Chapter 8: Fossils in Geological Context

Key Terms Paleontology: the study of extinct organisms, based on their fossilized remains. Fossils: the preserved remnants of once-living things, often buried in the ground. Geology: the study of Earth systems. Taphonomy: the study of what happens to the remains of an animal from the time of death to the time of discovery. Strata: layers of rock. Stratigraphy: the study of rock layers and the sequence of events they reflect.

Formation of Fossils

Strata

Issues?

Geological Time Scale Geological Time Scale (GTS): the categories of time into which Earth’s history is usually divided by geologists and paleontologists: eras, periods, epochs.

First appearance of mammals? Test question

How old is it? Provenience: the origin or original source (as of a fossil). Relative dating techniques: dating techniques that establish the age of a fossil only in comparison to other materials found above and below it. Lithostratigraphy: the study of geologic deposits and their formation, stratigraphic relationships, and relative time relationships based on their lithogic (rock) properties. Tephrostratigraphy: a form of lithostratigraphy in which the chemical fingerprint of volcanic ash is used to correlate across regions. Biostratigraphy: relative dating technique using comparison of fossils from different stratigraphic sequences to estimate which layers are older and which are younger.

Cont. Calibrated relative dating techniques: techniques that use regular or some what regular processes that can be correlated to an absolute chorology to estimate the age. Geometric polarity time scale: time scale composed of the sequence of paleomagnetic orientations of strata through time. Paleomagnetism: the magnetic polarity recorded in ancient sediments. Reversed or normal direction used to correlate with the geometric polarity time scale to infer age in a site.

Chronometric Dating Techniques

Piltdown Break

A Few More Techniques Radiocarbon dating: radiometric technique that uses the decay of 14C in organic remains such as wood and bone to estimate the time since death of the organism. Electronic trap: radiometric techniques that measure the accumulation of electrons in traps in the crystal lattice of a specimen. Electon spin resonance (ESR): electron trap technique that measures the total amount of radioactivity accumulated by a specimen such as tooth or bone since burial.