7.1: Fossil Study - An Evolving Process

MARY ANNING AND THE AGE OF WONDER

Mary Anning (1799–1847) is likely the most famous fossil hunter you’ve never heard of (Figure 7.1.1). Anning lived her entire life in Lyme Regis on the Dorset coast in England. As a woman, born to a poor family, with a minimal education (even by 19th-century standards), the odds were against Anning becoming a scientist (Emling 2011, xii). It was remarkable that Anning was eventually able to influence the great scientists of the day with her fossil discoveries and her subsequent hypotheses regarding evolution.

Figure \(\PageIndex{1}\): An oil painting of Mary Anning and her dog, Tray, prior to 1845. The “Jurassic Coast” of Lyme Regis is in the background. Notice that Anning is pointing at a fossil!

Figure \(\PageIndex{2}\): A Walk at Dusk, 1830-1835, by Caspar David Friedrich. The prehistoric world fascinated scholars and was an accepted part of Earth’s history, even if explanation defied non-secular thought.

Figure \(\PageIndex{3}\): The “Jurassic Coast” of Lyme Regis: the home of fossil hunter Mary Anning.

Figure \(\PageIndex{4}\): Plesiosaurus, illustrated and described by Mary Anning in an undated handwritten letter.

The time when Anning lived was a remarkable period in human history because of the Industrial Revolution in Britain. Moreover, the scientific discoveries of the 18th century set the stage for great leaps of knowledge and understanding about humans and the natural world. Barely a century earlier, Sir Isaac Newton had developed his theories on physics and become the president of the Royal Society of London (Dolnick 2011, 5). In this framework, the pursuit of intellectual and scientific discovery became a popular avocation for many individuals, the vast majority of whom were wealthy men (Figure 7.1.2).

In spite of the expectations of Georgian English society to the contrary, Anning became a highly successful fossil hunter as well as a self-educated geologist and anatomist. The geology of Lyme Regis, with its limestone cliffs, provided a fortuitous backdrop for Anning’s lifework. Now called the “Jurassic Coast,” Lyme Regis has always been a rich source for fossilized remains (Figure 7.1.3). Continuing her father’s passion for fossil hunting, Anning scoured the crumbling cliffs after storms for fossilized remains and shells. The work was physically demanding and downright dangerous. In 1833, while searching for fossils, Anning lost her beloved dog in a landslide and nearly lost her own life in the process (Emling 2011).

Around the age of 10, Anning located and excavated a complete fossilized skeleton of an ichthyosaurus (“fish lizard”). She eventually found Pterodactylus macronyx and a 2.7-meter Plesiosaurus, considered by many to be her greatest discovery (Figure 7.1.4). These discoveries proved that there had been significant changes in the way living things appeared throughout the history of the world. Like many of her peers, including Darwin, Anning had strong religious convictions. However, the evidence that was being found in the fossil record was contradictory to the Genesis story in the Bible. In The Fossil Hunter: Dinosaurs, Evolution, and the Woman Whose Discoveries Changed the World, Anning’s biographer Shelley Emling (2011, 38) notes, “the puzzling attributes of Mary’s fossil [ichthyosaurus] struck a blow at this belief and eventually helped pave the way for a real understanding of life before the age of humans.”

Intellectual and scientific debate now had physical evidence to support the theory of evolution, which would eventually result in Darwin’s seminal work, On the Origin of Species (1859). Anning’s discoveries and theories were appreciated and advocated by her friends, intellectual men who were associated with the Geological Society of London. Regrettably, this organization was closed to women, and Anning received little official recognition for her contributions to the field of natural history and paleontology. Even today, Anning’s contributions are largely overlooked, a wrong that will be hopefully corrected. It is clear that Anning’s knowledge, diligence, and uncanny luck in finding magnificent specimens of fossils earned her unshakeable credibility and made her a peer to many antiquarians (Emling 2011).

Fossil hunting is still providing evidence and a narrative of the story of Earth. Mary Anning recognized the value of fossils in understanding natural history and relentlessly championed her theories to the brightest minds of her day. Anning’s ability to creatively think “outside the box”—skillfully assimilating knowledge from multiple academic fields—was her gift to our present understanding of the fossil record. Given how profoundly Anning has shaped how we, in the modern day, think about the origins of life, it is surprising that her contributions have been so marginalized. Anning’s name should be on the tip of everyone’s tongue. Fortunately, at least in one sense of the word, it is. The well-known tongue twister, below, was actually written about Mary Anning:

She sells sea-shells on the sea-shore

The shells she sells are sea-shells, I’m sure

For if she sells sea-shells on the sea-shore

Then I’m sure she sells sea-shore shells.

