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Timeline of the great findings of Paleontology and Biology

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« on: September 05, 2008, 01:25:50 pm »

Timeline of the great findings of Paleontology and Biology

610-425 BC-Philosophers Thales, Anaximander, Pythagoras, Xenophanes and Herodotus propose that marine fossils found inland lived in the sea, and that the now dry land was once underwater. This correct supposition will be forgotten for centuries.

c.400 BC-Herodotus relates the griffin myth. (The myth is probably inspired by Protoceratops and Psittacosaurus remains.)

c.78-Pliny the Elder publishes a 37-volume natural history encyclopedia. Containing both accurate and inaccurate information, it will become the basis of many scientific disciplines.

150-The physician Galen travels from Turkey to Alexandria to study anatomy. Galen will establish the concept of humors (phlegm, blood, black bile and yellow bile) that determine both health and personality. Belief in these four humors will dominate medicine and biology for many centuries.

c.180-Pausanias records a description of the skeleton of the hero Ajax. (It is probably a fossil mastodon or rhinoceros.)

476-The last western emperor of the Roman Empire is deposed.

c.512-Townspeople in a district of Constantinople present a book on plants to their patron, Julia Anicia. Juliana's codex will stand as perhaps the best compilation of Western knowledge about plants for the next 1,000 years.

c.713-A Japanese chronicle, the Hitachi Fudoki, describes a shell mound, perhaps one of the oldest descriptions of prehistoric remains in medieval writings.

c.975-Syrian *****e Muslims known as the Brothers of Purity publish an encyclopedia, The Aim of the Sage, with thorough and accurate descriptions of the process of rock stratification.

c.1020-Muslim polymath ibn Sina (known in the West as Avicenna) writes an important work on erosion. Skeptical about alchemy, however, he doubts that bones can turn to stone and therefore rejects the explanation of fossils as organic remains.

1095-The Christian Crusades to Jerusalem begin.

1130-1140-Adelard of Bath writes Quaestiones Naturales stressing the need to look for natural causes of natural phenomena.

1171-As later chronicled by Ralph of Coggeshall in Essex, a river bank collapses to reveal giant fossil bones that are attributed to a 40-foot-tall man.

c.1200-Aristotle's writings, preserved largely by Muslim scholars, become available to Europeans. The writings will be partially or completely banned by the papacy over the next five decades, but finally become mandatory material for university lectures.

c.1256-Albertus Magnus publishes his Book of Minerals.

1267-Franciscan monk Roger Bacon writes Opus Majus naming experimentation as the best way to advance science. It will not be published until nearly 450 years after his death.

c.1285-Richard of Holdingham produces the Hereford Map, showing the "marvels of Africa" including winged salamanders, weird birds and people who walk on all fours.

c.1370-Theology master Nicole Oresme publishes De Causis Mirabilium describing natural causes of natural phenomena and discouraging invocations of God or demons to explain them.

1443-Workmen digging the foundation of St. Stephen's Cathedral in Vienna find a huge femur (probably from a mammoth). The bone is inscribed with its discovery date and the motto of Emperor Frederick III, and chained to one of the cathedral doors.

1455-Gutenberg invents the Western world's first working movable type.

1469-A new edition of Pliny's Natural History is published in Venice.

1483-Teodoro of Gaza publishes a Latin version of the work of Theophrastus (a student of Aristotle's and an outstanding botanist).

1492-Columbus sails to America.

c.1500-Leonardo da Vinci proposes that fossil marine shells have not been carried to their present locations by a deluge, nor created on the spot.

1514-King Manuel I of Portugal enhances the menagerie of animals owned by Pope Leo X through the gift of an Indian elephant. Curious crowds follow the beast the entire length of its journey through Italy.

1517-Martin Luther pens Ninety-Five Theses, leading to the Reformation.

1519-Tlaxcalteca warriors from the Yucatán present Cortés's army with "giant's bones" that are actually mastodon remains.

1523-Martin Luther and Philipp Melanchthon publish depictions of a "pope-ass" and a "monk-calf," obscene-looking monsters signifying divine displeasure with the Papacy.

1530-1536-Otto Brunfels publishes Herbarum Vivae Eicones with woodcuts by Hans Weiditz. It turns out to be Europe's first best-selling herbal.

1537-Anatomist Andreas Vesalius departs from the established teachings of classical scholars and begins showing his students real anatomy in human cadavers. He will later publish immensely popular Seven Books on the Structure of the Human Body.

1542-Leonhart Fuchs publishes Historia Stirpium naming roughly 500 plant species.

1543-Girolamo Fracastoro expounds the germ theory of disease. He also states that infection can spread through direct contact, clothes and airborne germs.

1546-German minerologist Georgius Agricola publishes On the Nature of Fossils, the first published paleontological treatise.

1551-1558-Conrad Gesner publishes Historia Animalium ("History of Animals") in four volumes.

1554-Guillaume Rondelet publishes a thick volume on Mediterranean fish, and includes the assertion that glossopetrae, or tongue stones, resemble shark teeth. The hypothesis attracts little attention.

1554-Roman naturalist Ippolito Salviani publishes History of Aquatic Animals.

1555-The first edition of Alessio Piemontese's Secreti is published, listing about 350 medical recipes along with observations of nature. The publisher, Girolamo Ruscelli, will later claim authorship. Enormously popular, the book will total 104 editions through 1699.

1561-c.1595-Georg Bocskay and Joris Hoefnagel produce Mira Calligraphiae Monumenta for the Holy Roman Emperors Ferdinand I and Rudolf II, showing specimens from the imperial court gardens. This is part of a larger effort to amass knowledge about the natural world.

1565-Conrad Gesner publishes De Omni Rerum Fossilium ("A Book of Fossil Objects").

1565-Antwerp doctor Samuel von Quicchelberg publishes a description of the first "imaginary museum" including items from the animal, vegetable and mineral world.

1573-French surgeon Ambroise Paré publishes the first edition of Des Monstres. At this time, surgeons are not regarded as real doctors, and Paré is roundly criticized for discussing larger issues of medicine and philosophy, considered well beyond his purview.

1583-Andrea Cesalpino publishes De Plantis, ordering plants in families.

1585-Michele Mercati establishes one of the first mineralogical curiosity cabinets in Europe.

1590-José de Acosta publishes Natural and Moral History of the Indies describing such weird creatures as iguanas.

1591-Girolamo Porro produces a plan for a botanical garden at Padua, expecting to assemble all the world's plants. Over the next century, well-traveled naturalists will abandon such goals as unrealistic.

1596-The work of Dutch cartographer Abraham Ortelius suggests the possibility of continental drift, which will be described more forcefully by Alfred Wegener centuries later.

1597-John Gerard publishes an unreliable herbal.

1598-Jean Bauhin, a former student of Conrad Gesner's, publishes a monograph of the medicinal waters and surrounding environment of the German fountains at Boll, the first publication of a complete set of fossils from a specific location.

1599-Ferrante Imperato publishes Natural History attempting to catalog all of nature's animal, vegetable and mineral forms.
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« Reply #1 on: September 05, 2008, 01:26:14 pm »

1600-William Gilbert, court physician to Elizabeth I, describes the earth's magnetism in De Magnete.

1603-Prince Federico Cesi establishes the Lincean, or Lyncean, Academy in Rome, perhaps the first scientific academy of the modern era.

1605-Richard Verstegan describes plesiosaur remains but thinks they belong to "fishes."

1616-Fabio Colonna publishes "Dissertation on Tongue Stones" arguing that "nobody is so stupid" that he or she will not agree that tongue stones are really shark teeth. Like Rondelet several decades earlier, he attracts little attention.

1616-Fortunio Liceti publishes De Monstrorum Natura claiming that God makes monsters not to show divine wrath but to cause wonder.

1616-Italian philosopher Lucilio Vanini suggests that humans descended from apes.

1619-Italian philosopher Lucilio Vanini is burned alive for suggesting that humans descended from apes.

1620-Francis Bacon publishes Novum Organum, stressing the importance of experimentation.

1623-Gaspard Bauhin publishes Pinax Theatri Botanici describing some 6,000 plants.

1624-Galileo presents to Cesi, founder of the Lincean Academy, a "little eyeglass" (a microscope). The invention will enable the Linceans to study natural objects with unprecedented precision. They will start with bees, then move on to flies and dust mites.

1628-William Harvey publishes On the Motions of the Heart and Blood explaining that blood travels away from the heart in arteries, and back to the heart in veins.

1628-Caspar Bartholinus publishes a slim volume on the unicorn and related topics, describing horned bugs, birds, snakes and people.

1637-Francesco Stelluti publishes a summary of research on fossil wood conducted by himself and fellow Lincean Academy member Federico Cesi. Though resulting from meticulous research, the work reaches the wrong conclusion, describing the origin of fossil wood as inorganic.

1639-Ulisse Aldrovandi posthumously publishes a history of serpents.

1641-Dutch anatomist Nicolaas Tulp produces the first formal description of an ape (a chimp, bonobo or orangutan).

1641-Calvinist lawyer Isaac La Peyrère seeks permission to publish his manuscript claiming that people have existed before Adam, and that Chaldeans can legitimately trace their civilization back 470,000 years. Permission is denied, but he will publish Men Before Adam anonymously 14 years later, inciting both outrage and mild amusement among religious leaders.

1641-René Descartes publishes Principles of Philosophy arguing that the universe is governed by simple laws and that natural processes could have shaped the earth.

1642-Civil war breaks out in England.

1646-Perhaps influenced by Francis Bacon's call for a compilation of popular errors, English physician Sir Thomas Browne writes Pseudodoxia Epidemica exposing errors in medicine and natural science.

1650-Irish archbishop James Ussher calculates the date of creation, based on the ages of biblical prophets. Using his calculations, theologians will identify the date of creation as on October 26, 4004 BC.

