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Posts treating: "Hunton Group"

Wednesday, 06 April 2016

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Levenea subcarinata pumilis brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-06 09:01:00]  recommend  recommend this post  (136 visits) info

 Devonian; DE,US
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One of the more common brachiopods that I found in the Bois d'Arc formation is Levenea subcarinata pumilis. It is similar to Rhipimelloides oblata except for a few key features. The hinge line is wide and straight and the presence of a wide, shallow fold/sulcus structure. Otherwise they share some similar traits like the rounded shape to the shell and the  pedicle valve extending slightly past the brachial valve. Another difference are the fine costae on the valve surfaces which on L. [...]

Unknown Rhynchonellid brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-04 21:01:00]  recommend  recommend this post  (115 visits) info

 Devonian; DE,US
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This next brachiopod is a bit of a mystery to me. I can not find any decriptions or images that match it in Amsden's "Stratigraphy and Paleontology of the Hunton Group" papers nor in Hall's "Paleontology of New York". It is a triangular to sub-pentagonal shaped shell with slightly convex to flat valves. There is a slight sulcus and fold but they are mostly expressed near the anterior margin. The pedicle valve's beak extends beyond the brachial valve and recurves so that the umbo opening is [...]

Nucelospira ventricosta from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-01 09:01:00]  recommend  recommend this post  (132 visits) info

 Devonian; US
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This little, rounded shell appears to be a Nucleospira based on the shape.  I found it in the Bois d'Arc formation in Oklahoma. The brachial valve is slightly smaller and less convex than the pedicle valve but both are nearly perfectly circular. My fossil is smooth on the surface of the valve, at least in the areas where there is still shell, but it should be covered with lots of tiny, needle like spines. They likely either did not preserve well or were weathered away. There is a small [...]

Camarotoechia haraganensis brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-29 09:01:00]  recommend  recommend this post  (162 visits) info

 US
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I found a few of these tiny, elongated brachiopods while searching the Bois d'Arc formation. I believe it is called Camarotoechia haraganensis. It's a small shell that is longer than it is wide. Both valves are equally convex with strong costellae (or ribs as I sometimes call them). The sides of each valve are fairly flat and nearly at a right angle to the rest of the valve. On the pedicle valve, the beak extends well past the brachial valve with little to no curving with the umbo at the [...]

Kozlowskiellina (Megakozlowskiella) velata brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-28 09:01:00]  recommend  recommend this post  (184 visits) info

 Devonian; US
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This highly decorated shell has a very long name: Kozlowskiellina (Megakozlowskiella) velata. It is related to Kozlowskiellina perlamellosa which is found in the Helderberg fauna of New York. The shell is triangular to half moon shaped with each convex valve featuring coarse plications (generally three on each side of the fold and four on each side of the sulcus). The shell is further decorated with strong concentric growth lamellae. The pedicle valve recurves, extends past the brachial [...]

Coelospira virginia brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-19 08:01:00]  recommend  recommend this post  (662 visits) info

 Devonian,Silurian; DE,US
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When I'm out collecting I often pick up anything that looks like it might be a fossil and sometimes I know what it is while other times it just looks similar to another shell. Such is the case with Coelospira virginia. This is a very small shell that I probably thought was an Atrypina sp. when I tossed it into my collecting bag. It wasn't until I got home and really looked closely at it that I saw there was a difference. White it does have the same rounded shape as Atrypina sp. with a wide fold [...]

Atrypina hami brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-16 08:01:00]  recommend  recommend this post  (184 visits) info

 Devonian; US
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Atrypina hami is an easy brachiopod to ID due to the wavy nature of the shell. It has a generally rounded appearance with flat to slightly concave brachial valve and a convex pedicle valve.  The pedicle valve extends beyond the pedicle valve and curves just slightly at the umbo. both valves have widely spaced, concentric growth lines and a handful of very wide ribs that affect the margin of the shell. It's this wavy appearance and the obvious growth lines that make this brachiopod [...]

Dicoelosia varica brachiopod from the Bois d'Arc formation 

Views of the Mahantango [2016-03-13 18:41:00]  recommend  recommend this post  (258 visits) info

 Devonian; US
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A highlight of my collecting trip to the Bois d'Arc formation was finding the tiny brachiopod Dicoelosia varica. It is somewhat common in certain horizons of the formation and I probably picked up a dozen or more specimens loose plus a number of specimens on matrix. such as the one below with three specimens.Dicoelosia varica is a member of Order Orthida and is very easy to identify. It is a small shell shaped like the letter "V" with two distinct. rounded lobes. Between the two lobes the shell [...]

Sphaerirhynchia lindenensis brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-10 09:01:00]  recommend  recommend this post  (143 visits) info

 Devonian; DE,US
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I found a number of these round, nut like brachiopods while searching the Bois d'Arc formation in Oklahoma. They are called Sphaerirhynchia lindenensis and seem to have a bit of variability in their features. Overall the shells are rounded to subpentagonal in outline and rectangular to square in cross section. Both valves are convex and have strong, rounded ribs decorating the surface. The margins of both valves are flat except along the anterior margin where the shell develops "teeth" that [...]

Atrypa oklahomensis brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-07 09:01:00]  recommend  recommend this post  (164 visits) info

 Devonian; US
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The brachiopod genera Atrypa makes an appearance in the Bois d'Arc formation, as one would expect. It's pretty much an index fossil for the Devonian period as far as I'm concerned. In this case we have Atrypa oklahomensis. The shell is rounded with a very convex brachial valve and a slightly convex to flat pedicle valve. The surface of both valves have regularly spaced ribs and fine concentric growth lines. There is a small fold and sulcus present to some degree on every specimen I have found [...]

