The Paleontology Portal
Paleontology, also spelled palaeontology or palæontology (), is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene Epoch (roughly 11,700 years before present). It includes the study of fossils to classify organisms and study interactions with each other and their environments (their paleoecology). Paleontological observations have been documented as far back as the 5th century BCE. The science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, and developed rapidly in the 19th century. The term itself originates from Greek παλαιός, palaios, "old, ancient", ὄν, on (gen. ontos), "being, creature", and λόγος, logos, "speech, thought, study".
Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of anatomically modern humans. It now uses techniques drawn from a wide range of sciences, including biochemistry, mathematics, and engineering. Use of all these techniques has enabled paleontologists to discover much of the evolutionary history of life, almost all the way back to when Earth became capable of supporting life, about 3.8 billion years ago. As knowledge has increased, paleontology has developed specialised sub-divisions, some of which focus on different types of fossil organisms while others study ecology and environmental history, such as ancient climates.
Body fossils and trace fossils are the principal types of evidence about ancient life, and geochemical evidence has helped to decipher the evolution of life before there were organisms large enough to leave body fossils. Estimating the dates of these remains is essential but difficult: sometimes adjacent rock layers allow radiometric dating, which provides absolute dates that are accurate to within 0.5%, but more often paleontologists have to rely on relative dating by solving the "jigsaw puzzles" of biostratigraphy (arrangement of rock layers from youngest to oldest). Classifying ancient organisms is also difficult, as many do not fit well into the Linnaean taxonomy classifying living organisms, and paleontologists more often use cladistics to draw up evolutionary "family trees". The final quarter of the 20th century saw the development of molecular phylogenetics, which investigates how closely organisms are related by measuring the similarity of the DNA in their genomes. Molecular phylogenetics has also been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend.
On this day...
Selected article on the prehistoric world and its legacies
(University of Antananarivo
specimen 8699) is a fossil mammalian
tooth from the Cretaceous
. A broken lower molar
about 3.5 mm (0.14 in) long, it is from the Maastrichtian
of the Maevarano Formation
in northwestern Madagascar. Details of its crown morphology
indicate that it is a boreosphenidan
, a member of the group that includes living marsupials
. Krause, who first described the tooth in 2001, interpreted it as a marsupial on the basis of five shared characters, but in 2003 Averianov and others noted that all those are shared by zhelestid
placentals and favored a close relationship between UA 8699 and the Spanish zhelestid Lainodon
. Krause used the tooth as evidence that marsupials were present on the southern continents (Gondwana
) as early as the late Cretaceous and Averianov and colleagues proposed that the tooth represented another example of faunal exchange between Africa and Europe at the time. (see more...
Selected article on paleontology in human science, culture and economics
Did you know?
- ... that within the United States, dinosaur fossils (example pictured) have been found in Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Georgia, Idaho, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, D.C., and Wyoming, but not in Florida, Hawaii, Illinois, Indiana, Kentucky, Maine, Michigan, New Hampshire, Ohio, Rhode Island, Vermont, Washington, West Virginia, or Wisconsin?
- ... that Ekgmowechashala was the only North American genus of primate during the Late Oligocene?
- ... that lice from mummified guinea pigs and mites preserved in amber while feeding on spiders have provided evidence for researchers in the field of paleoparasitology?
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