1651-William Harvey publishes Disputations Touching the Generation of Animals explaining that all animal life begins as eggs, whether in birds, amphibians or mammals.

1655-Danish scholar Ole Worm publishes Musei Wormiani Historia, a successful book about his cabinet of natural curiosities.

1658-Jesuit missionary Martino Martini publishes a manuscript explaining that documented Chinese history predates the time generally understood to mark the Noah's flood (2,300 BC).

1659-John Tradescant deeds his family treasures to fellow collector Elias Ashmole. Ashmole will later donate the collection to Oxford University, stipulating that a separate building is to be constructed for it.

1661-Robert Boyle publishes The Sceptical Chymist helping to transform alchemy into chemistry. Though an alchemist himself with his own cache of secret notebooks, Boyle begins writing up experiments for use by others.

1663-German physicist Otto von Guericke pieces together bones from different species to make a fossil "unicorn."

1664-Thomas Willis publishes The Anatomy of the Brain and Nerves.

1665-Robert Hooke publishes Micrographia showing views of natural objects, including fossils, available with the newly invented microscope.

1665-Le Journal des Savants is first published in France, and Philosophical Transactions of the Royal Society is first published in England.

1665-1678-Athanasius Kircher publishes Mundus Subterraneus.

1666-Physician Francesco Redi conducts experiments in spontaneous generation. He concludes that the dung and rotting meat in his experiments are merely breeding sites for preexisting vermin. Two years later, he will challenge the spontaneous generation claims of Kircher.

1666-Robert Boyle composes Free Inquiry into the Vulgarly Received Notion of Nature criticizing the notion that nature is capable of autonomy from God.

1667-Niels Stensen (Steno) describes his dissection of the head of a giant white shark and correctly identifies shark teeth, still generally thought (despite arguments to the contrary from Rondelet and Colonna in the preceding century) to be serpent tongues.

1667-The Royal Society of London conducts a sheep-to-human blood transfusion experiment. Remarkably, the human subject survives.

1667-Johann Homilius delivers a dissertation, De Monocerote, criticizing all those who doubt the existence of the unicorn, pointing to passages in the Bible as evidence for the creature's literal existence.

1668-Robert Hooke presents a lecture to the Royal Society claiming that earthquakes, not the biblical flood, have caused fossils to be found on mountaintops and buried in stone.

1668-Jan Swammerdam dissects a caterpillar for Cosimo de Medici, demonstrating that the butterfly wings already exist inside the caterpillar's body. A year later, he will publish Historia Insectorum Generalis.

1669-Niels Stensen (Steno) publishes Forerunner, showing diagrammatic sections of the Tuscany area geology, making the important point that sediments are deposited in horizontal layers.

1670-Agostino Scilla publishes Vain Speculation Undeceived by Sense arguing for the organic origin of fossils.

1672-1673-A German society of scholars reports that dragon bones have been found in the caves of the Carpathian Mountains and in Transylvania. (The bones probably really belong to a bear.)

1673-Dr. Olfert Dapper publishes Die Unbekante Neue Welt describing America. The book includes a picture of a unicorn with an American eagle on its back.

1673-Leeuwenhoek begins corresponding with the Royal Society of London describing his discoveries under the microscope.

1676-Naturalist Robert Plot describes what is actually a dinosaur bone. Although he accurately identifies it as the distal end of a femur, he attributes it to a giant human.

1679-Edward Lhwyd publishes a description of a "flatfish" in the Philosophical Transactions of the Royal Society. (The flatfish is really a trilobite, an ancient marine arthropod.)

1681-Thomas Burnet publishes The Sacred Theory of the Earth combining scripture with rationalism. He claims that mountains (viewed as ugly signs of decay) formed from a catastrophic flood, but that the earth will reassume a perfectly spherical shape.

1681-Amsterdam physician Gerard Blasius publishes Anatome Animalium examining animals' internal anatomy and skeletal structure.

1683-Oxford opens the Ashmolean Museum, the world's first public museum. The museum's practice of allowing entry to anyone who pays the admission fee horrifies scholars from continental Europe.

1693-Naturalist John Ray publishes Three Physicotheological Discourses about the Creation, the Deluge and the Conflagration, discussing conflicting theories about the nature of fossils.

1697-Scandinavian historian Olof Rudbeck publishes his attempt to chronologically measure sedimentary deposits, laying the foundations for the field of stratigraphy.

1699-Edward Tyson publishes Orang Outan, sive Homo sylvestris pointing out similarities between chimpanzee and human anatomy.

1699-Edward Lhwyd publishes a book devoted to British fossils. In it, he describes ichthyosaur remains as those of a fish.
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1704-D. Michael Bernhard Valentini assembles sources of "true and false" unicorn horns.

1705-The Ambonese Curiosity Cabinet by G.E. Rumphius is published. It provides detailed descriptions of soft and hard shellfish, minerals, rocks and fossils from Indonesia.

1705-Maria Sybilla Merian publishes Metamorphosis Insectorum Surinamensium describing insect species and other animals she has studied in Surinam.

1705-A giant fossil tooth is found along the banks of the Hudson River. It will initially be identified (by Cotton Mather) as that of a human giant who perished in Noah's flood, then correctly identified (by Georges Cuvier) as that of a mastodon.

1707-Hans Sloane publishes the first of two volumes describing the natural wonders of Jamaica. (The second volume will be published in 1725.)

1714-On the advice of Leibniz, Peter the Great opens a public museum in Saint Petersburg.

1715-Edmund Halley lectures the Royal Society that the age of the earth could be calculated by measuring the ocean's salinity since ocean salts result from sediments carried by rivers and streams.

1717-Dutch pharmacist Albertus Seba inventories his wonder cabinet for the avid collector Peter the Great, including 1,000 European insects and 400 animal specimens. The czar buys the inventory, and Seba begins his second collection, which he will describe in print starting in 1734.

1719-William Stukeley publishes "An Account of the Almost Entire Sceleton of a Large Animal in a Very Hard Stone." The fossil is a plesiosaur, but is identified as a crocodile.

1720-René Réaumur submits a report to the Paris Academy of Sciences proposing that a brief Noachian flood cannot account for the thick sedimentary layers (composed largely of broken shells) underlying the region of Tours. He suggests instead that the region was once covered by the sea.

1722-Benoît de Maillet anonymously publishes Telliamed, named after an oriental sage who says that the earth must be at least 2 billion years old, based on measurements of falling sea level. (In fact, no sage exists; the title is really the author's name spelled backward.)

1723-Antoine de Jussieu addresses a paper to the Académie des Sciences suggesting that an ancient object, e.g., a stone tool, made of the same material and by the same process as those used by a modern population probably has the same function.

1728-Hans Sloane publishes two papers on fossils found in Siberia and North America arguing that they are fossil elephants, not giants or monsters.

1731-Johann Jakob Scheuchzer publishes Sacred Physics, a pictorial account of earth's history based on the Old Testament. Included is a description of what he believes is a fossilized victim of the biblical flood.

1735-Linnaeus publishes Systema Naturae, laying the groundwork for the system of binomial nomenclature that will continue for over two centuries.

1739-Native Americans traveling with French soldiers find mastodon fossils along the Ohio River. The bones will be shipped back to France and become the first American fossils studied by scientists.

1744-Scholar and teacher Abraham Trembley publishes Mémoires Concerning the Natural History of a Type of Freshwater Polyp with Arms Shaped Like Horns. After watching them move and eat, he has concluded that the simple creatures (later to be classified as cnidarians) are animals, not plants.

1749-Georges-Louis Leclerc de Buffon publishes the first volume of Historie Naturelle, claiming that the planets were formed by a comet crashing into the sun. Under pressure from the Faculty of Theology of Paris, he will publish a retraction in the next volume.

1751-Encyclopedists Diderot and d'Alembert publish the first volume of the Encyclopedia, or Classified Dictionary of Sciences, Arts and Trades emphasizing a dispassionate presentation of factual information rather than reliance on age-old "wisdom."

1753-The British Museum opens.

1760-Giovanni Arduino proposes a naming system for geologic strata, in order of oldest to youngest: Primary: lacking fossils; Secondary: tilted with fossils; Tertiary: horizontal with fossils; Quaternary: sands and gravels overlying Tertiary strata. Although he does not relate these systems to scripture, many people will interpret them in terms of biblical events.

1762-George III purchases the Paper Museum of Cassiano Dal Pozzo, a 17th-century patron of arts and sciences. Preserved by the Albani family, this "museum" contains more than 7,000 science illustrations, including highly accurate depictions from the Lincean Academy that will prove invaluable to later science historians.

1767-Benjamin Franklin writes a thank-you letter to a wealthy Irish trader for a box of proboscidian "tusks and grinders." Franklin believes the remains belong to elephants but makes astute observations about how their climate must have differed from the present.

1768-James Cook sets sail on the Endeavour bound for the South Pacific. Accompanying Cook is naturalist Joseph Banks, who will collect tens of thousands of plant and animal specimens and initiate the exchange of flora and fauna between Europe, the Americas and the South Seas.

1769-William Hunter publishes a paper describing an American fossil proboscidian as a carnivore and suggesting that it is extinct.

1770-Erasmus Darwin has the allegorical motto E conchis omnia or "Everything from shells" painted on his carriage, promoting the idea of common descent. Bowing to social pressure, he removes it shortly thereafter.

1771-Joseph Priestly discovers that a plant can produce enough breathable air to sustain a mouse and keep a candle burning. Though he describes it in different terms, he has discovered oxygen.

1776-Patriots in the North American colonies sign the Declaration of Independence.

1776-Abbé Jacques-François Dicquemare describes reptilian fossils in Journal de Physique but refrains from speculating about their sources.

1778-Buffon publishes Les Epoques de la Nature, asserting that the earth is a staggering 74,832 years old, and has existed long before the arrival of humans or any other form of life.

c.1780-Abraham Gottlob Werner asserts that all rocks have been deposited by a primordial ocean. This "Neptunian" view is accepted with little question.

