Arthropod head problem
Budd
#### Budd

[Graham Budd](/wiki/Graham_Budd "Graham Budd")'s theory agrees with that of Scholtz and Edgecombe in accepting the protocerebral nature of the onychophoran antennae, and the two preoral appendages of [Fuxianhuia](/wiki/Fuxianhuia "Fuxianhuia"). However, he traces the origin of the "great appendages" in the differentiated frontal appendages of Cambrian lobopods such as *[Aysheaia](/wiki/Aysheaia "Aysheaia")* and *[Kerygmachela](/wiki/Kerygmachela "Kerygmachela")*, neither of which possess convincing antennae. Thus, in Budd's view, the order of the two anterior appendages of taxa such as *Fuxianhuia* are reversed: the antennae are the first antennae (deutocerebral) of the mandibulates; and the great appendages correspond to the primary antennae of the onychophorans and Cambrian lobopods. Following previous work by Dewel and colleagues, Budd accounts for their reversal by arguing that the mouth in basal lobopods was terminal, and that as it rotated backwards and downwards, it brought the anterior appendage backwards with it. Given this transformation, it is likely, under this theory, that the remnant of the great appendage/primary antenna is the labrum of extant arthropods. Because in this view *Fuxianhuia* possesses both a hypostome and a great appendage, the hypostome cannot be straightforwardly homologous with the labrum.


How did the mouth transform in basal lobopods according to Budd's theory?