A possible Lower Cambrian Chaetognath (arrow worm). (Paleontology)

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Date: Oct. 4, 2002
From: Science(Vol. 298, Issue 5591)
Publisher: American Association for the Advancement of Science
Document Type: Article
Length: 890 words

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The phylum Chaetognatha (also called arrow worm), with only about 100 living species, is found in oceans throughout the world and plays an important role in the food web as primary predators (1). Its fossil record, however, is sparse. The Carboniferous Paucijaculum samamithion has been the only definitive fossil chaetognath (2). Some of the Cambrian protoconodonts could be grasping spines of this group (3). The Middle Cambrian Amiskwia was considered as a chaetognath (4), but with a sluglike head, terminal anus, and cephalic tentacles, it could well be a mollusk.

We report a probable chaetognath Eognathacantha ercainella from the Lower Cambrian Maotianshan Shale [about 520 million years (Ma) old] near Haikou, Kunming (South China). The single specimen is an adult, 25 mm long. A certain straightness in preservation suggests that the body in Eognathacantha ercainella may have been relatively rigid. It consists of a head, a trunk, and a possible tail (Fig. 1, A and C). The rounded head is wider than long (Fig. 1, B and D), measuring about 2.8 mm in width; it is wider than the rest of the body. Projecting anteriorly and laterally from the head are about 12 slightly recurved grasping spines, each about 900 [micro]m long (Fig. 1B). As in modern chaetognaths, the spine bears an expanded base (Fig. 1B), which is likely embedded within the...

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Gale Document Number: GALE|A93457155