7-14-22 Mazon Creek ID

[Nimravis]

I am looking to see what members think this piece might be, I am pretty sure that it a Fauna fossil, but the length and lack of real detail have me scratching my head.

 

 

 

 

 

 

[connorp]

I might lean towards trace fossil.

[Nimravis]

This one below I am, but not sure about the one above.

 

I say this is a trail trace.

 

 

[connorp]

Alternatively, maybe a portion of the ribbon worm Archisymplectes rhothon?

[Nimravis]

9 minutes ago, connorp said:

Alternatively, maybe a portion of the ribbon worm Archisymplectes rhothon?

That is what I was leaning towards in the beginning, I have this one from tonight that I think is one. The below piece is how I am use to seeing them, not straight. That is why I hesitated on it.

 

[connorp]

14 minutes ago, Nimravis said:

That is what I was leaning towards in the beginning, I have this one from tonight that I think is one. The below piece is how I am use to seeing them, not straight. That is why I hesitated on it.

 

Yes that's how most I've seen look too. Rob does have a similar specimen to yours labeled as Archisymplectes in his gallery.

 

[Nimravis]

1 minute ago, connorp said:

Yes that's how most I've seen look too. Rob does have a similar specimen to yours labeled as Archisymplectes in his gallery.

 

Cool thanks- that might be the ticket, it was just odd to be with it being mostly straight. 

[IsaacTheFossilMan]

The white preservation reminds me more of Didontogaster cordylina. 

 

I've emailed someone who sold one that looks dead same as this - hopefully they can put me in contact with the buyer so I can confer with them.

 

[IsaacTheFossilMan]

See also Astreptoscolex anasillosus, though yours doesn't have the "leg" protrusions. 

 

[IsaacTheFossilMan]

Aaand there's also Esconites zelus.

 

[IsaacTheFossilMan]

Assuming yours is whole, can you measure its length with string or something flexible?

 

Esconites z. reaches only 4-14cm in length, and are usually identified by their jaw parts as they are often the best preserved:

 

Astreptoscolex a. is usually ~2.5cm in length, they are typically quite fat (so probably not your one), and lots of its specimen preserve conical teeth:

 

I can't seem to find a diagnostic feature of Didontogaster 

Try flicking through this paper:

Parry, L., Tanner, A. and Vinther, J. (2014), The origin of annelids. Palaeontology, 57: 1091-1103. https://doi.org/10.1111/pala.12129

 

 

 

 

 

[Nimravis]

@IsaacTheFossilMan Thanks, but it is not any of the species that you listed, the closest so far, if not exact is A. Rhothon, I don’t know of any thing else at this point.

[IsaacTheFossilMan]

Would you be able to post closeups of the ends of the fossil?

 

 

This dark mass is interesting.

[IsaacTheFossilMan]

A quick recap of Nemertine anatomy:

 

 

 

Reading from the publishing of A. rhothon, Schram, Frederick R. “Pseudocoelomates and a Nemertine from the Illinois Pennsylvanian.” Journal of Paleontology 47, no. 5 (1973): 985–89. http://www.jstor.org/stable/1303083:

 

,

 

It is senseless to identify a specimen simply because of a similar looking specimen in another collection, as that may be misidentified - it makes more sense to look at the holotype and diagnosis. 

 

I turn to plate 2 to show this:

 

 

Item 4 and 2 also bear superficial resemblance to your specimen, and they belong to Nemavermes mackeei. 

 

 

Assuming this white tract is the proboscis:

 

Thus the diameter of the body is 3.24u (where u is an undefined unit of length), and the diameter of the proboscis is 0.35u. 

The ratio of proboscis to body diameter is thus 1:9.257, whereas the expected for A. rhothon would be 1:~2.

 

I therefore find A. rhothon to be an improbable identification.

Edited July 15, 2022 by IsaacTheFossilMan

[Nimravis]

30 minutes ago, IsaacTheFossilMan said:

Would you be able to post closeups of the ends of the fossil?

 

 

This dark mass is interesting.