—T. Sullivan (1908)

DEVELOPING MODERN METHODS

Prior to the 19th century, the overwhelming majority of Westerners believed that the physical appearances of humans and all living things were unchanged since creation and that “Creation” was the work of “God,” as specified by the Holy Scriptures. To even consider that humans and animals might have evolved over time was practically an admission that the Christian God had made mistakes that needed correction in His creation of Earth and all living things (Emling 2011, 38). Thus, the Bible was viewed as a literal and rigid history of the world, and there was no tolerance for the possibility of natural forces in science to bring about change in speciation. To think otherwise was considered heresy and was punishable by excommunication from the Church—or even death. The limited vision imposed by the Church on this matter significantly restricted the way scholars could formulate hypotheses about natural history (Emling 2011, 39). In 1650, Bishop James Ussher made a famous calculation based on his study of the Old Testament that Creation occurred on Sunday (the first day of Creation), October 23, 4004 B.C. (Barr 1984, 575). Ussher’s chronology made sense in the face of limited evidence and the historical detail documented in the Bible. Many learned men, including Martin Luther, had made similar calculations using the Bible (Braterman 2013). Other physical evidence, such as prehistoric henges or megaliths, neatly fell into this timeline that the world was, at most, 6,000 years old. A dinosaur bone was discovered shortly after Ussher’s chronology had been published, but it was considered to have belonged to a giant human as the term “dinosaur” (“terrible lizard”) was not used until 1842. Fossils such as ammonites (Figure 7.1.5), vertebrae, and belemnites were often found in layers of crumbling cliffs. However, they were not recognized as the fossilized remains of creatures both extinct (terminated or vanished) and extant (still surviving). Instead, fossils were used in folk medicine or treasured as amulets for luck or protection. Because of a lack of evidence to the contrary and the overwhelming pressure of the Church, natural science was bordering on stagnation, and folklore unofficially explained most poorly understood natural phenomena. Simply put, “scientists were still trying to fit geologic evidence into Biblical chronology” (Leinhard 1998).

Definition: extinct

A word used to describe species that are no longer represented by living organisms.

Definition: extant

A word used to describe species that are currently alive today.

Figure \(\PageIndex{5}\): Ammonites are very common and date as far back as the early Jurassic with many variations. They are the fossilized remains of extinct water creatures that are characterized by tightly coiled shells. This ammonite has been cut in half to reveal the intricate interior structure and polished.

Figure \(\PageIndex{6}\): Murexsul (Miocene) This fossil was found at the Naval Weapons Center, China Lake, California, in 1945. The fossil was buried deep in the strata and was pulled out of the ground along with a crashed “Fat Boy” missile after atomic missile testing (S. Brubaker, March 9, 2018, pers. comm).

However, during the Scientific Revolution, Scotsman James Hutton hypothesized about the formation of Earth and provided a much longer timeline of events, which would eventually support the theory of evolution. Hutton’s theory of Deep Time was crucial to the understanding of fossils. Deep Time gave the history of Earth enough time—4.543 billion years—to encompass continental drift, the evolution of species, and the fossilization process. A second Scotsman, Charles Lyell, propelled Hutton’s work into his own theory of uniformitarianism, the doctrine that Earth’s geologic formations are the work of slow geologic forces. Uniformitarianism was a theory that clashed with the church’s doctrine of catastrophism, the belief that Earth’s formation was due to a set of relatively quick biblical catastrophic events. Noah’s flood, as described in the book of Genesis, is an example of a catastrophic event. Lyell’s three-volume work, Principles of Geology (1830–1833), was influential to naturalist Charles Darwin (see Chapter 2 for more information on Darwin’s work). In fact, Lyell’s first volume accompanied Darwin on his five-year voyage around the world on the HMS Beagle (1831–1836). The concepts proposed by Lyell gave Darwin an opportunity to apply his working theories of evolution by natural selection and a greater length of time with which to work. These resulting theories were important scientific discoveries and paved the way for the “Age of Wonder,” or the second Scientific Revolution (Holmes 2010, xvi).

Definition: Deep Time

James Hutton’s theory that the world was much older than biblical explanations allowed. This age could be determined by gradual natural processes like soil erosion.

Definition: uniformitarianism

The theoretical perspective that the geologic processes observed today are the same as the processes operating in the past.

Definition: catastrophism

The theoretical perspective that Earth is young and that any changes in the landscape resulted from sudden catastrophic events like volcano eruptions and floods.

