Portalia is regarded as a problematic organism awaiting a full redescription (Briggs and Conway Morris, 1986).
Portalia – from Portal Peak (2,911 m), north of the Burgess Shale in Banff National Park.
mira – from the Latin mirus, “wonderful,” in reference to the morphology of the animal.
Holotype –USNM83927 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Burgess Shale and vicinity: none.
Other deposits: none.
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
The Walcott Quarry on Fossil Ridge.
Brief history of research:
The only known specimen of Portalia was first illustrated by Walcott in a brief communication published in 1918 and refigured in a posthumous publication (Walcott, 1931). Walcott interpreted this fossil as a holothurian, a member of a group of echinoderms better known as sea-cucumbers. Madsen (1957) suggested Portalia might be a primitive sponge, but Durham (1974) thought that the holothurian affinity could not be rejected without further studies (see also Conway Morris, 1979). The relationships of Portalia remain difficult to establish (Briggs and Conway Morris, 1986).
The body of Portalia is sausage-shaped and the most distinctive features are a series of elongate tentacle-like structures covering the entire surface. These structures tend to split into several simple branches. A central strand within the body has been interpreted as part of the gut and the head has been tentatively identified as a darker indistinct area at one end.
Portalia is known from a single specimen.
Not enough is known about this organism to interpret its feeding strategy.