First Dinosaur Fossil

“The first proof that giant dinosaurs once walked the earth.”

  • Who Discovered it?: William Buckland and Gideon Mantell.
  • Year of Discovery: 1824

How was it Discovered?


People had always found fossil bones, but none had correctly identified them as extinct species. In 1677 English man Robert Plot found what 220 years later was identified as the end of the thigh bone of a giant biped carnivorous dinosaur. Plot gained great fame when he claimed it was the fossilized testicles of a giant and said it proved that story giants were real.

Science was clearly still in the dark ages until two English men, working independently, both wrote articles on their discovery of dinosaurs in 1824. They share the credit for discovering dinosaurs.

In 1809 (50 years before Darwin’s discovery of evolution) English country doctor Gideon Mantell lived in Lewes in the Sussex district of England. While visiting a patient one day, Mantell’s wife, Mary Ann, took a short stroll and then presented him with several puzzling teeth she had found. These massive teeth were obviously from an herbivore but were far too large for any known animal. Mantell, an amateur geologist, had been collecting fossil relics of ancient land animals for several years but could not identify these teeth. He returned to the site and correctly identified the rock strata as from the Mesozoic era. Thus, the teeth had to be many millions of years old.


These teeth were not the first large bones Mantell had found, but they were the most puzzling. Mantell took them to famed French naturalist, Charles Cuvier, who thought they came from an ordinary rhinoceros-like animal. Mantell set the teeth aside.

In 1822 Mantell came across the teeth of an iguana and realized that these teeth were exact miniatures of the ones he had found 13 years earlier. Combined with other large bones he had recovered from the site, Mantell claimed that he had discovered an ancient, giant reptile that he named Iguanodon (“Iguana-toothed”). He eagerly published his discovery in 1824.

During this same period William Buck-land, a professor at Oxford University, had been collecting fossils in the Stonesfield region of England. During an 1822 outing, he discovered the jaw and several thigh bones of an ancient and giant creature. (It turned out to be the same species discovered—but not identified—by Robert Plot 150 years before.)

Buckland determined from these bones that this monster had been a biped (two-legged) carnivore. From the bone structure, Buckland claimed that it belonged to the reptile family. Thus he named it megalosaurus (giant lizard) and published a paper on it in 1824. With these two publications, the era of dinosaurs had been discovered.


Fun Facts: The word dinosaur comes from the Greek words meaning terrible lizard.” Lots of dinosaurs were named after Greek words that suited their personality or appearance. Velociraptor means “speedy robber” and Triceratops means “three-horned head.

Order in Nature

All living plants and animals can be grouped and organized into a simple hierarchy.

  • Who Discovered it?: Carl Linnaeus
  • Year of Discovery: 1735

How was it Discovered?

Carl Linnaeus hated disorder. He claimed he could never understand anything that was not systematically ordered. Born in Sweden in 1707, he was supposed to become a priest like his father. But Carl showed little aptitude for, and no interest in, the priesthood and was finally allowed to switch to medicine.

He entered the University of Lund’s School of Medicine in 1727 but spent more time in the university’s small botanical garden than in class. Linnaeus had been fascinated by plants and flowers since he was a small child. In 1728 Linnaeus transferred to the University of Uppsala (partly because they had bigger botanical gardens). There he read a paper by French botanist Sebastian Vaillant that claimed (it was considered shockingly revolutionary at the time) that plants reproduced sexually and had male and female parts that corresponded to the sexual organs of animals.

The idea appealed to Linnaeus. As an obsessive cataloger, he had always detested the notion that each of the thousands of plants he saw in botanical gardens was individual and separate species. Linnaeus began to wonder if he could use the differences in plants’ reproductive parts as a means of classifying and ordering the vast array and profusion of plants. His dream of bringing order to the chaos of nature was born.

Glib, cordial, and with a natural talent for ingratiating himself with rich and powerful supporters, Linnaeus was able to arrange financial support for a series of expeditions across different areas of Sweden to study and catalog plant species. He spent months tramping across the countryside listing, describing, and studying every plant he found. His expeditions were always the picture of perfect order. He started each day’s hike precisely at 7:00 in the morning. Linnaeus stopped for a meal break at 2:00 P.M. He paused for a rest and lecture break at 4:00 P.M.

During these expeditions, Linnaeus focused his studies on the reproductive systems of each plant he found. Soon he discovered common characteristics of male and female plant parts in many species that he could group into a single category. He lumped these categories together into larger groups that were, again, combined with other groups into yet larger classifications. He found that plants fit neatly into groups based on a few key traits and that order did exist in the natural world.

