History of paleontology 1

History of paleontology

Duria Antiquior - A more Ancient Dorset is a watercolor painted in 1830 by thegeologist Henry De la Beche based on fossils found by Mary Anning. The late 18thand early 19th century was a time of rapid and dramatic changes in ideas about the

history of life on earth.

The history of paleontology traces thehistory of the effort to understand thehistory of life on Earth by studying the fossilrecord left behind by living organisms.Since it is concerned with understandingliving organisms of the past paleontologycan be considered to be a field of biology,but its historical development has beenclosely tied to geology and the effort tounderstand the history of the Earth itself.

In ancient times Xenophanes (570-480 BC)wrote about fossil sea shells indicating thatland was once under water. During theMiddle Ages, fossils were discussed by thePersian naturalist, Ibn Sina (known asAvicenna in Europe), in The Book ofHealing (1027), which proposed a theory ofpetrifying fluids that Albert of Saxony would elaborate on in the 14th century. The Chinese naturalist Shen Kuo(1031–1095) would propose a theory of climate change based on evidence from petrified bamboo.

In early modern Europe, the systematic study of fossils emerged as an integral part of the changes in naturalphilosophy that occurred during the Age of Reason. The nature of fossils and their relationship to life in the pastbecame better understood during the 17th and 18th centuries, and at the end of the 18th century the work of GeorgesCuvier ended a long running debate about the reality of extinction and led to the emergence of paleontology, inassociation with comparative anatomy, as a scientific discipline. The expanding knowledge of the fossil record alsoplayed an increasing role in the development of geology, particularly stratigraphy.

In 1822 the word "paleontology" was invented by the editor of a French scientific journal to refer to the study ofancient living organisms through fossils, and the first half of the 19th century saw geological and paleontologicalactivity become increasingly well organized with the growth of geologic societies and museums and an increasingnumber of professional geologists and fossil specialists. This contributed to a rapid increase in knowledge about thepast history of life on Earth, and progress towards definition of the geologic time scale largely based on fossilevidence. As knowledge of life's past history continued to improve, it became increasingly obvious that there hadbeen some kind of successive order to the development of life. This would encourage early evolutionary theories onthe transmutation of species.[1] After Charles Darwin published Origin of Species in 1859, much of the focus ofpaleontology shifted to understanding evolutionary paths, including human evolution, and evolutionary theory.[1]

The last half of the 19th century saw a tremendous expansion in paleontological activity, especially in NorthAmerica. The trend continued in the 20th century with additional regions of the Earth being opened to systematicfossil collection, as demonstrated by a series of important discoveries in China near the end of the century. The lastfew decades of the 20th century saw a renewed interest in mass extinctions and their role in the evolution of life onEarth.[2] There was also a renewed interest in the Cambrian explosion that saw the development of the body plans ofmost animal phyla. The discovery of fossils of the Ediacaran biota and developments in paleobiology extendedknowledge about the history of life back far before the Cambrian.

History of paleontology 2

Prior to the 17th centuryAs early as the 6th century BC, the Greek philosopher Xenophanes of Colophon (570-480 BC) recognized that somefossil shells were remains of shellfish, which he used to argue that what was at the time dry land was once under thesea.[3] Leonardo da Vinci (1452–1519), in an unpublished notebook, also concluded that some fossil sea shells werethe remains of shellfish. However, in both cases, the fossils were complete remains of shellfish species that closelyresembled living species, and were therefore easy to classify.[4]

In 1027, the Persian naturalist, Ibn Sina (known as Avicenna in Europe), proposed an explanation of how thestoniness of fossils was caused in The Book of Healing. He modified an idea of Aristotle's, which explained it interms of vaporous exhalations. Ibn Sina modified this into the theory of petrifying fluids (succus lapidificatus),which was elaborated on by Albert of Saxony in the 14th century and was accepted in some form by most naturalistsby the 16th century.[5]

Shen Kuo (Chinese: 沈括) (1031–1095) of the Song Dynasty used marine fossils found in the Taihang Mountains toinfer the existence of geological processes such as geomorphology and the shifting of seashores over time.[6] Usinghis observation of preserved petrified bamboos found underground in Yan'an, Shanbei region, Shaanxi province, heargued for a theory of gradual climate change, since Shaanxi was part of a dry climate zone that did not support ahabitat for the growth of bamboos.[7]

As a result of a new emphasis on observing, classifying, and cataloging nature, 16th century natural philosophers inEurope began to establish extensive collections of fossil objects (as well as collections of plant and animalspecimens), which were often stored in specially built cabinets to help organize them. Conrad Gesner published a1565 work on fossils that contained one of the first detailed descriptions of such a cabinet and collection. Thecollection belonged to a member of the extensive network of correspondents that Gesner drew on for his works. Suchinformal correspondence networks among natural philosophers and collectors became increasingly important duringthe course of the 16th century and were direct forerunners of the scientific societies that would begin to form in the17th century. These cabinet collections and correspondence networks played an important role in the development ofnatural philosophy.[8]

