Crania Brachiopod

Taxonomy

Inarticulate Brachiopod

Kingdom: Animalia
Phylum: Brachiopoda
Class: Craniata
Order: Craniida
Family: Craniidae
Genus: Crania
Species: Crania modesta
Author Citation White and St. John 1867

Geological Time Scale

Eon: Phanerozoic
Era: Paleozoic
Period: Carboniferous
Sub Period: Pennsylvanian
Epoch: Middle
International Age: Moscovian

Stratigraphy

Naco Formation

Provenance

Collector: DPS Ammonite
Acquired by: Field Collection

Dimensions

Length: 4.8 mm
Width: 4.6 mm

Location

Canyon Creek
Gila County
Arizona
United States

• arizona
• crania modesta
• desmoinian
• gila county
• modesta
• naco formation
• pennsylvanian
• petrocrania
• petrocrania modesta

Comments

Crania

 

Crania modesta is a rare calcium carbonate Pennsylvanian inarticulate brachiopod. The shell is very thin and the ornamentation of the shell below shows through. You can see the interior of a near circular 4.6 by 4.8 mm pedicle valve that attached itself to aLinoproductus prattenianus (photo #1). A bryozoan also covers the front and back of the Linoproductus (photos #2 & #4). Photo #2 is a different photo of the same Crania as in photo #1. The Crania has a thickened rim and a sub central knob. Rowell (1965, p. 289) lists Crania as the only Pennsylvanian genus with a calcified pedicle valve as stated by Sutherland (1973, p. 16).

 

 

The presence of a large bryozoan colony on the backside of the Linoproductus valve (photo #4) suggests why only the pedicle valve of the Crania was preserved. The entire Linoproductus shell with the Crania and small bryozoan colony on top (photo #2) was flipped over allowing the bryozoan to grow on the other side. The brachial valve dissolved away or was broken off from exposure before it was buried. The brachial valve was probable very thin like the pedicle valve.

 

Taxonomy from GBIF.

 

Photo 3 from plate 11, figure 17 from Mudge 1962.

 

Mudge, M. R., Yochelson, E. L., Douglas, R. C. et al. 1962. Stratigraphy and Paleontology of the Uppermost Pennsylvanian and Lowermost Permian Rocks in Kansas. United States Geological Survey Professional Paper 323:1-213. 

 

https://pubs.usgs.gov/pp/0323/report.pdf

 

 

Rowell, A. J. 1965. Inarticulata. In: R.C. Moore (ed.), Treatise on Invertebrate Paleontology. Part H. Brachiopoda, H260–H296. Geological Society of America and University of Kansas Press, Boulder.

 

Sutherland, P. K. and F. H. Harlow. 1973. Pennsylvanian brachiopods and biostratigraphy in southern Sangre de Cristo Mountains, New Mexico. Memoirs of the New Mexico Bureau of Mines and Mineral Resources 27:1–171. 

Free download:

https://geoinfo.nmt.edu/publications/monographs/memoirs/27/

 

First description in: 

 

White, C. A. and St. John, O. H. 1867. Descriptions of new sub-Carboniferous and Coal Mesures fossils collected upon the geological survey of Iowa, together with a notice of new generic characters observed in two species of brachiopods. Transactions of the Chicago Academy of Sciences 1:115-127.