Phylum: Mollusca (Mollusks)

Class:  Cephalopoda
Subclass:  Nautiloidea
(nautiloids - 'nautiluses')

Cretaceous Period: (click for Pennsylvanian Period)
Cymatoceras sp. Strata:  Mainstreet Limestone Period: Cretaceous (c. 99 mya) Tarrant Co., TX.  Jan. 13, 2013.	Cymatoceras sp. Strata:  Mainstreet Limestone Period: Cretaceous (c. 99 mya) Tarrant Co., TX.  Jan. 13, 2013.	Cymatoceras sp.? Strata:  Mainstreet Limestone Period: Cretaceous (c. 99 mya) Tarrant Co., TX.  Jan. 13, 2013.
Cymatoceras sp. [+] Strata:  Mainstreet Limestone Period: Cretaceous (c. 99 mya) Tarrant Co., TX.  Dec. 5, 2010.	Cymatoceras sp. Strata:  Mainstreet Limestone Period: Cretaceous  (c. 99 mya) Tarrant Co., TX.  2007.	Cymatoceras sp.? Strata:  Grayson Shale Period: Cretaceous  (c. 100- mya) Denton Co., TX.  Sep. 2, 2007.
ryncholite - nautiloid hood (beak) Strata:  Del Rio Formation Period: Cretaceous  (c. 100+ mya) Waco, Tx.  Nov. 17, 2007.	Cymatoceras sp. Strata:  uncertain  [+] Period: Cretaceous (c. 99 mya) Tarrant Co., TX.  13 May 2017.