Organism · Arthropods
Naraoia spinosa
Source time context (not species duration) · ≈ 539–487 Ma
Inferred life reconstruction
Naraoia spinosa
Overview
Naraoia spinosa is an arthropod with appendages beneath two shields covering the head and trunk. Its head shield is described as semicircular and its form as eyeless. It invites us to consider two large shields together with the small structures underneath.[1]
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Key facts
The description of a museum specimen recorded as this species also notes traces of the digestive tract. Clues preserved inside the body can be explored alongside its external shields.[4]
Time and place
It is known from Maotianshan and Yu’anshan Member material at Chengjiang in present-day Yunnan. Its occurrence has a Cambrian context. The Cambrian as a whole was roughly 540–490 million years ago.[4][3]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
A trunk shield follows the semicircular head shield. A pair of antennae lies at the front, and two-branched appendages connect to the body beneath the shields. Paired large spines and a concave margin between them are described at the rear.[1]
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Habitat and reproduction
What information survives beneath the two large shields? The museum describes appendage connections and traces of the digestive tract preserved in the specimen. Observation can broaden from the large outer shields to structures beneath and inside them.[1][4]
Fossil discovery
The museum record NMNS002459-F029429 connects the name Naraoia spinosa with traces of a digestive tract. A public 2007 abstract addressed two forms of this species and coexistence with other naraoiids. Internal specimen traces and comparisons among forms convey different questions.[4][2]
References
- National Museum of Natural Science — Two shields and appendages of Naraoia
- Zhang·Shu·Erwin (2007) — Cambrian naraoiids
- International Commission on Stratigraphy (2024) — Geological time chart
- National Museum of Natural Science — Naraoia spinosa specimen
- Royal Ontario Museum — Waptia fieldensis species account
- International Commission on Stratigraphy (2024) — Geological time chart
- Royal Ontario Museum. The Locality Today.
- Waptia — Study of a mandibulate arthropod from the Burgess Shale
- National Museum of Natural Science — Naraoia spinosa specimen
- International Commission on Stratigraphy (2024) — Geological time chart
- National Museum of Natural Science — Two shields and appendages of Naraoia
- Naraoia: a museum knowledge entry linked to the species
Research questions
What should be compared when fossils of the same species occur in two forms? The construction of the large shields and features of several specimens need to be examined together. The 2007 study addressed dimorphism while comparing the varied forms of naraoiids.[2]
Observation
Move your gaze from the semicircular head shield to the trunk shield behind it. Imagining the appendages below the shields and the paired posterior spines helps separate observation of the large shields from their small connections.[1]
Related organisms
Waptia fieldensisArthropodsSource time context (not species duration) · ≈ 539–487 MaArthropods of the Burgess Shale and Chengjiang
Waptia and Naraoia are Cambrian arthropods known from different fossil localities. Connect material from the Burgess Shale in present-day Canada and Chengjiang in Yunnan, China, to compare different arrangements of carapaces or shields and the appendages beneath them.