Discussion on the systematic position of the Early Cambrian priapulomorph worms

Response to “Discussion on the systematic position of the early cambrian priapulomorph worms”

“…The fact is that their restorations are certainly incorrect in this aspect. As seen in the available materials, there is support for: (1) the introverts of the three taxa being of similar size and outline; (2) their anterior introverts bearing 25 rows of scalids [1,2] and all of their rear introverts being equipped with many scattered scalids [2] ; and (3) a close similarity of the scalids between the taxa in arrangement, size and the morphology. In addition, circumoral scalids are visible in some specimens of X. peculiaris and Y. halteroformis, but this structure can also be found in bicaudal 'X.…”

“…peculiaris'. They also claimed [1] that X. peculiaris, Y. halteroformis and the bicaudal 'X. peculiaris' can be clearly distinguished by their posterior trunk and caudal appendage although their introverts exhibit rather close features.…”

“…Although Han et al [2] have documented many examples to support the synonymy of X. peculiaris and Y. halteroformis, Huang et al [1] insist that these two taxa are different species characterized by a monocaudal appendage, and that the specimens described by Han et al [2] are regarded by them as a bicaudal form 'X. peculiaris'.…”

“…peculiaris'. Huang et al [1] already mentioned that 'their introverts exhibit rather close features', however, their restorations of X. peculiaris [3,4] depict the lack of scalids on the rear part of the introvert, quite distinct from that of Y. halteroformis, which bears scattered scalids. Why did they ignore such an important feature by which X. peculiaris can be easily distinguished from Y. halteroformis?…”

“…Due to the combination of complex states of preservation and taphonomies in Chengjiang fossils, Huang et al [1] expressed different opinions to those of Han et al [2] on the morphology and systematic position of the fossil priapulomorph worms (Priapulomorpha) based on their additional materials. These diverse opinions are critical in any investigation of the diversity of the Introverta in the Cambrian explosion.…”