The Geology of Delaware

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Fish: Phlyum Chordata

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Fish: Phlyum Chordata <br>Source:  PBS.org

While sampling the lower Miocene Calvert Formation at the Pollack Farm Site, 30 fossil fish taxa were collected, consisting of 24 cartilaginous and 6 osteichthyes fishes. The fossils found in the lower Miocene bed have similar characteristics to an equally aged Formation in southern Delaware suggesting deposition occured in a subtropical, shallow-water, near shore environment.

The early Miocene Fish fossils found in Delaware are of two kinds, Chondrichthyes(consisting mainly of Sharks and rays) and Osteichthyes(commonly known as bony fish).

Paleontologists, at the Pollack Farm, were able to collect a large number of teeth and vertebrae from Chondrichthyes. However, because their bodies do not contain a true bone, full body fossils are very rare to find.

Osteichthyes, differ than Chondrichthyes, in that their skeleton is made of a stiffer bone, compared to their cartilaginous counterparts. Osteichthyes are often associated with dagger-like, isolated teeth

The stingray, dayatis americana, (shown above) is just one of the many Chondrichthyes and fish fauna found at the Pollack Farm Site, in Delaware! Click the image or the link below to view the fish collection.

Reference(s): 

Photographs from DGS Special Publication No. 21, 1998, R.N. Benson, ed.
Top left image: http:/www.pbs.org/oceanrealm/seadwellers

Photo Gallery
Carcharias cuspidata (Agassiz), composite detition, lingual view
2. Notorynchus sp., lower anterolateral tooth<br>3. Notorynchus sp., upper anterolateral tooth<br>4. Notorynchus sp., median tooth<br>12. Carcharodon subauriculatus (Agassiz), lower lateral tooth<br>13. Carcharodon subauriculatus (Agassiz), upper, second anterior tooth
22-23. Hemipristis serra Agassiz, upper lateral tooth
17. Galeocerdo contortus Gibbes, upper anterolateral tooth<br>18. Galeocerdo contortus Gibbes, lower anterolateral tooth
9. Isurus hastalis (Agassiz), lower lateral tooth<br>10. Isurus hastalis (Agassiz), upper, second anterior tooth
16. Paragaleus sp., lower tooth
17. Rhinoptera sp., isolated tooth<br>18. Sting ray tail spine
19-20. Ictalurus sp., dorsal spine
3-4. Carcharhinus brachyurus (Gunther), upper anterolateral tooth<br>5. Carcharhinus brachyurus (Gunther), upper lateral tooth<br>13. Negaprion sp. upper tooth<br>14. Negaprion sp. lower tooth<br>15. Negaprion sp. upper anterolateraltooth
24. Pogonias sp., fragment of pharyngeal with isolated teeth
22. Ictalurus sp., pectoral spine<br>23. Sphyraena sp., tooth