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GEOL 331/BSCI 333 Principles of Paleontology

Fall Semester 2018
Taphonomy: Making a Fossil Record


Mass accumulation of the Cretaceous floating crinoid Unitacrinus

Key Points:
•Taphonomy is the study of the incorporation of living things into the sedimentary record.
•Various factors (taphonomic filters) control the likelihood that a given body might become a body fossil.
•Diagenesis (chemical modification of the fossil material after deposition) results in varying types of preservation.
•Lagerstätten are localities of exceptional concentration or preservation of fossils.

"During each year, over the whole world, the land and the water have been peopled by hosts of living forms. What an infinite number of generations, which the mind cannot grasp, must have succeeded each other in the long roll of years! Now turn to our richest geological museums, and what a paltry display we behold!" --Charles Darwin, Chapter IX "On the Imperfection of the Geological Record", On the Origin of Species by Means of Natural Selection First Edition (1859)

Fossils as Sedimentary Particles, Burial & Taphonomic Filters:

Taphonomy: study of incorporation of living things into the sedimentary record

Taphonomic processes include necrolysis (the break up of organisms after death), biostratinomy (the burial process itself), and diagensis (the post-burial transformation of the organic material).

Many differences between biocenosis (life assemblages) and thanatocenosis (death assemblages) as revealed by studies of Aktuopaläontologie (taphonomic studies based on comparisions to natural or experimental examples of modern organisms being incorporated into sediment). Some differences include:

All the above represent taphonomic filters. Different organisms thus have different potential for fossilization.

In the case of vertebrates, it is common for the different individual bones (which have different hydrodynamic properties) to be transported different distances for the initial point of death: Voorhies groups.

Plants a special case: different organs (leaves, stems, trunks, fruit, flowers, seeds, pollen, etc.) are only very rarely preserved together. Each part generally given its own species name!

Autochthonous vs. Allochthonous fossils or fossil assemblages: in their original spot (in situ) vs. transported. Some autochthonous fossils might be in situ reefs; or they might be only vertically transported (sank from above).

Allochthonous fossil assemblages requires transport; therefore, imprint of transportation processes on the assemblage.


Diagensis: Modes of Fossilization:

Fossil Site Analysis:

Most of the discussion above primarily concerns the history of single individuals. However, much information can be gained by looking at the totality of the fossils from a single horizon at a single site. This data might include:


Lagerstätten:

German mining jargon for "motherload" or "bonanza". However, usually used outside Germany for what is properly "Fossil-Lagerstätten".

Adolph Seilacher proposed two major types of Fossil-Lagerstätten:

Some attributes of soft tissue preservation:

Some Famous Lagerstätten

To Syllabus.

Last modified: 29 August 2018

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Carbonized feathers on the forelimb of the Cretaceous dromaeosaurid dinosaur Microraptor