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Does anyone have advice on how to differentiate between cross sections of Nummulites vs Fusulinids

c21k wrote:Does anyone have advice on how to differentiate between cross sections of Nummulites vs Fusulinids

You shouldn't really have to worry about that; I rarely see cross sections so if you see something circular it's Nummulites and if it's elliptical/grain-shaped it's Fusulinida.

If they do give a cross section though, I guess the individual rings for Nummulites look more regular and uniform in thickness while Fusulinida has rings that are more bumpy. Not sure if that's a legitimate difference or a good way of describing it, but in general I'd say Nummulites cross sections are all very similar and recognizable, so once you can identify those you can just assume things that don't look like Nummulites are Fusulinida.

wec01 wrote:

c21k wrote:Does anyone have advice on how to differentiate between cross sections of Nummulites vs Fusulinids

You shouldn't really have to worry about that; I rarely see cross sections so if you see something circular it's Nummulites and if it's elliptical/grain-shaped it's Fusulinida.

If they do give a cross section though, I guess the individual rings for Nummulites look more regular and uniform in thickness while Fusulinida has rings that are more bumpy. Not sure if that's a legitimate difference or a good way of describing it, but in general I'd say Nummulites cross sections are all very similar and recognizable, so once you can identify those you can just assume things that don't look like Nummulites are Fusulinida.

I wrote a question with a cross-section of a fusulinid for a recent test.

How do you guys differentiate between trilobites when they're in a ball. The only thing i'm using is the color of the trilobite atm as for example eldredgeops is normally a darker color, and calymene lighter. Obviously, it isn't working well, but with pictures most of the trilobite isn't visible.

Rock&Roll92 wrote:How do you guys differentiate between trilobites when they're in a ball. The only thing i'm using is the color of the trilobite atm as for example eldredgeops is normally a darker color, and calymene lighter. Obviously, it isn't working well, but with pictures most of the trilobite isn't visible.

There are a number of features that are different, e.g. size, the laces, what the eyes look like, the shape of the body, etc. I wouldn't rely on the color of the specimen because that only depends on what rock it's fossilized in, which can vary.

UTF-8 U+6211 U+662F wrote:

Rock&Roll92 wrote:How do you guys differentiate between trilobites when they're in a ball. The only thing i'm using is the color of the trilobite atm as for example eldredgeops is normally a darker color, and calymene lighter. Obviously, it isn't working well, but with pictures most of the trilobite isn't visible.

There are a number of features that are different, e.g. size, the laces, what the eyes look like, the shape of the body, etc. I wouldn't rely on the color of the specimen because that only depends on what rock it's fossilized in, which can vary.

Yeah, for me I try to look for the eyes first as they are easy to distinguish between calymene and eldredgeops (the other trilobites are less likely to be enrolled). If you can't see the eyes, the segments and some other body parts are shaped slightly differently, and you may be able to use them to identify it. If you want to use the rock to help, calymene seems to be more likely to have matrix still between the ridges resulting in a less finished/polished look, but that's very unreliable/inconsistent (it's just a matter of preparation of the fossil) and I wouldn't use this as the sole basis for identification.

wec01 wrote:

UTF-8 U+6211 U+662F wrote:

Rock&Roll92 wrote:How do you guys differentiate between trilobites when they're in a ball. The only thing i'm using is the color of the trilobite atm as for example eldredgeops is normally a darker color, and calymene lighter. Obviously, it isn't working well, but with pictures most of the trilobite isn't visible.

There are a number of features that are different, e.g. size, the laces, what the eyes look like, the shape of the body, etc. I wouldn't rely on the color of the specimen because that only depends on what rock it's fossilized in, which can vary.

Yeah, for me I try to look for the eyes first as they are easy to distinguish between calymene and eldredgeops (the other trilobites are less likely to be enrolled). If you can't see the eyes, the segments and some other body parts are shaped slightly differently, and you may be able to use them to identify it. If you want to use the rock to help, calymene seems to be more likely to have matrix still between the ridges resulting in a less finished/polished look, but that's very unreliable/inconsistent (it's just a matter of preparation of the fossil) and I wouldn't use this as the sole basis for identification.

The features of the head are quite different between the trilobites. I tried to know characteristics of each trilobite, and used that to determine the genus. However you can reliably distinguish them works.

For any teams attending the National Tournament at Cornell University, there is an opportunity for you to visit the Museum of the Earth, which is located off-campus in Ithaca.

The Museum is hosting an Open House on Thursday, May 30, Friday, May 31, and Sunday, June 2. Discounted admission will be provided to teams that call ahead.

The Museum has an outstanding fossil collection on display, which should be of particular interest to the fossil event competitors. However, the Museum is worthwhile visiting for all team members.

Additionally, the Paleontological Research Institute (PRI) which runs the museum, is offering behind the scenes tours on Thursday and Friday for interested team members. Tours are limited to 10 people at a time and multiple tours will be offered.

Museum of the Earth is not on campus, and you will need transportation there.

The link to signing up for PRI behind the scenes tours of the research collection is now active.

Go to the National tournament website activities page.

https://www.scienceolympiad2019.org/aux ... activities

Click on the link Museum of the Earth and you will download a PDF document.You can sign up online. Your team can also visit the Museum of the Earth. Contact Maureen Bickley to inform her so that they provide you with discounted admission.There is a link in the shaded blue box to the sign ups for the Behind the Scenes Tours.

Regards,

Gary Vorwald
National Fossils Supervisor

Hey guys, can someone explain the difference between permineralization and replacement? Thanks in advance!

djliu9049890 wrote:Hey guys, can someone explain the difference between permineralization and replacement? Thanks in advance!

permineralization is when it fills the space between the original tissue and mineral replacement is when it replaces the original tissue