Jump to content

Trilobite damage pre or post fossilization?


ScottBlooded

Recommended Posts

So I find a lot of eldredgeops parts in this particular spot I’ve been digging for a few months (needmore formation outside Winchester VA). Particularly find a lot of cephalons. Some of them have been a bit warped/bent and I chalked it up to geologic forces doing the distorting. Came across this one the other day though that has a very focused dent in the glabella, like a piercing dent. I can’t for the life of me find the mold I split it from (it’s somewhere!) but it also has the corresponding dent, so I know it’s not damage done by me. Is there any way to know if the dent was pre fossilization/sign of predation? With it being so focused it didn’t feel the same as other specimen I’ve seen bent around the form of a natural split in the shale. Size is 1.5cm

75EC5118-C8B9-44A1-A5A3-767E6277AA9C.jpeg

05B1CE58-1DA0-4C22-8508-3D05D654E539.jpeg

155E0DAB-D0F3-4327-B2D5-024E87358A83.jpeg

6B863DB5-A928-4727-95FE-8FF8E1BAD4C0.jpeg

  • I found this Informative 1
Link to post
Share on other sites

Crush and compression damage can be fairly standard with trilobites, pending the formation and its depositional environment. As this is a moult, any number of factors could produce dents, cracks, and divots (think of how fragile a moulted piece of crab carapace is when being tossed around in the surf). Predation damage (and subsequent healing) tends to appear on the pleurae, librigenae,  and occasionally on the pygidium. Oddly enough, a good portion of predation damage appears on the left side.

  • I found this Informative 5
Link to post
Share on other sites

I think that is due to compression as the mud was compacted into shale.  It is a molt (no thorax/pygidium attached) so the animal was not alive when it happened. 

 

Don

  • I found this Informative 3
Link to post
Share on other sites
Just now, FossilDAWG said:

I think that is due to compression as the mud was compacted into shale.  It is a molt (no thorax/pygidium attached) so the animal was not alive when it happened. 

 

Don

Beat you to it. :P:D 

Link to post
Share on other sites
42 minutes ago, Kane said:

Predation damage (and subsequent healing) tends to appear on the pleurae, librigenae,  and occasionally on the pygidium. Oddly enough, a good portion of predation damage appears on the left side.

Why would more damage occur on the left side? Is it due to some some of “handedness” or disability in trilobite’s vision?

Edited by DPS Ammonite
  • I found this Informative 1
Link to post
Share on other sites

Thank you all for quick responses, this all makes sense and now I’ve got some new/interesting reading

Link to post
Share on other sites
38 minutes ago, DPS Ammonite said:

Why would more damage occur on the left side? Is it due to some some of “handedness” or disability in trilobite’s vision?

In addition to the one @Kane posted, Sundberg touches on the damage on one side phenomenon a bit too.

 

Personally, I like the Han Solo Hypothesis (my name for it) as in "I know a few maneuvers.", but then just lists slowly to the right...right before some armored fish with visegrips for jaws skips figuring out how many licks it takes to get to the center.

 

Generally, from what I have read, pre-mortem injuries that were survivable have signs of healing and regeneration in the molts, mortal injuries tend to be a bit more drastic and jagged.

 

AMNH has a nice article on the subject here.

 

However, with the description and photos I wonder if this is a result of the molting process or perhaps environmental damage due to the really pronounced glabella.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...