I will do it later today and tag you on them

 

Thanks

[IsaacTheFossilMan]

Just now, Nimravis said:

I will do it later today and tag you on them

 

Thanks

 

Closeups of the whole length would be beneficial too, as well as a measurement of the length of the specimen, and diameter at a given point, so I can gauge how big my "u"s are.

[Nimravis]

31 minutes ago, IsaacTheFossilMan said:

Would you be able to post closeups of the ends of the fossil?

 

 

This dark mass is interesting.

The funny thing with MC fossils is that the more pictures that I look at of the various types- worms, shrimp, bi-valves, etc., the more they look the same- lol

[IsaacTheFossilMan]

2 minutes ago, Nimravis said:

The funny thing with MC fossils is that the more pictures that I look at of the various types- worms, shrimp, bi-valves, etc., the more they look the same- lol

 

LOL! Common preservation of very old things, I guess.

 

 

That, or shapeshifting aliens...

[Nimravis]

2 hours ago, IsaacTheFossilMan said:

 

Closeups of the whole length would be beneficial too, as well as a measurement of the length of the specimen, and diameter at a given point, so I can gauge how big my "u"s are.

Here you go- it is 5mm wide and with a string it is 8.5 cm long. Here is a pic with a ruler.

 

 

 

Close up shots-

 

 

 

 

 

 

 

 

 

 

 

 

 

[IsaacTheFossilMan]

On 7/15/2022 at 2:47 PM, Nimravis said:

Here you go- it is 5mm wide and with a string it is 8.5 cm long. Here is a pic with a ruler.

 

 

 

Close up shots-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sorry for the late response; I didn't see this thread until now! I will check them out later when I am on my computer.

[IsaacTheFossilMan]

Still scratching my head over this one - having just printed a paper on Mazon Creek polychaetes, I'm off to bed to read it (and sleep)! I'll be back in the morning, putting a sticky tab on this one!

 

[IsaacTheFossilMan]

@Nimravis

 

The darker mass at the end of yours really does spark an interest.

 

It reminds me of the labial papillae of N. mackeei, which was described as having "little to note to describe the nematode external anatomy". The width of the proboscis/gut on your specimen, which I will hereby designate a temporary alias NR1 (NimRavis1) as to not get confused with further references to holo- and paratype fossils that I will discuss later.

 

Transcribed from Schram, F. R. (1973): "Pseudocoelomates and a Nemertine from the Illinois Pennsylvanian. Journal of Paleontology, 47(5), 985–989." http://www.jstor.org/stable/1303083 (red edited in by me):

Quote

Nemavermes mackeii n. sp. (Pl. 2, figs. 1-4; Text-fig. 1b)

 

Diagnosis:
Nematode of moderate to large size, fine hair-like projections of the cuticle; body long and relatively stout; well-developed labial papillae.

Holotype:
PE21551 (Pl. 2, fig. 1) in the Field Museum of Natural History.

Type locality:
Same as for P. konecniorum. [Peabody Coal Co. Pit 11, Will, Grundy, and Kankakee counties, Illinois. Middle Pennsylvanian, Carbondale Fm., Francis Creek Shale.]

Description:
There is little of note to describe the nematode external anatomy unless dealing with one of the highly decorated marine forms. But the fossil specimens at hand do preserve a few structures of interest. H124 has a number of fine hair-like structures (Pl. 2, fig. 2, 3) scattered about the surface. These spines are preserved as negative impressions on the surface of the fossil and are not unlike the cuticular decorations which occur on the free-living, marine nematodes in the orders Chromadorida and Monhysterida. T422 (Pl. 2, fig. 4) and PE21550 have some fleshy extensions on the head end which may be the remnants of oral papillae or cirri. These projections are preserved as distinct color differences in the rock (a type of preservation common in the Essex fossils). Several specimens have a detritus filled gut (Pl. 2, fig. 2).

 

In this context, the diagnosis of the creature was based off of several specimens, each having differing features (but lots in common). For example, the "hair-like projections" were described from a single specimen H124, and the papillae were described from both T422 and PE21550. Now let's take a look at the aforementioned specimens. 

