerate the extinction of land biota earlier than marine forms at the end of Triassic? Is it anoxia? The answer is
still debatable; however one of the probable reasons is introduced by Ward (2006), who argued that dinosaurs
became the monsters that ruled the Earth for more than 60 million years -- and survived mass extinctions that
destroyed many other species -- because they developed respiratory systems far more efficient than other terrestrial
creatures.
- Global anoxia
Global anoxia means reduction of oxygen in oceans below normal levels. It is believed that global anoxia may be one
of the decisive causes of Devonian mass extinction. Also, Wignall and Twitchett (1996) stated that the world's oceans
became anoxic at both low and high paleolatitudes in the Late Permian that may have been responsible for the mass
extinction at that time. Abbas et al. (2000) asserted that recent evidence quite convincingly indicates that the Late
Permian biotic crisis was in fact a binary extinction with a distinct end-Guadalupian extinction pulse preceding the
major terminal End-Permian Tartarian event by 5 m.y. They added that anoxia appears to be closely associated with
each of these End-Paleozoic binary extinctions. Alternatively, some authors attributed the Cenomanian/Turonian
extinction to global anoxia. Shen (2008) clued that during the Cenomanian / Turonian times the enhanced flux of

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volcanic ash inputted micro-nutrient iron into the ocean, fertilizing surface waters and generating a global
phytoplanktonic bloom, which in turn depleted oxygen in deep ocean.
Castle and Rodgers (2009) introduced another opinion concerning anoxia. These authors concluded that
characteristics and occurrences of algae in modern
aquatic environments and observations from the fossil record
propose that toxin-producing algae were present in the geologic
past and were an important factor in Phanerozoic
mass extinctions. They suggested that the large mass
of organic material produced by algal blooms can lead to
oxygen
depletion during decay, which indirectly causes death of some
biota.
- Volcanic eruptions
Some scientists consider volcanism as one of the most important reasons that led to mass extinctions in the fossil
record (MacLeod, 2000, 2001). Researchers pointed out that ash and dust resulted from these eruptions prevented
sunlight, then a distinct drop in temperature and plant production occurred, and poorly adapted organisms (including
dinosaurs), accordingly, died. It is also notable that some other scientists consider global anoxia to be triggered by
volcanism (see the above section on global anoxia).
Courtillot (1999) was one of those who suggested that cataclysmic volcanic activity can be linked not only to
the K/Pg mass extinction but also to most of the main mass extinction events in the history of Earth.
Some very large extrusions of sheet lava are considered to have had an effect on climatic change. It is
interesting to have a look over the subject of the "Deccan Traps" of India, which French researchers think to have
been more significant than the Haiti bolide.
- Asteroid impact
If you are curious about astronomy and would like to know the relationship between asteroids and catastrophic
events that may occur, you may like to have a visit to the following website:
http://curious.astro.cornell.edu/comets.php. There, you can simply know the difference between asteroids, comets,
meteors and meteorites. In spite of this, what is related to my article is the question that was asked to Prof. Britt
Scharringhousen (Professor of physics and astronomy, Beloit College in Wisconsin); what may happen if an asteroid
of about 10 km in diameter hits either land or ocean on Earth? She clearly said that many species of animals--
including the human race, if we aren't both lucky and resourceful!--will die out, either in the initial catastrophe, or in
the ensuing years due to lack of food and the general devastation of the environment (for details about how this
devastation of the environment can occur, please visit the above mentioned website).
However, no doubt, Alvarez et al. (1980) have entirely changed our thinking towards the causes of mass
extinctions by referring to asteroid impact as a strongly possible reason responsible for this phenomenon. Even
though, there are controversial opinions on this subject matter. For example, another team of scientists believe in the
non-impact hypotheses; some others believe in multiple causes (Molina et al., 1996; Twitchett, 2006; Elewa, 2008a,
b, g; Elewa and Dakrory, 2008a, b). Alvarez and his team focused their study on measuring iridium, which is very
rare on Earth’s surface but more common in the composition of asteroids. However, iridium is also common in rocks
from deep Earth; therefore some scientists presume that the presence of this iridium in the dinosaurs-bearing beds
may indicate volcanism to vanish these giant reptiles. Another context lies in the argument of whether single
meteorite impact or two successive impacts caused the K/Pg mass extinction.
