Description
Callianassa twinensi Fossil Crab in Nodule – Pysht Formation, Oligocene Epoch, Clallam County, Washington, USA
This is a professionally collected fossil specimen of Callianassa twinensi, a species of ghost shrimp-like decapod crustacean preserved within a natural stone nodule. It comes from the Pysht Formation, located in Clallam County, Washington, and dates to the Oligocene Epoch, approximately 28 to 23 million years ago.
Fossil Type & Species:
- Type: Invertebrate Fossil (Decapod Crustacean – Ghost Shrimp/Crab)
- Species: Callianassa twinensi
- Phylum: Arthropoda
- Class: Malacostraca
- Order: Decapoda
- Infraorder: Axiidea (ghost shrimps)
- Family: Callianassidae
- Described by: Rathbun, 1926
Geological & Stratigraphic Details:
- Location: Clallam County, Washington State, USA
- Formation: Pysht Formation
- Geological Age: Late Oligocene
- Epoch: Oligocene, Paleogene Period
- Age Range: ~28–23 million years ago
- Depositional Environment: Nearshore marine deltaic or estuarine setting, with fine-grained sediments forming nodular concretions around decaying organisms
- Biozone: Associated with benthic marine faunas typical of Oligocene Pacific Northwest
Morphology & Features: This fossil Callianassa twinensi shows:
- Preservation in a rounded calcareous nodule, cracked or split to reveal fossil detail
- Claw, carapace, or appendage impressions often visible depending on preparation
- Articulated segments and exoskeleton detail, occasionally displaying both claws and thorax
- Color and surface structure preserved in hues of beige, grey, or brown due to diagenetic minerals
Notable: Callianassa twinensi is a significant Oligocene crustacean species and is among the best-documented fossil ghost shrimp from the Pacific Northwest. Nodules from the Pysht Formation are highly sought after for their exceptional preservation of soft-bodied marine organisms. These concretions often preserve fossils in remarkable three-dimensional detail, making them favorites among collectors and researchers.
Specimen Details:
- Origin: Pysht Formation, Clallam County, Washington, USA
- Species: Callianassa twinensi
- Fossil Type: Decapod Crustacean in Concretion (Nodule)
- Geological Age: Late Oligocene Epoch
- Size Reference: Scale rule cube = 1cm (see photo for actual dimensions)
- Note: The exact specimen photographed is the one you will receive
Authenticity & Quality: This fossil is 100% genuine and collected from its original locality. It comes with a Certificate of Authenticity and has not been artificially enhanced or restored.
Why Choose This Fossil? Ideal for:
- Collectors of marine invertebrates and fossil crustaceans
- Educational use in palaeontology and arthropod evolution
- Geological research or natural history exhibitions
- Unique and display-worthy fossil gifts
Shipping & Packaging: We use eco-conscious packaging and tracked worldwide shipping. Every item is handled with great care to ensure it reaches you in perfect condition.
Add a rare and scientifically significant fossil decapod to your collection with this authentic Callianassa twinensi from the Pysht Formation.
All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.
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