#trigoniida

[uk-fossils]

Polished Fossil Bivalve | Lower Cretaceous Madagascar | Genuine Specimen with COA

Add a polished piece of prehistoric marine life to your collection with this exquisite Fossil Bivalve from the Lower Cretaceous period, discovered in Madagascar. Carefully polished to enhance its natural beauty, this specimen is a unique example of ancient marine molluscs and a stunning addition to any fossil or natural history collection.

Fossil Type: Bivalve Mollusc

Geological Period: Lower Cretaceous (~145 to 100 million years ago)

Location: Madagascar

Scale Rule: Squares/Cube = 1cm (Please see photo for full sizing details)

Specimen: The photo shows the exact item you will receive

Authenticity: All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity

Geological and Paleontological Information

This fossil bivalve originates from marine deposits formed during the Lower Cretaceous, a time when Madagascar was part of the southern supercontinent Gondwana. These ancient seas supported a diverse array of molluscs, including bivalves like this example. While the exact genus and species are not specified, bivalves from this region and period are often linked to families such as Trigoniidae, Inoceramidae, or Ostreidae, common in Cretaceous marine strata.

Phylum: Mollusca

Class: Bivalvia

Morphological Features: Typically two symmetrical shells joined by a hinge; this specimen is polished to reveal structural details such as growth lines, shell ridges, and colour banding within the mineralised shell

Depositional Environment: Shallow marine environment with fine-grained sediment, conducive to fossilisation of shell-bearing organisms

Geological Stage: Likely from the Barremian to Aptian stages of the Early Cretaceous (specific stratigraphy not provided)

Notable Aspects

Polished fossil bivalves from Madagascar are prized for their excellent preservation and the stunning patterns that emerge when polished. These fossils represent not only a window into marine life over 100 million years ago but also the geological history of Madagascar's evolving sedimentary basins.

Why Buy From Us?

100% genuine fossil guaranteed with Certificate of Authenticity

Polished for display, study, or gifting

Carefully sourced and curated specimen

Actual item shown in photographs

Own a beautifully preserved piece of natural history today with this authentic polished fossil bivalve from the Lower Cretaceous of Madagascar — a true relic of Earth’s ancient oceans.

[anticlluis]

FOSIL DE PTEROTRIGONIA

Periodo: Mesozoico / Cretácico superior

Antigüedad: 110 millones de años

Reino: Animalia

Filo: Mollusca

Clase: Bivalvia

Orden: Trigoniida

Familia: Trigoniidae

Género: Pterotrigonia

Especie: Pterotrigonia coihuicoensis

Peso: 167 g

Tamaño: 57 x 70 x 47 mm

40 € más gastos de envío

[alphynix]

Almost-Living Fossils Month #16 -- Fancy Triangle Clams

Trigonia was a genus of bivalve mollusc that first appeared in the Middle Triassic, around 245 million years ago. Part of a much older lineage (the trigoniidans) that originated over 400 million years ago in the Late Silurian or Early Devonian, and distantly related to modern freshwater mussels, these bivalves have been found in marine deposits all around the world.

Their triangular shells had complex internal hinges, and often featured elaborate patterns of ribs and tubercules (which may have been adaptations to increase burrowing efficiency) that made them very visually distinctive. They lived mainly in shallow coastal environments, and in some places their fossils are so common that they must have been very numerous animals in their ecosystems.

Trigonia costata was a species living in Europe during the Early-to-Middle Jurassic (~174-166 mya), around the time when the trigoniidans were exploding in diversity. Usually around 5-7.5cm in length (2-3″), it was one of the longest-lasting individual species of Trigonia and one of the most common at the time.

Along with their other trigoniidan relatives, various Trigonia species continued to evolve throughout the entire rest of the Mesozoic, and while almost all of them went extinct at the end of the Cretaceous a few did manage to hang on into the Cenozoic.

The last record of an actual Trigonia comes from Argentina at the very end of the Paleocene, about 56 million years ago. After a nearly 200-million-year run, this long-lived genus finally disappeared -- but although Trigonia itself was gone, that wasn’t quite the end of the trigoniidans altogether.

A single remaining lineage quietly continued on all the way into modern day, either descended from one of the Trigonia species or very closely related to the genus, living in waters off the coast of Australia and Tasmania. Known as Neotrigonia, they’re not quite as elaborately ornamented as some of their ancient relatives, but their complex shell hinges give them away as the only living trigoniidans -- and their anatomy can give us some hints about what Trigonia’s soft tissue parts may have looked like, such as the presence of an unusual boot-shaped muscular foot that helps them burrow rapidly into the seafloor.

[e-ziara]

🌊🌊 🐚 BENTHIARY 🐚 🌊🌊 day 1-2 I'm starting out Benthiary with the living fossil of Tasmania, Neotrigonia Margariteacea! It's the first of their family Trigoniidae to be discovered alive and now there's at least 8 of them total. Because of their ornamental look, these saltwater clams are also known as pearly brooch shells ✨ ✨ Some Ernst Haeckel influence here; I really really want to own his books! I just want to be an artsy naturalist ( = c = ) Really in love with my new black sketchbook. I'll be doing the rest of Benthiary starting from the most visible macrobenthos organisms to the tiny microbenthos creatures 💖