Enigmatic Ammonite Eggs (?)

[Pilobolus]

Hey all:

 

For your consideration and expertise, an ammonite partial collected by the poster's parent has some interesting features.  I don't know the exact formation of origin, but within the Rio Puerco river valley known to be Cretaceous period. I'm posting the best images I have at the moment, which, in addition to the partial with the scale cube (lower ammonite partial), are my attempts at using a smart phone to shoot down the dissection scope tube with the ocular removed...It's the best I can do at the moment.

 

In question are the egg like features you can see on the partial. Most ammo eggs I have seen are spherical and not bacilli-like. The black dots are lichens that are commonly found in area rocks, usually in small crevices that trap dew.

 

Thoughts?

[Fossildude19]

They look like fecal pellets, often associated with Ophiomorpha burrows. 

Shrimp poo? 

 

@Carl  @GeschWhat

 

[Plax]

I agree with fossil dude re the pellets but perhaps from an organism that was using a gastrochaenid (boring clam) burrow. The clam made the burrow in the shell and the shell dissolved away leaving the contents in relief.

[Auspex]

40 minutes ago, Plax said:

...perhaps from an organism that was using a gastrochaenid (boring clam) burrow. The clam made the burrow in the shell and the shell dissolved away leaving the contents in relief.

This is an elegant explanation for what we see here...
Each deposited 'chain' follows the course of a boring.

[Ludwigia]

Those are definitely fecal pellets and more than likely from a decapod.

[Pilobolus]

I'm loving it!

 

Thanks all!

 

What a cool find

[GeschWhat]

+1 for fecal pellets. Very cool! 

[RJB]

Very intersting for sure. 

 

RB

[erose]

4 hours ago, Fossildude19 said:

They look like fecal pellets, often associated with Ophiomorpha burrows. 

Shrimp poo? 

 

@Carl  @GeschWhat

 

I'm pretty sure the pellets that line the burrows designated Ophiomorpha are in fact small balls of mud not feces. If you have ever seen a crawfish "turret" that they build up out of the ground it is similar. Ophiomorpha were created by ghost shrimp when they lived in a substrate that required reinforcement. The same animals also create Thalasinoids and Spongeliomorpha(sp?). Each represents burrows in substrate of different types.

 

These do look like fecal pellets as they are much smaller and oblong compared to the larger spherical balls in Ophiomorpha.

 

I also don't think they were deposited inside borings in the ammonite's original shell. That shell was rather thin.  But general idea is probably correct. Quite intriguing as I have never seen pellets in that setting.

 

 

[abyssunder]

Your trace fossils nicely resemble Tomaculopsis tomaculopsis, in my opinion.

 

excerpt from G. Breton. 2011. Le Gault du Perthois: terriers, phosphates et petites crottes. Bulletin de l’Association G´eologique Auboise 31: 3–66

[piranha]

The name "Tomaculopsis Breton 2011" is not valid.  Unfortunately, it is preoccupied by a marine alga: Tomaculopsis Cribb 1960.

 

[abyssunder]

Ichnogenre Tomaculopsis igen. nov.

2006 b. cf. Tomaculum Groom, 1902 : Breton,p. 42, fig. 1 – 3.
2010. cf. Tomaculum : Breton in Colleté (coord.), fig. 154 G
Étymologie. Suffixe d’origine grecque –opsis « qui ressemble à … ». Le nom Tomaculopsis
fait référence à la ressemblance avec l’ichnogenre Tomaculum Groom, 1902.
Ichnoespèce-type : Tomaculopsis tomaculopsis isp. nov.

 

K.-H. Eiserhardt et al. 2001. Revision des Ichnotaxon Tomaculum Groom, 1902. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 221: 328-358

 

Edited March 13, 2018 by abyssunder

[GeschWhat]

1 hour ago, abyssunder said:

excerpt from G. Breton. 2011. Le Gault du Perthois: terriers, phosphates et petites crottes. Bulletin de l’Association G´eologique Auboise 31: 3–66

This has some great extant species examples! I wish I knew French - Google translate is giving me some really interesting (funny) results on some of these.  Thanks for posting it!

[piranha]

18 minutes ago, abyssunder said:

Ichnogenre Tomaculopsis igen. nov.

2006 b. cf. Tomaculum Groom, 1902 : Breton,p. 42, fig. 1 – 3.
2010. cf. Tomaculum : Breton in Colleté (coord.), fig. 154 G
Étymologie. Suffixe d’origine grecque –opsis « qui ressemble à … ». Le nom Tomaculopsis
fait référence à la ressemblance avec l’ichnogenre Tomaculum Groom, 1902.
Ichnoespèce-type : Tomaculopsis tomaculopsis isp. nov.

 

 

Just because it was accepted and published in a peer reviewed journal does not make it valid.  Mistakes happen.

Here is an example of a trilobite genus preoccupied by a lizard.  It took 31 years for this mistake to be corrected:

 

"I PROPOSED the new trilobite genus Opipeuter from the Ordovician of Spitsbergen (Fortey, 1974). I am indebted to Abigail Brown for pointing out to me that the name had been used a few years previously for a lizard (Uzzell, 1969).  I here propose the replacement name Opipeuterella (type species: O. inconniva Fortey, 1974) for Opipeuter Fortey, 1974, preoccupied."

