KGS Navigation Bar, Search, Contact, KGS Home, UK Home University of Kentucky at http://www.uky.edu Kentucky Geological Survey at http://www.uky.edu/kgs Search KGS at http://www.uky.edu/KGS/search.html contact kgs at http://www.uky.edu/KGS/about/contact.htm KGS Home at http://www.uky.edu/KGS/ UK Home at http://www.uky.edu KGS Home

KGS Home > Fossils

Click on the geologic period in the chart above.

Precambrian Eon
Cambrian Period
Ordovician Period
Silurian Period
Devonian Period
Mississippian Period
Pennsylvanian Period
Permian Period
Triassic Period
Jurassic Period
Cretaceous Period
Paleogene Period
Neogene Period
Quaternary Period


Precambrian Eon

The Precambrian Eon, that vast expanse of earth's history prior to 550 million years ago, is not represented in the surface rocks in Kentucky. Rocks of Precambrian age occur in Kentucky, but are below the surface. We know very little about the Precambrian in Kentucky, largely because the rocks are so difficult to reach. Based on the few wells that have been drilled down to it and based on what we know about the Precambrian rocks elsewhere, we can make some inferences about the Precambrian in Kentucky.
The later part of the Precambrian Eon saw the collision of crustal blocks in what is now Kentucky. This collision created a chain of mountains, which were later eroded during the later part of the Precambrian and Cambrian. We are not certain whether Precambrian sediments are still recognizable at depth, because separating Precambrian from Cambrian rocks when they occur below the surface is difficult. Life during most of the Precambrian was restricted to bacteria and algae. Blue-green bacterial structures called stromatolites are found in Precambrian sedimentary rocks throughout the world. During the latest stages of the Precambrian, a variety of fossils of multicelled animals (metazoans), called the Ediacaran fauna, are also found all over the world. This fauna includes animals that have been interpreted as sea pens and jellyfish (Cnidaria), flatworms, grazing animals of unknown type, and other uncertain types. Perhaps stromatolites and the Ediacaran fauna occur in the deeply buried rocks of Kentucky, as well.

Links to other sites

Precambrian:


Cambrian Period

Like the rocks of the Precambrian Eon, rocks of the Cambrian Period in Kentucky are poorly understood, and for the same reasons. What little we know about the Cambrian below the surface tells us that Kentucky was under seawater for a period of time, but there were also times when land was present. Based on the Cambrian in other areas, we can surmise that there was no land life except for perhaps bacteria, fungi, algae, and lichens (algae and fungi living together). The seas, however, may have been teeming with life; sea plant life would have included bacteria and algae, and animal life would have been entirely composed of invertebrates such as trilobites, other arthropods, brachiopods, sponges and sponge-like animals, and a host of unusual animals (now extinct) similar to those known as the Burgess Fauna. The Burgess Fauna was made famous by a series of excellently preserved fossils found in the Cambrian Burgess Shale in Canada. Early forms of mollusks, echinoderms, and small fish-like worms that later gave rise to conodonts and vertebrates may have existed during the Cambrian in Kentucky as well.

Links to other sites

Cambrian Age:

Burgess Shale fossils [important fossils for interpreting early invertebrate life in the Cambrian]:


Permian Period

Permian rocks do not occur in Kentucky. At that time, Kentucky was probably covered by silts and sands, which have since been completely eroded away. During the Permian, Kentucky was probably hot and arid. Large mammal-like reptiles, such as the sail-finned Dimetrodon, and others, probably lived in Kentucky. During the Permian, most of the continents were pushed together into one large land mass called Pangea. At the end of the Permian, something happened to cause the extinction of 90 percent of the animal and plant species on earth. This mass extinction was far greater in magnitude than the similar extinction of the dinosaurs at the end of the Cretaceous Period.


Triassic Period

Triassic rocks do not occur in Kentucky. At that time, Kentucky was probably covered by thin silts and sands, which have since been completely eroded away. During the Triassic, Kentucky was probably hot and arid, but areas with abundant plant life existed. Large mammal-like reptiles and other reptiles probably lived in Kentucky at that time. During the later part of the Triassic, early dinosaurs probably lived in Kentucky. The mass of continents called Pangea was still largely united, but some of the continents were starting to separate.


Jurassic Period

Jurassic rocks do not occur in Kentucky. At that time, Kentucky was probably covered by thin silts and sands, which have since been completely eroded away. During the Jurassic, Kentucky probably had areas with abundant plant life, and many dinosaurs and other reptiles probably lived in Kentucky. Conditions were tropical; whether they were humid or arid is not known.

Links to other sites

Jurassic Age:


Cretaceous Period

Cretaceous sediments are almost completely absent in Kentucky; only small areas of Cretaceous deposits occur in and near the Jackson Purchase Region in extreme western Kentucky. During most of the Cretaceous, Kentucky was land. If Cretaceous sediments covered any of this land, they have since been eroded away. However, during latest Cretaceous times, sea level rise coupled with subsidence in the Jackson Purchase Region led to deposition of coastal sediments in environments that included coastal plain, river, delta, and shallow sea. Because of the limited outcrops in the flat Jackson Purchase Region, very little in the way of fossils have been found in the Cretaceous sediments there. The most common fossils are coalified tree limbs. The potential exists for dinosaur fossils to be found in these sediments in Kentucky. Much more new research needs to be done on the Cretaceous in this region.

Links to other sites

Cretaceous Age:


Paleogene and Neogene Periods (Tertiary)

The Paleogene and Neogene are sometimes referred to as the Tertiary Period. Almost all of the Paleogene and Neogene sediments occur in the Jackson Purchase Region in extreme western Kentucky and most have not been consolidated (cemented) into rocks. Most of these sediments are shales, clay, or sands that were deposited in coastal or river and floodplain environments. The most common fossils are coalified limbs, logs, and stumps of lignite rank. Some beautifully preserved tree leaves have been found. The potential exists for a variety of mammal fossils to be found in these sediments in Kentucky, but a great deal of new research needs to be done on these sediments. Some of the mammal fossils found in Kentucky may have come from the Pliocene Series, the last series of the Neogene.

Links to other sites

Paleogene/Neogene (Cenozoic Era):