By 1735 he had described more than 4,000 species of plants and published his classification system in a book, Systema Naturae. This system described the eight levels Linnaeus finally built into his system: species, genus, family, order, Class, Subphylum, Phylum, and Kingdom. This system—based solely on the sexual elements of plants and (later) animals—was controversial with the public. But botanists found it easy to use and appealing.

Linnaeus’s system spread quickly across Europe and was often drawn as a tree, with giant branches being classes, down to the tiniest twigs of species. From these drawings came the concept of a “Tree of Life.”

Linnaeus spent the next 30 years touring Europe adding new plants to his system. In 1740 he added animal species into his system. By 1758 he had described and classified 4,400 animal species and more than 7,700 plant species.

In 1758, with the tenth edition of his book, he introduced the binomial (two-name) system of naming each plant and animal by species and genus. With that addition, Linnaeus’s system was complete. He had discovered both that order existed in the natural world and a system for describing that order—a system still very much alive and in use today.


Fun Facts: The world’s most massive living tree is General Sherman, the giant sequoia (Sequoiadendron giganteum) growing in the Sequoia National Park in California. It stands 83.82m (274.9 ft.) tall and has a diameter of 11.1 m (36 ft., 5 in.). This one tree is estimated to contain enough wood to make five billion matches—one for almost every person on Earth.


Radio Waves

All electric and magnetic energy waves are part of the one electromagnetic spectrum and follow simple mathematical rules.

  • Who Discovered it?: James Clerk Maxwell
  • Year of Discovery: 1864

How was it Discovered?


James Clerk was born in 1831 in Edinburgh, Scotland. The family later added the name, Maxwell. James sailed easily through his university schooling to earn top honors and a degree in mathematics. He held various professorships in math and physics thereafter.

As a mathematician, Maxwell explored the world—and the universe—through mathematics equations. He chose the rings of Saturn as the subject of his first major study. Maxwell used mathematics to prove that these rings couldn’t be solid disks, nor could they consist of gas. His equations showed that they must consist of countless small, solid particles. A century later, astronomers proved him to be correct.

Maxwell turned his attention to gasses and studied the mathematical relationships that governed the motion of rapidly moving gas particles. His results in this study completely revised science’s approach to studying the relationship between heat (temperature) and gas motion.

In 1860 he turned his attention to early electrical work by Michael Faraday. Faraday invented the electric motor by discovering that a spinning metal disk in a magnetic field created an electric current and that a changing electric current also changed a magnetic field and could create physical motion.

Maxwell decided to mathematically explore the relationship between electricity and magnetism and the “electrical and magnetic lines of force” that Faraday had discovered.

As Maxwell searched for mathematical relationships between various aspects of electricity and magnetism, he devised experiments to test and confirm each of his results. By 1864 he had derived four simple equations that described the behavior of electrical and magnetic fields and their interrelated nature. Oscillating (changing) electrical fields (ones whose electrical current rapidly shifted back and forth) produced magnetic fields and vice versa.

The two types of energy were integrally connected. Maxwell realized that electricity and magnetism were simply two expressions of a single energy stream and named it electromagnetic energy. When he first published these equations and his discoveries in an 1864 article, physicists instantly recognized the incredible value and meaning of Maxwell’s four equations.

Maxwell continued to work with his set of equations and realized that—as long as the electrical source oscillated at a high enough frequency—the electromagnetic energy waves it created could and would fly through the open air—without conducting wires to travel along. This was the first pre dic tion of radio waves.

He calculated the speed at which these electromagnetic waves would travel and found that it matched the best calculations (at that time) of the speed of light. From this, Maxwell realized that light itself was just another form of electromagnetic radiation. Because electrically charged currents can oscillate at any frequency, Maxwell realized that light was only a tiny part of a vast and continuous spectrum of electromagnetic radiation.

Maxwell predicted that other forms of electromagnetic radiation along other parts of this spectrum would be found. As he predicted, X-rays were discovered in 1896 by Wilhelm Roentgen. Eight years before that discovery, Heinrich Hertz conducted experiments following Maxwell’s equations to see if he could cause electromagnetic radiation to fly through the air (transmit through space in the form of waves of energy). He easily created and detected the world’s first radio waves, confirming Maxwell’s equations and predictions.


