http://dr-tommy.livejournal.com/ (![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png)
dr-tommy.livejournal.com) wrote in ![[community profile]](https://www.dreamwidth.org/img/silk/identity/community.png)
fandomhigh2006-01-16 03:52 am
dr-tommy.livejournal.com) wrote in fandomhigh2006-01-16 03:52 am
Entry tags:
Paleontology, Jan 16th (7th period)
On the blackboard is a rather badly-drawn diagram detailing the fossil-creation process:
"Today, we're going to talk about the creation of fossils. First, something has to die, obviously." He points to the first picture.
"Typically, the most important factor in the creation of a body fossil is that soon after death, the organism must be quickly buried by sediment deposits. If left exposed to the elements, animal and plant remains are prone to scavenging and attack by micro-organisms, so they rot and disintegrate, never making it past the starting line in the fossilization process.
So organisms living in and around shallow coastal waters, deltas and lakes where rivers dump their sediment loads have a much better chance of becoming fossils than organisms living on open plains or in dry, hilly areas." Tommy then points to the second picture.
"As a result, we generally have a much better fossil record for marine creatures than we do for land-dwellers. However, locations like underground caves often yield a large amount of fossils from land-dwelling animals.
Pointing to the third picture, Tommy continues, "After the fossil is buried, the flesh slowly rots away, leaving just the bones."
He then points to the fourth picture. "The sediment surrounding the skeleton slowly seeps in and either completely replaces the organic material- such as in dinosaur bones- or fills the gaps that once held liquids or gases- which is how we end up with petrified wood.
But... going back to our fossil skeleton," he indicates the last drawing, "eventually, the sea level drops and the sediment surrounding the skeleton hardens in to rock. And then, millions of years later, it's hopefully discovered by someone so that we can research it."
Hoping against hope that no one has fallen asleep during the lecture, Tommy then asks, "Any questions?"
"And one other thing. I didn't forget about your homework, unfortunately. So, if you can hand it in... and does anyone want to do a presentation today?" Tommy waits to see if there are any takers. "You just need to give a brief overview of your find, and then maybe answer a question or two from your classmates."
"Today, we're going to talk about the creation of fossils. First, something has to die, obviously." He points to the first picture.
"Typically, the most important factor in the creation of a body fossil is that soon after death, the organism must be quickly buried by sediment deposits. If left exposed to the elements, animal and plant remains are prone to scavenging and attack by micro-organisms, so they rot and disintegrate, never making it past the starting line in the fossilization process.
So organisms living in and around shallow coastal waters, deltas and lakes where rivers dump their sediment loads have a much better chance of becoming fossils than organisms living on open plains or in dry, hilly areas." Tommy then points to the second picture.
"As a result, we generally have a much better fossil record for marine creatures than we do for land-dwellers. However, locations like underground caves often yield a large amount of fossils from land-dwelling animals.
Pointing to the third picture, Tommy continues, "After the fossil is buried, the flesh slowly rots away, leaving just the bones."
He then points to the fourth picture. "The sediment surrounding the skeleton slowly seeps in and either completely replaces the organic material- such as in dinosaur bones- or fills the gaps that once held liquids or gases- which is how we end up with petrified wood.
But... going back to our fossil skeleton," he indicates the last drawing, "eventually, the sea level drops and the sediment surrounding the skeleton hardens in to rock. And then, millions of years later, it's hopefully discovered by someone so that we can research it."
Hoping against hope that no one has fallen asleep during the lecture, Tommy then asks, "Any questions?"
"And one other thing. I didn't forget about your homework, unfortunately. So, if you can hand it in... and does anyone want to do a presentation today?" Tommy waits to see if there are any takers. "You just need to give a brief overview of your find, and then maybe answer a question or two from your classmates."