However, most 16th century Europeans did not recognize that fossils were the remains of living organisms. Theetymology of the word fossil comes from the Latin for things having been dug up. As this indicates, the term wasapplied to wide variety of stone and stone-like objects without regard to whether they might have an organic origin.16th century writers such as Gesner and Georg Agricola were more interested in classifying such objects by theirphysical and mystical properties than they were in determining the objects' origins.[9] In addition, the naturalphilosophy of the period encouraged alternative explanations for the origin of fossils. Both the Aristotelian andNeoplatonic schools of philosophy provided support for the idea that stony objects might grow within the earth toresemble living things. Neoplatonic philosophy maintained that there could be affinities between living andnon-living objects that could cause one to resemble the other. The Aristotelian school maintained that the seeds ofliving organisms could enter the ground and generate objects resembling those organisms.[10]

History of paleontology 3

17th century

Johann Jakob Scheuchzer tried to explain fossilsusing Biblical floods in his Herbarium of the

Deluge (1709)

During the Age of Reason, fundamental changes in natural philosophywere reflected in the analysis of fossils. In 1665 Athanasius Kircherattributed giant bones to extinct races of giant humans in his Mundussubterraneus. In the same year Robert Hooke published Micrographia,an illustrated collection of his observations with a microscope. One ofthese observations was entitled Of Petrify'd wood, and other Petrify'dbodies, which included a comparison between petrified and ordinarywood. He concluded that petrified wood was ordinary wood that hadbeen soaked with "water impregnated with stony and earthy particles".He then suggested that several kinds of fossil sea shells were formedfrom ordinary shells by a similar process. He argued against theprevalent view that such objects were "Stones form'd by some extraordinary Plastick virtue latent in the Earthitself".[11] Hooke believed that fossils provided evidence about the past history of life on Earth writing in 1668:

...if the finding of Coines, Medals, Urnes, and other Monuments of famous persons, or Towns, orUtensils, be admitted for unquestionable Proofs,that such Persons or things have, in former times had abeing, certainly those Petrifactions may be allowed to be of equal Validity and Evidence, that there haveformerly been such Vegetables or Animals... and are true universal Characters legible to all rationalMen. [12]

Hooke was prepared to accept the possibility that some such fossils represented species that had become extinct,possibly in past geological catastrophes.[12]

This illustration from Steno's 1667 paper shows ashark head and its teeth along with a fossil tooth

for comparison.

In 1667 Nicholas Steno wrote a paper about a shark head he haddissected. He compared the teeth of the shark with the common fossilobjects known as tongue stones. He concluded that the fossils musthave been shark teeth. Steno then took an interest in the question offossils, and to address some of the objections to their organic origin hebegan studying rock strata. The result of this work was published in1669 as Forerunner to a Dissertation on a solid naturally enclosed in asolid. In this book, Steno drew a clear distinction between objects suchas rock crystals that really were formed within rocks and those such asfossil shells and shark teeth that were formed outside of those rocks.Steno realized that certain kinds of rock had been formed by thesuccessive deposition of horizontal layers of sediment and that fossilswere the remains of living organisms that had become buried in thatsediment. Steno who, like almost all 17th century natural philosophers,believed that the earth was only a few thousand years old, resorted tothe Biblical flood as a possible explanation for fossils of marineorganisms that were far from the sea.[13]

Despite the considerable influence of Forerunner, naturalists such asMartin Lister (1638–1712) and John Ray (1627–1705) continued toquestion the organic origin of some fossils. They were particularly

concerned about objects such as fossil Ammonites, which Hooke claimed were organic in origin, that did notresemble any known living species. This raised the possibility of extinction, which they found difficult to accept for

philosophical and theological reasons.[14] In 1695 Ray wrote to the Welsh naturalist Edward Lluyd complaining of such views: "... there follows such a train of consequences, as seem to shock the Scripture-History of the novity of

History of paleontology 4

the World; at least they overthrow the opinion received, & not without good reason, among Divines andPhilosophers, that since the first Creation there have have been no species of Animals or Vegetables lost, no newones produced."[15]

18th century

A drawing comparing jaws was added in 1799when Cuvier's 1796 presentation on living and

fossil elephants was published.

In his 1778 work Epochs of Nature Georges Buffon referred to fossils,in particular the discovery of fossils of tropical species such aselephants and rhinoceros in northern Europe, as evidence for the theorythat the earth had started out much warmer than it currently was andhad been gradually cooling.