Fun Facts: Astronomers have concluded that the most efficient way of making contact with an intelligent civilization orbiting another star is to use radio waves. However, there are many natural processes in the universe that produce radio waves. If we could translate those naturally produced radio waves into sound, they would sound like static we hear on a radio. In the search for intelligent life, astronomers use modern computers to distinguish between a “signal” (possible message) and the “noise” (static).


Atomic Light Signatures

“When heated, every element radiates light at very specific and characteristic frequencies.”

  • Who Discovered it?: Gustav Kirchhoff and Robert Bunsen.
  • Year of Discovery: 1859

How was it Discovered?


In 1814, German astronomer Joseph Fraunhofer discovered that the sun’s energy was not radiated evenly in all frequencies of the light spectrum, but rather was concentrated in spikes of energy at certain specific frequencies. Some thought it interesting, none thought it important. The idea lay dormant for 40 years.

Gustav Kirchhoff (born in 1824) was an energetic Polish physicist who barely stood five feet in height. Through the mid-1850s he focused his research on electrical currents at the University of Breslau. In 1858, while helping another professor with a side project, Kirchhoff noted bright lines in the light spectrum produced by flames and recalled having read about a similar occurrence in Fraunhofer’s articles. Upon investigation, Kirchhoff found that the bright spots (or spikes) in the light from his flame studies were at the exact same frequency and wavelengths that Fraunhofer had detected in solar radiation.

Kirchhoff pondered what this could mean and was struck by what turned out to be a brilliant insight: use a prism to separate any light beam he wanted to study into its constituent parts (instead of peering at it through a sequence of colored glass filters as was the custom of the day). Kirchhoff believed that this would let him find spikes in the radiation coming from any burning gas.

However, the scheme did not work well. The flame he used to heat his gasses was too bright and interfered with his observations.

Enter Robert Bunsen, the German-born chemist. In 1858, 47-year-old Bunsen had been developing photochemistry—the study of light given off by burning elements. During this work, Bunsen had invented a new kind of burner in which air and gas were mixed prior to burning. This burner (which we still use and call a Bunsen burner) produced an extremely hot (over 2700°F) flame that produced very little light.

Kirchhoff and Bunsen connected at the University of Heidelberg in 1859. Standing together, Kirchhoff barely reached Bunsen’s shoulder. The pair combined Kirchhoff’s prism idea with Bunsen’s burner and spent six months to design and build the first spectrograph (a device to burn chemical samples and use a prism to separate the light they produced into a spectrum of individual frequencies).

They began to catalog the spectral lines (specific frequencies where each element radiated its light energy) of each known element and discovered that each and every element always produced the same “signature” set of spectral lines that uniquely identified the presence of that element.

Armed with this discovery and their catalog of each element’s characteristic spectral lines, Kirchhoff and Bunsen made the first complete chemical analysis of seawater and of the sun—proving that hydrogen, helium, sodium, and half-a-dozen other trace elements common on Earth existed in the sun’s atmosphere. This proved for the first time that Earth was not chemically unique in the universe.

Kirchhoff and Bunsen had given science one of its most versatile and flexible analytical tools and had discovered a way to determine the composition of any star with the same accuracy as we determine sulfuric acid, chlorine, or any other compound.

That same technique allows astronomers to determine the chemical composition of stars millions of light years away. It also allowed physicists to understand our sun’s atomic fires that produce heat and light. That same technique allows other astronomers to calculate the exact speed and motion of distant stars and galaxies.


Fun Facts: Kirchhoff and Bunsen used their spectrograph to discover two new elements: cesium in 1860 (they chose that name because cesium means “sky blue,” the color of its spectrograph flame) and rubidium in 1861. This element has a bright red line in its spectrograph. Rubidium comes from the Latin word for red.

The Theory of Evolution

Species evolve over time to best take advantage of their surrounding environment, and those species most fit for their environment survive best.

  • Who Discovered it?: Charles Darwi3398n
  • Year of Discovery: 1858

How was it Discovered?

Darwin’s theory of evolution and its concept of survival of the fittest is the most fundamental and important discovery of modern biology and ecology. Darwin’s discoveries are 150 years old and are still the foundation of our understanding of the history and evolution of plant and animal life.

Charles Darwin entered Cambridge University in 1827 to become a priest but switched to geology and botany. He graduated in 1831 and, at age 22, took a position as naturalist aboard the HMS Beagle bound from England for South America and the Pacific.

The Beagle’s three-year voyage stretched into five. Darwin forever marveled at the unending variety of species in each place the ship visited. But it was their extended stop at the Pacific Ocean Galapagos Islands that focused Darwin’s wonder into a new discovery.

