hndmarshall Posted July 27, 2019 Share Posted July 27, 2019 found this in a gravel load from the Brazos river West of Houston Texas is this what it seems?...is this the fossilized fleshy insides of a clam or other shelled creature? Link to comment Share on other sites More sharing options...
caldigger Posted July 27, 2019 Share Posted July 27, 2019 Layered shell of oyster? Link to comment Share on other sites More sharing options...
Fossildude19 Posted July 27, 2019 Share Posted July 27, 2019 Oyster was my thought. Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Wrangellian Posted July 27, 2019 Share Posted July 27, 2019 I am not aware of any oyster that has that sort of cellular structure, but I've been surprised before. Is it not a rudist or coral of some sort? 2 Link to comment Share on other sites More sharing options...
FranzBernhard Posted July 27, 2019 Share Posted July 27, 2019 @Wrangellian is right! This is a somewhat river-dumbled, partial segment of the lower valve of a radiolitid rudist. Cellular structure is very typical of the lower valve. It could be genus Durania, but I am not sure. However, there are several entries about that genus from Texas here at TFF. But no problem confusing it with an oyster (especially fragments of the upper, lamellar valves of radiolitids); oysters are the closest living relatives of rudists. Text copied from: "Some Rudists from the Campanian St. Bartholomä-Formation": This fragment of the lower valve of a radiolitid rudist is in its natural, strongly weathered state. The left part is a natural, near vertical section throuth the valve, showing the typical cellular outer shell, nicely highlighted by weathering. The ligamentary pillar is also there, but also strongly weathered. The out-of-focus, lower part of the rudist fragment is still filled with limestone. Text copied from: "Some Rudists from the Campanian St. Bartholomä-Formation": From the outside, this specimen is rough, pitted, butchered and cracked and with a rather large amount of fossiliferous limestone attached to it, but it was clear, that it is a bi-valve radiolitid with its apex preserved - nothing that is super-abundant. I decided to cut off the apex first (to see if there is a L-pillar, yes, there is one, but not very well visible in the pic) and then cut it vertically. The vertical sections clearly show the different structures of the two valves: The lower valve is cellular, the upper valve massive-lamellar (When I think about it, this difference seems to be a very strange "behavior" .) This results in some borings of clionid sponges in the upper valve, in contrast to the lower valve, which is devoid of such borings. (I have read somewhere, that the cellular structure of the lower valve has evolved to avoid such borings - ?) The rudist is filled with sparry, somewhat drusy calcite and fossiliferous limestone (quite similar to the limestone outside of the rudist). The sparry calcite may result, at least in part, from recrystallization of the aragonitic inner shell. I think, the position of the teeth (T) can still be recognized. I will repost also this radiolitid fragment, text with slight modifications copied from "January 2019 Finds of the Month Entries": Upper left: Inside view of lower and upper valve with Lithophaga steinkern. Upper middle: Side view of specimen with lower (cellular) and upper (lamellar) valve. Upper right: Outside view of lower valve with well perserved ribs. Lower left: Oblique side view with Lithophaga. It is clearly visible that the steinkern and the bore hole filling stand somewhat out of the shell. This means, that the void of the rudist was already filled with sediment, when the Lithophaga was boring. Later on, the rudist filling was removed, but not the Lithophaga steinkern and the filling of the bore hole. The cellular structure of the lower valve and the lamellar structure of the upper are also quite well visible in this pic. Lower right: Detail of the area with Lithophaga. Franz Bernhard 4 Link to comment Share on other sites More sharing options...
Wrangellian Posted July 27, 2019 Share Posted July 27, 2019 Aha! Link to comment Share on other sites More sharing options...
Plantguy Posted July 28, 2019 Share Posted July 28, 2019 On 7/27/2019 at 1:37 AM, FranzBernhard said: I will repost also this radiolitid fragment, text with slight modifications copied from "January 2019 Finds of the Month Entries": Upper left: Inside view of lower and upper valve with Lithophaga steinkern. Upper middle: Side view of specimen with lower (cellular) and upper (lamellar) valve. Upper right: Outside view of lower valve with well perserved ribs. Lower left: Oblique side view with Lithophaga. It is clearly visible that the steinkern and the bore hole filling stand somewhat out of the shell. This means, that the void of the rudist was already filled with sediment, when the Lithophaga was boring. Later on, the rudist filling was removed, but not the Lithophaga steinkern and the filling of the bore hole. The cellular structure of the lower valve and the lamellar structure of the upper are also quite well visible in this pic. Lower right: Detail of the area with Lithophaga. Franz Bernhard Appreciate the rudist details and especially like the Lithophaga example! Regards, Chris Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now