In 1796 Georges Cuvier presented a paper on living and fossilelephants comparing skeletal remains of Indian and African elephantsto fossils of mammoths and of an animal he would later namemastodon utilizing comparative anatomy. He established for the firsttime that Indian and African elephants were different species, and thatmammoths differed from both and must be extinct. He furtherconcluded that the mastodon was another extinct species that alsodiffered from Indian or African elephants, more so than mammoths.Cuvier made another powerful demonstration of the power ofcomparative anatomy in paleontology when he presented a secondpaper in 1796 on a large fossil skeleton from Paraguay, which henamed Megatherium and identified as a giant sloth by comparing itsskull to those of two living species of tree sloth. Cuvier’sground-breaking work in paleontology and comparative anatomy leadto the widespread acceptance of extinction.[16] It also lead Cuvier toadvocate the geological theory of catastrophism to explain thesuccession of organisms revealed by the fossil record. He also pointedout that since mammoths and wooly rhinoceros were not the samespecies as the elephants and rhinoceros currently living in the tropics, their fossils could not be used as evidence for acooling earth.

This illustration is from William Smith's 1815work Strata by Organized Fossils.

In a pioneering application of stratigraphy, William Smith, a surveyorand mining engineer, made extensive use of fossils to help correlaterock strata in different locations. He created the first geological map ofEngland during the late 1790s and early 19th century. He establishedthe principle of faunal succession, the idea that each strata ofsedimentary rock would contain particular types of fossils, and thatthese would succeed one another in a predictable way even in widelyseparated geologic formations. At the same time, Cuvier andAlexandre Brongniart, an instructor at the Paris school of mineengineering, used similar methods in an influential study of thegeology of the region around Paris.

History of paleontology 5

19th century before Darwin

The age of reptiles

This illustration of fossil Iguanodon teeth with amodern iguana jaw for comparison is from

Mantell's 1825 paper describing Iguanodon.

In 1808, Cuvier identified a fossil found in Maastricht as a giantmarine reptile that he named Mosasaurus. He also identified, from adrawing, another fossil found in Bavaria as a flying reptile and namedit Pterodactylus. He speculated that an age of reptiles had preceded thefirst mammals.[17] Cuvier's speculation would be supported by a seriesof finds that would be made in Great Britain over the course of the nexttwo decades. Mary Anning, a professional fossil collector since ageeleven, collected the fossils of a number of marine reptiles from theJurassic marine strata at Lyme Regis. These included the firstichthyosaur skeleton to be recognized as such, which was collected in1811, and the first two plesiosaur skeletons ever found in 1821 and1823. Many of her discoveries would be described scientifically by thegeologists William Conybeare, Henry De la Beche, and WilliamBuckland.[18] It was Anning who observed that stony objects known as"bezoar stones" were often found in the abdominal region ofichthyosaur skeletons, and she noted that if such stones were brokenopen they often contained fossilized fish bones and scales as well assometimes bones from small ichthyosaurs. This led Buckland todeclare they were fossilized feces, which he named coprolites, and heused them to better understand ancient food chains.[19]

In 1824, Buckland found and described a lower jaw from Jurassic deposits from Stonesfield. He determined that thebone belonged to a carnivorous land-dwelling reptile he called Megalosaurus. That same year Gideon Mantellrealized that some large teeth he had found in 1822, in Cretaceous rocks from Tilgate, belonged to a giantherbivorous land-dwelling reptile. He called it Iguanodon, because the teeth resembled those of an iguana. In 1832Mantell would find, in Tilgate, a partial skeleton of an armoured reptile he would call Hylaeosaurus. In 1842 theEnglish anatomist Richard Owen would create a new order of reptiles, which he called Dinosauria, forMegalosaurus, Iguanodon, and Hylaeosaurus.[20]

This illustration of the fossil jaw of theStonesfield mammal is from Gideon Mantell's

1848 book Wonders of Geology.

This evidence that giant reptiles had lived on Earth in the past causedgreat excitement in scientific circles,[21] and even among somesegments of the general public.[22] Buckland did describe the jaw of asmall primitive mammal, Phascolotherium, that was found in the samestrata as Megalosaurus. This discovery, known as the Stonesfieldmammal, was a much discussed anomaly. Cuvier at first thought it wasa marsupial, but Buckland later realized it was a primitive placentalmammal. Due to its small size and primitive nature, Buckland did notbelieve it invalidated the overall pattern of an "age of reptiles", whenthe largest and most conspicuous animals had been reptiles rather thanmammals.[23]

Paleobotany and the origin of the word paleontology

History of paleontology 6

In 1828 Alexandre Brongniart's son, the botanist Adolphe Brongniart, published the introduction to a longer work onthe history of fossil plants. Adolphe Brongniart concluded that the history of plants could roughly be divided intofour parts. The first period was characterized by cryptogams. The second period was characterized by the appearanceof the conifers. The third period brought emergence of the cycads, and the fourth by the development of theflowering plants (such as the dicotyledons). The transitions between each of these periods was marked by sharpdiscontinuities in the fossil record, with more gradual changes within the periods. Brongniart's work is thefoundation of paleobotany and reinforced the theory that life on earth had a long and complex history, and differentgroups of plants and animals made their appearances in successive order.[24] It also supported the idea that theEarth's climate had changed over time as Brogniart concluded that plant fossils showed that during the Carboniferousthe climate of Northern Europe must have been tropical.[25]

