radiocarbon dating

Examples of radiocarbon dating in the following topics:

• Carbon Dating and Estimating Fossil Age

  • The age of fossils can be determined using stratigraphy, biostratigraphy, and radiocarbon dating.
  • Paleontologists rely on stratigraphy to date fossils.
  • Beds that preserve fossils typically lack the radioactive elements needed for radiometric dating ("radiocarbon dating" or simply "carbon dating").
  • The principle of radiocarbon dating is simple: the rates at which various radioactive elements decay are known, and the ratio of the radioactive element to its decay products shows how long the radioactive element has existed in the rock.
  • The half-life of carbon-14 is 5,730 years, so carbon dating is only relevant for dating fossils less than 60,000 years old.

• Pre-Cambrian Animal Life

  • These sponge-like fossils, named Coronacollina acula, date back as far as 560 million years.
  • These fossils from South Australia date back 650 million years, actually placing the putative animal before the great ice age extinction event that marked the transition between the Cryogenian period and the Ediacaran period.

• Early Human Evolution

  • The oldest of these, Sahelanthropus tchadensis, has been dated to nearly seven million years ago.
  • To date, it is unclear how this fossil fits with the picture given by molecular data.

• Early Hominins

  • Hominin footprints, similar to those of modern humans, found in Laetoli, Tanzania, are dated to 3.6 million years ago.
  • In the mid-1970s, the fossil of an adult female A. afarensis was found in the Afar region of Ethiopia, dated to 3.24 million years ago .
  • While most australopiths had a relatively slender, gracile build and teeth suited for soft food, there were also australopiths of a more robust build, dating to approximately 2.5 million years ago.

• The Origins of Archaea and Bacteria

  • This estimate is based on evidence from radiometric dating of meteorite material together with other substrate material from earth and the moon.
  • Although probable prokaryotic cell fossils date to almost 3.5 billion years ago, most prokaryotes do not have distinctive morphologies; fossil shapes cannot be used to identify them as Archaea.
  • Some publications suggest that archaean or eukaryotic lipid remains are present in shales dating from 2.7 billion years ago.

• Abscisic Acid, Ethylene, and Nontraditional Hormones

  • The plant hormone ethylene promotes ripening, as seen in the ripening of dates.

• Homo sapiens

  • Homo erectus is an extinct species of hominin that lived throughout most of the Pleistocene, with the earliest first fossil evidence dating to around 1.8 million years ago and the most recent to around 143,000 years ago

• The Pleistocene Extinction

  • In North America, the losses were quite dramatic and included the woolly mammoths (last dated about 4,000 years ago in an isolated population), mastodons, giant beavers, giant ground sloths, saber-toothed cats, and the North American camel, to name just a few .

• Evolution of Land Plants

  • Fossilized cells, cuticles, and spores of early land plants have been dated as far back as the Ordovician period in the early Paleozoic era.

• Vascular Tissue: Xylem and Phloem

  • The first fossils that show the presence of vascular tissue date to the Silurian period, about 430 million years ago.