Description
Barroisiceras onilahyense Ammonite Fossil – Coniacian Upper Cretaceous, Tulear, Madagascar
This genuine Barroisiceras onilahyense ammonite fossil is a highly collectable Upper Cretaceous marine cephalopod specimen from Tulear, also known as Toliara, in Madagascar. Dating from the Coniacian Stage of the Late Cretaceous, approximately 89 to 86 million years old, this fossil represents an ancient ammonite from the warm marine environments that surrounded Madagascar during the later part of the Mesozoic Era.
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
Barroisiceras onilahyense comes from the Coniacian Stage of the Upper Cretaceous Period. During this time, Madagascar was positioned within the southern hemisphere and bordered by warm marine basins connected to the wider Indian Ocean region. High global sea levels created extensive shallow seas, coastal shelves and carbonate-rich marine environments where ammonites, bivalves, gastropods, echinoids, fish and other marine organisms lived.
The Tulear, or Toliara, region of southwestern Madagascar is well known for fossil-bearing Cretaceous marine deposits. These rocks preserve evidence of ancient seaways and coastal marine settings that existed long before the modern landscape formed. Fossils from this region are valued by collectors because they combine strong palaeontological interest with a classic Madagascar fossil locality.
Fossil Type and Species
This specimen belongs to the ammonite species Barroisiceras onilahyense, a recognised Upper Cretaceous ammonite associated with Madagascar. Barroisiceras is an ammonite genus within the order Ammonitida and is generally associated with the family Collignoniceratidae, a group of Cretaceous ammonites known for ornamented shells, strong ribbing and important biostratigraphic value.
Ammonites were extinct marine cephalopods related to modern squid, octopus and cuttlefish. Unlike their living relatives, ammonites had a coiled external shell divided internally into chambers. The animal lived in the outer body chamber, while the older chambers helped regulate buoyancy, allowing it to move through the water column in ancient seas.
Morphology and Collectable Features
Barroisiceras ammonites are admired for their distinctive Cretaceous shell form and attractive natural ornamentation. Depending on preservation and growth stage, specimens may show a coiled shell with pronounced ribs, defined whorls, nodular ornament, tubercles, a shaped venter and visible shell contours. These features give the fossil a strong sculptural appearance and make it desirable for display.
The ribs and tubercles on ammonite shells were part of the shell’s natural structure and may have helped strengthen the shell or influenced movement through the water. In well-preserved examples, suture lines may also be visible. These complex lines mark where the internal chamber walls met the outer shell and are an important feature used by palaeontologists when studying ammonite classification and evolution.
Tulear, Madagascar Fossil Locality
Tulear, or Toliara, is one of Madagascar’s notable fossil regions, particularly for marine fossils from the Cretaceous Period. The surrounding sedimentary rocks record a time when the area was influenced by warm seas and active marine ecosystems. Ammonites from this region provide important evidence of the diverse cephalopod faunas that lived in the southern oceanic margins during the Late Cretaceous.
Barroisiceras onilahyense is especially interesting because it links the specimen to a named species, a clear Coniacian age and a recognised Madagascar locality. This makes it a strong addition to a fossil collection, especially for collectors interested in Cretaceous ammonites, African and Indian Ocean fossils, marine cephalopods and natural history specimens from Madagascar.
Depositional Environment
This Barroisiceras onilahyense ammonite was preserved in marine sediments laid down beneath a warm Cretaceous sea. After the ammonite died, its shell settled onto the sea floor and became buried by fine sediment, carbonate mud or shell-rich material. Over millions of years, burial, compaction and mineral-rich groundwater transformed the remains into a fossil.
The result is a natural record of an ancient marine animal that lived during the Coniacian Stage, in an ecosystem very different from the modern coastline of Madagascar. The fossil captures a moment from the Late Cretaceous seas, when ammonites were still diverse and widespread across many parts of the world.
Authenticity and Display
This is a genuine Barroisiceras onilahyense ammonite fossil from the Coniacian, Upper Cretaceous of Tulear, Toliara, Madagascar. It includes a Certificate of Authenticity lifetime guarantee generic card and is suitable for fossil collectors, geology enthusiasts, educational collections, natural history displays, display cabinets or as a distinctive gift for anyone interested in prehistoric marine life.
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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