Mosura fentoni
- 演化之聲
- Mar 20
- 3 min read
Updated: Apr 9
Age
Cambrian（Miaolingian）
505 Ma
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Dinocaridida
Order: Radiodonta
Family: Hurdiidae
Genus: Mosura
Species: Mosura fentoni
Morphological description
Mosura fentoni is known from a total of 60 specimens collected between 1990 and 2022. Its body length ranges from approximately 1.5 to 6.1 cm, making it one of the smallest known radiodonts. The head is subrectangular in shape and relatively short, comprising about 15% of the total body length.
Mosura fentoni possesses three eyes: a pair situated on lateral eye stalks and a single median eye positioned centrally on the dorsal surface of the head. The appendages bear six elongate endites. The trunk comprises up to 26 segments, representing the highest segment count known among radiodonts. The body is divided into a head, neck, and trunk. The neck consists of four segments, while the trunk is further subdivided into an anterior region of six segments (mesotrunk) and a posterior region composed of up to 16 segments (posterotrunk). As in other radiodonts, paired lateral flaps are present along the body; those on the anterior trunk are substantially larger than those on the posterior region.
Juvenile individuals possess fewer trunk segments. Evidence suggests that, during growth, additional posterior segments develop and become integrated with the anterior trunk region. This developmental pattern is uncommon but has been observed in a few other early arthropods, such as members of Fuxianhuiida.
Etymology
The generic name Mosura is derived from the fictional moth-like monster Mothra from Toho films, referring to the animal's overall appearance.
The species name honours Peter E. Fenton, a technician in the Invertebrate Palaeontology Department at the Royal Ontario Museum, in recognition of his long service and close collaboration with the authors.
Biological description
Fossils of Mosura fentoni have been discovered in the Burgess Shale of British Columbia, Canada, including localities such as Marble Canyon. The holotype specimen (ROMIP 67995) is a complete individual preserved in dorsal view. Additional important specimens include ROMIP 66108, ROMIP 67998, ROMIP 68004, ROMIP 69999, and ROMIP 67979, many of which preserve internal anatomical structures.
Mosura exhibits a combination of morphological traits seen in both hurdiid and non-hurdiid radiodonts. Phylogenetic analyses place it in a basal position within Hurdiidae, forming a sister relationship with other members of the family.
Based on its morphology, Mosura is interpreted as a small, actively swimming, nektonic predator. The absence of filtering structures such as setae or auxiliary spines on the endites indicates that it was not adapted for suspension feeding. Instead, the elongate, curved endites likely functioned as hooks to capture relatively large prey. It is inferred that Mosura grasped prey with its endites and then rotated the appendages backward to bring the prey toward the mouth for ingestion.
Its relatively small body size is considered to be closely related to ecological resource partitioning. Compared to other coexisting macrophagous radiodonts from the same localities, Mosura is significantly smaller, suggesting that it specialized in preying upon smaller organisms.
（Author: Bai Leng）
Reference
Moysiuk, J., Caron, Jean-Bernard (2025). Early evolvability in arthropod tagmosis exemplified by a new radiodont from the Burgess Shale. Royal Society Open Science.
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