The work of Anning, Darwin, Lyell, and others laid the foundation for the modern methods we use today. Though anthropology is focused on humans and our primate relatives (and not dinosaurs as many people wrongly assume), you will see that methods developed in paleontology, geology, chemistry, biology, and physics are often applied in anthropological research. In this chapter, you will learn about the primary methods and techniques employed by biological anthropologists to answer questions about fossils, the mineralized copies of once-living organisms (Figure 7.1.6). Ultimately, these answers provide insights into human evolution. Pay close attention to ways in which modern biological anthropologists use other disciplines to analyze evidence and reconstruct past activities and environments.

Definition: fossils

Mineralized copies of organisms or activity imprints.

EARTH: IT'S OLDER THAN DIRT

Scientists have developed precise and accurate dating methods based on work in the fields of physics and chemistry. Using these methods, scientists are able to establish the age of Earth as well as approximate ages of the organisms that have lived here. Earth is roughly 4.6 billion years old, give or take a few hundred million years. The first evidence for a living organism appeared around 3.5 billion years ago (bya). That is a huge amount of time to conceptualize, and many changes have taken place within that time. The scale of geologic time can seem downright overwhelming. In order to organize and make sense of Earth’s past, geologists break up that time into subunits. These subunits are human-made divisions along Earth’s timeline in the same way that inches and centimeters are human-made units that are used to divide up distance. The largest subunit is the eon. An eon is further divided into eras, and eras are divided into periods. Finally, periods are divided into epochs (see Figure 7.1.7) (Williams 2004, 37). Currently, we are living in the Phanerozoic eon, Cenozoic era, Quaternary period, and probably the Holocene epoch—though there is considerable academic debate about which epoch we are currently in.

Figure \(\PageIndex{7}\): The geologic time scale showing eons, eras, periods, epochs, and the correlating time frame.

Definition: bya

 Billion years ago.

Definition: eon

The largest unit of geologic time, spanning billions of years and divided into subunits called eras, periods, and epochs.

Definition: eras

Units of geologic time that span millions to billions of years and that are subdivided into periods and epochs.

Definition: periods

Geologic time units that span millions of years and are subdivided into epochs.

Definition: epochs

The smallest units of geologic time, spanning thousands to millions of years.

Though these divisions are human-made and, to some extent, arbitrary, they are based on major changes and events recorded in the geologic record. Events like significant shifts in climate or mass extinctions can be used to mark the end of one geologic time unit and the beginning of another. However, it is important to remember that these borders are not real in a physical sense; they are merely helpful organizational guidelines for scientific research. The boundaries are not fixed, and there can be significant debate regarding exact dates and names of particular periods and epochs. For instance, the current epoch has been traditionally known as the Holocene. It began around 10 thousand years ago (kya) during the warming period after that last major ice age. Some anthropologists argued that it shouldn’t be called the Holocene because it might not be a new epoch; perhaps it is simply a warm blip in a larger epoch that includes the Pleistocene. Today, there is lots of evidence to indicate human-driven climate change is warming the world and changing the environmental patterns faster than the natural cyclical processes. This has led some scientists within the stratigraphic community to argue for a new epoch beginning around 1950 with the Nuclear Age called the Anthropocene (Monastersky 2015; Waters et al. n.d.). Nobel Laureate Paul Crutzen places the beginning of the Anthropocene much earlier—at the dawn of the Industrial Revolution, with its polluting effects of burning coal (Crutzen and Stoermer 2000, 17–18). Geologist William Ruddiman argues that the epoch began 5,000–8,000 years ago with the advent of agriculture and the buildup of early methane gases (Ruddiman et al. 2008). Regardless of when the Anthropocene started, the major event that marks the boundary is the warming temperatures and mass extinction of nonhuman species caused by human activity (Figure 7.1.8). Researchers now declare that “human activity now rivals geologic forces in influencing the trajectory of the Earth System” (Steffen et al. 2018, 1).

Definition: Holocene

The geologic epoch from 10 kya to present. (See the discussion on Anthropocene for the debate on the current epoch name.)

Definition: kya

Thousand years ago.

Definition: Anthropocene

The proposed name for our current geologic epoch based on human-driven climate change.

Figure \(\PageIndex{8}\): The Chooz Nuclear Power, in a valley in Ardennes, France, is a reminder that human activity impacts the planet greatly.

GEOLOGIC PROCESSES

Figure \(\PageIndex{9}\): Map of Pangea reflecting the way our current continents fit into the landmass.