 

Irrelevant specimens have been omitted. (scale bars represent 5mm)

 

Zoomed in images, grouped and named:

 

 

 

 

Looking at T422: 

 

Measurements are as follows: 

1    1.00u    gut width
2    3.58u    right body width
3    4.17u    left body width
4    8.15u    total body width
5    23.60u   length segment 1
6    34.30u   length segment 2
7    12.27u   length segment 3
8    10.92u   length segment 4
9    12.19u   length segment 5
10   13.77u   length segment 6
11   11.44u   length segment 7
12   12.90u   length segment 8
13   13.97u   length segment 9
14   12.45u   length segment 10
15   9.67u    length segment 11
16   9.79u    scale 5mm

 

4 should be equal to 1+2+3, 1+2+3 = 8.75u. This is a high margin of error, so I will use the measurement of total width as NOT 4, but instead as 1+2+3, which means that the body width is taken as 8.75u. Thus the ratio of gut width to body width is 1:8.75. 

The length of the specimen is Σ(5 to 15), which is 167.48u. Given that 5mm is 9.79u, the specimen is 85.5mm long.

 

Looking at H124:

 

Measurements are as follows:

Figure 2:
4    16.72u   length segment 1
5    6.12u    length segment 2
6    5.82u    length segment 3
7    8.50u    length segment 4
8    5.60u    length segment 5
9    4.60u    length segment 6
10   5.00u    length segment 7
11   5.39u    length segment 8
12   7.54u    length segment 9
13   3.02u    scale 5mm

Figure 3:
1    1.00u   gut width
2    3.95u   right body width
3    3.34u   left body width
14   6.94u   scale 5mm

 

Following from figure 2, the total length of H124 is 65.29u. Given that 3.02u is 5mm, the length of H124 is 108.1mm. 

Following from figure 3, the ratio of gut width to body width is 1:8.29.

 

Looking at PE21551:

 

Measurements are as follows:

1    1.00   length segment 1
2    0.81   length segment 2
3    0.89   length segment 3
4    0.40   length segment 4
5    0.18   length segment 5
6    0.22   length segment 6
7    0.89   length segment 7
8    1.53   length segment 8
9    1.20   length segment 9
10   0.41   scale 5mm

 

The total length of PE21551 is 7.12u. Given 0.41u is 5mm, the total length is thus 86.8mm.

 

 

 

 

 

Comparing these to NR1:

The length of the specimens mentioned by Schram (1973)(ibid.) was around 86mm, but fluctuated by over 25%, giving us a range of around 63-110mm in length. Compared to NR1, this fits most pleasantly, NR1 having a length of 85mm.

The ratio of gut width to body width was 1:8.29 (H124) and 1:8.75 (T422). This is less accurate to the previous comparison of 1:9.257 (NR1), which is re-evaluated below:

Shown in this figure, the ratio of gut/proboscis width is calculated to be 1:8.74.

 

Using this new, more precise measurement, NR1 is shown to fit all expected measurements displayed by Nemavermes mackeii, furthermore, the presence of matter in the gut tract as shown by below figure backs up the description of Schram (ibid.) - "Several specimens have a detritus filled gut (Pl. 2, fig. 2)". 

 

NR1 compared to H124:

 

H124 is also notable for possessing the cuticular spines, which here is compared to cuticular features of NR1:

 

 

In conclusion, without a doubt, NR1 is Nemavermes mackeii. 

 

Isaac

 

 

Edited July 20, 2022 by IsaacTheFossilMan

[Nimravis]

@IsaacTheFossilMan Thank you very much for taking the time to put together such a thorough post- It is much appreciated, I will ID it as you indicated.

[IsaacTheFossilMan]

1 hour ago, Nimravis said:

@IsaacTheFossilMan Thank you very much for taking the time to put together such a thorough post- It is much appreciated, I will ID it as you indicated.

 

My friend, you are more than welcome! Do feel free to ask for elaboration on any point - you have a really, really nice specimen! 

 

You are very welcome, Nim(not sure what else to call you )

[Nimravis]

9 minutes ago, IsaacTheFossilMan said:

 

My friend, you are more than welcome! Do feel free to ask for elaboration on any point - you have a really, really nice specimen! 

 

You are very welcome, Nim(not sure what else to call you )

Thanks again- Ralph