This similar "shape". Why and/or what is it?

[SATXPaleo]

These "rocks" were found in North San Antonio, Texas. I started to notice, repeatedly, this similar shape in different "rock". So I started collecting them and now have a large sample of these "rocks" all with this particular shape. I feel the shape is so oddly unique that this can not be a coincidence. The shape is almost identical in each "rock" regardless of size and composition. I was hoping you could explain what this phenomenon is and why or what these are, and why this same shape is so common in "rocks" of different composition? I look forward to your explanation. Thanks for your time.

[Fossildude19]

Sorry, but not seeing any fossils here. 

I think the shapes are kind of similar, but that it is coincidence. Erosion/weathering can affect similar stone in similar ways.

The make up of the rock can also determine how it breaks apart. 

 

Flippers would be fossilized as individual finger bones, and not complete with skin and muscle.   

 

[Ludwigia]

You can remove the quotation marks from "rock", since these are all rocks. There is nothing at all unusual about finding similarly shaped sedimentary rocks, although there are noticeable differences in shapes, size and consistence in these when they are more closely observed. As to the "why or what" : Rocks on the surface weather, and then tend to split out of the formation along bedding planes and fracture lines which often run roughly parallel to each other, which explains the similarity in shape which can often be observed.

[SATXPaleo]

Maybe I didn't make my question clear. Do to the unique shape it leads me to think there is an answer to why they are so similar. I think there is more to these that may be being overlooked. My reasoning is they have the same amount of sides and the curves are similar. Even the tops have the same angles. And all of the bottom sides are flat. Could these be petrified rear flippers from a marine creature? With all do respect, I just find it hard to believe that nature would repeatedly produce a "rock" in such an oddly unique way. And that I would be able to come across them. And it is just a coincidence. I kindly ask that you take a second look, keeping my reasoning in mind. Thanks!

[Rockwood]

I think the problem becomes one of statistical probability at this point. The conditions previously mentioned virtually assure that two rocks will be shaped nearly this alike if enough rocks are looked at. 

Two pieces can be alike because they formed the same way, as fossils, but the similarity alone is statistically irrelevant. Other indications are needed. 

[digit]

As mentioned before these are certainly not "petrified" flippers of any marine creature. Those who are just starting out learning about fossils often imaging that the exact shape of the original structure are somehow preserved in the fossil form--this is virtually never the case. I think museum exhibits are partially a source of this misunderstanding when they try to demonstrate what the creature would have looked like from the scant fossil material representing a find. People often see forms reminiscent of imagined parts of animals--heads, limbs, and quite often the soft tissue of internal organs. We have seen many "petrified hearts" complete with imagined blood vessels and iron staining representing "fossilized blood". The key learning moment here is that soft tissues almost never are preserved except in the rarest and most exceptional of conditions. Even then the resulting fossil generally does not appear anything like it would have in life.

 

The pattern matching software in our advanced brains allows us to notice shapes and patterns that have been useful to our species as hunter-gatherers and as social creatures. It allows us to see hidden prey in deep camouflage, to notice and discern various edible plants and to be able to recognize other individuals by sight from partial visual input. These pathways in our brains are often fooled as sort of an optical illusion which allows us to see fanciful shapes in clouds or to recognize the profiles of people or animals in rock profiles. These shapes match some of the patterns we use when recognizing something from scant information and can fool the eye into "seeing" something that is not there. The term for this phenomenon that we all share is called "pareidolia" and it is an important concept that fossil hunters need to be aware of when trying to discern ambiguous visual information when trying to decide if an object is what we think it might be.

 

https://en.wikipedia.org/wiki/Pareidolia

 

I've seen triangular rocks that do a good job of imitating shark teeth and often fossil hunters will keep particularly interesting "fakers" as we call them. All of your rocks above have a great diversity in form and texture and size. The one "unifying" feature that they all share is that one end is narrower than the other. In your mind this is evoking the concept of a paddle and thus you are led to suspect that these all must be "petrified flippers" but they are most certainly not. Fossil remains of both plesiosaurs and ichthyosaurs have been found in Texas. These finds tend to be vertebrae and other isolated bones. Often the bones that make up the paddles/flippers are recovered. They have a distinctive shape and texture that allows them to be identified. Sometimes a block of matrix containing multiple bones in close association is recovered but if you do an internet image search for "ichthyosaur paddle" you will see that actual fossil specimens are nothing more than associated internal bones in a block of matrix with nothing but the internal bones delineating the shape of the paddle. You do not find a paddle shaped block of stone representing the flesh, tendons and skin than surrounded the bones. This soft tissue rots away very quickly and is not preserved. Most often the loose bones then scatter which is why most finds are isolated bones.

 

You are sampling rocks while collecting to only select those that are matching your concept of a paddle. You could just as easily have selected only the rounded rocks if you thought you were seeing skulls. There is nothing special about the rocks you selected.

 

4 hours ago, SATXPaleo said:

With all do respect, I just find it hard to believe that nature would repeatedly produce a "rock" in such an oddly unique way. And that I would be able to come across them. And it is just a coincidence. I kindly ask that you take a second look, keeping my reasoning in mind.

 

Nature produces rocks according to physical processes. We've already mentioned that the properties of rock layers in bedding planes and the nature of how they weather produce similar shapes. We often find layers with large number of rounded rocks. We don't jump to the conclusion that these various rocks of different sizes, shapes and colors must be somehow a nest of eggs since eggs are also rounded but we conclude that rocks in a river are often tumbled till they have smooth rounded shaped. It is the explanation that most easily explains the evidence.

