Unranked clade (stem group arthropods)
It has been suggested that Waptia is closely related to Canadaspis and Perspicaris (Briggs and Fortey, 1989), with the group being allied to the crustaceans (Briggs, 1983; Wills et al., 1998; Briggs et al., 2008). However, some researchers argue instead that Waptia is at most a stem-lineage crustacean (Bergström and Hou, 2005), or perhaps even in the stem lineage to the arthropods (Hou and Bergström, 1997; Walossek and Müller, 1998).
Waptia – from Wapta Mountain (2,778 m), just north of Fossil Ridge, in British Columbia, Canada, named after the Stoney First Nation Nakoda word “Wapta” meaning “running water.”
fieldensis – from Field, the mountain peak (2,643 m) and small town near Fossil Ridge, British Columbia, Canada. The name was given by William Cornelius Van Horne (General Manager of the Canadian Pacific Railway), to honor Cyrus West Field a promoter of the first telegraph cable across the Atlantic Ocean.
Syntypes –USNM57681 andUSNM57682 (W. fieldensis) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Burgess Shale and vicinity: none.
Other deposits: Waptia cf. fieldensis from the Spence Shale Member of the Langston Formation, Utah (Briggs et al. 2008).
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
The Walcott and Raymond Quarries on Fossil Ridge
Brief history of research:
Waptia was first described by Walcott (1912), who designated Waptia fieldensis as the type species of the type genus. Various authors have since commented on its affinities (e.g. Briggs, 1983; Briggs et al., 1994; Hou and Bergström, 1997; Walossek and Müller, 1998; Wills et al., 1998; Hou and Bergström, 2005). However, no detailed work on its morphology has since been completed. Despite this, specimens of Waptia cf. fieldensis have been described from the Spence Shale in Utah (Briggs et al., 2008), and Waptia has been compared to Pauloterminus spinodorsalis from the Sirius Passet biota in North Greenland (Taylor, 2002). Waptia-like specimens from southwest China (Li, 1975; Hou and Bergström, 1991) were at one point assigned to Waptia (Chen, 2004), but a re-examination of the specimens showed they were different enough to be assigned to their own genus, Chuandianella (Liu and Shu, 2004, 2008; Hou et al., 2009).
Waptia bears a bivalved head shield consisting of two roughly oval valves that narrow anteriorly and fold along a median line that functions as a hinge. Beneath this carapace, the head bears a pair of long, slender antennae and a pair of small eyes on stalks. Details of other head appendages cannot be seen due to compaction against the head and carapace. The body trunk is long and slender and bears ten pairs of appendages. The first four pairs of appendage are segmented walking limbs with terminal spines and setae on their back margin, and the next six pairs of appendages are segmented branches lined with setae (hair-like bristles) and bearing blade-shaped filaments. Behind these appendages there is an abdomen consisting of five elongated segments. The abdomen terminates in a forked tail that consists of two oval blades. The trace of a straight gut is apparent in some specimens, stretching from the head to the base of the forked tail.
Waptia is common in the Burgess Shale, with over 1,400 specimens collected from the Walcott Quarry (Conway Morris, 1986; Caron and Jackson, 2008) and 70 specimens collected from the Raymond Quarry.
Waptia lived on or near the sea floor and scavenged for food. It used its two types of appendages to both walk on the sea floor and to swim through the water column. The first four pairs of segmented walking limbs would have been used for balancing and moving around on the sea floor, and the animal could have propelled itself through the water column by waving the bladed filaments of the posterior six appendages. The tail flaps would have helped stabilize and steer Waptia while swimming. The bladed filament may also have had a use in gas exchange. The eyes and antennae were presumably used to sense the environment, and the head appendages would pick up food particles in the sediment and bring them to the mouth.