GEOL 204 Dinosaurs, Early Humans, Ancestors & Evolution:
The Fossil Record of Vanished Worlds of the Prehistoric Past

Spring Semester 2018
Into the Darkness of Prehistory: Our Long Quest for Origins

Assorted fossils from Johann Georg Heck's 1851 Iconographic Encyclopaedia of Science, Literature, and Art

Natural philosophy transcends a mere description of Nature. It does not consist of a sterile accumulation of facts. It is the privilege of the curious and active mind of humanity to occasionally drift out of the present and into the darkness of prehistory, to gain a sense of what cannot yet be clearly discerned, and thus to take delight in the ancient myths of geognosy in their many recurring forms. -- Alexander von Humboldt, Views of Nature (1808)

We admire the power by which the human mind has measured the movements of the globes, which nature seemed to have concealed forever from our view; genius and science have burst the limits of space, and observation interpreted by reason have unveiled the mechanism of the world. Would there not also be some glory for man to know how to burst the limits of time and, by observations, to recover the history of this world and the succession of events that preceded the birth of the human species? -- Georges Cuvier, Preliminary Discourses on Researches on Fossil Bones (1812)

Introduction to Course
Let's go straight to some definitions:

Paleontology sits at the nexus of two major other sciences: biology (the study of life) and geology (the study of the Earth). (For example, here at University of Maryland there are paleontology classes taught in GEOL and in BSCI). Within geology, paleontology intersects with sedimentology, stratigraphy, geochronology, paleoenvironmental analysis, paleoclimatology, and geochemistry; within biology, it intersects with organismal and evolutionary biology, ecology, evo-devo, and many other subdisciplines. And when you add in the fossils of early humans and their activities, it intersects with archaeology (the study of human artifacts) and anthropology (the study of humans). We will explore all these different fields of study in our quest to examine the primary question of this course: (where "things" include both "conditions of the world" and "the living things that were there", and the "ancient past" can be as recent as the melting back of the last major glaciation 11,700 years ago or as far back as the dawn of Life well before 3,800,000,000 years ago.)

In this course we will examining the principles and methods that paleontologists and allied scientists use to discover, reconstruct, and interpret organisms and events of the prehistoric past. We will look at several case studies from the "Age of Animals" (basically the last 600 million years), including the origins of animal life; dinosaurs and their diversity; and the origin of our own species. We will also look at major events that have effected the diversity of life: in particular, major episodes of environmental change, up to and including the great mass extinctions.

We will also look at issues of Paleontology (and Science in general) as a human activity: how is Science done? We will look at the role paleontology plays in addressing some of the challenges of modern times, such as climate change and the biodiversity crisis. We will look at the interactions (sometimes good, sometimes not so much) between the science of paleontology and the popular media. And we will look at the perplexing problem that sizable percentages of the American public (far out of scale compared to other industrialized, literate, wealthy, technologically-adept countries) fail to accept the discoveries of the scale of geologic time and the fact of the evolutionary origins of all living things.

Some things to keep in mind about this course:

And now, a little historical background...

Into the Darkness of Prehistory: Our Long Quest for Origins

BIG QUESTION: How have people explained the origins of the Earth, Life, and Humanity in the past?

Humans have long sought explanations for where we, the rest of the living world, and the physical universe came from. Every culture has its own creation myths, in which they provided these answers. Just a tiny fraction of these include:

Creation stories are as varied as the cultures they came from, so it is impossible to say anything universal or absolute about them. Indeed, there are many other cultures in which a single origin of the world wasn't accepted: instead, the world and its inhabitants are eternal. In these cosmogonies it is often thought that there are vast cycles of the rise and fall of civilizations, but in which the living creatures of the world and the landscapes in which they dwell remain largely unchanged.

Indeed, in both the traditional creation stories and eternal cosmogonies, there are certain commonalities found in the vast number of them:

This is perfectly understandable: in the written and/or oral traditions of peoples, the world had remained largely the same: the mountains were mountains, goats were goats, and so on.

Fossils were of course present throughout the history of humans. There are stone tools that predate our own species that show earlier species of our genus Homo collected fossils. How were fossils explained?

In some cases, fossils might be thought to be unusual rocks that happened to look like the parts of living things. Or spill over from the Creation. Or attempts by diabolic forces to create life. Or the bones of dragons, giants, ogres, or other mythical beasts.

Of great importance, though, is how they got into rock in the first place. If rocks are as old as Creation, then they can't be parts of once living things. Since the accumulating evidence showed that they WERE the parts of living things, then rocks cannot be as old as Creation. In other words, rocks were formed sometime between the beginning of the Earth and the present day, and fossils were the remains of living things incorporated into that rock.

The above idea was considered by various thinkers, but most importantly articulated by Nicolas Steno (1638-1686): Danish priest, anatomist, early geologist and paleontologist, and recent honoree of a Google doodle. His 1669 work De solido intra solidum naturaliter contento dissertationis prodromus argued exactly the above: that rocks must be the product of activity within the history of the Earth rather than part of its beginning, and fossils are the remains of dead organisms that were incorporated into their structure. He famously showed that "glossopetrae" ("tongue stones") collected from rocks around the world were in fact the fossilized teeth of sharks.

(Importantly, Steno was primarily an observational scientist rather than a theoretical/philosophical one: his explanations were based on first hand observation of physical evidence (in the field or in the lab) rather than created as thought experiments to fit a particular philosophy.)

Over the next two centuries (1660s to 1860s or so), the basic discoveries of paleontology were established:

We will come back to the modern understanding of these different concepts in the weeks to come.

To Lecture Notes.

Last modified: 12 January 2018

Assorted fossils from Johann Georg Heck's 1851 Iconographic Encyclopaedia of Science, Literature, and Art