The increasing attention being paid to fossil plants in the first decades of the 19th century would trigger a significantchange in the terminology for the study of past life. The editor of the influential French scientific journal, Journal dePhisique, a student of Cuvier's named Henri Marie Ducrotay de Blanville, coined the term "paleozoologie" in 1817to refer to the work Cuvier and others were doing to reconstruct extinct animals from fossil bones. However,Blanville began looking for a term that could refer to the study of both fossil animal and plant remains. After tryingsome unsuccessful alternatives, he hit on "paleontologie" in 1822. Blanville's term for the study of the livingorganisms of the past quickly became popular and was anglicized into "paleontology".[26]

Catastrophism, uniformitarianism and the fossil recordIn Cuvier's landmark 1796 paper on living and fossil elephants, he referred to a single catastrophe that destroyed lifeto be replaced by the current forms. As a result of his studies of extinct mammals, he realized that animals such asPalaeotherium had lived before the time of the mammoths, which lead him to write in terms of multiple geologicalcatastrophes that had wiped out a series of successive faunas.[27] By 1830, a scientific consensus had formed aroundhis ideas as a result of paleobotany and the dinosaur and marine reptile discoveries in Britain.[28] In Great Britain,where natural theology was very influential in the early 19th century, a group of geologists that included Buckland,and Robert Jameson insisted on explicitly linking the most recent of Cuvier's catastrophes to the biblical flood.Catastrophism had a religious overtone in Britain that was absent elsewhere.[29]

Partly in response to what he saw as unsound and unscientific speculations by William Buckland and otherpractitioners of flood geology, Charles Lyell advocated the geological theory of uniformitarianism in his influentialwork Principles of Geology.[30] Lyell amassed evidence, both from his own field research and the work of others,that most geological features could be explained by the slow action of present day forces, such as vulcanism,earthquakes, erosion, and sedimentation rather than past catastrophic events.[31] Lyell also claimed that the apparentevidence for catastrophic changes in the fossil record, and even the appearance of directional succession in thehistory of life, were illusions caused by imperfections in that record. For instance he argued that the absence of birdsand mammals from the earliest fossil strata was merely an imperfection in the fossil record attributable to the factthat marine organisms were more easily fossilized.[31] Also Lyell pointed to the Stonesfield mammal as evidence thatmammals had not necessarily been preceded by reptiles, and to the fact that certain Pleistocene strata showed amixture of extinct and still surviving species, which he said showed that extinction occurred piecemeal rather than asa result of catastrophic events.[32] Lyell was successful in convincing geologists of the idea that the geologicalfeatures of the earth were largely due to the action of the same geologic forces that could be observed in the presentday, acting over an extended period of time. He was not successful in gaining support for his view of the fossilrecord, which he believed did not support a theory of directional succession.[33]

History of paleontology 7

Transmutation of species and the fossil recordJean Baptiste Lamarck used fossils in his arguments for his theory of the transmutation of species in the early 19thcentury.[34] Fossil finds, and the emerging evidence that life had changed over time, fueled speculation on this topicduring the next few decades.[35] Robert Chambers used fossil evidence in his 1844 popular science book Vestiges ofthe Natural History of Creation, which advocated an evolutionary origin for the cosmos as well as for life on earth.Like Lamarck's theory it maintained that life had progressed from the simple to the complex.[36] These earlyevolutionary ideas were widely discussed in scientific circles but were not accepted into the scientificmainstream.[37] Many of the critics of transmutational ideas used fossil evidence in their arguments. In the samepaper that coined the term dinosaur Richard Owen pointed out that dinosaurs were at least as sophisticated andcomplex as modern reptiles, which he claimed contradicted transmutational theories.[38] Hugh Miller would make asimilar argument, pointing out that the fossil fish found in the Old Red Sandstone formation were fully as complexas any later fish, and not the primitive forms alleged by Vestiges.[39] While these early evolutionary theories failed tobecome accepted as mainstream science, the debates over them would help pave the way for the acceptance ofDarwin's theory of evolution by natural selection a few years later.[40]

This diagram of the geologic time scale from an1861 book by Richard Owen shows the

appearance of major animal types.