One more opinion was introduced by MacLeod (2000, 2001), who considered tectonic factors - giving rise to
flood-basalt volcanism and sea-level fall - appear to exhibit the greatest level of association with large-scale
extinction events over the course of the last 600 million years. He believes that extraterrestrial impacts have certainly
played an important role in Earth history and may have enhanced the ‘death of the dinosaurs.’ However, asteroid
impacts, according to his opinion, do not appear to be the primary agents responsible for the overall patterns in the
geological extinction record.
2. OTHER HYPOTHESES
The other hypotheses include: Sustained and significant global warming (Mayhew et al., 2008), clathrate gun
hypothesis (Hecht, 2002), hydrogen sulfide emissions from the seas (Kump et al., 2005), oceanic overturn (Wilde
and Berry, 1984), a nearby nova, supernova or gamma ray burst (Melott and Thomas, 2009), and plate tectonics
(Hooper Virtual Paleontological Musuem; Retrieved 16 July 2012). Some authors believe in variations of the Earth’s
orbit to cause cooling cycles within intervals of warm conditions leading to extinctions (e.g. Herbert, 1992; Mitchell et
al., 2008; Noort and Elewa, 2011).

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3. OSTRACODS AND EXTINCTIONS
Although ostracods, like other creatures, have generally suffered from extinctions, yet the research of Elewa on the
Maatstrichtian to early Eocene intervals of Egypt as well as other countries of North and West Africa and the Middle
East revealed stability of ostracods of these intervals in the studied regions (see Elewa, 2002). He explained this idea
on the bases of the ability of ostracods of these regions to migrate to new more stable environments; or in other
words: changes of distribution rather than origination or extinction of ostracod assemblages (Elewa, 2002; Elewa and
Morsi, 2004). Another case of stability based on migration is shown in the Paleogene ostracods of Egypt and the
southern Tethys (Elewa, 2005a); however a reduced ostracod migration activity along the shores of Tethys was
noticed during the middle Eocene-late Eocene intervals (Elewa, 2004a). On the other hand, Elewa (2004b, 2005b,
2007) exemplified polymorphism and adaptability as parallel ways to migration for ostracods to survive.
4. THE MYSTERY OF DINOSAURS EXTINCTION!!
One of the most attractive and strange opinions assumed that sex disability was responsible for extinction of
dinosaurs. Close (1988) disputed this idea and stated that it is not acceptable to attribute the disappearance of
dinosaurs, since 65 million years, to their sex disability!! He rejected this assumption by explaining how the male
have to keep one of his legs on ground during sex to prevent killing the female. It is astounding, however, that some
recent reptiles, which have different sizes for males compared to females, show correlation between kind of gender
and temperature, in which higher temperatures merely produce individuals (either males or females) that have bigger
body size, and vice versa. Consequently, there will be no reproduction, and hence extinction of this group must
occur!!
Actually, there are several unpersuasive, and still disproved, theories and hypotheses on the extinction of
dinosaurs. I’ll mention some of them to present condensed summary on this subject matter. Subsequently, I’ll finalize
with my opinion and leave the decision to readers; which is acceptable and which is feeble. Just, before proceeding,
you should think of the complications that make this job difficult!! Jablonski (1994) mentioned two important problems
that disabled agreements of causes of mass extinctions; these are:
1. Difficulties in resolving the fine details of taxon ranges, and abundances immediately prior to and after an
extinction boundary; and
2. The scarcity of simple, unitary cause-and-effect relations in complex biological systems.
Returning to theories and hypotheses, we can summarize some of them in the following:
1. Asteroid impact has killed dinosaurs.
2. Volcanism caused dinosaurs extinction.
3. Abrupt climatic changes (e.g. changes in temperature from low to high, and vice versa).
4. One of the newly presented ideas is the role of Jell-O® in the mass extinction of dinosaurs. This idea
explains the nutritional impact of Jell-O® on animals whose digestive and circulatory systems were
unprepared for it.
