Starfish Fossil?

[piranha]

Al Dente,

The comparison is interesting but unfortunately it's incorrect comparing apples and oranges. The figures you show from Schuchert, 1915 are actually examples of Palaeaster from New York, and represent an entirely different species. When Etheridge discovered the Sydney Basin starfish in 1892, he used North American genera to name the various Australian species. Attached for comparison is the figure of Palaeaster stutchburii referred to by Dr. Jell. Although you believe this analysis must be based only on age and basic outline, I would encourage you to take a moment and read the detailed evaluation again. In stark contrast to a thorough point by point analysis, your argument seems to fall short of the mark. I'm in agreement that the other fossils posted do look like Evactinopora, but the first one appears to match with Etheridge's figured specimen and Jell's general assessment of Palaeaster.

[squali]

To avoid any confusion, this is the photo that Dr. Jell referenced in the description in the previous post.

Piranha,

I am confused. Which of the 2 star shaped fossils in the photo is the discussion about?

[piranha]

Piranha,

I am confused. Which of the 2 star shaped fossils in the photo is the discussion about?

The description is based on the larger specimen and he also notes some interesting features on the separated arm to the left.

[Al Dente]

We will have to agree to disagree on this. It is nice to see the original drawing but it is missing the pores that go from the outside to the center canal which is also missing on the drawing. I can clearly see ossicles in the drawing that are missing from the fossil on post #1. The fossil in post #1 shares all these features with the other bryozoans posted on this thread. I think it is more likely that all are the same than to assume the one is different because the outline resembles a seastar.

[piranha]

We will have to agree to disagree on this. It is nice to see the original drawing but it is missing the pores that go from the outside to the center canal which is also missing on the drawing. I can clearly see ossicles in the drawing that are missing from the fossil on post #1. The fossil in post #1 shares all these features with the other bryozoans posted on this thread. I think it is more likely that all are the same than to assume the one is different because the outline resembles a seastar.

One of the salient points made by Dr. Jell is the weathering of the carbonate skeleton in the carbonate matrix. According to his explanation we are looking at a weathered slice running through the middle of the animal. That explains why we are not seeing a classic textbook depiction. It should also be noted that you are assuming the evaluation has been formulated 'because the outline resembles a seastar'. Dr. Jell hasn't suggested that for a moment, actually he has provided very technical details supporting his conclusions.

[Xiphactinus]

I'm going to jump in here too....these are definitely evactinoptera. We find these in the Burlington fm. in Missouri that look exactly like the fossils in question.

Here is a website with a really, really good photo.

http://www.crinus.info/otherfossils/data/evact.htm

[piranha]

I'm going to jump in here too....these are definitely evactinoptera. We find these in the Burlington fm. in Missouri that look exactly like the fossils in question.

Here is a website with a really, really good photo.

http://www.crinus.info/otherfossils/data/evact.htm

That Evactinopora is only1.7 cm across. Auspex asked earlier and no one responded, but I'm also curious if anyone can show an example of Evactinopora that matches the size (10 cm x 12 cm) of the original posted image? I have only seen much smaller specimens but would like to see something with similar dimensions for comparison.

[Xiphactinus]

That Evactinopora is only1.7 cm across. Auspex asked earlier and no one responded, but I'm also curious if anyone can show an example of Evactinopora that matches the size (10 cm x 12 cm) of the original posted image? I have only seen much smaller specimens but would like to see something with similar dimensions for comparison.

Piranha -

I've seen really big ones, but can't tell you the exact measurements.

Meek and Worthen mention 10 cm specimens:

Evactinopora grandis Ulrich, 1890: Geol. Sur. Illinois, vol. VIII, p. 511, pi. Ixxili, tig. 4. A very large, robust form, with four rays arranged at right angles to one another, and measuring from 6 to 10 centimeters from end to end. Horizon and localities. — Lower Carboniferous, Burlington limestone : Louisiana, Hannibal. 

[piranha]

Taking into account the possibility of an enormous Evactinopora, I'm a bit surprised that three Australian experts, all came to the same conclusion on the first specimen, with two of them arriving independently at the same genus of Palaeaster. It's even more perplexing considering all the precise details that were provided by Dr. Jell, who has been working on a monograph of Australian fossil asterozoans for 30+ years, could somehow manage to get it so completely wrong.

[mikeymig]

Very interesting thread I enjoyed the back and forth. The large "starfish" looked like a crinoid holdfast to me and I think I saw some crinoid stems on the plate.

Mikey

[Xiphactinus]

Pirahna - to clarify my position, the larger specimen looks totally different from the others. The one larger one has a defined central body. I'm sure it's a starfish. The others are different, and those are what I think are evactinoptera. To your point. There is someone who is much more expert than I am that says something else.

[piranha]

In the spirit of a good debate, I presented the opinions expressed here to one of the Australian paleontologists; that the large specimen is Evactinopora.

Here is the ask and answer just received on the photo containing the large specimen with associated bits and pieces:

Q: Question for you on the starfish you looked at earlier. A number of people at the fossil forum are claiming it's not Palaeaster, but instead a giant Evactinopora. I have seen reports that some Evactinopora could get quite large, but considering this specimen is 10 cm x 12 cm, does that seem at all plausible to you?