Geological time scale and the history of life

Geologists such as Adam Sedgwick, and Roderick Murchisoncontinued, in the course of disputes such as The Great DevonianControversy, to make advances in stratigraphy. They described newgeological epochs such as the Cambrian, the Silurian, the Devonian,and the Permian. Increasingly, such progress in stratigraphy dependedon the opinions of experts with specialized knowledge of particulartypes of fossils such as William Lonsdale (fossil corals), and JohnLindley (fossil plants) who both played a role in the Devoniancontroversy and its resolution.[41] By the early 1840s much of thegeologic time scale had been developed. In 1841, John Phillipsformally divided the geologic column into three major eras, thePaleozoic, Mesozoic, and Cenozoic, based on sharp breaks in the fossilrecord.[42] He identified the three periods of the Mesozoic era and allthe periods of the Paleozoic era except the Ordovician. His definitionof the geological time scale is still used today.[43] It remained a relativetime scale with no method of assigning any of the periods' absolutedates. It was understood that not only had there been an "age ofreptiles" preceding the current "age of mammals", but there had a time(during the Cambrian and the Silurian) when life had been restricted tothe sea, and a time (prior to the Devonian) when invertebrates had beenthe largest and most complex forms of animal life.

Expansion and professionalization of geology and paleontologyThis rapid progress in geology and paleontology during the 1830s and 1840s was aided by a growing internationalnetwork of geologists and fossil specialists whose work was organized and reviewed by an increasing number ofgeological societies. Many of these geologists and paleontologists were now paid professionals working foruniversities, museums and government geological surveys. The relatively high level of public support for the earthsciences was due to their cultural impact, and their proven economic value in helping to exploit mineral resourcessuch as coal.[44]

History of paleontology 8

Another important factor was the development in the late 18th and early 19th centuries of museums with largenatural history collections. These museums received specimens from collectors around the world and served ascenters for the study of comparative anatomy and morphology. These disciplines played key roles in thedevelopment of a more technically sophisticated form of natural history. One of the first and most importantexamples was the Museum of Natural History in Paris, which was at the center of many of the developments innatural history during the first decades of the 19th century. It was founded in 1793 by an act of the French NationalAssembly, and was based on an extensive royal collection plus the private collections of aristocrats confiscatedduring the French revolution, and expanded by material seized during French military conquests. The Paris museumwas the professional base for Cuvier, and his professional rival Geoffroy Saint-Hilaire. The English anatomistsRobert Grant and Richard Owen both spent time studying there. Owen would go on to become the leading Britishmorphologist while working at the museum of the Royal College of Surgeons.[45] [46]

19th century after Darwin

Evolution

This photo of the second Archaeopteryx skeleton to befound was taken in 1881 at the Humboldt Museum in

Berlin.

Charles Darwin's publication of the On the Origin of Species in1859 was a watershed event in all the life sciences, especiallypaleontology. Fossils had played a role in the development ofDarwin's theory. In particular he had been impressed by fossils hehad collected in South America during the voyage of the Beagle ofgiant armadillos, giant sloths, and what at the time he thought weregiant llamas that seemed to be related to species still living on thecontinent in modern times.[47] The scientific debate that startedimmediately after the publication of Origin led to a concertedeffort to look for transitional fossils and other evidence ofevolution in the fossil record. There were two areas where earlysuccess attracted considerable public attention, the transitionbetween reptiles and birds, and the evolution of the modernsingle-toed horse.[48] In 1861 the first specimen of Archaeopteryx,an animal with both teeth and feathers and a mix of other reptilianand avian features, was discovered in a limestone quarry inBavaria and described by Richard Owen. Another would be foundin the late 1870s and put on display at a Museum in Berlin in1881. Other primitive toothed birds were found by Othniel Marshin Kansas in 1872. Marsh also discovered fossils of severalprimitive horses in the Western United States that helped trace theevolution of the horse from the small 5-toed Hyracotherium of the

Eocene to the much larger single-toed modern horses of the genus Equus. Thomas Huxley would make extensive useof both the horse and bird fossils in his advocacy of evolution. Acceptance of evolution occurred rapidly in scientificcircles, but acceptance of Darwin's proposed mechanism of natural selection as the driving force behind it was muchless universal. In particular some paleontologists such as Edward Drinker Cope and Henry Fairfield Osbornpreferred alternatives such as neo-Lamarckism, the inheritance of characteristics acquired during life, andorthogenesis, an innate drive to change in a particular direction, to explain what they perceived as linear trends inevolution.[49]

History of paleontology 9

This diagram by O.C. Marsh of the evolution of horsefeet and teeth over time was reproduced in T.H

Huxley's 1876 book, Professor Huxley in America.

There was also great interest in human evolution. Neanderthalfossils were discovered in 1856, but at the time it was not clearthat they represented a different species from modern humans.Eugene Dubois created a sensation with his discovery of JavaMan, the first fossil evidence of a species that seemed clearlyintermediate between humans and apes, in 1891.