 

Given that ichthyosaur/plesiosaur paddles/flippers would have decomposed and the internal bones would either rarely be preserved in their original association or more commonly disassociated and preserved as isolated bones and given that these finds are rare in themselves, it is pretty easy to be certain that you did not find dozens of paddles/flippers but instead common rocks vaguely shaped as what you believe these paddles/flippers should look like.

 

We are keeping your reasoning in mind. We've experienced countless others new to fossils who have the same reasoning--but it's faulty. We enjoy sharing our combined fossil knowledge here on the forum. We have nothing to gain by explaining to you that these are most certainly not a group of fossils but just rocks. Nothing to gain that is other than possibly you as a new member if you choose to learn what we have to share. Nobody joins this forum knowing all the answers--we come here to learn and we hope that you are learning from our feedback.

 

Texas has lots of fossil material to offer. Some searching here on the forum will quickly reveal the types of fossils being found and general ideas of where they are being located. There are paleontological societies in Dallas and Austin and I'd encourage you to join one if you are close so that you may learn from the  experts about the fossils in your local area.

 

 

Cheers.

 

-Ken

[Fossildude19]

6 hours ago, SATXPaleo said:

Maybe I didn't make my question clear. Do to the unique shape it leads me to think there is an answer to why they are so similar. I think there is more to these that may be being overlooked. My reasoning is they have the same amount of sides and the curves are similar. Even the tops have the same angles. And all of the bottom sides are flat. Could these be petrified rear flippers from a marine creature? With all do respect, I just find it hard to believe that nature would repeatedly produce a "rock" in such an oddly unique way. And that I would be able to come across them. And it is just a coincidence. I kindly ask that you take a second look, keeping my reasoning in mind. Thanks!

 

Your question was perfectly clear.

With all due respect, I stand by my statement. 
These are not fossils, and are merely rocks that are vaguely similarly shaped. Probably chert, limestone, or sandstone.

Mosasaur paddle bones: IMAGES.

It is not uncommon to see similarly shaped rocks in certain areas. 
 

It would be well worth your time to join a local fossil/rock/mineral hunting club to put yourself in touch with more experienced people.   

 

[Storystone222]

On 2/22/2021 at 2:46 AM, SATXPaleo said:

Maybe I didn't make my question clear. Do to the unique shape it leads me to think there is an answer to why they are so similar. I think there is more to these that may be being overlooked. My reasoning is they have the same amount of sides and the curves are similar. Even the tops have the same angles. And all of the bottom sides are flat. Could these be petrified rear flippers from a marine creature? With all do respect, I just find it hard to believe that nature would repeatedly produce a "rock" in such an oddly unique way. And that I would be able to come across them. And it is just a coincidence. I kindly ask that you take a second look, keeping my reasoning in mind. Thanks!

I have a lot of rocks of the same shape, I find Specific shape groups of all kinds of shapes all the time, and I too believe there is something more to them you should drop them in acid, grind and polish the out side and cut some in half and investigate. I have found some really interesting things. There is no such thing as just a rock 

[SATXPaleo]

Thank you for your time and thoughts and suggestions. I will continue to investigate until I have concluded to exactly what this shape of "rock" is. If possible look at these "rocks". The similarities are beyond coincidence. Any thoughts anyone?

[digit]

These latest pieces all appear to be some sort of chert. This material is high in silica and fractures with these sharp clean edges and so is the type that Native Americans used for knapped projectile points, blades, and scrapers.

 

 

Cheers.

 

-Ken

[Fossildude19]

It really is not beyond coincidence.  

Similar geology in the rocks makes for similar fracture patterns, and that is all. 

As you can see here, the resemblance is quite superficial. 

 

 

 

 

[SATXPaleo]

I now have over 130 samples I have surface recovered from approximately a 5 mile stretch starting at private land then following creek beds. I actually found a match to one of my original pictures I posted. I'll share those and otherd to see what you y'all think. Much more thought provoking than the originals.  I now have a sample size with so many similarities that coincidence is no longer rational. There is an explanation which is why I came to the forum to being with. I believe I have stumbled upon marine life that is now being uncovered by surface erosion. I stick by my theory that an event of major perportion took place here in North San Antonio, Texas that buried these creatures under sediment and over time, by whatever process that took place and these "rocks" are the result of this process. I think the following samples will most definitely give support for my theory. I know very little about the history of San Antonio related to it's fossil record in relation to marine life.  I went to the Witte Museum here in town and there was absolutely nothing related to sea turtles of San Antonio which shocked me honesty.  These are few pictures but I will post close ups of the ones I think are most compelling. 

[Kane]

To my eye, they all look quite different and disparate in several ways. 

[Fossildude19]

I still see no evidence of these being fossils.  

 I see sandstone, ironstone, chert, and limestone.  

 

No bilateral symmetry. No bone textures. No bone morphology. 

 

Please take your items to a local museum or university paleontologist, and ask their opinion. 

Or, join a local rock/fossil/mineral club, and have the members tell you what you see. 

 

Similarly shaped finds really are not all that unusual. Like I said, similar chemical makeup, geology, combined with steady weathering, erosion, and breakage will turn up similarly (but only superficially) shaped objects.

 

Unfortunately, we are not likely to change your mind about this, as it appears you have already made a decision without keeping an open mind. 

 

Locking this topic, as further discussion is not likely to change anyone's mind, either way.    

 

Here is a PDF about a Texas turtle, from the Arlington Archosaur site. 

[Auspex]

On 2/22/2021 at 3:46 AM, SATXPaleo said:

Do [sic] to the unique shape it leads me to think there is an answer to why they are so similar.

Rocks tend fracture in polygon shapes, and sedimentary rocks fracture into flat polygons. If you have established a certain search image, and are looking for it, you will find many.