5. Another idea refers to mammal competition. The believers of this idea attributed the vanishing of dinosaurs
to eating their eggs by small mammals!!
6. A strange idea explains how dinosaurs have killed themselves by their spines due to mistaken position when
they intend to have a rest on the ground.
7. A minor opinion suggests that insects have killed dinosaurs.
8. One of the new theories explaining dinosaur’s extinction is the energy-based theory of Gawle and Czech
(2013). They proposed ideas which build on Luis Alvarez’s impact theory by adding the energy-based
mechanism underlying the mass extinction event- the final missing element to make the famous theory
completes, according to their opinion.
Whatever the reason of extinction of dinosaurs, it is necessary to refer to the terrible effects of the most acceptable
reason “extraterrestrial bolide impact”. Scientists already studied, and still discovering, these effects and discussed
the chain events that might occur after the impact. As specialists know, the effects include the following:
1. Making small or big crater in the area of collision, according to the size of the meteorite that stroke Earth,
2. This crater hurtles out small rounded masses of glassy material (e.g. tektites), and
3. Tsunamies occur as a result of shock waves that are sent through the crust and upper mantle.

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Not only the above events are very dangerous, but also the following long-term effects are horribly destructive:
1. The heat produced by the meteorite when penetrates the atmosphere, and the heat wave resulting from
tektites cause enormous fires;
2. Soot and dust prevent sunlight, and consequently photosynthesis; this leads to disturbing food chain;
3. Preventing sunlight causes the so-called “Nuclear Winter Effect”;
4. There are, however, some other processes that may well occur, like potential injections of CO2.
Thompson and Crutzen (1988) examined the acute effects of a large bolide impact using a global three-dimensional
atmospheric circulation model, and could conclude some results related to temporal and geographical evolution of
land surface temperature effects, stratospheric ozone depletion, and nitric acid formation.
To be specific, only the K/Pg mass extinction is strongly ascribed to the impact; even though, there are
debatable opinions concerning this topic.
Regardless, the acceptable hypothesis to me is the combination of extraterrestrial bolide impact and
environmental changes to interpret disappearance of dinosaurs at the K/Pg boundary (multi-causal scenario or the
Press-Pulse Theory of Arens and West (2008)), where impact led to abrupt extinction, while environmental changes
generated gradual disappearance. Generally, I support the opinion of Elewa and Dakrory (2008a), who are
convinced that the combination of multiple reasons could be acceptable to both believers in impacts, or catastrophes,
and those that approve the gradual effects.
5. DID DINOSAURS SURVIVE MASS EXTINCTION?
Fassett et al. (2011) used a new direct-dating method called U-Pb (uranium-lead) dating to determine the age of two
dinosaur fossils from the San Juan Basin of northwestern New Mexico and southwestern Colorado, United States.
They could successfully date the age of these two dinosaur fossils by comparing their results with previous age-
dating methods. This claim is asserted to establish the survival of dinosaurs into the Paleogene.
However, Renne and Goodwin (2012) debated this suggestion of Fassett et al. and argued that it is entirely
possible that the fossil fragments studied by Fassett et al. were reworked postmortem.
Moreover, Koening and his colleagues (Koenig et al. 2012) stated that Fassett et al. ignore previously
published work that directly questions their stratigraphic interpretations (Lucas et al., 2009), and fail to provide
sufficient descriptions of instrumental, geochronological, and statistical treatments of the data to allow evaluation of
the potentially complex diagenetic and recrystallization history of bone. These shortcomings led them to question the
validity of the U-Pb dates published by Fassett et al. and their conclusions regarding the existence of Paleocene
dinosaurs. Based on their comment, Koenig et al. concluded that Fassett et al. have failed to provide the
extraordinary evidence needed to support the extraordinary claim that dinosaurs survived the K/T impact event and
lived into the Paleocene.
