The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore, but the crater is named after the onshore community of Chicxulub Pueblo. It was formed slightly over 66 million years ago when a large meteorite, about ten kilometers in diameter, struck Earth. The crater is estimated to be 200 kilometers in diameter and 20 kilometers in depth. It is the second largest confirmed impact structure on Earth, and the only one whose peak ring is intact and directly accessible for scientific research.
The Vrije Universiteit Amsterdam is a public research university in Amsterdam, Netherlands, being founded in 1880. The VU Amsterdam is one of two large, publicly funded research universities in the city, the other being the University of Amsterdam (UvA). The literal translation of the Dutch name Vrije Universiteit is "Free University". "Free" refers to independence of the university from both the State and the Dutch Reformed Church. Both within and outside the university, the institution is commonly referred to as "the VU". Although founded as a private institution, the VU has received government funding on a parity basis with public universities since 1970. The university is located on a compact urban campus in the southern Buitenveldert neighbourhood of Amsterdam and adjacent to the modern Zuidas business district.
The Vrije Universiteit Brussel is a Dutch and English-speaking research university located in Brussels, Belgium. It has four campuses: Brussels Humanities, Science and Engineering Campus, Brussels Health Campus, Brussels Technology Campus and Brussels Photonics Campus.
Walter Alvarez is a professor in the Earth and Planetary Science department at the University of California, Berkeley. He and his father, Nobel Prize–winning physicist Luis Alvarez, developed the theory that dinosaurs were killed by an asteroid impact.
Chicxulub Pueblo is a town, and surrounding municipality of the same name, in the Mexican state of Yucatán.
The Late Cretaceous is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after creta, the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period.
The Shiva crater is the claim by paleontologist Sankar Chatterjee and colleagues that the Bombay High and Surat Depression on the Indian continental shelf west of Mumbai, India represent a 500-kilometre (310 mi) impact crater, that formed around the Cretaceous-Paleogene boundary. Chatterjee and colleagues have claimed that this could have contributed to the K-Pg extinction event. Other scholars have questioned the claims, finding that there is no evidence of an impact structure.
The Alvarez hypothesis posits that the mass extinction of the non-avian dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth. Prior to 2013, it was commonly cited as having happened about 65 million years ago, but Renne and colleagues (2013) gave an updated value of 66 million years. Evidence indicates that the asteroid fell in the Yucatán Peninsula, at Chicxulub, Mexico. The hypothesis is named after the father-and-son team of scientists Luis and Walter Alvarez, who first suggested it in 1980. Shortly afterwards, and independently, the same was suggested by Dutch paleontologist Jan Smit.
Gerta Keller is a geologist and paleontologist whose work has focused on global catastrophes and mass extinctions. She has been a professor of geosciences at Princeton University since 1984 and received emeritus status in July 2020. Keller contests the mainstream Alvarez hypothesis that the impact of the Chicxulub impactor, or another large celestial body, directly caused the Cretaceous–Paleogene extinction event. Keller maintains that such an impact predates the mass extinction and that Deccan volcanism and its environmental consequences were the most likely major cause, but possibly exacerbated by the impact. Considered a leading authority on catastrophes and mass extinctions, including the biotic and environmental effects of impacts and volcanism, Keller is one of few scientists whose work has consistently supported the contention, with nearly half of her 300 publications being articles which address the asteroid impact/volcano controversy
The term iridium anomaly commonly refers to an unusual abundance of the chemical element iridium in a layer of rock strata at the Cretaceous–Paleogene (K–Pg) boundary. The unusually high concentration of a rare metal like iridium is often taken as evidence for an extraterrestrial impact event.
The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at 66 million years, with radiometric dating yielding a more precise age of 66.043 ± 0.011 Ma.
William Alvin Clemens Jr. was a paleontologist at the University of California at Berkeley. He was faculty of the Department of Paleontology from 1967, then the Department of Integrative Biology from 1994 to his retirement and curator of the UC Museum of Paleontology. Clemens was also director of the museum (1987–1989) and chair of the Department of Paleontology (1987–1989). He was awarded a Guggenheim Fellowship (1974–75), a U.S. Senior Scientist Award by the Alexander von Humboldt Foundation, the Romer-Simpson Medal (2006), and was made a Fellow of the California Academy of Sciences.
The climate across the Cretaceous–Paleogene boundary is very important to geologic time as it marks a catastrophic global extinction event. Numerous theories have been proposed as to why this extinction event happened including an asteroid known as the Chicxulub asteroid, volcanism, or sea level changes. While the mass extinction is well documented, there is much debate about the immediate and long-term climatic and environmental changes caused by the event. The terrestrial climates at this time are poorly known, which limits the understanding of environmentally driven changes in biodiversity that occurred before the Chicxulub crater impact. Oxygen isotopes across the K–T boundary suggest that oceanic temperatures fluctuated in the Late Cretaceous and through the boundary itself. Carbon isotope measurements of benthic foraminifera at the K–T boundary suggest rapid, repeated fluctuations in oceanic productivity in the 3 million years before the final extinction, and that productivity and ocean circulation ended abruptly for at least tens of thousands of years just after the boundary, indicating devastation of terrestrial and marine ecosystems. Some researchers suggest that climate change is the main connection between the impact and the extinction. The impact perturbed the climate system with long-term effects that were much worse than the immediate, direct consequences of the impact.
Johannes "Hans" van der Zouwen is a Dutch sociologist, and Emeritus Professor of Social Research Methodology at the Vrije Universiteit in Amsterdam, known for his pioneering work with Felix Geyer in the field of sociocybernetics.
Hendrik (Henk) van der Flier is a Dutch psychologist, and Professor of Work and Organizational Psychology at the Vrije Universiteit Amsterdam and at its Kurt Lewin Institute (KLI), known for his work on comparability of psychological test performances.
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary(K–T)extinction, was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs. Most other tetrapods weighing more than 25 kilograms also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. It marked the end of the Cretaceous period, and with it the Mesozoic era, while heralding the beginning of the current era, the Cenozoic. In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary or K–T boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows unusually high levels of the metal iridium, which is more common in asteroids than in the Earth's crust.
T. rex and the Crater of Doom is a nonfiction book by UC Berkeley professor Walter Alvarez that was published by Princeton University Press in 1997. The book discusses the research and evidence that led to the creation of the Alvarez hypothesis, which explains how an impact event was the main cause that resulted in the Cretaceous–Paleogene extinction event.
Since the 19th century, a significant amount of research has been conducted on the Cretaceous–Paleogene extinction event, the mass extinction that ended the dinosaur-dominated Mesozoic Era and set the stage for the Age of Mammals, or Cenozoic Era. A chronology of this research is presented here.
Tanis is a paleontological site in southwestern North Dakota, United States. It is part of the heavily studied Hell Creek Formation, a geological region renowned for many significant fossil discoveries from the Upper Cretaceous and lower Paleocene. Uniquely, Tanis appears to record in detail, extensive evidence of the direct effects of the giant Chicxulub asteroid impact which struck the Gulf of Mexico 66.043 million years ago, and wiped out all non-avian dinosaurs and many other species. The extinction event caused by this impact began the Cenozoic, in which mammals—including humans—eventually came to dominate life on Earth.
Alan Russell Hildebrand is a planetary scientist and Associate Professor in the Department of Geoscience at the University of Calgary. He has specialized in the study of asteroid impact cratering, fireballs and meteorite recovery. His work has shed light on the extinction event caused by the Chicxulub asteroid at the end of the Cretaceous period. Hildebrand is one of the leaders of the Prairie Meteorite Network search project.
