Worthenella cambria (USNM 57643) – Holotype, part and counterpart. Left, plate 22 of Walcott (1911), showing a retouched image of the original specimen described (figure 2) together with other “worms.” Right, images of the same specimen. Specimen length = 60 mm. Specimen wet – direct light (left column), dry – polarized light (right column). Walcott Quarry.
© SMITHSONIAN INSTITUTION – NATIONAL MUSEUM OF NATURAL HISTORY. PHOTOS: JEAN-BERNARD CARON
This animal is related to arthropods, but its systematic status within this group is unknown (Briggs and Conway Morris, 1986).
Worthenella – Possibly after the American palaeontologist Amos Henry Worthen, who died in 1888, just as Walcott’s career was taking off.
cambria – from the Welsh Cambria meaning Wales, in reference to the age of the fossil.
Burgess Shale and vicinity: none
Other deposits: none
The Walcott Quarry on Fossil Ridge.
Worthenella was first described by Walcott from a single specimen in a 1911 monograph dealing with various Burgess Shale worms. Walcott interpreted this animal as a polychaete annelid (or bristle worm), in the same family as the animal Wiwaxia (which is now interpreted as a primitive mollusc). However, this interpretation was questioned (Conway Morris, 1979), and the affinities of Worthenella have remained difficult to establish because this singular fossil is too poorly known (Briggs and Conway Morris, 1986).
The animal is elongate with a small head and bears at least 46 segments of similar dimensions. Appendages or tentacles are present beneath the head, but their preservation is poor and it is difficult to know their precise nature and arrangement. The anterior 34 segments seem to bear filamentous branches on their ventral sides, with the following 8 segments equipped with longer appendages. The gut is straight and the anus is terminal.
This animal is known from a single specimen.
Not enough is known about this organism to interpret its ecology.
BRIGGS, D. E. G. AND S. CONWAY MORRIS. 1986. Problematica from the Middle Cambrian Burgess Shale of British Columbia, p. 167-183. In A. Hoffman and M. H. Nitecki (eds.), Problematic fossil taxa (Oxford Monographs on Geology and Geophysics No. 5). Oxford University Press & Clarendon Press, New York.
CONWAY MORRIS, S. 1979. The Burgess Shale (Middle Cambrian) fauna. Annual Review of Ecology and Systematics, 10(1): 327-349.
WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.
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