In the same time, Ludwig (2012) mentioned some doubt about the method used by Fassett et al. to extract
U/Pb ages from the U/Pb isotopic analyses.
In response to these comments, Fassett et al. (2012a, b) replied to defend their opinion. But still the story did
not end.
It is worth mentioning, that Wilkinson et al. (2012), clued that sauropod megaherbivores were responsible for
the greenhouse warming around 150 million years ago.
6. MINOR MASS EXTINCTIONS
Distinguishing the “Big Five” does not mean that there were no minor extinctions. Some of these bioevents are those
of the Silurian. Several scientists consider that Silurian represents one of the quiet and stable periods of Earth
history; however Calner (2008) mentioned opposing opinion through interesting review of the subject. Another case
is presented by Abdelhady (2008), for the Cenomanian/Turonian macroinvertebrates, who noticed evidences for
selective extinction at the C/T boundary. Julien Louys (2008) introduced excellent examples of Quaternary faunal
extinction in Southeast Asia. Authors are still working on causes and effects of these minor extinctions, but this is not
our point of interest in this article.

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7. CURRENT MASS EXTINCTION
Several articles and news introduce evidences to clue that human (anthropogenic) activities are responsible for the
sixth mass extinction.
Wilcove et al. (1998) used five major categories (including: overexploitation; habitat destruction; the
introduction of non-native (alien) species; the spread of diseases carried by alien species; pollution) to quantify
threats to imperiled species in the United States of America.
Elewa (2008h), in his edited volume on mass extinction, stated that man is accelerating extinction of
organisms in our world. How it is pity to know that man is responsible for this big disaster!!
Glavin (2006) assured that we are in the center of an extraordinary, cataclysmic disappearance of animals,
plants, and human cultures.
Andryszewski (2008), however, stated that some scientists believe in the effect of human on accelerating
species extinctions, but she has doubt on whether human impact is great enough to accelerate the normal range of
background extinction.
Albeit, the possibility that asteroid impact could be one of the leading causes to current mass extinction is still
acceptable. Chyba et al. (1993) mentioned that the explosion over Tunguska, Central Siberia, in 1908, which
released 10 to 20 megatons, typically represents a fate for stony asteroids tens of meters in radius entering the
Earth's atmosphere at common hypersonic velocities.
Firestone et al. (2007) provided evidence for an extraterrestrial (ET) impact event at ≅12.9 ka, which is
suggested to cause abrupt environmental changes that contributed to Younger Dryas (YD) cooling, major ecological
reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period of North
America.
Firestone and West declared in the year 2005, through the media (based on Lawrence Berkeley National
Laboratory release), that a distant supernova that exploded 41,000 years ago may have led to the extinction of the
mammoth.
Interestingly, Leaky and Lewin (1996) introduced the way to expand our knowledge and procedures to save
our planet Earth from facing probable dangerous mass extinction that could lead to vanishing of mankind and living
creatures.
Newitz (2013) tried to explore how scientific breakthroughs today will help us avoid disasters tomorrow.
8. AVOIDING MASS EXTINCTIONS
One of the recommended options to avoid mass extinctions is introduced by Rosenzweig (2005), who said that
preserving Earth's diversity of species requires that conservation biology turn much of its attention to reconciliation
ecology, which is the science of sharing our habitats with wild things. In another article that was written by Ihunweze
(2009), the author suggested that proper environment impact assessment must be carried out before any project is
executed. As well, concerted effort must be made by government and industrialists to cut down on the emission of
polluting gases to tolerable levels. Internationally agreed standards for emissions and waste discharges from
industries must be kept (see the following website: http://ezinearticles.com/?expert=Fortune_Ihunweze). He
mentioned other suggested solutions that are focused on our behavior towards environment. Similarly, Elewa
(2008h) proposed seven important steps to avoid the sixth mass extinction; these are:
1. Looking to peace, between peoples, and between them and other creatures, as a strategic plan;
2. Minimizing all kinds of pollution to the least by searching for substitutive products that are not harmful to the
environment;
3. Caring of endangered animals and plants in naturally protected areas of the world;
4. Encouraging scientists, especially biologists, to shed more light on this serious problem through the media;
5. Reactivating the environmental program of the United Nations (UNEP) in the field of protecting plants and
animals from loss;