1784-Charles Willson Peale establishes a natural history museum in Philadelphia, one of the first successful American museums.

1784-Historian and naturalist Cosimo Alessandro Collini publishes a description of the first known pterosaur.

1785-Thomas Jefferson publishes Notes on the State of Virginia refuting Buffon's claim that America's harsh, moist climate stunts the growth of its inhabitants. He also addresses the issue of race, describing Native Americans favorably, but African slaves unfavorably.

1787-Caspar Wistar and Timothy Matlack inform the American Philosophical Society of Philadelphia that they have discovered a "giant's bone" in New Jersey. (The bone probably belongs to a dinosaur.) Soon afterwards, the bone is lost.

1787-Anatomist and artist Petrus Camper publishes On the Absurdity of the Supposed Unicorns arguing that no land species has a cranial structure that can support a single heavy bone mass above the eyes.

1788-Juan-Bautista Bru mounts the first relatively accurate fossil reconstruction of an extinct animal from South America. Georges Cuvier classifies it as a giant sloth.

1789-French polymath Antoine Lavoisier publishes a paper on French geology defining peacefully deposited pelagic sediments and violently deposited littoral sediments. He argues that these sediments illustrate a fluctuating sea level on an ancient planet.

1789-The French Revolution begins.

1794-James Hutton publishes An Investigation of the Principles of Knowledge. Buried in the 2,138-page philosophical tome is a chapter about variety in nature in which Hutton anticipates Charles Darwin's theory of natural selection.

1795-James Hutton overturns the "Neptunian" view of rock formation in his Theory of the Earth, suggesting instead that forces of rock creation are balanced by forces of rock destruction.

1799-Faujas publishes a description of the Maastricht animal, a spectacular mosasaur found in chalk quarries in the Netherlands, describing it as a crocodile.

1799-Charles White publishes An Account of the Regular Gradation in Man, and in Different Animals and Vegetables, a treatise on the great chain of being, showing people of color at the bottom of the human chain.

1799-Thomas Jefferson publishes a paper describing Megalonyx, a North American fossil ground sloth similar to the one found in South America.

1799-Alexander von Humboldt names the Jurassic System, after the Jura Mountains. This time period will later be identified as the "middle period" for the dinosaurs.

1799-George Shaw publishes a description of a platypus even though he suspects the odd animal might be a hoax.

1799-The British government purchases the collection of Scottish anatomist John Hunter, forming the Hunterian Museum.

1799-William Smith maps rock formations in the vicinity of Bath, England, making perhaps the world's first geologic map. The same year, Smith, Joseph Townsend and Benjamin Richardson recognize the Permo-Triassic boundary, though not necessarily by that name. (The Permo-Triassic boundary will later be identified as marking the earth's most catastrophic mass extinction.)
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1800-Erasmus Darwin publishes Phytologia declaring that leaves breathe air through tiny pores, sugar and starch are the products of plant "digestion," and nitrates and phosphorus promote vegetation.

1800-Lamarck proposes his theory of evolution.

1802-Lamarck coins the term biology.

1802-A Massachusetts boy named Pliny Moody finds fossil footprints, probably from theropod dinosaurs, on his father's farm. They are initially identified as the tracks of Noah's raven.

1802-In Natural Theology, William Paley uses the analogy of a watch requiring a watchmaker to argue that the universe implies an intelligent designer.

1803-The United States purchases the Louisiana Territory from France.

1803-U.S. President Thomas Jefferson appoints Meriwether Lewis and William Clark to explore the uncharted West. Among the marvels Lewis and Clark are expected to find are erupting volcanoes, mountains of salt, unicorns, living mastodons and seven-foot-tall beavers. They will find none of these, but will find fossils.

1804-James Parkinson publishes the first of a three-volume work entitled Organic Remains of a Former World. In this volume, he describes fossils as the remains of Noah's Flood. In the next several years, he will recognize fossils as the remains of a world before people, and acknowledge as much in the third volume, published in 1811.

1804-Georges Cuvier suggests that fossils found in the area around Paris are "thousands of centuries" old. This casual observation pushes the age of the earth well beyond its commonly accepted limits. Cuvier also publishes a paper explaining that the fossil animals he has studied bear no resemblance to anything still living, an unambiguous endorsement of the theory of extinction.

1809-Charles Darwin is born on February 12. (Abraham Lincoln is born the same day.)

1809-Jean-Baptiste de Monet de Lamarck publishes Philosophie Zoologique proposing that animals can acquire new characteristics during their lives and pass those characteristics on to their offspring, an idea for which he is openly ridiculed by Georges Cuvier.

1810-Mary Anning's brother Joseph discovers the world's first fossil ichthyosaur. Mary Anning will collect the fossil the next year.

1811-Georges Cuvier identifies the "biblical flood" victim, described by Johann Jakob Scheuchzer in 1731, as a giant salamander.

1812-Georges Cuvier correctly identifies pterosaurs as flying reptiles. His conclusions will be largely ignored for many years.

1815-Relying largely on fossils to identify strata, civil engineer William Smith publishes a geologic map of England, Wales and part of Scotland, the largest region so far documented. Four years later, Smith will be arrested and sent to debtors' prison.

1815-1822-Lamarck restates his transmutational theories in a seven-volume study on invertebrates, Histoire Naturelle des Animaux sans Vertèbres.

1818-Physician William Wells hypothesizes about selection and human evolution. Charles Darwin will later acknowledge Wells as someone who anticipated the theory of natural selection.

1820-Gideon Mantell discovers, in England, a fossil trunk of a tree resembling that of a tropical palm, evidence of a much warmer climate.

1820-1821-Mary Anning excavates the world's first fossil plesiosaur to be correctly identified, formally described by Henry De la Beche and William Conybeare.

1822-Etienne Geoffroy publishes Anatomical Philosophy discussing similarities between skeletal structures — such as bat wings, paws and hands — that support the evolutionary claims of Lamarck. He also argues that arthropods and vertebrates have similar but inverse body plans, an assertion that will ultimately be widely accepted.

1822-William Buckland publishes an account of how ancient hyenas lived and fed, based on their fossil remains. This is one of the first descriptions of living habits based on fossil evidence.

1822-William Buckland finds a skeleton covered in ocher. Called the Red Lady, it will later be identified as Cro-Magnon (and male).

1822-Omalius d'Halloy names the Cretaceous System, after massive chalk deposits. This time period will later be identified with the last dinosaurs and the first flowering plants.

1822-William Conybeare and William Phillips name the Carboniferous System, a period associated with coal deposits. This time period will also become known as the Mississippian and Pennsylvanian Periods in the United States.

1824-William Buckland publishes Notice on the Megalosaurus ("giant lizard"), the first dinosaur fossil to be described and named, although the term "dinosaur" doesn't yet exist. Buckland also announces the discovery of the first fossil mammal from the Mesozoic.

1825-Gideon Mantell publishes Notice on the Iguanodon, the second description of a dinosaur and the first description of an herbivorous fossil reptile.

1825-1827-Robert Grant publishes a series of articles on sea sponges demonstrating that they are animals (not plants) and supporting the theory of transmutationism.

1826-M. Charles Desmoulins publishes Hist. Nat. des Races Humaines arguing for 16 distinct, unchanging human species.

1827-1838-John James Audubon publishes Birds of America, in four volumes.

1828-Adolphe Brongniart publishes Prodrome d'une histoire des Végétaux Fossils, a study of fossil plants. He outlines four distinct phases in plant prehistory: (1) primitive plants from the Coal Measures, (2) the first conifers, (3) domination by cycads and conifers, and (4) flowering plants.

1828-A year after discovering the mammalian egg cell, Karl Ernst von Baer publishes Entwickelungsgeschichte der Thiere tracing the developmental history of animals.

1828-Mary Anning discovers Britain's first recognized pterosaur fossil. (Gideon Mantell has already found pterosaur remains, but has attributed them to a bird).

1829-Jules Desnoyers names the Quaternary System, a time in which humans have lived.

1829-Philippe-Charles Schmerling discovers a Neanderthal fossil, the partial cranium of a small child. The fossil will not be accurately identified as Neanderthal, however, for a century, though Charles Lyell will illustrate it in Antiquity of Man in 1863.

1830-Charles Lyell publishes Principles of Geology, a book that Charles Darwin will later take with him aboard the Beagle.

1830-Georg Goldfuss announces that he sees "hairs" on a pterosaur fossil. This outlandish assertion will be supported by later finds.

1831-Patrick Matthew publishes On Naval Timber and Arboriculture with an appendix describing what Charles Darwin will later name natural selection. After becoming aware of Matthew's hypothesis, Darwin will acknowledge it in a reprint of On the Origin of Species.

1831-1836-Charles Darwin sails on the Beagle, visiting, among other locations, the Galápagos Islands.

1832-Gideon Mantell finds the first fossil Hylaeosaurus, an ankylosaur. He will formally name it the following year, making it the third identified dinosaur species.

1834-William Whewell coins the term "scientist."

1834-Friedrich von Alberti names the Triassic System. This time period will later by identified with the first dinosaurs.

1835-Adam Sedgwick names the Cambrian System, recognizing the first rich assemblage of fossils in the rock record. Roderick Murchison names the Silurian System. He believes (not entirely accurately) that the Silurian predates the fossils of land plants, and consequently any economically valuable coal seams. Murchison and Sedgwick will later develop a bitter priority dispute over these systems.

1836-Edward Hitchcock publishes his first paper on stone footprints in Connecticut. He continues to study and publish papers on these footprints, believing they have been made by giant birds. (They will later prove to be the footprints of bipedal dinosaurs.)

1836-Henry Riley and Samuel Stutchbury name Thecodontosaurus, the fourth named dinosaur species.

1837-Hermann von Meyer names Plateosaurus, the fifth named dinosaur species.

c.1837-Charles Darwin formulates the theory of natural selection to explain evolution. Fearful of the reaction his theory will cause, he delays publishing.