Through the study of fossils, anthropologists are able to learn a great deal about the history of Earth. If you were to closely examine the map of the world, you might notice that the seven continents seem to have outlines that could fit together if rotated and adjusted like puzzle pieces (Figure 7.1.9). Moreover, the geologic features of those puzzle pieces fit together and reveal many similarities. For instance, the White Cliffs of Dover, England, geologically match La Côte d’Albâtre (the Alabaster Coast) across the English Channel in France (Figures 7.1.10 and 7.1.11).

Figure \(\PageIndex{10}\): The White Cliffs of Dover, England, with the English Channel in the foreground.

Figure \(\PageIndex{11}\): The geologically similar cliffs across the English Channel along La Côte d’Albâtre (Alabaster Coast) in France.

Figure \(\PageIndex{12}\): The landscape of the San Andreas Fault is scarred by the movement of tectonic plates during earthquakes.

The shapes of the continents are easier to see from above and when looking at a map. From this perspective, it is not a far reach of the imagination to see how the shapes could fit together. However, in 1596, long before the advent of flight or space travel that would give such a perspective to a person studying geography, Abraham Ortelius theorized about the way the continents were shaped. Ortelius came up with the concept that one supercontinent called Pangea had existed much earlier in Earth’s history (USGS 2012). Approximately 200 million years ago (mya), Pangea started to slowly break apart, with the resulting pieces of land shifting and moving through the process of continental drift. In the late Triassic (roughly 135 mya), Pangea broke into two supercontinents called Laurasia and Gondwanaland, with additional movement that changed the physical representation of the landmasses and resulted in our current land configuration of seven continents. It is important to remember that continental drift continues to this day and will continue for the life of our planet. In another 250 million years, the map of Earth will look significantly different than it does today.

Definition: Pangea

A supercontinent that existed during the Paleozoic era.

Definition: mya

Million years ago.

Definition: continental drift

The slow movement of continents over time.

Ortelius’s theory made sense in some respects; after all, was it just sheer coincidence that the continents shared such complementary shapes? Yet the problem was that there was no scientific way to explain how continental drift occurred. Remember, too, that up until the late 1700s, the concept of Deep Time did not exist. In the absence of these vital pieces of information, it was impossible to explain what force would have been strong enough or how there was enough time in the history of the world to allow for the movement of huge masses of land to the various corners of the planet. In 1912, an answer was proposed, using the fossil record as evidence. Alfred Wegener used the fossilized remains of a fern, Glossopteris, that have been found on nearly every continent. He theorized that the only way this ancient plant could have existed in all of those areas was if the landmasses had been connected at some point in Earth’s early history. With this evidence (and much more), Wegener was able to develop his Tectonic Plate Theory. Simply put, Earth’s landmasses are relatively “thin, brittle fragments floating on top of hot, squishy material” (Murck 2001, p. 16). There is bound to be movement, even of large fragments. Furthermore, there are ridges or shelves in the Atlantic and Pacific Oceans that reflect the shifting of the planet’s crust. This theory not only supports the breakup of Pangea but also provides the basis for our current understanding of how earthquakes work. Physicists monitor the movement of tectonic plates for earthquake activity along known fault lines such as the San Andreas in California (Figure 7.1.12).

Definition: Tectonic Plate Theory

The scientific theory that Earth is divided into plates that are capable of movement.

Figure \(\PageIndex{13}\):  Fossils of the red panda, a close ancestor of this modern red panda, were found in Gray, Tennessee. The animal is now only found in Asia; specifically, in China and Nepal.

Besides the examples provided above, Pangea is also supported by the evidence found in the fauna of the fossil record. At the Gray Fossil Site in Gray, Tennessee, for instance, fossilized remains of the red panda (Pristinailurus bristoli) dating back four million years to the late Miocene era have been discovered (Figure 7.1.13). Red pandas are considered a “living fossil” because they have changed so little in millions of years and because they are represented in the fossil record. Today, red pandas are endangered and found exclusively in China and Nepal. Thus, the existence of the red panda in the Miocene in the Appalachian Mountains but living only in Asia today is clear evidence that the red panda moved freely and that our continents were part of a supercontinent (Wallace and Wang 2004, 556).

REFERENCES

Barr, James. 1984. “Why the World Was Created in 4004 BC: Archbishop Ussher and Biblical Chronology,” Bulletin of the John Rylands University Library of Manchester 67: 575–608.

Braterman, Paul S. 2013. “How Science Figured Out the Age of the Earth.” Special issue, “Determining the Age of the Earth,” Scientific American, October 20. https://www.scientificamerican.com/article/how-science-figured-out-the-age-of-the-earth/

Crutzen, Paul J., and Eugene F. Stoermer. 2000. “The ‘Anthropocene.’” Global Change Newsletter 41: 17–18.