On the first island in the chain he visited (Chatham Island), Darwin found two distinct species of tortoise—one with long necks that ate leaves from trees, and one with short necks that ate ground plants. He also found four new species of finches (small, yellow birds common across much of Europe). But these had differently shaped beaks from their European cousins.

The Beagle reached the third Galapagos Island (James Island) in October 1835. Here, right on the equator, no day or season seemed any different than any other.

As he did every day on shore, Darwin hoisted his backpack with jars and bags for collecting samples, a notebook for recording and sketching, and his nets and traps and set off across the frightful landscape through twisted fields of crunchy black lava thrown up into giant ragged waves. Gaping fissures from which dense steam and noxious yellow vapors hissed from deep in the rock blocked his path. The broken lava was covered by stunted, sunburned brushwood that looked far more dead than alive.

In a grove of trees filled with chirping birds, Darwin found his thirteenth and fourteenth new species of finches. Their beaks were larger and rounder than any he’d seen on other islands. More important, these finches ate small red berries.

Everywhere else on Earth finches ate seeds. In these islands, some finches ate seeds, some insects, and some berries! More amazingly, each species of finch had a beak perfectly shaped to gather the specific type of food that species preferred to eat.

Darwin began to doubt the Christian teaching that God created each species just as it was and that species were unchanging. He deduced that, long ago, one variety of finch arrived in the Galapagos from South America, spread out to the individual islands, and then adapted (evolved) to best survive in its particular environment and with its particular sources of food. These findings he reported in his book, A Naturalist’s Voyage on the Beagle.

After his return to England, Darwin read the collected essays of economist Thomas Malthus, who claimed that, when human populations could not produce enough food, the weakest people starved, died of disease, or were killed in the fighting. Only the strong survived. Darwin realized that this concept should apply to the animal world as well.

He blended this idea with his experiences and observations on the Beagle to conclude that all species evolved to better ensure species survival. He called it natural selection.

A shy and private man, Darwin agonized for years about revealing his theories to the public. Other naturalists finally convinced him to produce and publish Origin of Species. With that book, Darwin’s discoveries and theory of evolution became the guiding light of biological sciences.


Fun Facts: Bats, with their ultrasonic echolocation, have evolved the most acute hearing of any terrestrial animal. With it, bats can detect insects the size of gnats and objects as fine as a human hair.


“Microorganisms too small to be seen or felt exist everywhere in the air and cause disease and food spoilage.”

  • Who Discovered it?: Louis Pasteur
  • Year of Discovery: 1856

How was it Discovered?


In the fall of 1856, 38-year-old Louis Pasteur was in his fourth year as Director of Scientific Affairs at the famed Ecole Normale in Paris. It was an honored administrative position. But Pasteur’s heart was in pure research chemistry and he was angry.

Many scientists believed that microorganisms had no parent organism. Instead, they spontaneously generated from the decaying molecules of organic matter to spoil milk and rot meat. Felix Pouchet, the leading spokesman for this group, and had just published a paper claiming to prove this thesis.

Pasteur thought Pouchet’s theory was rubbish. Pasteur’s earlier discovery that microscopic live organisms (bacteria called yeasts) were always present during, and seemed to cause, the fermentation of beer and wine, made Pasteur suspect that microorganisms lived in the air and simply fell by chance onto food and all living matter, rapidly multiplying only when they found a decaying substance to use as nutrient.

Two questions were at the center of the argument. First, did living microbes really float in the air? Second, was it possible for microbes to grow spontaneously (in a sterile environment where no microbes already existed)?

Pasteur heated a glass tube to sterilize both the tube and the air inside. He plugged the open end with guncotton and used a vacuum pump to draw air through the cotton filter and into this sterile glass tube.

Pasteur reasoned that any microbes floating in the air should be concentrated on the outside of the cotton filter as the air was sucked through it. Bacterial growth on the filter indicated microbes floating freely in the air. Bacterial growth in the sterile interior of the tube meant spontaneous generation.

After 24 hours the outside of his cotton wad turned dingy gray with bacterial growth while the inside of the tube remained clear. Question number 1 was answered. Yes, microscopic organisms did exist, floating, in the air. Any time they concentrated (as on a cotton wad) they began to multiply.

Now for question number 2. Pasteur had to prove that microscopic bacteria could not spontaneously generate.

Pasteur mixed a nutrient-rich bullion (a favorite food of hungry bacteria) in a large beaker with a long, curving glass neck. He heated the beaker so that the bullion boiled and the glass glowed. This killed any bacteria already in the bullion or in the air inside the beaker. Then he quickly stoppered this sterile beaker. Any growth in the beaker now had to come from spontaneous generation.