1837-Louis Agassiz presents the theory of the Ice Age at a meeting of the Swiss Society of Natural Sciences. The shocked audience reacts with hostility.

1838-1842-Celebrity painter John Martin produces dramatic illustrations of feisty dinosaurs, for books written largely for the public. These dragon-like depictions are hits with their intended audience but many scientists reject them as inaccurate.

1839-Roderick Murchison and Adam Sedgwick name the Devonian System.

1840-1850-Several scientists see chromosomes under the microscope, but don't understand what they are.

1841-Roderick Murchison names the Permian System.

1841-William Smith's nephew John Phillips formally proposes the geologic eras Paleozoic, Mesozoic and Cainozoic (Cenozoic).

1841-1842-English anatomist Sir Richard Owen proposes the term Dinosauria ("terrible lizards").

1842-Richard Owen names Cetiosaurus, the sixth named dinosaur species.

1842-Based on Agassiz's Ice Age theory, self-taught science enthusiast Charles Maclaren publishes a newspaper article explaining that substantial ice sheets in the northern hemisphere would have lowered global sea level.

1842-P.T. Barnum lures crowds of thousands to see his "Feejee Mermaid."

1843-Louis Agassiz completes Les Poissons Fossiles describing fossil fish of the world. This single monograph increases tenfold the formally described vertebrates known to science.

1843-Based on earlier interpretations by Samuel Thomas von Soemmering, Edward Newman portrays a pterosaur as a furry bat.

1844-Vestiges of the Natural History of Creation is published, arguing that species evolve over time to superior forms, directed by divine intervention. Although it's an immensely popular book, it is considered heretical, and the author (essayist Robert Chambers) keeps his identity secret until his death 27 years later.

1845-The School of Medicine in Paris creates a gallery of comparative anatomy.

1846-Joseph Leidy identifies in pork the parasite that causes trichinosis, a potentially fatal human disease.

1847-Jakob Mathias Schleiden and Theodor Schwann announce that cells are the basic units of all living structures.

1848-The American Association for the Advancement of Science is established.

1848-Richard Owen describes "homologies" — similarities of design in bird wings, fish fins and human hands.

c.1849-Showmen Moses Kimball and P.T. Barnum purchase the contents of the Peale Museum (established in 1784).

1849-Based on a humerus 58 inches in circumference, Mantell names a new dinosaur species: Pelorosaurus, the first recognized sauropod.

1851-1854-Charles Darwin publishes monographs on cirripedes (marine invertebrates including barnacles) in four volumes. His thorough research wins him the Royal Medal.

1853-1854-Under the supervision of Sir Richard Owen, Benjamin Waterhouse Hawkins constructs scenes of prehistoric life in Crystal Palace Park.

1856-The first recognized fossil human, a Neanderthal, is discovered near Düsseldorf.

1856-Louis Agassiz publishes Essay on Classification advocating a theory of multiple creations and contradicting both evolution and Noah's ark.

1858-Although he uses different terminology, Alfred Russel Wallace independently reaches the same conclusion as Darwin: natural selection is the driving force behind evolution. Wallace's and Darwin's papers are both read at the same Linnean Society meeting.

1858-The first relatively complete dinosaur skeleton, of Hadrosaurus foulkii, is found in New Jersey.

1858-Rudolf Virchow finalizes the cell theory originally announced by Schleiden and Schwann 11 years earlier by declaring that cells are the basic units of all living things, and all cells are formed by the division of existing cells.

1859-Charles Darwin publishes On the Origin of Species. The initial printing (1,000 copies) sells out in a day.

1859-Catholic priest Jean-Jacques Pouech describes fossil eggshell fragments. They will eventually prove to be the first described dinosaur eggs.

1859-An exceptionally well-preserved skeleton is discovered in Bavaria. Two years later, this bird-like, bipedal dinosaur will be named Compsognathus, meaning "dainty jaw."

1860-John Phillips diagrams the progressive but fluctuating diversity of life on earth based on the fossil record. His work evidences massive extinctions at the end of the Paleozoic and Mesozoic, and increased diversity in each subsequent age.

1861-Civil war breaks out in the United States.

1861-First recognized fossil Archaeopteryx lighographica skeleton is found in the stone quarries of Solnhofen.

1861-In his presidential address to the Geological Society of London, Leonard Horner proposes removing the world's "creation" date of 4004 BC from the English Bible, citing geological evidence of a much older planet.

1862-Lord Kelvin asserts that the earth and sun are cooling from their initial formation, between 20 and 400 million years ago. He will later adopt the smaller number.

1863-Abraham Lincoln forms the National Academy of Sciences.

1863-Alfred Russel Wallace describes the "Wallace line," the dividing line between Indo-Malayan and Austro-Malayan fauna, in Proceedings of the Royal Geographical Society of London.

1863-T.H. Huxley publishes Man's Place in Nature discussing human and primate paleontology, and showing similarities between humans and other animals.

1865-Sir John William Dawson of McGill University identifies "shells" of huge foraminiferal protozoans. Known as Eozoön or "dawn animal," this find is used as an argument against evolution because it shows a relatively "modern" animal early in the fossil record. It will prove, however, to be a geologically young pseudofossil formed by heat and pressure on limestone.

1865-John Lubbock publishes Prehistoric Times arguing that modern Tasmanians and Fuegians are throwbacks to archaic humans.

1866-German zoologist Ernst Haeckel publishes General Morphology of Organisms, the first detailed genealogical tree relating all known organisms, incorporating the principles of Darwinian evolution.

1866-Austrian monk Gregor Mendel proposes his thesis on the basic laws of heredity. His work will be largely ignored until 1900.

1868-Ernst Haeckel publishes Natürliche Schöpfungsgeschichte, subdividing humanity into 12 separate species. He also asserts that evolution consists of 22 phases, the 21st being the "missing link" between apes and humans.

1868-Thomas Henry Huxley publishes "On the Animals which are Most Nearly Intermediate between Birds and Reptiles," arguing that birds are descendants of dinosaurs. This suggestion will not be taken very seriously for another century.

1868-Three human skulls and other skeletal remains, roughly 30,000 years old, are discovered at a rock shelter called Cro-Magnon (old French for "big hole").

1869-Huxley, Norman Lockyer and others found Nature Magazine, which becomes one of the world's two most important scientific journals. (The other journal is Science.)

1869-Biochemistry graduate student Johann Friedrich Miescher begins examining bandages from hospital patients in hopes of finding something interesting. He eventually succeeds, and determines that cell nuclei are composed of nitrogen, phosphorus and chromatin. He names the substance nuclein.

1870-The rivalry between fossil collectors O.C. Marsh and E.D. Cope turns ugly when Marsh publicly points out Cope's error in reconstructing a fossil marine reptile (putting its head on the tip of its tail). Their rivalry is the public's gain as they try to outdo each other in identifying new dinosaur species — over 130.

1870-O.C. Marsh discovers the first North American pterosaur, from chalk deposits in Kansas. He calculates the wingspan at 20 feet. The following year, he will collect more fossils that confirm this calculation.

1871-Charles Darwin publishes The Descent of Man.

1871-Lord Kelvin suggests that "the germs of life might have been brought to the earth by some meteorite," an idea that will enjoy support a century later.

1873-Francis Galton publishes a paper entitled "Hereditary Improvement" arguing that people "of really good breed" should be encouraged to reproduce while their inferiors should be discouraged from doing so. This, he argues, will improve humanity the way selective breeding improves livestock.

1874-The Hamburg Tierpark features an "anthropological-zoological" display of Lapps acting out "daily life" with reindeer. The show draws enthusiastic crowds.

1876-Charles Doolittle Walcott becomes the first to successfully find and describe elusive trilobite legs, ending speculation about how the animals moved.

1876-Robert Koch validates the germ theory of disease, postulated by Louis Pasteur in the 1860s, and publishes a paper identifying a bacterium as the cause of anthrax.

1877-Comparative anatomy professor François Louis Paul Gervais undertakes thin-section microscopy studies of fossil eggs. His work will be largely forgotten until Roy Chapman Andrews discovers dinosaur eggs in Mongolia in the 1920s.

1877-A new Archaeopteryx fossil is discovered in Solnhofen, complete with a toothy jaw. This well-preserved fossil, which will become known as the Berlin Archaeopteryx, supports Huxley's previous observations about its reptilian affinities.

c.1878-Charlotte Hill collects a well-preserved fossil butterfly, later named Prodryas persephone, from the Florissant Formation in Colorado. The fossil is about 35 million years old.

1878-Entire skeletons of Iguanodon are discovered in Belgium, enabling a more accurate reconstruction of this dinosaur than those of Owen and Waterhouse Hawkins in the 1850s. Engineer-turned-paleontologist Louis Dollo will publish the first of several papers on these fossils in 1882.

1878-Sketches of Creation author Alexander Winchell loses his job at the University of Vanderbilt for suggesting that Adam descended from earlier humans. Winchell's critics are particularly incensed by the notion that Adam's ancestors just might have been black.

1879-Charles Lapworth resolves a priority dispute between Adam Sedgwick and Roderick Murchison by assigning older rocks to the Cambrian (named by Sedgwick), younger rocks to the Silurian (named by Murchison), and naming the Ordivician System in between.

1879-The United States Geological Survey is formed.

1879-Eight-year-old Maria de Sautuola finds a Paleolithic cave drawing of bison on her father's property in Spain. It is the oldest artwork yet discovered, but it will be dismissed as a forgery for years, considered too beautiful to be the work of prehistoric savages.

1882-Karl Alfred von Zittel describes an exceptionally well-preserved pterosaur wing showing flight membranes in detail.

1882-Charles Darwin publishes his final letter to Nature, on the dispersal of freshwater bivalves. His obituary appears the same month.