Darwin, Charles. 1859. On the Origin of Species. London, UK: John Murray.

Dolnick, Edward. 2011. The Clockwork Universe: Isaac Newton, the Royal Society, and the Birth of the Modern World. New York: HarperCollins.

Emling, Shelley. 2009. The Fossil Hunter: Dinosaurs, Evolution, and the Woman Whose Discoveries Changed the World. New York: St. Martin’s Griffin.

Holmes, Richard. 2010. The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science. New York: Vintage.

Leinhard, John H. 1998. “The Age of the Earth: Science, Religion, and Perception.” Distinguished Lecture presented for the Shell Distinguished Lecture Series, Shell E&P Technology Company, Houston, May 21. https://www.uh.edu/engines/shell.htm

Lyell, Charles. 1830-1833. Principles of geology, being an attempt to explain the former changes of the Earth’s surface, by reference to causes now in operation. Volumes 1, 2 and 3. London: John Murray

Monastersky, Richard. 2015. “Anthropocene: The Human Age.” Nature 519 (7,542): 144–147.

Murck, Barbara. 2001. Geology: A Self-Teaching Guide. New York: John Wiley & Sons.

Ruddiman, William F., Zhengtang Guo, Xin Zhou, Hanbin Wu, and Yanyan Yu. 2008. “Early Rice Farming and Anomalous Methane Trends.” Quaternary Science Reviews 27 (13–14): 1,291–1,295.

Steffen, Will, Johan Rockström, Katherine Richardson, Timothy M. Lenton, Carl Folke, Diana Liverman, Colin P. Summerhayes, et al. 2018. “Trajectories of the Earth System in the Anthropocene.” PNAS 115 (33): 8,252–8,259.

Sullivan, Terry and Harry Gifford. 1908. She sells sea-shells. London: Francis, Day, and Hunter.

United States Geological Survey. Historical Perspectives. 2012. United States Geological Survey, last updated August 7. https://pubs.usgs.gov/gip/dynamic/historical.html

Wallace, Steven C., and Xiaoming Wang. 2004. “Two New Carnivores From an Unusual Late Tertiary Forest Biota in Eastern North America.” Nature 431 (7,008): 556–559.

Waters, Colin N., Jan Zalasiewicz, Anthony D. Barnosky, Alejandro Cearreta, Agieszka Galuszka, Juliana A. Ivar Do Sul, Catherine Jeandel, et al. N.d. “Is the Anthropocene Distinct From the Holocene?” In Strati 2015 2nd International Congress on Stratigraphy, Graz, Austria, July 19–23, 2015. Unpublished MS.

Williams, Linda D. 2004. Earth Science Demystified. New York: McGraw-Hill Professional.

FIGURE ATTRIBUTIONS

Figure 7.1.1 Mary Anning by B. J. Donne from the Geological Society/NHMPL is in the public domain.

Figure 7.1.2 A Walk at Dusk (object 93.PA.14 at the J. Paul Getty Museum) by Casper David Friedrich (German 1774-1840) is in the public domain and part of the Getty Open Content Program.

Figure 7.1.3 lyme-regis-coast-sea-cliffs-924431 by jstarj and has been designated under a Pixabay License.

Figure 7.1.4 Mary Anning Plesiosaurus by Mary Anning (1799-1847) is in the public domain.

Figure 7.1.5 Ammonite by Sarah S. King and Lee Anne Zajicek is under a CC BY-NC 4.0 License.

Figure 7.1.6 Murexsul from the Maturango Museum, Ridgecrest, California, by Sarah S. King and Lee Anne Zajicek is under a CC BY-NC 4.0 License.

Figure 7.1.7 Geologic time scale by United States Geological Survey is in the public domain.

Figure 7.1.8 Chooz Nuclear Power Plant-9361 by Raimond Spekking is used under a CC BY-SA 4.0 License.

Figure 7.1.9 Pangaea continents by LucasVB is used under a CC BY-SA 3.0 License.

Figure 7.1.10 White Cliffs Of Dover 2 by Eleanor Nelson available on www.PublicDomainPictures.net has been designated to the public domain (CC0 1.0).

Figure 7.1.11 Etretat 07 August 2005 019 by anonymous is used under a CC BY-SA 3.0 License.

Figure 7.1.12 Aerial-SanAndreas-CarrizoPlain by John Wiley User:Jw4nvc – Santa Barbara, California is used under a CC BY 3.0 License.

Figure 7.1.13 Red Panda (25193861686) by Mathias Appel has been designated to the public domain (CC0 1.0).