Eocene Green River Formation ichnofossils

[allen.wallace]

I would like some help identifying some trace fossils. These are all from the same site from the "Soldier Summit Fossil Track Horizon" area in the Eocene Green River Formation. My grandson and I collected these for his science fair project, so any insight is welcome.

 

• Fossil A is obviously a tail feather. It's length is 55mm. 
• Fossil B has shore-bird tracks, but please notice the insect track in the right side. What kind of insect could have made this?
• Fossil C and D are different sides of the same rock. For side C,  I initially thought that this might be bird tracks, but I they don't look anything like the classic pattern in the sample B.
• Fossil D is covered with fine lines, perhaps some worm tracks? Close-ups E and F zoom in on these tracks.
• Close-up E shows a mottled pattern on the left, perhaps an alge mat? On the left, a wavy track. I don't know how a worm could create this pattern.
• Close-up F shows fine lines.

 

 

[allen.wallace]

I can upload larger pictures if anyone asks.

[doushantuo]

Maybe this will help?

 

2007-Bohacsetal-GreenRiverFormationIchnofossils.pdf

 

Continental Ichnofossils of the Green River and Wasatch Formations,
Eocene,Wyoming: A Preliminary Survey, Proposed Relation to Lake-Basin
Type, and Application to Integrated Paleo-Environmental Interpretation

 

KEVIN M. BOHACS
STEPHEN T. HASIOTIS
TIMOTHY M. DEMKO

The Mountain Geologist, Vol. 44, No. 2 (April 2007), p 79-108

 

This one is written by some people well-versed in continental ichnology,but it is a technical paper.

Just holler if you need further help,there's a heap of pretty savvy people on this forum

edit: it's a pretty nifty paper,and I noticed they remarked upon something i was about to say myself:

 

with ichnofossils it is important to note spatial relationships,both lateral and vertical.

and perhaps you might indeed upload larger pix,if technically feasible

 

 

[Rockwood]

A - mold fossil of a body feather from a large bird

C - mold fossils of coprolites 

[Rockwood]

6 hours ago, allen.wallace said:

I don't know how a worm could create this pattern.

Perhaps by employing the same method of body undulations that a snake does when traveling along a surface ?

[RJB]

Cool stuff.  I use to hunt soldier summit many years ago.  I thought it was bought up by a developer and posted now?   I use to find lots of bird tracks but what I was really after was the rain drops. 

 

RB

[abyssunder]

E - the undulating one is either Undichna or Cochlichnus. See discussion here .

 

[Rockwood]

59 minutes ago, abyssunder said:

E - the undulating one is either Undichna or Cochlichnus. See discussion here .

 

My thought was the latter. The mechanics at this scale seem problematic as undichna to me.

[abyssunder]

Considering its dimensions I would go with the latter.
Can you post a high-res image of it?

[allen.wallace]

[Rockwood]

Cochlichnus, thought to be nematode trails. 

The roughened surface appearance would be expected where preservation is initiated by the die off of algal blooms.

[abyssunder]

1 hour ago, allen.wallace said:

Tell me please, because I may not see it correctly, is it like a groove in the sediment or not? Can you post another picture of it in a lateral view (parallel to the sediment surface)?

Thank you!

[Rockwood]

9 minutes ago, abyssunder said:

Tell me please, because I may not see it correctly, is it like a groove in the sediment or not? Can you post another picture of it in a lateral view (parallel to the sediment surface)?

Thank you!

Which way is up ?

[abyssunder]

43 minutes ago, Rockwood said:

Which way is up ?

It's a good question!

 

 

[abyssunder]

I'm waiting the OP's answer, meantime I'll post a picture from here .

 

Cochlichnus anguineus, Eocene, Green River Formation

 

 

 

[abyssunder]

It's hard to decide what might be on the surface of specimen "D", but I guess, the other ichnos beside Cochlichnus might be Planolites (left side of the Cochlichnus terminal - "E" in your photo) associated with microbial mat, and Helminthoidichnites (or maybe something similar, like Helminthopsis or Gordia)
 for the others, like the one shown in "F".

[allen.wallace]

I have struggled with the deciding if I'm seeing an epirelif or a hyporelief. Certainly the Planolites? tracks in picture F are raised, but the Cochlichnus appear to be both groved and raised. FYI, I added the words epirelif and hyporelief to my vocabulary! This forum is great!

[abyssunder]

20 hours ago, allen.wallace said:

I have struggled with the deciding if I'm seeing an epirelif or a hyporelief. Certainly the Planolites? tracks in picture F are raised, but the Cochlichnus appear to be both groved and raised. FYI, I added the words epirelif and hyporelief to my vocabulary! This forum is great!

I think, Cochlichnus (C. anguineus) might be fixed in the determination. I'm not aware to think that in "F" are Planolites characters, but the Helminthoidichnites / Helminthopsis features might be in consideration.