 History in the rocks -- a quick look at fossils and paleontology
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 Podcast
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What is a fossil?
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Generally speaking, a fossil is any evidence of past plant or animal life that is preserved in the material of the Earth's crust. Fossils are the mineralized or otherwise preserved remains — or other traces (such as footprints) — of animals, plants, and other organisms. The word fossil is derived from the Latin word fossus, which means "having been dug up".
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What gets preserved? Mostly hard parts, and other parts that can be mineralized. Note that not all critters have hard parts.
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Paleontology -- understand the history of life on Earth by understanding the fossil record left behind by living organisms.
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Aside from the science of paleontology, there's been an interesting interplay over the years between culture and fossils
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History of fossil discoveries / interpretations
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Fossils aren't hard to find -- probably have been discovered since long before written history
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Greeks & Romans may well have been familiar with fossils in their part of the world; it's been suggested that fossils of dinosaurs and other ancient animals may have made their way into classic mythology, in an attempt to explain the odd things they found. Interesting that many of the ancient myths originated in lands now known to host many fossil beds; also, in many of the old stories, monsters emerge from the ground after big storms -- just as fossils are often eroded out of hillsides by those very storms.
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In a more traditionally scientific vein, in the 6th century BC, Xenophanes of Colophon recognized that some fossil shells were the remains of shellfish, and used this to argue that now-dry land was once under the sea.
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No real evidence of study of fossils until the Renaissance. It was easy to overlook possibility of fossils as ancient life because of prevailing philosophies
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Aristotelian theory maintained that it was possible for the seeds of living organisms to enter the ground and generate objects that resembled those organisms.
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Neoplatonic theory maintained that there could be affinities between living and non living objects ("ideal forms") that could cause one to resemble the other.
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Literal interpretation of bible -- fossils represent life wiped out by, or washed up by Noah's flood.
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 16th century -- Leonardo, Gesner. Some fossils felt to be of organic origin, others possibly formed naturally within the rock.
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17th century -- Hooke, Steno. Fossils found that didn't look like existing creatures, raised possibility of extinction (hard to swallow theologically)
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18th century -- Linnaeus classifies species. Cuvier develops comparative anatomy, catastrophism. Cuvier & Smith independently develop stratigraphy
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19th century -- Dinosaurs; Darwin publishes "Origin of Species"; Neanderthal and other ancient hominids found
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20th century -- radiometric dating, plate tectonics, K-T boundary extinction, more hominids
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6 ways to make a fossil
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So, you want to be a fossil -- the odds are against you
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The fossil record
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The totality of fossils and their placement in rock formations (all the fossils in the world) is known as the fossil record.
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One criticism of evolution: jumps in fossils along evolutionary path; "gaps" in fossil record
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Fossil record is like scattered frames from an old movie that's been torn up
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Most frames lost; some damaged; surviving frames are scattered across the globe. We have to gather the surviving snapshots, interpolate between them.
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Due to the odds against a carcass being fossilized, gaps in the fossil record are to be expected
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Scientists have found many transitional fossils.
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Wrapup
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Sources and other links
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Keywords -- fossil record fossilization gap evolution paleontology geology history science
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License The use of these shownotes is governed by a Creative Commons (Attribution-NonCommercial-ShareAlike 2.5) license
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