Reconstruction of Waptia fieldensis.
© MARIANNE COLLINS
Waptia belongs to its own family, Waptiidae, along with a few other similar forms, most notably Chuandianella from China (Hou & Bergström 1991). Outside of its palp-bearing mandibles, Waptia possesses limbs with 5-segmented distal branches typical of pancrustaceans (the group including crustaceans and hexapods) (Vannier et al. 2018), but the pancrustacean affinity of waptiids and other hymenocarines remains in question.
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.
Burgess Shale and vicinity: none.
Other deposits: Waptia cf. fieldensis from the Spence Shale Member of the Langston Formation, Utah (Briggs et al. 2008).
The Walcott and Raymond Quarries on Fossil Ridge
Waptia was first described by Walcott (1912), who designated Waptia fieldensis as the type species of the genus. Various authors commented on its affinities (e.g., Briggs 1983; Briggs et al. 1994; Hou & Bergström 1997; Walossek & Müller 1998; Wills et al. 1998; Bergström & Hou 2005). Waptia cf. fieldensis has 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 & 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 & Shu 2004, 2008; Hou et al. 2009; Zhai et al. 2022). Waptia specimens from the Burgess Shale were more recently comprehensively restudied and redescribed by Vannier et al. (2018), documenting clear mandibulate affinities and possible shared characters with pancrustaceans. Waptia and Chuandianella have also served to document early brood care via the preservation of eggs under the carapace, with different egg sizes between genera (Caron & Vannier 2016; Ou et al. 2020), and later developmental stages (Liu et al. 2022).
Like other hymenocarines, Waptia has a tubular body with segmental “rings” enclosed in a bivalved carapace. Mandibles are well developed and located very anteriorly, close to the insertion of the two large, pedunculate eyes and elongate antennules, without evidence of post-antennular appendage. Between the eyes, a sclerite covers additional sensory organs. It also bears paired semi-rigid flaps for its tailpiece, called caudal rami. However, the morphoanatomy of Waptia also substantially departs from that of other hymenocarines. The maxillules, behind the mandibules, are differentiated, bearing a rounded brush-like element distally. The following three pairs of appendages are similar and raptorial: they are uniramous, with four basal podomeres (limb segments) bearing strong spinose extensions called endites, and five terminal podomeres, including the claw. The seventh pair of appendage has a similar distal part with five podomeres, but the basal part is instead made of annulations bearing short lamellae. The following six pairs are entirely annulated, and bear much longer and wider lamellae. Body segments bearing these limbs are distinct, but segments housing the last two pairs are fused. The remaining posterior body is an abdomen (limbless).
Waptia is common in the Burgess Shale, with over 1,400 specimens collected from the Walcott Quarry (Conway Morris 1986; Caron & Jackson 2008) and 70 specimens collected from the Raymond Quarry.
The large lamellar thoracic appendages of Waptia clearly point to a swimming lifestyle. The frontal “basket” of raptorial limbs and mandibles with palps point in turn to a distinct role in predation, food manipulation and mastication. Similar to a number of modern crustaceans, like shrimps, Waptia was brooding eggs under its carapace rather than depositing them in sediment.
http://paleobiology.si.edu/burgess/waptia.html