 

Fortey, R.A. (2005)

Opipeuterella, a replacement name for the trilobite Opipeuter Fortey, 1974, preoccupied.

Journal of Paleontology, 79(5):1036

[abyssunder]

Etymology. Suffix of Greek origin -opsis "who looks like ...". The name Tomaculopsis
refers to the resemblance to the ichnogenous Tomaculum Groom, 1902.

 

Ok. Let's call it Tomaculum problematicum.

[Pilobolus]

Well, well, well...less agreement=more intrigue!

 

I failed to mention the size of these buggers, which in the long dimension, are just 1 mm.

 

Let me know if better images are needed, and thanks for the interest.

[doushantuo]

Length/width ratio would suggest Tomaculum(principally Ordovician).

Tomaculum has been found inside Hyolith shells

They look like thalassinoid anomuran coprolites,BTW.So:Agreeing with Ludwigia

if crustacean in nature, a transverse section would show the structures in the lowermost pic(Navesink fecal pellets)

 

 

[Carl]

Late to the game again, but, obviously, I agree with them being tiny coprolites. And erose is right on with the Ophiomorpha pellets being mud rather than coprolites. But I would strongly disagree that coprolites in question are from thalassinoid anomurans, whose pellets are very cylindrical rather than ovoid. 

[GeschWhat]

1 hour ago, Carl said:

And erose is right on with the Ophiomorpha pellets being mud rather than coprolites.

I meant to ask before about the Ophiomorpha pellets. Is there something new that has come out? Everything I've read defines the lumps as fecal pellets. I can't seem to find it now, but I saw a video a few years back showing a crab making little spit balls for their burrow construction . 

[Carl]

4 hours ago, GeschWhat said:

I meant to ask before about the Ophiomorpha pellets. Is there something new that has come out? Everything I've read defines the lumps as fecal pellets. I can't seem to find it now, but I saw a video a few years back showing a crab making little spit balls for their burrow construction . 

Please see if you can find those refs - I'm very interested in getting this straight. I've only read that they form balls of sediment, maybe with their mouths, with which to plaster the walls of their burrows. We get a lot of Ophiomorpha ion NJ and the burrow wall pellets definitely don't look like coprolites. But maybe more importantly, they don't look like known copprolites from the kind of shrimp that made Ophiomorpha.

[GeschWhat]

1 hour ago, Carl said:

Please see if you can find those refs - I'm very interested in getting this straight. I've only read that they form balls of sediment, maybe with their mouths, with which to plaster the walls of their burrows. We get a lot of Ophiomorpha ion NJ and the burrow wall pellets definitely don't look like coprolites. But maybe more importantly, they don't look like known copprolites from the kind of shrimp that made Ophiomorpha.

Me too! The papers I have just refer to round or ovoid "pellets" but do not specify a fecal origin. However, these online descriptions describe them as being lined by fecal pellets. So are the ones lined with fecal pellets Ophiomorpha or the ones lined with spit balls? What is the other one called?

 

KU Ichnology

San Joaquin Valley Geology

University of Maryland

Wikipedia

[Carl]

14 hours ago, GeschWhat said:

Me too! The papers I have just refer to round or ovoid "pellets" but do not specify a fecal origin. However, these online descriptions describe them as being lined by fecal pellets. So are the ones lined with fecal pellets Ophiomorpha or the ones lined with spit balls? What is the other one called?

 

KU Ichnology

San Joaquin Valley Geology

University of Maryland

Wikipedia

I've never seen or heard of any examples of Ophiomorpha actually lined with coprolites. The burrows and feces are generally preserved separately but both are identified as having come from anomurans because of comparison with extant examples.

[GeschWhat]

38 minutes ago, Carl said:

I've never seen or heard of any examples of Ophiomorpha actually lined with coprolites. The burrows and feces are generally preserved separately but both are identified as having come from anomurans because of comparison with extant examples.

Now I'm confused. Here is burrow example from Eagle Ford Group, the pellets are similar to what was found on the ammonite. Would this be considered Ophiomorpha or something else?

[doushantuo]

O.puerilis as made by juvenile callianassids:

 

 

From Frey's classic 1978 review

[Carl]

5 minutes ago, GeschWhat said:

Now I'm confused. Here is burrow example from Eagle Ford Group, the pellets are similar to what was found on the ammonite. Would this be considered Ophiomorpha or something else?

I would not call that Ophiomorpha. I was just call that an invertebrate coprolite mass. Ophiomoprha pellets are circular and don't overlap and the burrows tend to be quite circular in cross-section. There are various ichnotaxa applied to these things like Alcyonidiopsis and Tubotomaculum. I suspect these are formed when drifts of these microcoprolites (which are all hydrodynamically identical and thus prone to accumulating) wind up filling some sort of chamber (I call these masses "chamber pots"). I have seen them as ammonite, bivalve, and snail steinkerns as well as probable burrow fills.