Description
Genuine Owenites egrediens Ammonite Fossil
This carefully chosen specimen is a genuine Owenites egrediens ammonite fossil from Lower Triassic deposits on Timor in Southeast Asia. Dating from the Olenekian Stage, it represents an extinct marine cephalopod that lived during the remarkable recovery of ocean ecosystems following the end-Permian mass extinction.
Triassic ammonites are particularly appealing to collectors because they predate the more familiar Jurassic and Cretaceous examples. This specimen comes from an important chapter in the history of life, when ammonoid cephalopods were rapidly diversifying and repopulating the world’s oceans.
The photograph shows the actual fossil you will receive rather than a stock image or representative example. Its individual coiling, preservation, colour, matrix and natural surface characteristics can therefore be examined before purchase. Full sizing is shown in the accompanying photograph.
Fossil Classification and Geological Information
Scientific name: Owenites egrediens
Species authority: Welter, 1922
Fossil type: Ammonoid cephalopod
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ceratitida
Genus: Owenites
Geological period: Triassic
Epoch: Early Triassic
Stage: Olenekian
Associated interval: Smithian
Locality: Timor, Southeast Asia
The species Owenites egrediens was described by Otto Welter in his 1922 study of Lower Triassic ammonites from Timor. The genus Owenites had previously been established by Alpheus Hyatt and James Perrin Smith in 1905 and is recognised as an Early Triassic ceratitid ammonoid genus.
Distinctive Owenites Shell Morphology
The shell of Owenites egrediens grew as a flat spiral, with each successive whorl increasing in size as the animal matured. The central visible area is known as the umbilicus, the lateral sides are called the flanks, and the outermost edge is the venter.
Members of Owenites generally possess a compact, relatively involute shell in which the later whorls conceal a considerable portion of the earlier growth. The whorls may appear compressed or moderately inflated, producing a streamlined outline suited to movement through the water.
Depending on preservation, visible features can include curved growth lines, subdued ribbing, whorl margins, portions of the ventral profile and traces of the original shell surface. Ornamentation may change during development, so the inner juvenile whorls can differ from the larger outer portion.
The exact appearance of any fossil is also influenced by mineral replacement, pressure within the surrounding sediment and later weathering. Areas of attached matrix, natural fractures, incomplete shell or variations in surface texture are authentic characteristics of its long geological history.
Ceratitic Suture Pattern
One of the defining features of many Triassic ammonoids is the ceratitic suture pattern. Sutures formed where the internal chamber walls, known as septa, met the outer shell wall. In ceratitic ammonoids, the lobes of these sutures are commonly subdivided or serrated while the intervening saddles remain comparatively smooth and rounded.
Where exposed, this pattern may appear as a series of intricate lines across the fossil’s surface. Suture form is highly important in ammonoid classification because it records structural differences between major evolutionary groups.
The shell’s older inner portion was divided into numerous buoyancy chambers by the septa. A narrow tube called the siphuncle connected these chambers and helped regulate their liquid and gas content. The living animal occupied the final, largest section of the shell, known as the body chamber.
Olenekian Lower Triassic Age
The Olenekian is the second and final stage of the Early Triassic Epoch. It followed the Induan and preceded the Anisian Stage of the Middle Triassic. This places the fossil at approximately 249 to 247 million years old, although numerical boundaries are periodically refined as geological dating improves.
Occurrences of Owenites egrediens from Timor are commonly associated with the Smithian interval of the Olenekian. The Smithian records a time when ammonoids underwent rapid evolutionary expansion, producing diverse shell forms within a relatively brief geological interval.
This diversification occurred in the aftermath of the end-Permian mass extinction, the most severe known extinction event in Earth’s history. Marine ecosystems were gradually being rebuilt, and ammonoids were among the groups that recovered rapidly. Their abundance and evolutionary turnover make them valuable index fossils for dating Lower Triassic marine rocks.
Early Triassic Marine Life
The living Owenites was a free-moving marine mollusc related to other cephalopods. Its soft body would have included a head, eyes, grasping appendages and a muscular funnel through which water could be expelled for jet-propelled movement.
The chambered shell provided protection and buoyancy control. Its streamlined form suggests an animal capable of moving through the water column rather than remaining permanently on the seabed. It may have captured small marine animals or scavenged organic material using a hard beak surrounded by its appendages.
The surrounding sea supported other ammonoids, nautiloids, bivalves, gastropods, brachiopods, conodont-bearing animals and fish. These communities occupied marine environments that remained biologically stressed and variable during the prolonged recovery from the end-Permian crisis.
Lower Triassic Geology of Timor
During the Early Triassic, the rocks now exposed on Timor were accumulating within a marine setting along the margins of the ancient Tethys Ocean. The modern island did not yet exist, and the region formed part of a complex arrangement of marine basins, continental margins and offshore sedimentary environments.
Mud, carbonate material and the remains of marine organisms accumulated across the seabed. After death, an ammonoid shell could descend through the water and become buried beneath soft sediment. Rapid burial protected it from complete destruction by currents, scavengers and chemical dissolution.
As additional sediment accumulated, pressure compacted the surrounding material. Mineral-rich groundwater could fill the chambers, replace the original shell or create an internal mould preserving the ammonoid’s form. Later tectonic activity uplifted and deformed the sedimentary rocks, eventually exposing Lower Triassic fossil-bearing material at the surface.
Actual Fossil and Certificate of Authenticity
This is a genuine fossil specimen and not a replica, cast or modern reproduction. It has been individually selected for its natural appearance, geological significance and collectable character. Variations in colour, matrix, mineralisation, completeness and surface preservation are genuine results of fossilisation and natural weathering.
The listing photograph shows the exact Owenites egrediens ammonite fossil that will be supplied. Full sizing is provided in the photograph so the specimen’s dimensions can be assessed before purchase.
The fossil includes a generic Certificate of Authenticity card carrying a lifetime guarantee of authenticity. It is an excellent addition to a Triassic fossil collection, ammonoid display, geological teaching collection or natural-history cabinet and offers a distinctive example of marine life from the earliest part of the Mesozoic Era.
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