1883-Geologist James Hall names Cryptozoon, based on cabbagelike rocks up to meter across. Although Hall's biologic interpretation of these structures will be heavily criticized, it will ultimately prove correct.

1886-Geologist Charles Gould publishes Mythical Monsters surveying weird creatures from several cultures and explaining that some myths might have been inspired by fossil remains of extinct animals.

1886-John Bell Hatcher develops the "ant hill method of collecting minute fossils," collecting hundreds of tiny fossil teeth and jaws pushed to the surface by ants. He even carries shovelfuls of ants and sediment to other fossil localities in need of excavation by the arthropods.

1887-Harry Govier Seeley determines that dinosaurs consist of "lizard-hipped" (saurischian) and "bird-hipped" (ornithischian) branches.

1888-German anatomist W. von Waldeyer names chromosomes.

1891-Ethnologist Frank Cushing learns of a Zuni legend explaining how many life forms turned to stone when the earth was young. The Zunis apply this explanation to fossils found in the American southwest.

1894-Eugène Dubois publishes his monograph of Pithecanthropus erectus, or Java Man, a missing link between humans and apes.

1895-A team of paleontologists, including Samuel Williston, Elmer Riggs and Barnum Brown, successfully excavates a Triceratops fossil in Wyoming.

1896-Dublin anatomist Daniel Cunningham concludes that Neanderthals represent an intermediate step between Pithecanthropus erectus and modern humans.

1896-A gelatinous blob washes ashore in St. Augustine, Florida. Cephalopod expert Addison Verrill describes the blob as the remains of a giant octopus but, after examining a tissue sample, reverses his decision and describes it as a decomposing whale.

1897-Renowned physicist Lord Kelvin gives a lecture at London's Victoria Institute claiming that the sun, which is cooling from its initial formation, can be no more than 20 million years old.

1897-Marie Curie begins research of "uranium rays" that will lead to the discovery of radioactivity.

1899-Charles Doolittle Walcott identifies Chuaria, millimeter-sized black fossil disks. He thinks they're compressed shells of marine invertebrates. He's wrong about that, but correct in deducing a biologic origin — the fossils are actually from unusually large planktonic alga.
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1901-Harry Govier Seeley publishes Dragons of the Air, the first popular book on pterosaurs, arguing that they were warm-blooded and should be classified parallel to birds, in between reptiles and mammals. This is in direct opposition to Richard Owen's classification of pterosaurs as cold-blooded and poor flyers.

1902-Barnum Brown of the American Museum of Natural History discovers Tyrannosaurus rex.

1902-Walter Sutton deduces that chromosomes separate for reproduction. This becomes the basis for the chromosome theory of inheritance, to become official two years later.

1903-Physicist Ernest Rutherford lectures the British Association that radioactivity could power the sun and maintain its heat, meaning the sun and earth could be much older than Lord Kelvin's estimate.

1905-Albert Einstein proposes the special theory of relativity (E=mc2).

1905-K.S. Merezhkovsky suggests that chloroplasts originated as a cyanobacterium swallowed by a protozoan, i.e., algal and plant cells result from two independent organisms that became symbionts. The idea will be largely forgotten until it is suggested again in the 1960s.

1906-The New York Zoological Park displays Ota Benga, an African Pygmy, in its Monkey House.

1907-The Mauer jaw is discovered in Germany. It will become the type specimen for Homo heidelbergensis (Archaic Homo sapiens, precursors to Neanderthals).

1908-Charles and George Sternberg discover a dinosaur mummy, a duckbill dinosaur with skin, tendons and bits of flesh all fossilized.

1908-Otto Hauser finds the body of a Neanderthal youth at Le Moustier. Later paleoanthropologists will attach limited importance to this find, however, since Hauser keeps burying and "rediscovering" the Neanderthal for important visitors.

1908-1911-Oliver P. Hay publishes several articles contending that dinosaurs had crocodilian postures (not upright legs), and recommending that museums clearly distinguish between fossil bones and casts. The first idea will never catch on, but the second eventually will.

1909-Charles Doolittle Walcott discovers the fossils of soft-bodied animals in the Burgess Shale in the Canadian Rockies. He proceeds to publish several papers in which he describes these animals, which lived over 500 million years ago, as primitive ancestors of modern groups.

1909-The Abbé Breuil discovers carefully buried Neanderthal skeletons in France.

1909-Arthur Smith Woodward lectures the British Association for the Advancement of Science on "excess growth" and tooth loss in dinosaurs, citing these things as evidence of "racial senility" that doomed the dinosaurs to extinction.

1911-A hand axe, possibly 200,000 years old and of Neanderthal design, is found in Norfolk, England. The axe has been fashioned to give prominence to a fossil bivalve.

1911-Charles Dawson discovers the Piltdown skull in southern England. Excavations of faked fossils will continue for years.

1911-1914-Ernst Stromer and Richard Markgraf find fossils of three carnivorous dinosaur species in Egypt. The fossils will be formally described in the 1930s, then completely destroyed in a 1944 WWII bombing.

1912-Alfred Wegener proposes the theory of continental drift. His ideas will be almost completely ignored until the late 1960s.

1913-Geologist-physicist Arthur Holmes concludes that the breakdown of radioactive isotopes in igneous rocks can be used to determine when the rocks solidified. The ability to determine the absolute ages of rocks will enable scientists to better date fossils.

1914-World War I begins in Europe.

1914-Charles Doolittle Walcott identifies fossil bacteria in Cryptozoon-like structures (stromatolites).

1914-Peyrony finds the remains of Neanderthal baby in southwestern France. Because no one knows the bones are Neanderthal, they are not examined closely and are later believed lost. They will be rediscovered and described nearly 90 years later.

1915-Calvin Bridges identifies strains of mutant fruit flies with extra pairs of wings. Decades later, these strains will help biologists understand Hox genes that control the head-to-toe anatomy of widely varying animals.

1916-Two duckbill dinosaur fossils, with extremely rare skin impressions, sink to the bottom of the Atlantic when a German warship fires on the vessel carrying them.

1917-The Bolshevik Revolution begins in Russia.

1920-Women gain the right to vote in the United States.

1921-Fossil mammal expert William Diller Matthew suggests dinosaurs were driven extinct by mountain building, continental uplift and replacement by mammals.

1921-Miners at Broken Hill in the British colony of Northern Rhodesia, Africa, find leg bones and a skull that will later be classified as Homo heidelbergensis.

1922-The American Museum of Natural History begins a series of excavations in central Mongolia, led by Roy Chapman Andrews. Hoping to find fossil human remains, Chapman's team instead finds dinosaurs.

1924-1934-British biochemist J.B.S. Haldane publishes 10 mathematical papers arguing that natural selection of genetic variations, as described by Mendel, can enable populations to adapt to change.

1925-Raymond Dart publishes a description of the "Taung Child," a hominid child's skull from Africa. He classifies it as Australopithecus africanus and concludes that it's the missing link between humans and apes.

1925-Tennessee schoolteacher John Thomas Scopes is tried for teaching evolution in the famous "Scopes Monkey Trial." Two-time presidential candidate William Jennings Bryan leads the prosecution. Labor lawyer Clarence Darrow leads the defense and goads Bryan into declaring that humans are not mammals. The conviction will be overturned on a technicality, and the anti-evolution law will remain on the books for decades.

1926-Harvard geology professor William Morris Davis publishes a paper entitled "The Value of Outrageous Geological Hypotheses" warning against quick dismissal of new ideas. The paper will become famous.

1929-Davidson Black announces the find of Sinanthropus pekinensis, or Peking Man. The fossil will be lost during World War II.

1929-Estonian paleobiologist Alexander Audova publishes a paper rejecting racial senility as the cause of dinosaur extinction and instead pointing to environmental change.

1931-The highly influential paleobotanist Sir Albert Charles Seward rejects the biologic interpretation of Cryptozoon fossils (stromatolites). This rejection will become known among paleontologists as "Seward's folly."

1932-A Harvard expedition to Australia collects Kronosaurus queenslandicus, a 135 million-year-old marine reptile fossil with a 9-foot skull and banana-sized teeth. Researchers excavate the fossil from a limestone quarry with the aid of an explosives expert nicknamed "The Maniac."

1936-Robert Broom finds the first skull of an adult australopithecine near Johannesburg.

1937-Anthropologist Ales Hrdlicka publishes a paper asserting that aboriginal peoples of the Americas always resembled modern Native Americans. This view will predominate for decades.

1938-Fishermen find a coelacanth, a fish long believed to be extinct, off the coast of South Africa.

1939-About 200 worked ivory fragments, roughly 32,000 years old, are found in the Hohlenstein-Stadel cave in Germany. Three decades later, the pieces will be reassembled as statue of a lion-headed man.

1939-World War II begins in Europe.

1940-Frank Morton Carpenter collects a 2.5-foot wing from a dragonfly-like giant insect that lived in Oklahoma during the Permian Period.

1940-1944-Seventeen dinosaur fossils, including several type specimens (fossils used as examples of named species) are lost when the European museums housing them are damaged or destroyed in various WWII battles.

1941-Anthropologist E.T. Hall excavates the ruins of a dwelling in New Mexico occupied between 700 and 900 AD. He finds two fossil jawbones of Eocene mammals that were deliberately carried to the dwelling by Paleo-Indians.

1942-Ernst Mayr publishes Systematics and the Origin of Species, and Julian Huxley publishes Evolution: The Modern Synthesis. Both books are significant contributions to the neo-Darwinian synthesis combining elements of natural selection, genetics, mutation, population biology and paleontology.

1943-Oswald Avery, Colin MacLeod and Maclyn McCarty submit a paper for publication in the Journal of Experimental Medicine describing nucleic acid DNA as the carrier of genetic messages.

1944-Theoretical physicist Erwin Schrödinger publishes What is Life? arguing that living organisms store and pass along information, perhaps using something like Morse code. This book will inspire James Watson, Francis Crick and Maurice Wilkins, who will share the Nobel prize for discovering the structure of DNA.

