Reply to discussion of “Permian—Triassic vertebrate footprints from South Africa: Ichnotaxonomy,producers and biostratigraphy through two major faunal crises” by Marchetti,L., Klein,H., Buchwitz,M., Ronchi,A., Smith,R.M.H., DeKlerk,W.J., Sciscio,L., and Groenewald,G.H. (2019)

Our recent comprehensive review of the Permian-Early Triassic tetrapod tracksites from South Africa includes a revision of the ichnotaxonomy and the incorporation of a large quantity of new material. The paper also discusses, in light of the revised ichnotaxonomy and palaeontology of several sites, trackmaker attribution and the biostratigraphy of Permian-Early Triassic tetrapod tracks. Precise information about the fossiliferous localities was provided where possible and when sites were relocated. Three footprint associations were described (FA I-III) and highlight their potential stratigraphic value. The youngest (FA III) was recognized at four different localities and is likely Induan in age. A recent comment by Gastaldo and Neveling (2019) regarded one of these FA III localities, the Bethel tracksite, which received criticism for its unclear geographic placement and its stratigraphic position. Further comments included a discussion of the possible palaeoecological interpretation of this tracksite. In replying to these queries, we provided more precise geographic and stratigraphic information, confirming the occurrence of this tracksite ~15 m above the faunal transition which we consider to be currently coinciding with the Permian-Triassic boundary (PTB). Palaeoecological inferences are herein further clarified.     

Discussion of “Permian—Triassic vertebrate footprints from South Africa: Ichnotaxonomy,producers and biostratigraphy through two major faunal crises” by Marchetti,L., Klein,H., Buchwitz,M., Ronchi,A., Smith,R.M.H., DeKlerk,W.J., Sciscio,L., and Groenewald,G.H. (2019)

A newly devised tripartite subdivision of the Karoo Basin, South Africa, is based on a number of vertebrate-trackways spanning the Middle Permian (Wordian/Capitanian) to Lower Triassic (reportedly Induan) rocks of the Beaufort Formation. The youngest Footprint Assemblage (FA III) is reported to occur in the lowermost Triassic rocks of the Palingkloof Member. One collection site from which seven trackways are reported, Bethel farm, is a classic South African locality where some authors place the end-Permian extinction event and, coincidentally, the vertebrate-based terrestrial Permian—Triassic Boundary. Published GPS coordinates for the Bethel farm site, though, indicate that these trackways originate from exposures of the Burgersdorp Formation near the town of Aliwal North. Outcrops here are assigned to the Cynognathus Assemblage Zone, and indicate a Middle Triassic age assignment. In addition, we caution the use of any small temporally or spatially restricted dataset, which is of severely limited utility, in making broad generalizations about paleoenvironmental or paleoecological interpretations.