Professor Nick Cutter (![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
itsananomaly) wrote in ![[community profile]](https://www.dreamwidth.org/img/silk/identity/community.png)
fandomhigh2024-10-09 07:28 pm
itsananomaly) wrote in fandomhigh2024-10-09 07:28 pm
Entry tags:
Introduction to Fossils - Wednesday Period 1
“Good morning,” Cutter began that week’s class, “this week we’re going to start looking at the different types of fossils and this week we’re going to begin by looking at Trace fossils,” he explained, “trace fossils are a fossil record of biological activity by lifeforms but not the actual remains of the organism itself,”
“Trace fossils may consist of physical impressions made on or in the substrate by an organism. For example, burrows, bio erosion or erosion caused by the evacuation of liquid waste, footprints, feeding marks and root cavities may all be trace fossils,” he continued, “Traces are better known in their fossilized form than in modern sediments. This makes it difficult to interpret some fossils by comparing them with modern traces, even though they may be extant or even common. The main difficulties in accessing extant burrows stem from finding them in consolidated sediment, and being able to access those formed in deeper water. Trace fossils are best preserved in sandstones he grain size and depositional facies both contributing to the better preservation. They may also be found in shales and limestones,”
“Trace fossils are generally difficult or impossible to assign to a specific maker. Only in very rare occasions are the makers found in association with their tracks. Further, entirely different organisms may produce identical tracks. Therefore, conventional taxonomy is not applicable, and a comprehensive form of taxonomy has been erected. At the highest level of the classification, five behavioural modes are recognized,
• Domichnia, dwelling structures reflecting the life position of the organism that created it.
* Fodinichnia, three-dimensional structures left by animals which eat their way through sediment, such as deposit feeders;
* Pascichnia, feeding traces left by grazers on the surface of a soft sediment or a mineral substrate;
* Cubichnia, resting traces, in the form of an impression left by an organism on a soft sediment;
* Repichnia, surface traces of creeping and crawling.”
“Fossils are further classified into form genera, a few of which are even subdivided to a "species" level. Classification is based on shape, form, and implied behavioural mode,” Cutter concluded, “for this week I have bought some examples of Trace fossils for you to have a look at it and as always if there’s any questions I’ll be happy to help,”
“Trace fossils may consist of physical impressions made on or in the substrate by an organism. For example, burrows, bio erosion or erosion caused by the evacuation of liquid waste, footprints, feeding marks and root cavities may all be trace fossils,” he continued, “Traces are better known in their fossilized form than in modern sediments. This makes it difficult to interpret some fossils by comparing them with modern traces, even though they may be extant or even common. The main difficulties in accessing extant burrows stem from finding them in consolidated sediment, and being able to access those formed in deeper water. Trace fossils are best preserved in sandstones he grain size and depositional facies both contributing to the better preservation. They may also be found in shales and limestones,”
“Trace fossils are generally difficult or impossible to assign to a specific maker. Only in very rare occasions are the makers found in association with their tracks. Further, entirely different organisms may produce identical tracks. Therefore, conventional taxonomy is not applicable, and a comprehensive form of taxonomy has been erected. At the highest level of the classification, five behavioural modes are recognized,
• Domichnia, dwelling structures reflecting the life position of the organism that created it.
* Fodinichnia, three-dimensional structures left by animals which eat their way through sediment, such as deposit feeders;
* Pascichnia, feeding traces left by grazers on the surface of a soft sediment or a mineral substrate;
* Cubichnia, resting traces, in the form of an impression left by an organism on a soft sediment;
* Repichnia, surface traces of creeping and crawling.”
“Fossils are further classified into form genera, a few of which are even subdivided to a "species" level. Classification is based on shape, form, and implied behavioural mode,” Cutter concluded, “for this week I have bought some examples of Trace fossils for you to have a look at it and as always if there’s any questions I’ll be happy to help,”
