Where: Foard County, Texas (33.8° N, 99.6° W: paleocoordinates 2.2° N, 29.0° W)
• coordinate estimated from map
• outcrop-level geographic resolution
When: Choza Formation (Clear Fork Group), Leonardian (286.0 - 273.0 Ma)
• Lower part of the Choza Fm.
Environment/lithology: pond; shale
•of fossils. The most distinctive feature of the bone-bearing shale, outside of the fact that it has fossils, is the occurrence of two types of vertically oriented ovoid structures. One type consists of mottled red and green, hard nodules that range from one to four inches in maximum diameter and up to eighteen inches in length. They are rich in vertebrate remains. They appear to have formed around the bones after deposition, presumably as a result of the reducing action of organic materials. Their vertical orientation is somewhat
•puzzling. The contained vertebrate remains are usually oriented with their long axes vertical, and it seems quite certain that this position was attained after the formation of the nodules. Specimens of vertebrates free in the shale rather than in nodules are orientated with their long axes horizontal and have been subjected to considerable distortion and breakage. The most reasonable suggestion seems to be that the vertical orientation of the nodules was developed during compaction of the shales, which has been extensive, with the long axes shifting to become normal to the compacting forces.
•The other vertical structures [...] have been termed pipes and have given the name to the site. They pass from the base to the top of the fossiliferous bed and, at the top, are continuous with the siltstone layer that caps the bed. Their composition is similar to the capping siltstone. The pipes are oval in cross section with maximum diameters from about four to twelve inches. Orientation of the long diameters is random, even in the 'clumps' in which the pipes tend to occur. These structures do not contain vertebrates, although specimens are found 'plastered' to their sides and occasionally penetrating the pipe for a short distance.
•The origin of the pipes is by no means certain. It is thought that they were formed in open holes by the introduction of the sediment that formed the siltstone layer. Superficially, they resemble lungfish burrows of the Arroyo and Vale (Romer and Olson, 1954), but the shape, size, composition, weathering, and fossil content differ. The most probable explanation is that these openings were formed by the root-like shafts of some type of plant, possibly some
•Equisetales, that rotted to leave openings that were later filled by sediment. There is no question that the red shales surrounding the pipes were deposited in a shallow pond, and such a pond might well have provided suitable habitat for the type of vegetation envisaged." (Olson, 1955 pp. 60-63)
Size class: macrofossils
Preservation: concretion
Collected by E. C. Olson in 1949
Primary reference: E. C. Olson. 1958. Fauna of the Vale and Choza: Summary, Review, and Integration of the Geology and the Faunas. Fieldiana Geology 10(32):397-448 [R. Butler/E. Dunne]more details
Purpose of describing collection: taxonomic analysis
PaleoDB collection 177006: authorized by Richard Butler, entered by Emma Dunne on 15.03.2016
Creative Commons license: CC BY (attribution)
Taxonomic list
Amphibia | |
Diplocaulus recurvatus Olson 1952 tetrapod | |
Trimerorhachis sp. Cope 1878 tetrapod | |
Osteichthyes | |
"Lysorophus tricarinatus" = Brachydectes newberryi
"Lysorophus tricarinatus" = Brachydectes newberryi Cope 1868 amniote | |
Gnathorhiza dikeloda Olson 1951 lungfish |