Tylostoma castelli - Snail Steinkern
Quick Facts
Fossil Name: Tylostoma castelli (Steinkern)
Common Names: Glen Rose Snail, Cretaceous Snail
Scientific Name: Tylostoma castelli
Geological Period/Age: Early Cretaceous (Albian Stage), approximately 110 million years old
Location/Formation: Lower Glen Rose Formation, Comal County, Texas, USA
This fossil is the remains of a common sea snail that lived in the shallow seas of Texas during the age of dinosaurs. As one of the most abundant and recognizable fossils from its formation, Tylostoma castelli provides a direct connection to the coastal environment where some of the world's most famous dinosaur tracks were made.
Composition & Appearance
Fossil Type: Gastropod (a marine snail).
Preservation: This specimen is a steinkern, a German term meaning "stone kernel." This type of fossil is an internal mold. After the snail died, its empty shell filled with mud and sediment. Over millions of years, the original aragonite shell dissolved away completely, leaving a solid, rock cast of the shell's interior.
Appearance: The fossil has a classic high-spired (tall, conical) snail shape. Because it is a steinkern, it is smooth and lacks any of the external shell's ornamentation, such as growth lines or color patterns. You are seeing the shape of the space inside the snail's shell, perfectly preserving the form of its internal whorls.
Composition: The fossil is composed of the lithified sediment of the Glen Rose Formation, typically a durable, dense limestone or marl.
Significance of the FossilA Common Citizen of the Dinosaur Coast: Tylostoma is an extremely common fossil in the Glen Rose Formation. Finding one is a quintessential experience for fossil hunters in Central Texas. It represents the everyday, background fauna of this ancient coastal ecosystem.
Paleoenvironmental Indicator: The presence of this gastropod indicates a specific ancient environment: a shallow, warm, low-energy marine setting with a soft, muddy or sandy bottom, such as a lagoon or protected bay.
Living Alongside Giants: The Glen Rose Formation is world-famous for preserving the fossilized trackways of giant dinosaurs like the sauropod Sauroposeidon and the fearsome carnivore Acrocanthosaurus. This very snail crawled along the seafloor just offshore from the muddy flats where these dinosaurs walked, making it a true contemporary of these iconic creatures.
Paleo-Ecological Associations(The following information is based on scientific reconstructions of the ancient Glen Rose ecosystem.)
Environment: Lived in the calm, shallow waters of the Western Interior Seaway, which was just beginning to advance across North America. It preferred the soft sediment of near-shore environments.
Associated Fauna: It shared its habitat with a rich community of other invertebrates, including bivalves (Arctica gibbosa, Trigonia), oysters (Exogyra), echinoids (sea urchins like Salenia), and ammonites.
Lifestyle: Tylostoma castelli was a slow-moving, epifaunal (living on the surface) or shallow infaunal (living just beneath the surface) gastropod. It likely grazed on algae or fed on organic detritus in the sediment as it moved across the seafloor.
Fossil Name: Tylostoma castelli (Steinkern)
Common Names: Glen Rose Snail, Cretaceous Snail
Scientific Name: Tylostoma castelli
Geological Period/Age: Early Cretaceous (Albian Stage), approximately 110 million years old
Location/Formation: Lower Glen Rose Formation, Comal County, Texas, USA
This fossil is the remains of a common sea snail that lived in the shallow seas of Texas during the age of dinosaurs. As one of the most abundant and recognizable fossils from its formation, Tylostoma castelli provides a direct connection to the coastal environment where some of the world's most famous dinosaur tracks were made.
Composition & Appearance
Fossil Type: Gastropod (a marine snail).
Preservation: This specimen is a steinkern, a German term meaning "stone kernel." This type of fossil is an internal mold. After the snail died, its empty shell filled with mud and sediment. Over millions of years, the original aragonite shell dissolved away completely, leaving a solid, rock cast of the shell's interior.
Appearance: The fossil has a classic high-spired (tall, conical) snail shape. Because it is a steinkern, it is smooth and lacks any of the external shell's ornamentation, such as growth lines or color patterns. You are seeing the shape of the space inside the snail's shell, perfectly preserving the form of its internal whorls.
Composition: The fossil is composed of the lithified sediment of the Glen Rose Formation, typically a durable, dense limestone or marl.
Significance of the FossilA Common Citizen of the Dinosaur Coast: Tylostoma is an extremely common fossil in the Glen Rose Formation. Finding one is a quintessential experience for fossil hunters in Central Texas. It represents the everyday, background fauna of this ancient coastal ecosystem.
Paleoenvironmental Indicator: The presence of this gastropod indicates a specific ancient environment: a shallow, warm, low-energy marine setting with a soft, muddy or sandy bottom, such as a lagoon or protected bay.
Living Alongside Giants: The Glen Rose Formation is world-famous for preserving the fossilized trackways of giant dinosaurs like the sauropod Sauroposeidon and the fearsome carnivore Acrocanthosaurus. This very snail crawled along the seafloor just offshore from the muddy flats where these dinosaurs walked, making it a true contemporary of these iconic creatures.
Paleo-Ecological Associations(The following information is based on scientific reconstructions of the ancient Glen Rose ecosystem.)
Environment: Lived in the calm, shallow waters of the Western Interior Seaway, which was just beginning to advance across North America. It preferred the soft sediment of near-shore environments.
Associated Fauna: It shared its habitat with a rich community of other invertebrates, including bivalves (Arctica gibbosa, Trigonia), oysters (Exogyra), echinoids (sea urchins like Salenia), and ammonites.
Lifestyle: Tylostoma castelli was a slow-moving, epifaunal (living on the surface) or shallow infaunal (living just beneath the surface) gastropod. It likely grazed on algae or fed on organic detritus in the sediment as it moved across the seafloor.
