Spiriferina walcotti

Overview

Spiriferina walcotti is an Early Jurassic brachiopod with a transversely broad shell. A long hinge and raised central fold characterize its exterior. It offers a broad outline different from that of a rounded bivalve.^[1]

Key facts

Radial ridges extend on either side of the raised central region. Examine the horizontal line formed by the long hinge alongside the outward-spreading ridges. Lines running in different directions provide clues to the shell’s shape.^[1]

Time and place

The species literature discusses Sinemurian material from the Early Jurassic. The entire Jurassic spanned approximately 200–140 million years ago. Specimen 0.245 in a study of the Gaillac museum collection connects to the description.^[1][2]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

The outline of the two closed valves is broad across, with a long hinge at the rear. A prominent central fold and radial ridges on both sides are described. Overall silhouette and surface structures can be examined at different scales.^[1]

The Spiriferina walcotti specimen at the Gaillac museum has a shell length of 17.5 mm, width of 26.2 mm, and thickness of 14.3 mm. This small shell came from Early Jurassic strata at Baupte, France, and bears coarse folds spreading on either side of a central elevation.^[3]

Habitat and reproduction

The two valves surround the body inside. Material of this species reveals the broad outline formed by the closed valves. Following the conspicuous fold and ridges in turn allows the outer covering to be read.^[1]

Fossil discovery

A study of the Eudes-Deslongchamps collection at Gaillac connected species descriptions with plates. Specimen 0.245 is linked to the description of Spiriferina walcotti. This research revisits old fossils by reading collection numbers, text, and illustrations together.^[1]

References

1. Gaillac Museum study — Spiriferina walcotti
2. International Commission on Stratigraphy (2024) — Geological time chart
3. Alméras et al. (2014) — Les Brachiopodes de la collection Eudes-Deslongchamps du muséum de Gaillac
4. Makridin (1964) — The shell and variation of Rhynchonella
5. Study in the Sorbonne collection — Shell of Rhynchonella rouillieri

Research questions

Where should comparisons of a broad shell begin? The long hinge, central fold, and ridges spreading to either side are separate features. Looking beyond overall resemblance and separating each part helps explain species descriptions.^[1]

Observation

First look at the horizontal line of the long hinge and locate the raised central fold. Following the ridges spreading to either side reveals the broad shell’s outline and surface form together.^[1]