Diplacanthograptus spiniferus

Overview

Diplacanthograptus spiniferus is an Ordovician graptolite with small tubes arranged in rows. Repeated tubes can be examined along its long, slender colonial skeleton. This illustration is based on the outline of the colonial skeleton of specimen GSC31729.^[1]

Key facts

The whole specimen and the enlarged basal view in the paper show the same fossil. TextFig4i presents the full, elongated colonial skeleton, while 4j details the base with its short, stout spines. Looking first at the overall form and then at a small part reveals different information from a single specimen.^[1]

Time and place

It is a graptolite that lived during the Ordovician. GSC31729, the basis of the illustration, came from Lower Utica strata at Neuville in present-day Quebec, Canada. The paper examined the species by comparing material from several localities in northeastern North America.^[1]

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

Size, form and skeleton

The colonial skeleton gradually widens upward from its base, with repeated boundaries of small tubes along the edges. Two short, diverging spines are visible at the base. Among the species’ specimens, the 1974 study also described colonial skeletons at least 7 cm long excluding their basal spines.^[1]

Habitat and reproduction

The study includes fossils collected from several strata, including the Utica Shale of present-day Quebec and New York. Tubular skeletons preserved at separated localities provide material for comparing organisms of ancient seas. It is also interesting to follow the forms in which the same species survived at different sites.^[1]

Fossil discovery

Riva’s 1974 paper brought together earlier names and illustration records for this species. Its bibliography includes a varietal name from 1908 followed by a species name from 1912. Connecting the current name with names in older literature lets us read a long accumulation of specimen records together.^[1]

References

1. A revision of some Ordovician graptolites of eastern North America
2. Maletz·Klafack (2026) — Colonial graptolites on the seafloor
3. Riva (1974) — Comparative study of Ordovician graptolites of North America

Research questions

The researchers noted variation among specimens in the length, thickness, and bilateral arrangement of basal spines. Some spines are thin and long; others are short and thick. Comparing such differences across specimens helps distinguish similar-looking graptolites and understand variation within one species.^[1]

Observation

The representative magnet repeats the same reconstruction motif in a decorative arrangement. Grouping and spacing are artistic; the description below concerns each source motif. The illustration presents the colonial skeleton of one specimen in Riva’s TextFig4i–j in an accessible form. First find the slender overall outline and the two basal spines. The upper part retains the oblique orientation of the original drawing, while color and shading are interpretations used to show the skeletal arrangement.^[1]