6. Keeping stability of nature by stopping insecure programs leading to disturbing our environment; and
7. Studying the major mass extinctions of the fossil record to know the reasons that led to these awful bioevents.
In conclusion, this review introduces short, condensed matter on one of the mysterious phenomena that occurred
and may occur in the future; it is “Mass Extinction” with particular focus on extraterrestrial bolide impact as one of the
strongly acceptable causes of extinction of dinosaurs.

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REFERENCES
Abbas, S., Abbas, A. and Mohanty, S. (2000): Anoxia during the Late Permian binary mass extinction and dark
matter. Current Science, 78(11):3.
Abdelhady, A,A. (2008): Cenomanian?Turonian mass extinction of macroinvertebrates in the context of paleoecology
– a case study from North Wadi Qena, Eastern desert, Egypt. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–
Verlag Publishers, Heidelberg, Germany, 103-128.
Alvarez, L.W., Alvarez, W., Asaro, F., and Michel, H. V. (1980): Extraterrestrial cause for the Cretaceous-Tertiary
extinction. Science, 208:1095-1108.
Andryszewski, T. (2008): Mass Extinction: Examining the Current Crisis. Lerner Publishing Group, USA, 111 p.
Arens, N.C. and West, I.D. (2008): Press-pulse: a general theory of mass extinction? Paleobiology, 34 (4):456-471.
Calner, M. (2008): Silurian global events – at the tipping point of climate change. In: Mass Extinction (A.M.T. Elewa,
Ed.), Springer–Verlag Publishers, Heidelberg, Germany, 21-58.
Castle, J. and Rodgers, J. (2009): Hypothesis for the role of toxin-producing algae in Phanerozoic mass extinctions
based on evidence from the geologic record and modern environments. Environmental Geosciences, 16 (1):1-23.
Chyba, C.F., Thomas, P.J., Zahnle, K.J. (1993): The 1908 Tunguska explosion: atmospheric disruption of a stony
asteroid. Nature, 361:40-44.
Close, F. (1988): END: Cosmic Catastrophe and the Fate of the Universe. Simon & Schuster, England.
Courtillot, V. (1999): Evolutionary Catastrophes: The Science of Mass Extinction. Cambridge University Press.
Elewa, A.M.T. (2002): Paleobiogeography of Maastrichtian to Early Eocene Ostracoda of North and West Africa and
the Middle East. Micropaleontology, USA, 48(4): 391-398.
Elewa, A. M. T. (2004a): Application of geometric morphometrics to the study of shape polymorphism in Eocene
ostracodes from Egypt and Spain. In Elewa A. M. T. (ed.): Morphometrics-Applications in Biology and
Paleontology. Springer-Verlag Publishers, Heidelberg, Germany, 7-28.
Elewa, A. M. T. (2004b): Quantitative analysis and palaeoecology of Eocene Ostracoda and benthonic foraminifera
from Gebel Mokattam, Cairo, Egypt. Palaeogeogr., Palaeoclimat., Palaeoecol., Elsevier, The Netherlands. 211(3-
4): 309-323
Elewa, A. M. T. and Morsi, A. A. (2004): Palaeobiotope analysis and palaeoenvironmental reconstruction of the
Paleocene-early Eocene ostracodes from east-central Sinai, Egypt. In: The Palynology and Micropalaeontology
of Boundaries (A. B. Beaudoin, and M. J. Head, Eds.), The Geological Society, London, 293-308.
Elewa, A. M. T. (2005a) Paleoecology and Paleogeography of Eocene Ostracod Faunas from the Nile Valley
between Minia and Maghagha, Upper Egypt. In: Migration in Organisms: Climate, Geography, Ecology (A.M.T.
