Medullosan fossils may be found in rocks that were deposited during both the Pennsylvanian and Permian Periods as impressions, compressions, casts and molds.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001475.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001475-391x1024.jpg)
Neuropteris sp.OPC 3016-1475; Medullosan (Seed Fern); Middle Pennsylvanian (Desmoinesian); Skiatook Group, Seminole Formation; Tulsa County, Oklahoma; CC BY-NC-ND 4.0
Neuropteris sp.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001483.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001483-704x1024.jpg)
Neuropteris sp.OPC 3019-1483; Medullosan (Seed Fern); Middle Pennsylvanian (Desmoinesian); Skiatook Group, Coffeyville Formation; Tulsa County, Oklahoma; CC BY-NC-ND 4.0
Neuropteris sp.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001492.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001492-951x1024.jpg)
Neuropteris sp.OPC 3020-1492; Medullosan (Seed Fern); Middle Pennsylvanian (Desmoinesian); Skiatook Group, Seminole Formation; Tulsa County, Oklahoma; CC BY-NC-ND 4.0
Neuropteris sp.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Macroneuropteris-00001476.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Macroneuropteris-00001476-464x1024.jpg)
Neuropteris sp. (Macroneuropteris scheuchzeri)OPC 3016-1476; Medullosan (Seed Fern); Middle Pennsylvanian (Desmoinesian); Skiatook Group, Seminole Formation; Tulsa County, Oklahoma; CC BY-NC-ND 4.0
Neuropteris sp. (Macroneuropteris scheuchzeri)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001488.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001488-612x1024.jpg)
Neuropteris sp.OPC 3019-1488; Medullosan (Seed Fern); Middle Pennsylvanian (Desmoinesian); Skiatook Group, Coffeyville Formation; Tulsa County, Oklahoma; CC BY-NC-ND 4.0
Neuropteris sp.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001473.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Neuropteris-00001473-1024x1020.jpg)
Neuropteris sp.OPC 3016-1473; Medullosan (Seed Fern); Middle Pennsylvanian (Desmoinesian); Skiatook Group, Seminole Formation; Tulsa County, Oklahoma; CC BY-NC-ND 4.0
Neuropteris sp.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Alethopteris-PTC-00000005.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Alethopteris-PTC-00000005.jpg)
Alethopteris sp.PTC-5; Medullosan (Seed Fern); Pennsylvanian; Locality unknown; CC BY-NC-ND 4.0
Alethopteris sp.
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Trigonocarpus-00014063.jpg)
![](https://samnoblemuseum.ou.edu/wp-content/uploads/2017/08/Trigonocarpus-00014063-853x1024.jpg)
Trigonocarpus sp.OPC 3238-14063; Medullosan (Seed Fern); Pennsylvanian; Schuylkill County, Pennsylvania; CC BY-NC-ND 4.0