Plate with 4 Sowerbyella brachiopods

Scientific identification

Genus: Sowerbyella
Family: Sowerbyellidae
Common name: Strophomenid brachiopod
Author: Denis Arcand

The specimen corresponds to a small plate bearing four brachiopods attributed to Sowerbyella. These are most likely valves or internal/external molds of flattened strophomenids, preserved on an Ordovician shale matrix. Supported by: The BRA code in the filename designates Brachiopoda as the principal taxon, and Sowerbyella is the first taxonomic keyword. The expected appearance is that of small broad, subcircular brachiopod shells with a rounded outline, typical of a strophomenid. Species-level confirmation requires: A species-level determination would require more precise observation of ornamentation, convexity, hinge line, interarea, and possible internal details; the species is therefore not imposed here. Certainty: The filename indicates Sowerbyella as the principal taxon. The attribution is retained with good confidence at genus level, but the species is not forced without additional visible diagnostic characters.

Geology and provenance

Formation: Nicolet River Formation
Group: Lorraine Group
Locality: Écluse de Chambly
Region: Richelieu Valley
Province: Quebec
Country: Canada

Lithostratigraphy

Locality: CEDC- Chambly Écluse de Chambly Region: Richelieu Valley Formation: Nicolet River Formation Group: Lorraine Group Depositional environment: Soft muddy seafloor Note: The RPMF site code is associated with a shale site in the provided nomenclature. No precise formation is forced here.

Observed lithology

Description: Dark fine-grained fossiliferous shale bearing small brachiopods in low relief. Interpretation: Calm marine siliciclastic sediment favorable to the preservation of small flattened shells. Certainty: High confidence

Physical description

Assemblage description: Small fossiliferous plate bearing four brachiopods attributed to Sowerbyella on a dark shale matrix. Associated fossils: No certain associated fossil is indicated in the filename; possible secondary shelly debris may be present without being confirmed.

Matrix description

Fossil assemblage: Sparse shelly assemblage Fossil density: Low Species composition: Mixed / uncertain Plate surface: Weathered Relief: High relief Ornamentation: Fine growth lines Rock type: Calcareous Shale Color: Brown / Dark gray - Mottled - Medium-dark Shape: Sub-rounded block Dimensions: W 3.8 × L 5.1 × T 1.2 cm (centimeters) Approximate volume: 23.3 cm (centimeters)³ Note: Assemblage dominated by Sowerbyella; the plate appears to represent a small homogeneous set of brachiopods rather than a mixture of taxa. Additional note: Dimensions converted from the nomenclature code 1.5×2 inches. Thickness is estimated and should be verified on the specimen.

Taphonomy

Summary: Sowerbyella brachiopods preserved in low relief on a small shale plate from a calm marine environment. Evaluator: Paleontologist Transport origin: Indeterminate Occurrence position: Reworked Articulation: Moderate Fragmentation: High Abrasion: Low Compression: Low Observed processes: Small brachiopods preserved on a shale plate, probably as flattened valves or molds with low relief. Interpretation: The specimen probably represents a small concentration of benthic brachiopods preserved on a low-energy muddy marine seafloor. Taphonomic quality: B — Moderately good preservation of a small identifiable assemblage Justification: The principal taxon is identifiable at least to genus based on the nomenclature and expected appearance, even though the plate remains small and not highly detailed. Evaluation date: 2026-03-09T00:00:00

Palaeoecological interpretation

Interpretation: Small assemblage of benthic filter-feeding brachiopods living on or above an Ordovician muddy seafloor. Hypothesis: Sowerbyella probably occupied a relatively calm marine environment where fine mud favored burial and preservation of scattered or weakly concentrated valves. Certainty: Moderate; the general ecological interpretation is robust for strophomenid brachiopods, but the specific microenvironment remains uncertain. Note: The specimen mainly documents the local presence of strophomenid brachiopods in an Ordovician shale context.

Conservation state

General state: Fair Stability: Monitor closely Scientific readability: Poor Note: The specimen remains interpretable and displayable, but matrix friability requires cautious handling.

Museum exhibition value

Provenance: Type or figured specimen provenance documented Aesthetic appeal: High aesthetic and educational value Systematic collections: Systematic value not assessed Note: Modest museum interest but good educational potential as a small example of an Ordovician brachiopod.

Scientific value

Completeness / preservation: Poor preservation with limited diagnostic features Taxonomic novelty: Not evaluated for taxonomic novelty Note: Useful specimen for documenting the presence of small strophomenid brachiopods in an Ordovician shale, with good comparative value within the collection.

Public exhibit text

This small plate preserves several brachiopods attributed to Sowerbyella, a filter-feeding marine invertebrate that lived on muddy seafloors more than 450 million years ago.