© Marianne Collins
In the journal Nature, the University of Toronto's Martin Smith and the Royal Ontario Museum's Jean-Bernard Caron, describe Nectocaris pteryx, a puzzling soft-bodied creature found in the Burgess Shale, a renowned fossil site in Canada.
Long thought perhaps a shrimp ancestor, a newly-found fossil reveals the creature was instead an ancestral cephalopod, albeit with two-tentacles instead of eight seen in modern octopi. The find, "extends the cephalopods' fossil record by over 30 million years, and indicates that primitive cephalopods lacked a mineralized shell, were hyperbenthic (seabed-dwelling), and were presumably carnivorous," says the study.
© Jean-Bernard Caron
"The funnel's position and shape fits comfortably within the range of morphologies observed in extant cephalopods," write the authors.
The find suggests shells typical of later cephalopods evolved along the way and were not a starting feature of the species, suggests Stefan Bengtson of the Swedish Museum of Natural History, in a commentery accompanying the report:
"Cephalopods, uniquely among animals, have invented directed jet propulsion by the effective use of a funnel, or siphon, through which water can be expelled from a body cavity at high speed and in any direction. This funnel is what can send them shooting out of the water, and a similar feature now seems to propel Nectocaris out of the murky sea of enigma into a position as a possible stem-group cephalopod - that is, one that preceded the last common ancestor of all living cephalopods (the crown-group cephalopods) but that still had evolved one"Bengston suggests that researchers need to confirm that Nectocaris pteryx possessed a radula, a shelled ribbon used to manipulate food in today's cephalopods, before the new species can be definitively added to the family.
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