He slid the beaker into a small warming oven, used to speed the growth of bacterial cultures.

Twenty-four hours later, Pasture checked the beaker. All was crystal clear. He checked every day for eight weeks. Nothing grew at all in the beaker. Bacteria did not spontaneously generate. Pasteur broke the beaker’s neck and let normal, unsterilized air flow into the beaker. Seven hours later he saw the first faint tufts of bacterial growth. Within 24 hours, the surface of the bullion was covered.

Pouchet was wrong. Without the original airborne microbes floating into contact with a nutrient, there was no bacterial growth. They did not spontaneously generate.

Pasteur triumphantly published his discoveries. More important, his discovery gave birth to a brand new field of study, microbiology.


Fun Facts: The typical household sponge holds as many as 320 million disease-causing germs.

Doppler Effect

“Sound- and light-wave frequencies shift higher or lower depending on whether the source is moving toward or away from the observer.”

  • Who Discovered it?: Christian Doppler
  • Year of the Discovery: 1848

How was it Discovered?


Austrian-born Christian Doppler was a struggling mathematics teacher—struggling both because he was too hard on his students and earned the wrath of parents and administrators and because he wanted to fully understand the geometry and mathematical concepts he taught. He drifted in and out of teaching positions through the 1820s and 1830s as he passed through his twenties and thirties. Doppler was lucky to land a math teaching slot at Vienna Polytechnic Institute in 1838.

By the late 1830s, trains capable of speeds in excess of 30 mph were dashing across the countryside. These trains made a sound phenomenon noticeable for the first time. Never before had humans traveled faster than the slow trot of a horse. Trains allowed people to notice the effect of an object’s movement on the sounds that the object produced.

Doppler intently watched trains pass and began to theorize about what caused the sound shifts he observed. By 1843 Doppler had expanded his ideas to include light waves and developed a general theory that claimed that an object’s movement either increased or decreased the frequency of sound and light it produced as measured by a stationary observer. Doppler claimed that this shift could explain the red and blue tinge to the light of distant twin stars. (The twin circling toward Earth would have its light shifted to a higher frequency—toward blue. The other, circling away, would shift lower, toward red.)

In a paper he presented to the Bohemian Scientific Society in 1844, Doppler presented his theory that the motion of objects moving toward an observer compresses sound and light waves so that they appear to shift to a higher tone and to a higher frequency color (blue). The reverse happened if the object was moving away (a shift toward red). He claimed that this explained the often observed red and blue tinge of many distant stars’ light. Actually, he was wrong. While technically correct, this shift would be too small for the instruments of his day to detect.

Doppler was challenged to prove his theory. He could n’t with light because telescopes and measuring equipment were not sophisticated enough. He decided to demonstrate his principle with sound.

In his famed 1845 experiment, he placed musicians on a railway train playing a single note on their trumpets. Other musicians, chosen for their perfect pitch, stood on the station platform and wrote down what note they heard as the train approached and then receded. What the listeners wrote down was consistently first slightly higher and then slightly lower than what the moving musicians actually played.

Doppler repeated the experiment with a second group of trumpet players on the station platform. They and the moving musicians played the same note as the train passed. Listeners could clearly hear that the notes sounded different. The moving and stationary notes seemed to interfere with each other, setting up a pulsing beat.

Having proved the existence of his effect, Doppler named it the Doppler Shift. However, he never enjoyed the fame he sought. He died in 1853 just as the scientific community was beginning to accept and to see the value of, his discovery.

The Doppler Effect is one of the most powerful and important concepts ever discovered for astronomy. This discovery allowed scientists to measure the speed and direction of stars and galaxies many millions of light years away. It unlocked mysteries of distant galaxies and stars and led to the discovery of dark matter and of the actual age and motion of the universe. Doppler’s discovery has been used in the research efforts of a dozen scientific fields.

Few single concepts have ever proved more useful. Doppler’s discovery is considered to be so fundamental to science that it is included in virtually all middle and high school basic science courses.



Fun Facts: Doppler shifts have been used to prove that the universe is expanding. A convenient analogy for the expansion of the universe is a loaf of unbaked raisin bread. The raisins are at rest relative to one another in the dough before it is placed in the oven. As the bread rises, it also expands, making the space between the raisins increase. If the raisins could see, they would observe that all the other raisins were moving away from them although they themselves seemed to be stationary within the loaf. Only the dough—their “universe”—is expanding.