Pygocephalus cooperi

Overview

Pygocephalus cooperi is a crustacean known for a front shield, segmented abdomen, and tail fan. Specimens connecting its body regions and other specimens revealing leg arrangement have been studied. Clues from small fossils together reveal its overall organization.^[1]

Key facts

GSC 12858 preserves structures extending from the shield through the thorax and abdomen, along with elements of the tail fan. Connections among major body regions are useful. They can be compared with leg evidence from other specimens.^[1]

Time and place

It is known through research on Carboniferous crustacean material. The Carboniferous spanned approximately 360–300 million years ago. A 2026 study examined pygocephalomorph specimens and cuticular structures together.^[1][2]

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

Size, form and skeleton

The thoracic region lies beneath the front shield, followed by a segmented abdomen and tail fan. GSC 12810 and 12811 provide comparative evidence for thoracic-leg arrangement. Major regions of the front body, abdomen, and tail can be examined alongside small appendages.^[1]

The type specimen of Pygocephalus cooperi measures approximately 3.5 cm from the base of the antennules to the abdomen. Its ventral exposure reveals plates beneath the thorax and leg attachment sites. This length measures a specimen with the abdomen preserved folded.^[3]

Habitat and reproduction

Are the trunk and legs always preserved in the same way? Some specimens reveal connections between major regions, while others show the arrangement of thoracic legs. Different evidence combines to explain the crustacean’s body.^[1]

Fossil discovery

A 2026 study separately described the preserved regions of several specimens assigned to the species. A specimen with connected shield and abdomen, leg material, and tail-fan elements were used in morphological comparisons. Research can continue through several clues even when no single fossil provides every answer.^[1]

References

1. Laville et al. (2026) — Specimens and exoskeletal structure of Pygocephalus
2. International Commission on Stratigraphy (2024) — Geological time chart
3. Pinto·Würdig (2014) — Reassessment of Pygocephalus morphology and classification
4. Charbonnier·Garassino (2012) — Solnhofen arthropods in the Paris Natural History Museum
5. National Museum of Natural History, Paris — Age and locality of specimen A33518 from Eichstätt

Research questions

How does the end of a segmented abdomen connect to a tail fan? Comparing abdominal and tail elements suggests how several appendages compose the rear of an elongated body. This research examines small connections within a broad outline.^[1]

Observation

Move your gaze from the front shield to the segmented abdomen and tail fan. Examining thoracic-leg positions separately reveals different arrangements within each body region.^[1]