Developments in North America

A major development in the second half of the 19th century was arapid expansion of paleontology in North America. In 1858 JosephLeidy described a Hadrosaurus skeleton, which was the firstNorth American dinosaur to be described from good remains.However, it was the massive westward expansion of railroads,military bases, and settlements into Kansas and other parts of theWestern United States following the American Civil War thatreally fueled the expansion of fossil collection.[50] The result wasan increased understanding of the natural history of NorthAmerica, including the discovery of the Western Interior Sea thathad covered Kansas and much of the rest of the MidwesternUnited States during parts of the Cretaceous, the discovery severalimportant fossils of primitive birds and horses, and the discoveryof a number of new dinosaur genera including Allosaurus,Stegosaurus, and Triceratops. Much of this activity was part of afierce personal and professional rivalry between two men, Othniel Marsh, and Edward Cope, which has becomeknown as the Bone Wars.

Overview of developments in the 20th century

Developments in geologyTwo 20th century developments in geology had a big effect on paleontology. The first was the development ofradiometric dating, which allowed absolute dates to be assigned to the geologic timescale. The second was the theoryof plate tectonics, which helped make sense of the geographical distribution of ancient life.

Geographical expansion of paleontologyDuring the 20th century paleontological exploration intensified everywhere and ceased to be a largely European andNorth American activity. In the 135 years between Buckland's first discovery and 1969 a total of 170 dinosaurgenera were known. In the 25 years after 1969 that number increased to 315. Much of this increase was due to theexamination of new rock exposures, particularly in previously little-explored areas in South America and Africa.[51]

Near the end of the century the opening of China to systematic exploration for fossils has yielded a wealth ofmaterial on dinosaurs and the origin of birds and mammals.[52]

History of paleontology 10

Mass extinctionsThe 20th century saw a major renewal of interest in mass extinction events and their effect on the course of thehistory of life. This was particularly true after 1980 when Luis and Walter Alvarez put forward the Alvarezhypothesis claiming that an impact event caused the Cretaceous–Tertiary extinction event, which killed off thenon-avian dinosaurs along with many other living things.[53] Also in the early 1980s Jack Sepkoski and David M.Raup published papers with statistical analysis of the fossil record of marine invertebrates that revealed a pattern(possibly cyclical) of repeated mass extinctions with significant implications for the evolutionary history of life.

Evolutionary paths and theory

Photo shows the fossils of Taung childdiscovered in South Africa in 1924.

Throughout the 20th century new fossil finds continued to contribute tounderstanding the paths taken by evolution. Examples include majortaxonomic transitions such as finds in Greenland, starting in the 1930s(with more major finds in the 1980s), of fossils illustrating theevolution of tetrapods from fish, and fossils in China during the 1990sthat shed light on the dinosaur-bird relationship. Other events that haveattracted considerable attention have included the discovery of a seriesof fossils in Pakistan that have shed light on whale evolution, and mostfamously of all a series of finds throughout the 20th century in Africa(starting with Taung child in 1924[54] ) and elsewhere have helpedilluminate the course of human evolution. Increasingly, at the end ofthe century, the results of paleontology and molecular biology were

being brought together to reveal detailed phylogenetic trees.

The results of paleontology have also contributed to the development of evolutionary theory. In 1944 GeorgeGaylord Simpson published Tempo and Mode in Evolution, which used quantitative analysis to show that the fossilrecord was consistent with the branching, non-directional, patterns predicted by the advocates of evolution driven bynatural selection and genetic drift rather than the linear trends predicted by earlier advocates of neo-Lamarckism andorthogenesis. This integrated paleontology into the modern evolutionary synthesis.[55] In 1972 Niles Eldredge andStephen Jay Gould used fossil evidence to advocate the theory of punctuated equilibrium, which maintains thatevolution is characterized by long periods of relative stasis and much shorter periods of relatively rapid change.[56]

Cambrian explosion

Photo shows a complete Anomalocaris fossilfrom the Burgess shale.

One area of paleontology that has seen a lot of activity during the1980s, 1990s, and beyond is the study of the Cambrian explosionduring which many of the various phyla of animals with theirdistinctive body plans first appear. The well-known Burgess ShaleCambrian fossil site was found in 1909 by Charles Doolittle Walcott,and another important site in Chengjiang China was found in 1912.However, new analysis in the 1980s by Harry B. Whittington, DerekBriggs, Simon Conway Morris and others sparked a renewed interestand a burst of activity including discovery of an important new fossilsite, Sirius Passet, in Greenland, and the publication of a popular and controversial book, Wonderful Life by StephenJay Gould in 1989.[57]

History of paleontology 11

Pre-Cambrian fossils

Photo shows a Spriggina fossil from theEdiacaran.