Elewa, Ed.), Springer–Verlag Publishers, Heidelberg, Germany, 25-70.
Elewa, A. M. T. (2005b): Morphological variability and adaptability in Egyptian Eocene ostracod species Paracosta
Mokattamensis (Bassiouni) From the Eocene of Egypt. In: Migration in Organisms: Climate, Geography, Ecology
(A.M.T. Elewa, Ed.), Springer–Verlag Publishers, Heidelberg, Germany, 71-84.
Elewa, A. M. T. (2007): Predation due to changes in environment: Ostracod provinciality at the Paleocene-Eocene
thermal maximum in North and West Africa and the Middle East. In: Predation in Organisms - A Distinct
Phenomenon (A.M.T. Elewa, Ed.), Springer–Verlag Publishers, Heidelberg, Germany, In Elewa A. M. T. (ed.):.
Springer–Verlag Publishers, Heidelberg, Germany, 7-26.
Elewa, A.M.T. (2008a): Mass Extinction. Springer–Verlag Publishers, Heidelberg, Germany, 252 p.
Elewa, A.M.T. (2008b): Mass Extinction – A General View. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag
Publishers, Heidelberg, Germany, 1-4.
Elewa, A.M.T. (2008c): Late Ordovician mass extinction. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag
Publishers, Heidelberg, Germany, 5-8.
Elewa, A.M.T. (2008d): Late Devonian mass extinction. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag
Publishers, Heidelberg, Germany, 59-60.
Elewa, A.M.T. (2008e): Late Permian mass extinction. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag
Publishers, Heidelberg, Germany, 61-62.
Elewa, A.M.T. (2008f): Late Triassic mass extinction. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag
Publishers, Heidelberg, Germany, 63-64.
Elewa, A.M.T. (2008g): K-Pg Mass Extinction. In Elewa AMT (ed.): Mass Extinction. Springer–Verlag Publishers,
Heidelberg, Germany, 129-132.
Elewa, A.M.T. (2008h): Current Mass Extinction. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer-Verlag Publishers,
Heidelberg, Germany. 191-194.
Elewa, A.M.T. and Dakrory, A.M. (2008a): Causes of mass extinction at the K/Pg boundary: A case study from the
North African Plate. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag Publishers, Heidelberg, Germany,
133-148.

Greener Journal of Physical Sciences ISSN: 2276-7851 Vol. 4 (2), pp. 013-021, March 2014.
www.gjournals.org
20
Elewa, A.M.T. and Dakrory, A.M. (2008b): Patterns and causes of mass extinction at the K/Pg boundary: Planktonic
foraminifera from the North African Plate. In: Mass Extinction (A.M.T. Elewa, Ed.), Springer–Verlag Publishers,
Heidelberg, Germany, 149-158.
Elewa, A.M.T. and Joseph, R. (2009): The History, Origins, and Causes of Mass Extinctions. Journal of Cosmology,
2: 201-220.
Erwin, D.H. (2001): Lessons from the past: Biotic recoveries from mass extinctions. Proceedings of the National
Academy of Sciences of the USA (PNAS), 98(10):5399-5403.
Fassett, J.E., Heaman, L.M. and Simonetti, A. (2011): Direct U-Pb dating of Cretaceous and Paleocene dinosaur
bones, San Juan Basin, New Mexico. Geology, 39(2):159-162.
Fassett, J.E., Heaman, L.M. and Simonetti, A. (2012a): Direct U-Pb dating of Cretaceous and Paleocene dinosaur
bones, San Juan Basin, New Mexico: REPLY Geology, 40:e260-e261.
Fassett, J.E., Heaman, L.M. and Simonetti, A. (2012b): Direct U-Pb dating of Cretaceous and Paleocene dinosaur
bones, San Juan Basin, New Mexico: REPLY Geology, 40:e263-e264.
