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The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, [a] 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 ...
Lancian fauna characteristic of Hell Creek are found as high as a few meters below the boundary. [8] The K–Pg boundary is generally situated near the contact between the upper Hell Creek and the lower Ludlow member of the Fort Union Formation, though in some areas (e.g. in North Dakota) the boundary is well within the Ludlow member, 3 metres ...
K–Pg boundary mammalian species were generally small, comparable in size to rats; this small size would have helped them find shelter in protected environments. It is postulated that some early monotremes, marsupials, and placentals were semiaquatic or burrowing, as there are multiple mammalian lineages with such habits today.
In 1998, a meteorite, approximately 2.5 millimeters (1 ⁄ 8 in) across, was described from a deep sea sediment core from the North Pacific, from a sediment sequence spanning the Cretaceous–Paleogene boundary (when the site was located in the central Pacific), with the meteorite being found at the base of the K-Pg boundary iridium anomaly ...
K-Pg boundary sample from Wyoming.The intermediate claystone layer contains 1000 times more iridium than the upper and lower layers (San Diego Natural History Museum).. The Cretaceous–Paleogene ("K-Pg" or "K-T") extinction event around 66 million years ago wiped out all non-avian dinosaurs and many other species.
The End Cretaceous extinction, or the K–Pg extinction (formerly K–T extinction) occurred at the Cretaceous (Maastrichtian) – Paleogene transition. [19] The event was formerly called the Cretaceous-Tertiary or K–T extinction or K–T boundary; it is now officially named the Cretaceous–Paleogene (or K–Pg) extinction event.
The climate across the Cretaceous–Paleogene boundary (K–Pg or formerly the K–T 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.
The Scollard Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. [1] [3] Its deposition spanned the time interval from latest Cretaceous to early Paleocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event.