1946-Geologist Reg Sprigg discovers fossils near the Ediacara Hills in Australia. The fossils are of multicellular organisms that predated the Cambrian Period, making them the oldest complex fossils yet discovered. At least some of the fossils are generally assumed to be related to modern cnidarians like jellyfish and corals.

1947-American Museum of Natural History curator Edwin Colbert finds a massive quarry of Coelophysis dinosaurs in New Mexico and concludes from their skeletons that these Triassic dinosaurs were swift runners with a bird-like posture.

1947-Rudolph Zallinger completes The Age of Reptiles mural in the Yale Peabody Museum. This image of slow-moving dinosaurs will prevail until the 1960s.

1948-Mary Leakey finds the skull of the ape Proconsul, about 16 million years old. Although a very significant find, it does little to bolster Louis and Mary Leakey's meager research funding.

1949-French prehistorian André Leroi-Gourhan discovers the Cave of the Reindeer near the village of Arcy-sur-Cure where he will conduct a 15-year excavation. Discoveries at Arcy will include evidence of a growing artistic sense among Neanderthals, including the collection of fossil mollusk shells and fossil coral.

1951-Barbara McClintock publishes a paper describing "jumping" genes that can move around within an organism's genome.

1952-Russian geologist Boris Sokolov establishes the term Vendian. Based on rock strata in the Soviet Union, it designates the period immediately preceding the Cambrian, coinciding with fossils found near the Ediacara Hills.

1952-1953-Stanley Miller and Harold Urey combine gases generally believed to be in the earth's early atmosphere (methane, ammonia and water vapor) and charge them with electricity. These experiments produce several amino acids.

1953-Piltdown Man is determined to be a hoax: the jaw of an ape and a human skull.

1953-James Watson and Francis Crick publish their paper on the molecular structure of DNA in Nature Magazine. Rosalind Franklin, whose X-ray photographs of DNA were essential to this discovery, publishes a paper on her own research in the same issue.

1953-Fiesel Houtermans and Claire Patterson publish independent estimates inferring the age of the earth through radiometric dating of meteorites. Both estimates are over 4.5 billion years.

1954-Elso Barghoorn and Stanley Tyler report the discovery of bacterial cells in Canadian rock formations that are nearly 2 billion years old.

1956-Paleontologist M.W. de Laubenfels publishes a paper suggesting that the dinosaurs were driven to extinction by a meteorite impact. His paper will not be taken seriously, but this hypothesis will be presented again in 1980 with more compelling evidence.

1956-Keith Runcorn publishes a paper describing polar wandering based on paleomagnetic studies of Europe and North America. He suggests continental drift, but his paper attracts little attention.

1957-The Soviet Union launches Sputnik.

1957-Francis Crick proposes the "central dogma" of genetic information transfer: DNA specifies RNA and RNA specifies cell proteins.

1959-Mary Leakey finds hominid skull belonging to Australopithecus boisei.

1961-Henry Morris and Old Testament Scholar J.C. Whitcomb publish The Genesis Flood, attracting new support for the previously insignificant biblical literalist movement.

1961-Martin Glaessner determines fossils in the Ediacara Hills of South Australia (Ediacaran fauna) to be Precambrian in age (approximately 600 million years old), making them the oldest-known multicelled organisms.

1961-Gene Shoemaker and E.C.T. Chao publish a paper characterizing the Ries Basin in Bavaria as the result of a meteorite impact. This will help pave the way for eventual acceptance of asteroid and comet impacts as potential causes of mass extinction.

1963-Fred Vine and Drum Matthews publish a paper describing magnetic stripes formed at ocean ridges. Their findings will pave the way for the acceptance of continental drift over the next decade.

1964-W. Brian Harland and Martin J.S. Rudwick publish a theory that the earth experienced a great ice age in the Neoproterozoic (late Precambrian). Rudwick suggests that the climate's return to moderate conditions paved the way for the evolution of multicelluar life.

1964-Louis Leakey describes Homo habilis, meaning "handy." The new species designation is not well received by the scientific community.

1964-Vincent Dethier publishes "Microscopic Brains," an article on insect behavior, in Science. He calls for a more empathetic approach to animal subjects, even tiny invertebrates.

1966-Harry Whittington begins reexamining Burgess Shale fossils originally identified by Charles Walcott starting in 1909. Over the next two decades, Whittington (with the assistance of his graduate students Simon Conway Morris and Derek Briggs), will eventually overturn some of Walcott's theories and propose that most of the animals left no living relatives.

1966-Willi Hennig works on a new approach to assessing evolutionary relationships, known as cladistics. Although it will be hotly debated, this technique will eventually become standard practice in paleontology, botany and zoology.

1967-Lynn Sagan (later Lynn Margulis) hypothesizes that chloroplasts originated as cyanobacteria, and that mitochondria originated as bacteria. She suggests that both were engulfed by other cells and began functioning as symbionts.

1967-Richard Leakey finds two fossil skulls, Omo I and Omo II, in Ethiopia. Though initially dated at 130,000 years, the fossils will later be dated (using argon decay) at 195,000 years, and designated as the oldest examples of Homo sapiens.

1968-A.G. Cairns-Smith publishes a paper suggesting that the first life on earth might have been fine-grained clay crystals. He will publish on this topic several more times, but the experimental evidence will remain scant.

1969-Americans land the first man on the moon.

1969-John Ostrom publishes a description of Deinonychus with a frontispiece illustration by Bob Bakker, suggesting that the dinosaur is alert, agile and intelligent.

1969-R.H. Whittaker proposes to divide all living things into five kingdoms: Animalia, Plantae, Fungi, Protista and Monera.

1971-A.G. Sharov describes a pterosaur with fossil "hair" impressions at Sordes pilosus (hairy devil).

1971-Polish and Mongolian paleontologists discover the entwined skeletons of a Protoceratops and a juvenile Velociraptor in the Gobi Desert, most likely locked in mortal combat.

1971-Grad student Douglas Lawson discovers the humerus of a giant pterosaur in Texas. Over the next four years, he will continue collecting and finally publish a description of Quetzalcoatlus northropi, the largest flying animal ever found, with an estimated wingspan of 39 feet.

1972-Stephen Jay Gould and Niles Eldredge publish their theory of punctuated equilibrium, stating that evolution often occurs in short bursts, followed by long periods of stability.

1972-Bob Bakker publishes "Anatomical and Ecological Evidence of Endothermy in Dinosaurs" in Nature, arguing that dinosaurs were warm-blooded animals.

1973-Peter and Rosemary Grant begin a long-term study of finches on the Galapagos Islands. In succeeding years, as they watch finches adapt to alternating wet and dry conditions, the Grants will uncover evidence that evolution proceeds more rapidly than what Darwin estimated.

1974-Donald Johanson and his team discover a female fossil hominid (to be later named Australopithecus afarensis) and call her Lucy. Lucy's discovery establishes that hominids walked upright before developing large brains, overturning some long-held beliefs about hominid evolution. Her status as a direct ancestor of modern humans, however, will remain controversial.

1974-John Ostrom publishes a paper titled "Archaeopteryx and the Origin of Flight" reviving Thomas Henry Huxley's arguments from the 1860s.

1975-Mary-Claire King and Allan Wilson publish their finding that human and chimpanzee DNA sequences differ by roughly 1 percent, meaning humans have more in common with chimps than chimps do with gorillas. King and Wilson suggest that humans and chimps differ largely in the DNA that switches on and off genes.

1976-Paleontologists looking for cave bear remains explore Sima de los Huesos ("Pit of the Bones") at Atapuerca, Spain. For many years afterwards, it will remain the densest accumulation of fossil human bones ever discovered.

1976-Overturning the classifications introduced by R.H. Whittaker seven years earlier, Carl Woese proposes to divide all living things into three categories: Bacteria, Archaea and Eukarya.

1977-Submersible vehicle Alvin reveals deep sea vents on the ocean floor that give rise to an ecosystem owing nothing to photosynthesis. This finding prompts speculation that life on earth first arose in deep-sea, not shallow-water, ecosystems.

1977-Fred Sanger and collaborators publish the first complete DNA sequence of an organism, a bacteriophage, or virus infecting bacteria.

1978-J.W. Kitching discovers a clutch of prosauropod eggs in South Africa, the oldest dinosaur embryos yet found. They will show that sauropods walked on all fours as small animals, but the significance of this find will be overlooked for nearly three decades.

1978-Mary Leakey announces the discovery of fossil footprints at Laetoli demonstrating that hominids walked upright 3.6 million years ago.

1980-Louis W. Alvarez, Walter Alvarez, Frank Asaro and Helen V. Michel publish their asteroid impact theory of dinosaur extinction. The theory will not gain widespread acceptance among scientists for several years.

1980-Christiane Nüsslein-Volhard and Eric Wieschaus describe genetic mutations affecting the body plan of the fruit fly Drosophila, and identify genes controlling the basic body plans of all animals. These genes will eventually be known as Hox genes.

1983-German paleobiologist Adolf Seilacher suggests that most of the Ediacaran fossils discovered in the 1940s are not related to any modern forms. Calling them vendobionts, he argues that they went extinct after the emergence of large predators. Seilacher's interpretation, however, will remain in dispute.

1982-1983-Amateur fossil collector Bill Walker finds a dinosaur claw in a Surrey clay pit. A previously unknown theropod, the animal will be formally named Baryonix walkeri and nicknamed "Claws."

1984-Richard Leakey and his team discover Turkana Boy, the most complete Homo erectus fossil yet discovered.

1984-David Raup and Jack Sepkoski publish the controversial claim that mass extinctions are regularly spaced at 26 million years.

1987-Jenny Clack finds Acanthostega, the most complete Devonian tetrapod yet discovered. It has evidence for functional gills as well as legs, strongly suggesting that animals evolved legs while still living in the water.