Firestone, R.B., West, A., Kennett, J.P., Becker, L., Bunch, T.E., Revay, Z.S., Schultz, P.H., Belgya, T., Kennett,
D.J., Erlandson, J.M., Dickenson, O.J., Goodyear, A.C., Harris, R. S., Howard, G. A., Kloosterman, J. B., Lechler,
P., Mayewski, P.A., Montgomery, J., Poreda, R., Darrah, T., Que Hee, S.S., Smith, A.R., Stich, A., Topping, W.,
Wittke, J.H. and Wolbach, W.S. (2007): Evidence for an extraterrestrial impact 12,900 years ago that contributed
to the megafaunal extinctions and the Younger Dryas cooling. Proceedings of the National Academy of Sciences
of the USA (PNAS), 104(41):16016–16021.
Gawle, R. and Czech, Z. (2013): The energy – based theory explaining dinosaur extinction and selectivity of
Cretaceous – Tertiary extinction event coincided with a large meteorite impact. International Letters of Chemistry,
Physics and Astronomy, 3(2013): 12-20.
Glavin, T. (2006): The Sixth Extinction: Journeys Among the Lost and Left Behind. St. Martin's Press, 318 p.
Hecht, J. (2002): Methane prime suspect for greatest mass extinction. New Scientist.
Herbert, T.D. (1992): Paleomagnetic calibration of Milankovitch cyclicity in Lower Cretaceous sediments. Earth and
Planetary Science Letters, 112(1), 15-28.
Hooper Virtual Paleontological Musuem. Speculated Causes of the Permian Extinction. Retrieved 16 July 2012.
Jablonski, D. (1994): Mass Extinctions: Persistent Problems and New Directions. Abstracts of Papers Presented to
"New Developments Regarding the K/T Event and Other Catastrophes in Earth History". Held February 9-12,
1994, in Houston, TX, published by the Lunar and Planetary Institute, 3303 Nasa Road 1, Houston, TX 77058.
Koenig, A.E., Lucas, S.G., Neymark, L.A., Heckert, A.B., Sullivan, R.M., Jasinski S.E. and Fowler, D.W. (2012):
Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New Mexico: COMMENT.
Geology, April 1, 40: e262.
Kump, L.R., Pavlov, A. and Arthur, M.A. (2005): Massive release of hydrogen sulfide to the surface ocean and
atmosphere during intervals of oceanic anoxia. Geology, 33:397–400.
Lantzy R., Dacey M., Mckenzie, F. (1977): Catastrophe theory: Application to the Permian mass extinction. Geology,
5(12):724-728.
Leaky, R.E. and Lewin, R. (1996): The Sixth Extinction: Patterns of Life and the Future of Humankind. Anchor Books,
271 p.
Louys, J. (2008): Quaternary extinctions in Southeast Asia. In Elewa AMT (ed.): Mass Extinction. Springer–Verlag
Publishers, Heidelberg, Germany, 159-190.
Ludwig, K.R. (2012): Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New
Mexico: COMMENT. Geology. April 1, 40: e258.
MacLeod, N. (2000): Extinction! First Science.com.
MacLeod, N. (2001): Extinction. in Encyclopaedia of Life Sciences. Macmillan, London.
Matthew, S. (2009): The Late Ordovician glaciation and mass extinction: Relation to basaltic weathering and volcanic
degassing? Portland GSA Annual Meeting (18-21 October 2009).
Mayhew, P.J., Jenkins, G.B. and Benton, T.G. (2008): A long-term association between global temperature and
biodiversity, origination and extinction in the fossil record". Proceedings of the Royal Society B: Biological
Sciences, 275(1630):47–53.
McAnena, A., Flögel, S., Hofmann, P., Herrle, J.O., Griesand, A., Pross, J., Talbot, H.M., Rethemeyer, J.,
Wallmann, K. and Wagner, T. (2013): Atlantic cooling associated with a marine biotic crisis during the mid-
Cretaceous period. Nature Geoscience (Letters), 6: 558-561.
