Description
Metengonoceras dumbli Ammonite Fossil – Woodbine Formation, Cenomanian Upper Cretaceous, Texas
This genuine Metengonoceras dumbli ammonite fossil is a highly collectable Upper Cretaceous marine cephalopod specimen from the Woodbine Formation of Arlington, Tarrant County, Texas, USA. Dating from the Cenomanian Stage, approximately 100 to 94 million years old, this fossil represents an ancient ammonite from the warm coastal and shallow marine environments that once covered parts of Texas during the Late Cretaceous.
This fossil is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. It has been carefully chosen as an individual fossil specimen, with a photo that shows the actual piece you will receive. Full sizing please see photo.
Geology and Geological Age
Metengonoceras dumbli comes from the Woodbine Formation, a well-known Cenomanian geological unit exposed in parts of north-central Texas. The Woodbine Formation records a time when the region was shaped by changing sea levels, coastal plains, river systems, deltas, estuaries and shallow marine environments. These deposits formed along the margin of the developing Western Interior Seaway and the Gulf Coastal Plain, creating a varied landscape where marine and nearshore life could flourish.
During the Cenomanian Stage of the Upper Cretaceous, warm climates and high global sea levels allowed shallow seas to spread across large areas of North America. The sediments of the Woodbine Formation preserve evidence of this changing world, including marine fossils such as ammonites, oysters, bivalves, gastropods, fish remains and other invertebrates.
Fossil Type and Species
This specimen belongs to the ammonite species Metengonoceras dumbli, a recognised Cenomanian ammonite associated with the Woodbine Formation of Texas. Metengonoceras is a distinctive ammonite genus within the order Ammonitida and is commonly placed within the family Engonoceratidae. Members of this group are known for their compressed shell forms and complex sutures, making them especially interesting to collectors and students of Cretaceous ammonite evolution.
Ammonites were extinct marine cephalopods related to modern squid, octopus and cuttlefish. Unlike their living relatives, ammonites possessed an external chambered shell. The living animal occupied the outer body chamber, while the earlier chambers helped regulate buoyancy, allowing the animal to move through the water column in ancient marine environments.
Morphology and Collectable Features
Metengonoceras dumbli is valued for its distinctive Cretaceous ammonite character. The shell is typically compressed and relatively smooth compared with heavily ribbed ammonites, with an elegant coiled form and a strong focus on whorl shape and suture pattern. Depending on preservation and growth stage, examples may show a narrow profile, subtle shell contours, defined whorls, chamber structure, natural mineral replacement or visible sutural detail.
The suture pattern is one of the most important features in ammonite identification. These intricate lines mark where the internal chamber walls joined the outer shell. In engonoceratid ammonites such as Metengonoceras, the sutures can be particularly diagnostic and form part of the fossil’s scientific interest.
This specimen is ideal for collectors interested in Texas fossils, Woodbine Formation ammonites, Upper Cretaceous marine life, fossil cephalopods and natural history display pieces.
Woodbine Formation and Tarrant County Locality
The Woodbine Formation of Texas is an important Cretaceous fossil-bearing unit, especially in areas around Tarrant County and the Dallas-Fort Worth region. Arlington and the wider Tarrant County area are known for exposures of Woodbine sediments that help document the changing environments of Cenomanian Texas.
These rocks were deposited in a complex setting influenced by rivers, shorelines, deltas and marine incursions. The presence of ammonites such as Metengonoceras dumbli shows the marine influence within the formation and helps link these deposits to wider Late Cretaceous seaway systems across North America.
Depositional Environment
This Metengonoceras dumbli ammonite was preserved after its shell settled into sediment within a warm coastal to shallow marine environment. Fine mud, silt, sand or carbonate-rich material gradually covered the shell, helping protect it from destruction. Over millions of years, burial, compaction and mineral-rich groundwater transformed the remains into a fossil.
The fossil therefore records an animal that lived in the ancient seas and coastal waters of Cenomanian Texas. It represents a time when the landscape of Arlington and Tarrant County was very different from today, with marine conditions extending into areas that are now inland.
Authenticity and Display
This is a genuine Metengonoceras dumbli ammonite fossil from the Woodbine Formation, Cenomanian, Upper Cretaceous of Arlington, Tarrant County, Texas, USA. It includes a Certificate of Authenticity lifetime guarantee generic card, making it a desirable addition to a fossil collection, geology study set, natural history display or educational cabinet.
The fossil has been carefully selected, and the photo shows the actual specimen you will receive. Full sizing please see photo.
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