1987-Allan Wilson and Rebecca Cann announce that all humans share a common ancestor who lived in Africa as recently as 150,000 years ago. Because the discovery is based on examination of mitochondrial DNA, the ancestral entity will be given the popular (and somewhat misleading) name of "Mitochondrial Eve." The controversial finding will be supported by another discovery in 2000.

1989-Philip Gingerich finds a fossil whale, Basilosaurus in Egypt. It has tiny legs, just inches long, retaining all five toes. Five years later, he will discover an even more primitive whale ancestor, Rodhocetus, with even bigger hind legs, in Pakistan.

1990-The Human Genome Project is launched with the goal of sequencing all 3 billion base pairs of human DNA by 2005.

1990-Mongolia invites the American Museum of Natural History to reinstate excavations in the Gobi desert.

1991-The Soviet Union ends, and so does the Cold War.

1991-Chicxulub crater is discovered in the Yucatán Peninsula, supporting the asteroid impact theory first suggested in 1980.

1992-Ian Campbell and collaborators publish a paper pointing to the Siberian Traps, an area of massive volcanic activity, as the cause of the Permo-Triassic mass extinction 251 million years ago.

1992-Paleontologists led by Jim Kirkland discover Utahraptor, a super-sized velociraptor that conveniently supports the super-sized velociraptors that will appear in the screen version of Jurassic Park a year later.

1992-Joe Kirschvink publishes "Late Proterozoic Low-latitude Glaciation: The Snowball Earth," a short book section in a specialized monograph. This snowball earth hypothesis will attract little attention until expanded by Paul Hoffman and his collaborators several years later.

1993-J. William Schopf publishes a description of the oldest fossils known to science — 3.5 billion-year-old microfossils of the Apex Basalt in Australia. His claim that some of the microbes could photosynthesize and produce oxygen will later be questioned.

1993-On an expedition in the Gobi desert, paleontologists from the American Museum of Natural History discover the skeleton of an Oviraptor dinosaur crouching over a nest of eggs, apparently incubating them in the same fashion as modern birds.

1993-Roland Anderson and Jennifer Mather publish "Personalities of Octopuses" in the Journal of Comparative Psychology.

1994-Elaine Morgan supports the "aquatic ape" hypothesis that modern humans evolved from semiaquatic apes, as suggested by our hairless bodies and subcutaneous layers of fat.

1994-In what will later be named Chauvet cave, French cavers discover 32,000-year-old paintings showing 400 animal images.

1994-Anthropologist Ron Clark finds previously overlooked foot bones, showing both ape and human qualities, from Sterkfontein. Future finds will associate these bones with a skeleton nicknamed Little Foot.

1995-Lee Berger and Ron Clarke publish an article in the Journal of Human Evolution arguing that the Taung child, discovered in 1924, may have been killed by a bird of prey.

1996-Alan Walker and Pat Shipman publish a description of advanced vitamin A poisoning in a 1.7 million-year-old Homo erectus skeleton. They assert that it is evidence of both meat eating, caused by consuming the liver of a large carnivore, and sufficient sociability in Homo erectus to care for an ill and incapacitated individual.

1996-The 9,500-year-old Kennewick Man skeleton is found in the northwestern United States. Bearing little resemblance to modern Native Americans, it suggests a more complicated early population of the Americas than previously thought.

1996-Using "molecular clock" estimates of mutation rates, Greg Wray and collaborators hypothesize that metazoan phyla diverged from each other 1 billion years ago, or even earlier. In other words, they argue that metazoans existed hundreds of millions of years before the earliest metazoan fossils (about 600 million years old) yet found.

1996-Chen Pei Ji unveils Sinosauropteryx prima from Liaoning, China, the first feathered dinosaur discovered, at the Society of Vertebrate Paleontology's annual meeting.

1997-Paleontologist Karen Chin receives a 17-inch coprolite excavated in Saskatchewan. Estimated at 65 million years old and full of crunched bone, it is likely the calling card of a T. rex.

1998-Paul Hoffman, Alan Kaufman, Galen Halverson and Daniel Schrag publish a Neoproterozoic snowball earth theory arguing that in the late Precambrian, the earth underwent global glaciations followed by extreme greenhouse conditions, spurring the evolution of multicellular life forms.

1998-Shuhai Xiao, Yun Zhang and Andrew Knoll publish a description of fossilized animal embryos in Nature Magazine. Chia-Wei Li, Jun-Yuan Chen and Tzu-En Hua simultaneously publish another description of embryos in Science Magazine. The embryos all come from the Doushantuo phosphorites in southern China, and all are estimated to be approximately 570 million years old, making them the oldest fossil embryos so far discovered.

1998-Andrew Parker publishes a paper suggesting that Cambrian animals developed flickering color displays at the same time that eyes evolved.

1999-Chinese paleontologists discover an exceptionally well-preserved feathered dinosaur, probably a juvenile dromaeosaur. Citing the confusion caused by language barriers and jet lag, the paleontologists' American collaborators nickname the fossil "Dave the fuzzy raptor," after a character alluded to in a Cheech and Chong routine. This fossil will be assigned to the genus Sinornithosaurus. (The next fuzzy discovery will be nicknamed "Chong.")
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« Reply #5 on: September 05, 2008, 01:27:58 pm »

2000-Phil Currie publishes a paper suggesting that T. rex was a social animal that hunted in packs.

2000-Based on studies of Y chromosomes, Peter Underhill publishes his finding that all modern humans share a common ancestor, bolstering the 1987 announcement from Cann and Wilson. This suggests a "bottleneck" event (population crash) among human ancestors living in Africa roughly 150,000 years ago.

2000-A research team led by Paul Sereno discovers Rugops primus ("first wrinkle face") in the Sahara. This dinosaur's resemblance to South American fossils suggests that Africa separated from the ancient landmass of Gondwana more recently than previously thought.

2000-Sally McBearty and Alison Brooks publish "The Revolution that Wasn't" challenging the long-held notion of a "big bang" in human intellectual evolution approximately 40,000 years ago. Instead, they cite evidence for earlier appearances of modern behavior.

2001-The International Human Genome Sequencing Consortium (Human Genome Project) publishes the initial sequence and analysis of the human genome in Nature Magazine. Celera Genomics simultaneously publishes a draft human genome sequence in Science Magazine.

2001-Joshua Smith and collaborators publish a description of a giant sauropod from Egypt, possibly the largest Cretaceous sauropod yet discovered. It is considered a possible food source for three large carnivorous dinosaur species discovered decades earlier by Ernst Stromer.

2001-Luann Becker and collaborators publish a paper describing carbon fullerenes (buckyballs) at the Permo-Triassic boundary in China, Japan and Hungary. Because they can occur in meteorites, the fullerenes are cited as evidence of a meteorite impact at the end of the Permian. Other scientists will have difficulty reproducing their results, however, and the researchers' claim will remain controversial.

2001-Chris Henshilwood and collaborators publish a description of 77,000-year-old artwork: stones carved with lines and triangles, from Blombos Cave on the Southern Cape coast of Africa. Three years later, Henshilwood and collaborators will describe more Blombos artifacts: tiny snail shells that were apparently pierced and worn as jewelry about 76,000 years ago.

2002-David Lordkipanidze and collaborators excavate a 1.77 million-year-old Homo erectus skull of a "toothless old man" in Dmanisi. New bone growth after the loss of his teeth suggests that he was cared for by others, the oldest evidence yet found of care for the sick in fossil hominids.

2002-Michel Brunet and collaborators publish a description of Sahelanthropus tchadensis, a hominid fossil from western central Africa. Suspected to be 6 to 7 million years old, it is possibly the oldest hominid fossil yet found. Its location, in Chad, is expected to spur hominid fossil hunting west of Africa's Rift Valley.

2003-A bus-length blob (similar to the St. Augustine blob of 1896) washes ashore in Chile. Though some suspect it is the remains of a giant octopus, DNA analysis will reveal a year later that it is just old whale blubber.

2003-M.R. Sánchez-Villagra, O. Aguilera and I. Horovitz publish a description of Phoberomys, a fossil rodent from Venezuela the size of a buffalo.

2003-Paleontologists in Germany identify the world's oldest pantry: an underground burrow system probably dug by an extinct species of ground squirrel or hamster. Estimated at 17 million years old, the food stash is stuffed with more than 1,800 fossilized nuts.

2003-Two separate teams, digging 2,000 miles apart, find two new Antarctic dinosaurs in the same week. One appears to be a Jurassic sauropod, the other a Cretaceous theropod.

2003-Paleontologists led by John Horner find a T. rex fossil that will later yield evidence of blood vessels and blood cells. The fossil will also prove to be an egg-laying female.

2004-Heather Wilson and Lyall Anderson publish a paper describing the oldest land animal fossil yet discovered: Pneumodesmus newmani, a 428 million-year-old, centimeter-long millipede found by amateur fossil hunter Mike Newman.

2004-M.-Y. Zhu and collaborators publish a description of munched trilobite parts inside another arthropod, confirming earlier suspicions that other animals snacked on the little water bugs.

2004-Naama Goren-Inbar and her team announce the discovery of controlled fire use by hominids at a 790,000-year-old site in Israel, pushing the earliest known use of fire back 300,000 years from previous estimates.

2004-The International Union of Geological Sciences adds a new period to the earth's geologic timescale: the Ediacaran. Ranging from approximately 600 million years ago to 542 million years ago, it begins after the last Snowball Earth ice age and precedes the Cambrian. It's the first new geologic period designated in 120 years.

2004-X. Wang and Z. Zhou publish a description of the first known pterosaur egg containing an exquisitely preserved embryo. Though the egg is slightly smaller than the average chicken egg, the embryo sports a 27-centimeter wingspan. Several months later, Z. Zhou and F. Zhang publish a description of a Cretaceous bird embryo, the first found with feathers.