Prior to 1950 there was no widely accepted fossil evidence of lifebefore the Cambrian period. When Charles Darwin wrote The Originof Species he acknowledged that the lack of any fossil evidence of lifeprior to the relatively complex animals of the Cambrian was a potentialargument against the theory of evolution, but expressed the hope thatsuch fossils would be found in the future. In the 1860s there wereclaims of the discovery of pre-Cambrian fossils, but these would laterbe shown not to have an organic origin. In the late 19th centuryCharles Doolittle Walcott would discover stromatolites and other fossilevidence of pre-Cambrian life, but at the time the organic origin ofthose fossils was also disputed. This would start to change in the 1950swith the discovery of more stromatolites along with microfossils of the

bacteria that built them, and the publication of a series of papers by the Soviet scientist Boris Vasil'evich Timofeevannouncing the discovery of microscopic fossil spores in pre-Cambrian sediments. A key breakthrough would comewhen Martin Glaessner would show that fossils of soft bodied animals discovered by Reginald Sprigg during the late1940s in the Ediacaran hills of Australia were in fact pre-Cambrian not early Cambrian as Sprigg had originallybelieved, making the Ediacaran biota the oldest animals known. By the end of the 20th century paleobiology hadestablished that the history of life extended back at least 3.5 billion years.[58]

Notes[1] Buckland W & Gould SJ (1980). Geology and Mineralogy Considered With Reference to Natural Theology (History of Paleontology). Ayer

Company Publishing. ISBN 978-0405127069.[2] Bowler Evolution: The History of an Idea pp. 351-352[3] Desmond p. 692-697.[4] Rudwick The Meaning of Fossils p. 39[5] Rudwick The Meaning of Fossils p. 24[6] Shen Kuo,Mengxi Bitan (梦溪笔谈; Dream Pool Essays) (1088)[7] Needham, Volume 3, p. 614.[8] Rudwick The Meaning of Fossils pp. 9-17[9] Rudwick The Meaning of Fossils pp. 23-33[10] Rudwick The Meaning of Fossils pp. 33-36[11] Hooke Micrographia observation XVII[12] Bowler The Earth Encompassed (1992) pp. 118-119[13] Rudwick The Meaning of Fossils pp 72-73[14] Rudwick The Meaning of Fossils pp 61-65[15] Bowler The Earth Encompassed (1992) p. 117[16] McGowan the dragon seekers pp. 3-4[17] Rudwick Georges Cuvier, Fossil Bones and Geological Catastrophes p. 158[18] McGowan pp. 11-27[19] Rudwick, Martin Worlds Before Adam: The Reconstruction of Geohistory in the Age of Reform (2008) pp. 154-155.[20] McGowan p. 176[21] McGowan pp. 70-87[22] McGowan p. 109[23] McGowan pp. 78-79[24] Rudwick The Meaning of Fossils pp. 145-147[25] Bowler The Earth Encompassed (1992)[26] Rudwick Worlds before Adam p. 48[27] Rudwick The Meaning of Fossils pp. 124-125[28] Rudwick The Meaning of Fossils pp. 156-157[29] Rudwick The Meaning of Fossils pp. 133-136[30] McGowan pp. 93-95

History of paleontology 12

[31] McGowan pp. 100-103[32] Rudwick The Meaning of Fossils pp. 178-184[33] McGowan pp. 100[34] Rudwick The Meaning of Fossils p. 119[35] McGowan p. 8[36] McGowan pp. 188-191[37] Larson p. 73[38] Larson p. 44[39] Ruckwick The Meaning of fossils pp. 206-207[40] Larson p. 51[41] Rudwick The Great Devonian Controversy p. 94[42] Larson pp. 36-37[43] Rudwick The Meaning of Fossils p. 213[44] Rudwick The Meaning of Fossils pp. 200-201[45] Greene and Depew The Philosophy of Biology pp. 128-130[46] Bowler and Morus Making Modern Science pp. 168-169[47] Bowler Evolution: The History of an Idea p. 150[48] Larson Evolution p. 139[49] Larson pp. 126-127[50] Everhart Oceans of Kansas p. 17[51] McGowan p. 105[52] Bowler p. 349[53] Alvarez, LW, Alvarez, W, Asaro, F, and Michel, HV (1980). "Extraterrestrial cause for the Cretaceous–Tertiary extinction". Science 208

(4448): 1095–1108. Bibcode 1980Sci...208.1095A. doi:10.1126/science.208.4448.1095. PMID 17783054.[54] Garwin, Laura; Tim Lincoln. "A Century of Nature: Twenty-One Discoveries that Changed Science and the World" (http:/ / www. press.

uchicago. edu/ Misc/ Chicago/ 284158_brain. html). University of Chicago Press. pp. 3–9. . Retrieved 2009-07-19.[55] Bowler p. 337[56] Eldredge, Niles and S. J. Gould (1972). "Punctuated equilibria: an alternative to phyletic gradualism" (http:/ / www. blackwellpublishing.

com/ ridley/ classictexts/ eldredge. asp) In T.J.M. Schopf, ed., Models in Paleobiology. San Francisco: Freeman Cooper. pp. 82-115. Reprintedin N. Eldredge Time frames. Princeton: Princeton Univ. Press, 1985. Available here (http:/ / www. nileseldredge. com/ NELE. htm).