A: In a word: no. Evactinopora is a bryozoan, with a very different structure not seen in the fossils. Evactinopora also has considerable relief, whereas these fossils are almost flat on a bedding plane. Peter Jell is the man with this kind of thing.

[Al Dente]

So your expert is saying this is also a seastar?

[Al Dente]

And this one?

[piranha]

So your expert is saying this is also a seastar?

Please read the comments carefully.

In the spirit of a good debate, I presented the opinions expressed here to one of the Australian paleontologists; that the large specimen is Evactinopora.

Here is the ask and answer just received on the photo containing the large specimen with associated bits and pieces:

Q: Question for you on the starfish you looked at earlier. A number of people at the fossil forum are claiming it's not Palaeaster, but instead a giant Evactinopora. I have seen reports that some Evactinopora could get quite large, but considering this specimen is 10 cm x 12 cm, does that seem at all plausible to you?

A: In a word: no. Evactinopora is a bryozoan, with a very different structure not seen in the fossils. Evactinopora also has considerable relief, whereas these fossils are almost flat on a bedding plane. Peter Jell is the man with this kind of thing.

[piranha]

Just in case any confusion persists, here is the photo of the large specimen identified as a starfish, with numbers designating the associated "fossils" referenced above.

[Auspex]

Just in case any confusion persists, here is the photo of the large specimen identified as a starfish, with numbers designating the associated "fossils" referenced above.

IMG1.jpg

Thanks, Scott; Mr. Confusion is not our friend

[Scylla]

... But Mr. Confusion seems to be my constant companion. :[

[Al Dente]

Your expert is correct that Evactinopora have considerable relief. Below is a drawing I borrowed from the Lake Neosho website showing the 3-D nature of these bryozoa. All of these fossils are on erosional surfaces so we are looking at slices through the fossil, not the complete specimen. A slice through the middle would give a star shaped fossil, an oblique slice would give something similar to the specimen in post #64. I think your expert has closed his eyes to other possibilities by discounting these fossils as anything but starfish because they are flat.

[Scylla]

So a rock saw would end this debate? Saw a 5 cm thick slab off the rock parallel to the exposed surface. If the fossil is a starfish it would not be harmed and would be thinned to the point where you could hang it on your wall for display. If it is still present on the cut surface, then you'll have a clean, unweathered cross-section of an Evactinopora to show. Is that right?

[piranha]

Your expert is correct that Evactinopora have considerable relief. Below is a drawing I borrowed from the Lake Neosho website showing the 3-D nature of these bryozoa. All of these fossils are on erosional surfaces so we are looking at slices through the fossil, not the complete specimen. A slice through the middle would give a star shaped fossil, an oblique slice would give something similar to the specimen in post #64. I think your expert has closed his eyes to other possibilities by discounting these fossils as anything but starfish because they are flat.

Unfortunately you continue to overlook the fact that the experts have not evaluated the other fossils or commented on them. Although it's getting redundant, let me reiterate the only photo evaluated by the experts is this one:

The associated fossils discussed by two of the experts are the numbered fossils in the attached photo. In Dr. Jell's analysis, he specifically mentions the disconnected arm to the left, it really is clear if you take a moment to read back the comments carefully. Let me reiterate another point; the other fossils in the other photos certainly look like Evactinopora, but again the experts have not evaluated those fossils. The expert that made the comment about the fossils being flat on the bedding plane is referring to the photo attached here, and quite frankly, doesn't have his eyes closed to other possibilities about the other fossils, as you have erroneously stated, because the subsequent photos and fossils were not and have not been discussed with any of the experts. There has been a wealth of excellent information so far, plenty for everyone to learn, and even the chance that a new starfish species has been discovered. Regretfully, as you continue to press this false argument in spite of the clear record presented in this thread, the result is a muddled mess that is difficult for many folks to follow.

[FossilDAWG]

Have the specimens been sent to Dr. Jell, or is that planned?

Don

[Al Dente]

I'm well aware that your expert has only looked at the first photo. My statement is that if he discounted the first fossil as being Evactinopora because it is has no relief, then he has discounted the others because they have no relief. One cannot make the argument that fossil #1 is not Evactinopora because it is flat, then say the others can be Evactinopora even though they are flat.

[piranha]

I'm well aware that your expert has only looked at the first photo. My statement is that if he discounted the first fossil as being Evactinopora because it is has no relief, then he has discounted the others because they have no relief. One cannot make the argument that fossil #1 is not Evactinopora because it is flat, then say the others can be Evactinopora even though they are flat.

The experts have not commented on the other specimens. None of the experts is offering the false choice you continue to assert:

"One cannot make the argument that fossil #1 is not Evactinopora because it is flat, then say the others can be Evactinopora even though they are flat."

Here is the statement from my previous post:

"Let me reiterate another point; the other fossils in the other photos certainly look like Evactinopora, but again the experts have not evaluated those fossils."

Just to be crystal clear, I'm the one trying to agree with you that the others look like Evactinopora, the rest of the statement is quite self-explanatory.

I would urge you to please take the time to read the comments more carefully to avoid all of these confusing and redundant exchanges.

[Al Dente]

I understand what you are saying Piranha. I'm saying the reason your expert used for disqualifying the first fossil from being Evactinopora is invalid. They can have little relief and still be Evactinopora as we have seen with the other examples.