Melott, A.L. and Thomas, B.C. (2009): Late Ordovician geographic patterns of extinction compared with simulations
of astrophysical ionizing radiation damage. Paleobiology, 35:311-320.

Greener Journal of Physical Sciences ISSN: 2276-7851 Vol. 4 (2), pp. 013-021, March 2014.
www.gjournals.org
21
Mitchell, R.N., Bice, D.M., Montanari, A., Cleaveland, N.C., Christianson, K,T., Coccioni, R. and Hinnov, L.A. (2008):
Oceanic anoxic cycles? Orbital prelude to the Bonarelli Level (OAE 2). Earth and Planetary Science Letters, 267,
(1–2): 1–16.
Molina, E., Arenillas, I. and Arz, J.A. (1996): The Cretaceous/Tertiary boundary mass extinction in planktic
foraminifera at Agost, Spain. Rev. Micropaléont., 39(3):225-243.
Newitz, A. (2013): Scatter, Adapt, and Remember: How Humans Will Survive a Mass Extinction. Knopf Doubleday
Publishing Group, 320 p.
Noort, P.C. van den and Elewa, A.M.T. (2011): The celestial factor. Journal of Ecology and the Natural Environment,
3(16): 492-498.
Pálfy, J., Mortensen, J.K., Carter, E.S., Smith, P.L., Friedman, R.M. and Tipper, H.W. (2000): Timing the end-Triassic
mass extinction: First on land, then in the sea? Geology, 28(1):39-42.
Prothero, D.R. (1998): Bringing Fossils to Life: An Introduction to Paleobiology. WCB/McGrow-Hill, USA.
Raup, D.M. and Sepkoski, J.J. (1982): Mass extinctions in the marine fossil record. Science, 215:1501-1503.
Renne, P.R. and Goodwin MB. (2012): Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan
Basin, New Mexico: COMMENT. Geology. April 1, 40: e259.
Rosenzweig, M.L. (2005): Avoiding mass extinction: basic and applied challenges. The American Midland Naturalist,
153(2):195-208.
Sagan, C. (1995): Pale Blue Dot: A Vision of the Human Future in Space. Headline Book Publishing, London.
Shen, B. (2008): Global Anoxia and mass extinction at the Cenomanian-Turonian boundary triggered by subduction
zone volcanism. Joint Annual Meeting, Celebrating the International Year of Planet Earth, October 5-9, Houston,
Texas.
Sheehan, P.M. The Late Ordovician mass extinction. Annual Review of Earth and Planetary Sciences, 2001:29:331-
364.
Thompson, S.L. and Crutzen, P.J. (1988): Acute Effects of a Large Bolide Impact Simulated by a Global Atmospheric
Circulation Model. Topical Conference on Global Catastrophes in Earth History: An Interdisciplinary Conference
on Impacts, Volcanism, and Mass Mortality, October 20-23, 1988, Snowbird, Utah.
Twitchett, R.J. (2006): The palaeoclimatology, palaeoecology and palaeoenvironmental analysis of mass extinction
events. Palaeogeogr., Palaeoclimat., Palaeoecol., 2006:232(2006):190-213.
Ward P. Out of Thin Air: Dinosaurs, Birds, and Earth's Ancient Atmosphere. Joseph Henry Press, 296p.
Wignall, P.B. and Twitchett, R.J. (1996): Oceanic anoxia and the End Permian mass extinction. Science,
272(5265):1155 – 1158.
Wilcove, D.S., Rothstein, D., Dubow, D., Phillips, A. and Losos, E. (1998): Quantifying Threats to imperiled species in
the United States. BioScience, 48(8):9.
Wilde, P. and Berry, W.B.N. (1984): Destabilization of the oceanic density structure and its significance to marine
"extinction" events. Palaeogeogr., Palaeoclimat., Palaeoecol., 48(2–4):143–162.
Wilkinson, D.M., Nisbet, E.G. and Ruxton, G.D. (2012): Could methane produced by sauropod dinosaurs have
helped drive Mesozoic climate warmth? Current Biology, 22(9):2.