Waukeshaaspis eatonae
- 演化之聲
- Mar 18
- 2 min read
Updated: 2 days ago
Age
Silurian（Telychian）
435 Ma
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Trilobita
Order: Phacopida
Family: Dalmanitidae
Genus: Waukeshaaspis
Species: Waukeshaaspis eatonae
Morphological description
Waukeshaaspis eatonae is a medium-sized trilobite with noticeable variation among individuals. The average body length is approximately 6 cm. The cephalon is semicircular in shape, and the genal spines are relatively long, extending posteriorly to reach the pygidium. A distinct facial suture is present on the cephalon, facilitating molting. The pygidium exhibits a pronounced median embayment along its posterior margin.
Etymology
Waukesha: refers to the locality where the fossils were discovered
-aspis: derived from the Greek word for shield
Species name: in honor of Carrie Eaton
Biological description
Fossils of Waukeshaaspis eatonae were discovered in the Waukesha Biota of Wisconsin, a fossil assemblage containing a variety of trilobites. However, most trilobite specimens from this biota are fragmentary and rare. In contrast, Waukeshaaspis eatonae is exceptionally well preserved, with approximately 200 specimens recovered, indicating that this species likely held a strong ecological advantage in its environment.
The pygidium displays a distinct embayment, contrasting sharply with the caudal spines commonly observed in other dalmanitid trilobites. Caudal spines have been proposed to be associated with burrowing or enrollment behavior, which initially led to the assumption that this species lacked such capabilities. However, subsequent observations show that within Dalmanitidae, species with elongated genal spines typically possess either reduced caudal spines or none at all. This suggests that the genal spines may have functionally replaced the role of the caudal spine. The pygidial embayment may therefore have served a different function, potentially related to respiration or waste expulsion while the animal was enrolled.
All known specimens of Waukeshaaspis eatonae represent adult individuals. The absence of juvenile specimens is most likely the result of taphonomic bias rather than a true absence in the original population.
（Author: Bai Leng）
Reference
Randolfe, E. A., Gass, K. C. (2024). Waukeshaaspis eatonae n. gen. n. sp.: a specialized dalmanitid (Trilobita) from the Telychian of southeastern Wisconsin. Journal of Paleontology.
42.722374, -88.899974
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