Strophonella bransoni brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-04 09:01:00]  recommend  recommend this post  (195 visits) info

 Devonian; DE,US,IN
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Another flat brachiopod from the class Strophomenata that can be found in the Bois d'Arc formation is Strophonella bransoni. It has a rounded to subrectangular shape with a (notably) convex brachial valve and concave pedicle valve. The surface of the valves have many thin costellae decorating it, which stand out in relief somewhat, and on some specimens very fine concentric growth lines can be seen. Amsden's original description for the species indicates that the pedicle valve has a small beak [...]

Eatonia sp. brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-01 09:01:00]  recommend  recommend this post  (630 visits) info

 Devonian,Silurian; CA,US
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I believe that this next Brachiopod is an Eatonia sp. While Eatonia medialis is listed by Amsden* as being known from the Haragan and Bois d'Arc formations of Oklahoma, the specimen below does not appear to conform to specimens I have found in the Kalkberg formation of New York or Licking Creek formation of Virginia (both formations are correlative to the aforementioned Oklahoma formations).The shell is rounded to sub-pentagonal in shape with coarse plications. The pedicle valve has a sulcus [...]

Rhipdomelloides oblata brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-27 09:01:00]  recommend  recommend this post  (193 visits) info

 Devonian; US
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Perhaps the most common fossil brachiopod to be found in the Bois d'Arc formation is Rhipidomelloides oblata. Most are small but some can get about an inch in width. The shell is rounded to subrectangular with both valves generally convex. A gentle curve is sometimes present in the anterior margin. The pedicle valve has a beak that recurves over the brachial valve. Both valves have fine striae and concentric lines decorating their surface.Pedicle valveAnteriorBrachial valvePosteriorProfileWhile [...]

Stropheodonta gibbera brachiopod from the Boid d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-24 09:01:00]  recommend  recommend this post  (193 visits) info

 Devonian; DE,US
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The highly convex shape of the shell of this next specimen is indicative of the species Stropheodonta gibbera. I collected it from the Bois d'Arc formation in Oklahoma. The shell is subrectangular in shape with a rounded anterior margin and straight hing line. The pedicle valve is very convex while the brachial valve is very concave. This arrangement of valves is typical of the class Strophomenata. The surface of both valves have fine costellae that have low relief and fine concentric growth [...]

Inarticulate brachiopods from the Bois d'Arc formartion 

Views of the Mahantango [2016-02-21 09:01:00]  recommend  recommend this post  (178 visits) info

 Devonian; DE,US
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The Bois d'Arc formation has some inarticulate brachiopods that can be found but they are often fragile and weather away quickly. I was fortunate enough to find two examples of varying preservation. I can't locate any literature that describes species that could be found and it appears that the inarticulate brachiopods were ignored by Amsden when he initially described the brachiopod fauna from the Lower Devonian of Oklahoma.The first is a Lingula type specimen. I am not sure if the shell is [...]

Orthostrophia strophomenoides brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-18 09:01:00]  recommend  recommend this post  (172 visits) info

 Devonian; US
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Orthostrophia strophomenoides is a species that I have not found anywhere else from the lower Devonian but is fairly prolific in the Bois d'Arc formation of Oklahoma. I have posted about specimens from the Haragan formation in the past but other than that I have not seen any specimens of the genus from elsewhere in the world. The shell of Orthostrophia strophomenoides is subrectangular in outline with both valves being slightly convex. The surface of the valves are decorated with coarse striae [...]

Meristella atoka brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-15 09:01:00]  recommend  recommend this post  (199 visits) info

 Devonian; DE,US
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I've written about the brachiopod Meristella atoka from the Haragan formation of Oklahoma a few years back, but these next examples come from the Bois d'Arc formation. Both have the typical subtriangular to subpentagonal shape (this means they are roughly shaped like a triangle or pentagon when looking at a valve from the dorsal or ventral side), smooth shell with just a few concentric growth lines and a simple fold and sulcus. The latter feature is highly variable as can be seen in the two [...]

Leptanea rhomboidalis brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-12 09:01:00]  recommend  recommend this post  (211 visits) info

 Devonian; DE,US
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As may be expected, one of the more common brachiopod fossils from the Bois d'Arc formation is Leptanea rhomboidalis. The shell of the specimens I found are typical for the species with a rectangular outline when viewed from the dorsal or ventral side. Both valves are relatively flat with wide, concentric growth rings and decorated with fine striae  The margins of both valves (except along the hinge) are turned 90 degrees from the rest of the shell and this is most noticeable at the [...]

Anastrophia grossa brachiopod from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-09 09:01:00]  recommend  recommend this post  (175 visits) info

 Devonian,Silurian; DE,US
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The genus Anastrophia first becomes widely seen in the Silurian and it extends into the lower Devonian before disappearing from the fossil record. The specimens below are Anastrophia grossa from the Bois d'Arc formation of Oklahoma. The shell is subpentagonal in outline with coarse costae present on both valves. There is a shallow sulcus on the pedicle valve that becomes much more expressed at the anterior margin forming a "u" shape. The corresponding fold is also shallow. Both valves are [...]

The Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-02-06 09:01:00]  recommend  recommend this post  (182 visits) info

 Devonian; BE,US
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      While the majority of my vacation last fall was to Utah and Wyoming, I did a quick couple of days in Texas and Oklahoma. Texas was kind of a bonus for the visit as my primary goal was to collect in the prolifically fossiliferous exposures of lower Devonian aged rocks found around Clarita, Oklahoma. There are two main formations that are extremely productive, the Haragan formation and the Bois d'Arc formation. They are sequential formations, with the latter [...]
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