MicroCT Reveals Detailed Head Morphology of Arthropod, Leanchoilia illecebrosa
Tomographic models of Leanchoilia illecbrosa juveniles from the Cambrian (Stage 3) Chengjiang biota of South China (A) YKLP11423, 5mm-long juvenile, ventral view; (B) YKLP11422, 7mm-long juvenile, ventral view.

Javier Ortega-Hernández and Yu Liu, Professor of Paleobiology, Yunnan University, China have collaborated for years in the study of Chengjiang arthropods and their evolutionary significance.

Their latest paper in Current Biology shows with unprecedented clarity the head morphology of the species Leanchoilia illecebrosa – a member of Megacheira, a major extinct group characterized by distinctively raptorial great appendages. Ortega-Hernández’s and Liu’s reexamination of Leanchoilia demonstrates the presence of a labrum – a flap-like structure overlying the mouth opening in most modern arthropods – and offers renewed support to the hypothesis that megacheirans are distant relatives of modern chelicerates (e.g. horseshoe crabs, scorpions and spiders).

The Chengjiang biota in the Yunnan Province of China contains one of the most species-rich and well-preserved fossiliferous deposits for the early Cambrian (ca. 518 million years old), including numerous arthropod species.

However, several Chengjiang arthropods have an unfamiliar morphology, are extremely rare, or are incompletely preserved, which often leads to many of these species being problematic, poorly known, or often both, thus hindering their contribution towards reconstructing the evolution of this major animal group.

This paper is the fifth in a series of publications that represent an ongoing collaboration between the research groups led by Ortega-Hernández and Liu to study and restudy these fossils. This study along with others in Current Biology (v29:1, 2019), BMC Evolutionary Biology (v19, 2019, and v20, 2020), and Geological Magazine (March 27, 2020) consists of the study, and often restudy, of exceptional arthropod fossils from the early Cambrian (ca. 518 million years ago) using microCT to reveal exceptional details of the preserved anatomy that are completely inaccessible through conventional preparation tools. EurekAlert! press release.