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Monday, 25 April 2016

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Misc. fossil bits and pieces from the Bois D'Arc formation 

Views of the Mahantango [2016-04-25 09:01:00]  recommend  recommend this post  (261 visits) info

 Devonian; DE,US
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To close out this series of posts featuring fossils I found in the Bois D'Arc formation of Oklahoma, I have a few pieces left from my finds that don't merit a full blog post entry so I'm consolidating them here. They are each interesting in their own right and deserve at least a mention.This is a piece I kept as a curiosity. It appears to be the mold from some sort of epitheca that belongs to a coral (like Favosites conicus) or Bryozoan (like Lichenalia sp.).  There is some sort of [...]

Kettneraspis sp. trilobite from the Bois D'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-21 09:01:00]  recommend  recommend this post  (192 visits) info

 Devonian; DE,US
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One of the spinier trilobites that can be found in the Bois D'Arc formation is Kettneraspis sp. it is usually a small fossil and it is best if you find it just peeking out from the rock. I found two nearly complete specimens while searching last August and some disarticulated pieces as well.This is the first articulated specimen. It is about 75% there but the delicate spines are all weathered away and the left free cheek of the cephalon is missing. It's not bad for a surface find as most of the [...]

Cordania falcata trilobite from the Bois D'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-19 09:01:00]  recommend  recommend this post  (149 visits) info

 Devonian; DE,US,IL
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Cordania falcata is a small trilobite and is uncommon in the Bois D'Arc formation. I found two examples that were prone and mostly complete, but neither were attached to matrix. Below is the better specimen of the two. It is about 95% complete and is missing a portion of the right genal spine. The trilobite itself is nearly oval shaped with a large rounded cephalon that typically has long genal spines that extend nearly the length of the thorax and pygidium. There is a small glabella with one [...]

Platyceras sp. gastropod from the Bois D'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-14 09:01:00]  recommend  recommend this post  (167 visits) info

 Devonian; DE,US
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As Platyceras sp. gastropods were abundant during the Devonian, it is no surprise to find one in the Bois D'Arc formation. This specimen has some added interest as there is a crinoid holdfast anchored to it.  The Platyceras shell is spiral shaped with a roughly rectangular cross section. The whorls are offset from the central axis and slightly angled. The exterior of the shell is decorated with wavy growth lines and some regular crenulations that follow the curve of the spiral. The crinoid [...]

Favosites conicus coral from the Bois D'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-12 09:01:00]  recommend  recommend this post  (150 visits) info

 Devonian; DE,US
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Favosites conicus is perhaps the easiest coral to ID from the Bois d'Arc formation. It's typically a small colony that looks like a gumdrop or beehive.  The base of the coral colony is flat with a wrinkled epitheca that is indicative of the colony growing on a semisolid substrate. The rest of the colony forms a conical mound composed of interlocking hexagonal cells of varying size. I have not found many that are greater than an inch or two in diameter or height which likely indicates there [...]

Streptelasma (Enterolasma) strictum ? coral from the Bois D'Arc formation of Oklahoma. 

Views of the Mahantango [2016-04-10 09:01:00]  recommend  recommend this post  (750 visits) info

 Devonian; DE,US
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I can't find very much info on the corals that are found within the Bois D'Arc formation so I have been comparing what I found with similar examples from the Kalkberg formation of New York which is of equivalent age. I found numerous examples of a small, conical rugose coral that had prominent raised lines running along the flanks.  It looks very similar to Streptelasma (Enterolasma) strictum from the Kalkberg formation.Specimen #1Specimen #2I found the specimens shown on this page in [...]

Lichenalia sp. bryozoans from the Bois D'Arc formation of Oklahoma 

Views of the Mahantango [2016-04-08 09:01:00]  recommend  recommend this post  (258 visits) info

 Devonian; DE,US
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Among the more easily identified bryozoan fossils that I found in the Bois D'Arc formation are these Lichenalia sp. examples. It's a small, encrusting fossil that I often found as loose discs. They likely started their colonies on a solid surface and could have used a crinoid segment or ostracod molt as a base. None of the examples that I found have the underside clean enough of matrix for me to tell. for sure. The fossils resemble a net with lots of small openings side by side with each other [...]

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 [...]

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 [...]

Pelecypod molds and casts from the Bois d'Arc formation of Oklahoma 

Views of the Mahantango [2016-03-25 08:01:00]  recommend  recommend this post  (649 visits) info

 Devonian; DE,US
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As I mentioned in the previous post, I found a few specimens of pelecypod in the Bois d'Arc formation that are just casts or molds that I can't really ID. This specimen looks like it may belong to the genus Nucula or Grammysia.This next specimen looks similar to a Modiomorpha sp.This last specimen is a real mystery to me. There is no surface ornamentation preserved but both valves are present. It has very convex valves with what appears to be a flat hinge line.I found the specimens shown on [...]

Actinopteria sp. pelecypods from the Bois d'Arc formation 

Views of the Mahantango [2016-03-22 08:01:00]  recommend  recommend this post  (156 visits) info

 Devonian; DE,US
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I found a few pelecypod mold and casts during my hunt among the rocks of the Bois d'Arc formation in Oklahoma. All are without shell material and some have little detail with which to help identify them. One group of specimens does have some detail and appears to belong to the genus Actinopteria and may be A. textilis. The fossils I found are all of single valves but show impressions of the interior or exterior of the left or right valves. The shells have an overall rectangular outline with a [...]

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  (631 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 [...]
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