Ceraurus pleurexanthemus

Overview

Ceraurus pleurexanthemus is a trilobite with striking long spines spreading from both sides of its head and from its small tail shield. Follow the exoskeleton from the broad head through the segmented thorax to the tail.^[1]

Key facts

Bed 3 of the Walcott–Rust Quarry yielded many articulated specimens of varied sizes. The museum explains that specimens preserving appendages were also found and used in Walcott’s first descriptions of trilobite appendages.^[1]

Time and place

The museum introduces it as a trilobite commonly found in Trenton-age rocks in present-day central New York State, USA. That account labels this interval Middle Ordovician.^[1]

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

Size, form and skeleton

The thorax has eleven segments, and the broad, short head is roughly semicircular. Later comparative specimens MCZ111708 and MCZ111715 introduced by the museum measure 4.4 and 4.2 centimeters respectively.^[1]

Habitat and reproduction

The museum explains that the species is most common in strata representing deep continental-shelf environments. The spiny exoskeletons preserved in rocks now on land provide evidence for studying ancient marine life.^[1]

Fossil discovery

The species name traces back to Green’s 1832 description. The museum introduces later comparative specimens and Harrington’s 1959 reconstruction separately, using long-accumulated material to explain its form.^[1]

References

1. Ceraurus pleurexanthemus — Phylum Arthropoda
2. Pojeta et al. (2003) — Armour of a spiny Ordovician chiton
3. Harvard Museum of Comparative Zoology — Spines and articulated exoskeleton of Ceraurus

Research questions

The museum account brings together studies from 1913 and later. It tells a research story of sequential comparisons of grooves and small bumps on the head and the connections between thoracic segments and the tail.^[1]

Observation

Find the long spines on either side of the head in the illustration and count the eleven thoracic segments. Then follow the pair of long spines spreading from the small tail shield to examine the exoskeleton’s outline.^[1]