Extending the footprint record of Pareiasauromorpha to the Cisuralian: earlier appearance and wider palaeobiogeography of the group

Pareiasauromorpha is one of the most important tetrapod groups of the
Permian. Skeletal evidence suggests a late Kungurian origin in North
America, whereas the majority of occurrences come from the Guadalupian and
Lopingian of South Africa and Russia. Pareiasauromorpha footprints include
the ichnogenus Pachypes, that is, however, unknown from strata older than
late Guadalupian. A revision of several Pachypes-like footprints from the
Cisuralian–Guadalupian of Europe and North America confirm the occurrence
of this ichnogenus and of the ichnospecies Pachypes ollieri n. comb.
beginning in the Artinskian. This is the earliest known occurrence of
Pachypes and it coincides with the Artinskian reptile radiation. Based on
a synapomorphy-based track-trackmaker correlation, Pachypes ollieri n.
comb. can be attributed to nycteroleter pareiasauromorphs such as
Macroleter. Therefore, the earliest occurrences of pareiasauromorph
footprints precede by at least 10 Myr the earliest occurrence of this
group in the skeletal record. Moreover, the palaeobiogeography of the
group is extended to the Cisuralian and Guadalupian of western Europe.