2004-Using CT scans on femurs of the early hominid Orrorin tugenensis discovered in Kenya, Galik and collaborators push back the development of bipedalism in hominids to 6 million years ago (2 million years earlier than in Australopithecus anamensis).

2004-Qingjin Meng and collaborators publish a description of an adult Psittacosaurus dinosaur associated with 34 juveniles, apparent evidence of parental care.

2004-A team of Japanese researchers take the first photograph ever of a giant squid in the wild. Unfortunately, they rip off one of the poor creature's tentacles in the process.

2004-Peter Brown, Mike Morwood and collaborators announce the find of an 18,000-year-old hominid skeleton on the Indonesian island of Flores. Found near the remains of giant lizards and pygmy elephants, it is formally named Homo floresiensis and nicknamed the "hobbit," because it is just 1 meter tall, with a tiny brain case. Though some suspect it's a kind of malformed, small-brained midget, this interpretation will be weakened by braincase scans showing well-developed temporal and frontal lobes — and further weakened by the announcement of several more individuals of the same species.

2005-Yaoming Hu, Jin Meng, Yuanqing Wang and Chuankui Li publish a description of two large carnivorous mammals from the Cretaceous, one of which appears to have the remains of a diminutive dinosaur in its stomach. These fossils overturn long-held notions that Mesozoic mammals were all rat-sized plebeians scurrying around dinosaur feet.

2005-Yohannes Haile-Selassie and colleagues announce the find of a nearly 4 million-year-old hominid from Ethiopia, possibly the remains of Australopithecus anamensis.

2005-Eric Buffetaut and colleagues announce the discovery of diminutive dinosaur eggs from China. At less than an inch long, they may be the littlest dinosaur fossil eggs yet found, the researchers claim.

2005-Adrian Glover and Thomas Dahlgren announce the discovery of a new species of marine worm, discovered off the Swedish coast, that lives on whale bones on the sea floor. They name the specis Osedax mucofloris, meaning (literally) "bone-eating snot flower."

2005-M.A. Whyte announces the discovery of a 330 million-year-old trackway of a 5-foot-long, six-legged water scorpion (eurypterid) that could walk on land while the first tetrapods tried to do the same thing.
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   posted 02-12-2006 08:17 PM                       
New fossil may revise the timeline for hominid evolution
By Walter Gilberti
14 August 2002

A new fossil discovery has thrown the widely accepted time and place for the divergence of the evolutionary lines of humans and chimpanzees into somewhat of a turmoil. Working in southern Chad in central Africa, a team of researchers led by French paleontologist Michel Brunet has uncovered the nearly complete cranium and lower facial fragments of a creature that appears to reside almost at the point of transition between apes and hominids. Hominids are primates that exhibit erect posture and bipedal locomotion, a category that includes humans and their evolutionary forebears.

The fossil—nicknamed Toumai or “hope of life” in the Goran language of southern Chad—has been given the scientific (Genus, species) name Sahelanthropus tchadensis, since it was discovered in the sahel, a semiarid region of central and west Africa that separates the Sahara from the more southerly tropical forests. A preliminary analysis of the fossil appeared in the July issue of the journal Nature.*

What is particularly striking about this discovery is not that it exhibits some hominid characteristics, but that it is 7 million years old. Some experts in the field are hailing the find as having the most far-reaching implications for the theory of human evolution since the discovery of the “Taungs child” by South African anthropologist Raymond Dart in 1924. Dart, who along with Charles Darwin before him suspected that Africa, not Asia, was the cradle of humankind, named the fossil Australopithecus, or “southern ape. Subsequent discoveries throughout the Great Rift Valley region of eastern and southern Africa have transformed that supposition into a fact.

The validity of the Brunet team’s claim that the discovery is in fact a hominid remains to be determined. One anthropologist at the Natural History Museum in Paris described the fossil as belonging to a proto-gorilla. However, there is ample reason to conclude that the Chad fossil has a unique significance. The remains exhibit a curious ensemble of primitive ape and more advanced hominid characteristics. For example, while the specimen seems to have a sagittal crest—a ridge of bone at the top of the skull that serves to anchor the massive chewing muscles found in the great apes—this feature seems to be combined with more advanced dental characteristics, in particular, the absence of a diastema—a space between the canines and the incisors and premolars that allow for the meshing of the large canine teeth found in apes.

Sahelanthropus reveals a cranial capacity (brain size) within the chimpanzee range (320 -380 cc), and yet its face is not nearly as prognathic as that of a chimp, and is less so than even more recent austalopithecine discoveries, such as the 3.5 million-year old “Lucy,” discovered by Donald Johanson in Ethiopia more than 25 years ago.

Prognathism, or the appearance of a “muzzle” denoting a sharp outward facial angle common among four-legged animals, began to recede in higher primates, whose diurnal behavior and arboreal lifestyle led to the emergence of acute color vision, and a consequent reduction in the importance of the olfactory sense. This tendency became less pronounced as hominids evolved, and has all but disappeared in modern humans. To find a fossil this ancient exhibiting a characteristic this seemingly advanced is indeed remarkable, and raises important questions about the evolutionary process, as well as the current perception of how the hominid line evolved.

Then there is the question of the location of Sahelanthropus. To many paleoanthropologists, Chad is somewhat off the beaten path for hominid evolution, when compared with the famous fossil troves of southern and eastern Africa. In a recent op-ed piece in the New York Times, Harvard anthropologist Daniel Lieberman offered an amusing analogy; “Like the drunk in the old joke, searching for his keys under a lamppost because the light is better there, we’ve focused on these two regions because fossils preserve best there. Yet Africa was a huge and complex place, full of diverse habitats that might have been wonderful places to be a human ancestor—but where the bones don’t fossilize well.”

According to Brunet, the Chad location “suggests that an exclusively East African origin of the hominid clade [a clade is an evolutionary lineage distinguished by certain derived characteristics—WG] is unlikely to be correct. It will never be possible to know precisely where or when the first hominid species originated, but we do know that hominids had dispersed throughout the Sahel and East Africa (Brunet, et al, 2002).”

It is the antiquity of Sahelanthropus, however, that calls into question some basic assumptions about the chimp/hominid timeline. While the Brunet team has been unable to use the standard potassium-argon radio-isotope dating technique for establishing the approximate age of the specimen due to the lack of volcanic ash at the site, a comparative examination of the remains of other animals from the same strata with positively dated specimens from Kenya place the Brunet team’s discovery as having lived between 6 and 7 million years ago. This is nearly 2 million years earlier than the currently accepted point of separation for the human and chimp lines, and a million years earlier than the next oldest fossil, Orrorin tugenensis, which was discovered in Kenya and whose hominid credentials are currently under dispute.

A 7 million-year old “hominid” would place it as having existed during the late Miocene, a 15 million year chunk of the Tertiary period (“Age of Mammals”) that witnessed the growth of vast tropical rainforests. The Miocene could be considered a “golden age” for the evolution of higher primates, particularly monkeys. But ape evolution was also undergoing rapid change, with the ancestors of the modern “great apes,” chimps, bonobos, gorillas and orangutans, beginning to diverge. There has also been a small amount of fossil evidence that suggests that hominid evolution had been well under way during the Miocene, with the remains of a possible proto-hominid, Ramapithecus, existing 14 million years ago and having a distribution as distant as the Indian subcontinent.

How does one account for the existence of a fossil primate that exhibits hominid characteristics, but is considerably older than the widely accepted boundary between upright walking hominids and chimpanzees? Humans share more than 98 percent of their DNA with chimpanzees, making the ape the closest living relative to Homo sapiens. Recent developments outside the field of paleontology, specifically in molecular biology, have determined the point of divergence to be approximately 5 million years ago, a date that is based on what some researchers call the “molecular clock.”

Genes are segments of the DNA molecule. Each gene, or a combination of genes, codes for the assembly of amino acids that combine in long chains forming proteins. However, there are segments of the DNA molecule where mutations accumulate but have no effect on the makeup of the organism. Since deleterious mutations would be absent because those individual organisms would have been selected against by nature, the molecular clock is based on the notion that if one establishes the number of these neutral alterations that are present in a segment of a human DNA molecule, but absent in the chimp’s DNA, and assuming that these mutations occur at a constant rate, one can then extrapolate backward in time to the point of divergence.

While this method has gained a certain acceptance—and has also served as the basis for the “mitochondrial Eve” hypothesis that purports to establish the date that modern humans evolved and began their migration out of Africa—the Sahelanthropus discovery, along with the recent hominid skull uncovered at the Dmanisi site in the Georgian Republic, indicates that the fossil record still has much to say on these questions.

Another important issue that Sahelanthropus raises pertains to the process of human evolution: whether humans evolved by way of a linear progression of intermediate types, or was more complicated, a tangle of evolutionary branches out of which the human line emerged. In his article in Nature, Brunet comments: “Sahelanthropus is the oldest and most primitive known member of the hominid clade, close to the divergence of hominids and chimpanzees. Further analysis will be necessary to make reliable inferences about the phylogenetic position of Sahelanthropus relative to known hominids.”

Whether Sahelanthropus is a direct human ancestor is certainly an open question. In fact it is likely that at the base of hominid evolution, within the vast expanse of tropical rainforests that girdled the earth during the Miocene, and among the flourishing and evolving ape populations, from which today’s few descendants are mere relicts, there was such a diversity that the tendencies in the direction of hominid evolution were recurrent and fairly common. Sahelanthropus could be a direct human ancestor, or an extinct Miocene ape that has left no descendants.

The fossil’s importance as a major contributor to the study of human origins is best summed up by UC Berkeley paleoanthropologist Tim White, who commented: “This is a great extension onto the fossil record. But that’s the real story here—it’s an opening window.”

* Brunet, Michel. et al. (2002). A new hominid from the upper Miocene of Chad, Central Africa. Nature. (418).145-151.

[ 02-12-2006, 08:19 PM: Message edited by: Jason ]
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