Geobulletin alpha

Source info:

Author:	Dave
Date:	2016-02-27 09:01:00
Blog:	Views of the Mahantango
URL:	http://viewsofthemahantango.blogspot.com/2016/02/rhipdomelloides-oblata-brachiopod-from.html

Summary:

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 this next fossil is somewhat large it is also compressed nearly flat which makes it more difficult to identify. I'm a fairly confident though that this too is a specimen of Rhipidomelloides oblata. The shell is rounded to ovate with both valves decorated with numerous fine costae. This specimen is flattened but in life both valves would have been slightly convex. The posterior is mostly obscured by matrix or by the shell being flattened.Brachial valveAnteriorPedicle valvePosteriorProfileI wrote a post about similar specimens of Rhipdomelloides oblata from the Haragan formation. I found the specimens shown on this page in the Bois d'Arc formation (Cravatt Member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc overlies the Haragan formation but both are the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.References:  "Stratigraphy and Paleontology of the Hunton Group in the Arbuckle Mountain Region, Part V - Bois d'Arc Articulate Brachiopods " Amsden, 1958, Oklahoma Geological Survey Bulletin 82

Content analysis:

Stratigraphic context:

Recognized stratigraphic terms [n]:	Devonian [2]
Agenames chronostratigraphy [rating]:	Devonian [0.33] Paleozoic [0.33] Phanerozoic [0.33]

Geographic context:

Location	Country	Latitude	Longitude
Bois d'Arc	US	37.5948	-96.9209
Oklahoma	US	35.3091	-98.521

Keywords:

Amsden, anterior margin, Arbuckle Mountain Region, beak, Bois d'Arc Articulate, Bois d'Arc formation, Brachiopods, Clarita, common fossil brachiopod, concentric lines, Coyemans, Cravatt Member, fine striae, flattened.Brachial valveAnteriorPedicle valvePosteriorProfileI, gentle curve, Geological Survey Bulletin, Haragan formation, Helderberg fauna, Hunton Group, inch, life, Lockhovian stage, New Scotland formations.References, New York, numerous fine costae, OK, Oklahoma, Paleontology, Rhipdomelloides oblata brachiopod, Rhipidomelloides oblata, shell, similar specimens, Stratigraphy, surface.Pedicle, valves, width