[57] Briggs, D. E. G.; Fortey, R. A. (2005). "Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation"(http:/ / paleobiol. geoscienceworld. org/ cgi/ reprint/ 31/ 2_Suppl/ 94. pdf). Paleobiology 31 (2 (Supplement)): 94–112.doi:10.1666/0094-8373(2005)031[0094:WSSSGA]2.0.CO;2. .

[58] Schopf, J. William. "Solution to Darwin's dilemma: Discovery of the missing Precambrian record of life" (http:/ / www. pubmedcentral. nih.gov/ articlerender. fcgi?artid=34368). Proceedings of the National Academy of Sciences. . Retrieved 2007-11-15.

References• Bowler, Peter J. (2003). Evolution:The History of an Idea. University of California Press. ISBN 0-52023693-9.• Bowler, Peter J. (1992). The Earth Encompassed:A History of the Environmental Sciences. W. W. Norton.

ISBN 0-393-32080-4.• Bowler, Peter J.; Iwan Rhys Morus (2005). Making Modern Science. The University of Chicago Press.

ISBN 0-226-06861-7.• Desmond, Adrian (1975). "The Discovery of Marine Transgressions and the Explanation of Fossils in Antiquity".

American Journal of Science, Volume 275.• Larson, Edward J. (2004). Evolution: the remarkable history of scientific theory. Modern Library.

ISBN 0-679-64288-9.• McGowan, Christopher (2001). The Dragon Seekers. Persus Publishing. ISBN 0-7382-0282-7.• Everhart, Michael J. (2005). Oceans of Kansas: A Natural History of the Western Interior Sea. Indiana University

Press. ISBN 0-253-34547-2.• Greene, Marjorie; David Depew (2004). The Philosophy of Biology:An Episodic History. Cambridge University

Press. ISBN 0-521-64371-6.• Needham, Joseph (1986). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the

Heavens and the Earth. Caves Books Ltd. ISBN 0-253-34547-2.• Robert Hooke (1665) Micrographia (http:/ / www. gutenberg. org/ etext/ 15491) The Royal Society

History of paleontology 13

• Palmer, Douglas (2005) Earth Time: Exploring the Deep Past from Victorian England to the Grand Canyon.Wiley, Chichester. ISBN 9780470022214

• Rudwick, Martin J.S. (1997). Georges Cuvier, Fossil Bones, and Geological Catastrophes. The University ofChicago Press. ISBN 0-226-73106-5.

• Rudwick, Martin J.S. (1985). The Meaning of Fossils (2nd ed.). The University of Chicago Press.ISBN 0-226-73103-0.

• Rudwick, Martin J.S. (1985). The Great Devonian Controversy: The Shaping of Scientific Knowledge amongGentlemanly Specialists. The University of Chicago Press. ISBN 0-226-73102-2.

• Rudwick, Martin J.S. (2008). Worlds Before Adam: The Reconstruction of Geohistory in the Age of Reform. TheUniversity of Chicago Press. ISBN 0-226-73128-6.

• Zittel, Karl Alfred von (1901). History of geology and palaentology to the end of the Nineteenth Century (http:/ /www. archive. org/ details/ historyofgeology00zittrich). Charles Scribner's Sons, London.

External links• History of paleontology (http:/ / www. strangescience. net)• History of palaeoentomology in Russia (http:/ / palaeoentomolog. ru/ english. html)

Article Sources and Contributors 14

Article Sources and ContributorsHistory of paleontology  Source: http://en.wikipedia.org/w/index.php?oldid=459700091  Contributors: 121a0012, Abyssal, Alan Liefting, Ancheta Wis, Anglo Pyramidologist, Apokryltaros,Autodidactyl, Banus, Bender235, Bibliomaniac15, Brand35, CarolGray, CommonsDelinker, Crystallina, Dekimasu, Dialectric, Dr.Bastedo, DuncanHill, Eumolpo, Firsfron, Fred.e, Fyyer,GoingBatty, Hmains, Invertzoo, J. Spencer, Jagged 85, John.Conway, Julius Sahara, Just plain Bill, Knight1993, Kozuch, Look2See1, MWAK, Macdonald-ross, Malkinann, Meegs, Mikenorton,Miyagawa, Mwtoews, NatureA16, Nehrams2020, OhanaUnited, Orangemarlin, PericlesofAthens, Petri Krohn, Professor marginalia, Ragesoss, Rjd0060, Rjwilmsi, Rusty Cashman, SNP,Shyamal, Signalhead, Smith609, Tafkam, TimVickers, Timoteostewart, Vanished user, Vsmith, WereSpielChequers, Ynhockey, Ziegelangerer, 16 anonymous edits

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