Kannemeyeriiformes


Kannemeyeriiformes is a group of large-bodied Triassic dicynodonts. As a clade, Kannemeyeriiformes has been defined to include the species Kannemeyeria simocephalus and all dicynodonts more closely related to it than to the species Lystrosaurus murrayi.

Evolutionary history

Despite being the most species-rich group of dicynodonts in the Triassic Period, kannemeyeriiforms exhibit much less diversity in terms of their anatomy and ecological roles than do dicynodonts from the Permian Period.
Lystrosauridae is thought to be the most closely related group to Kannemeyeriiformes, and since the earliest lystrosaurids are known from the Late Permian, the divergence of these two groups must have occurred at least as far back as this time, implying that a long ghost lineage must exist. Although no kannemeyeriiforms have been found in the Late Permian yet, the recent discovery of Sungeodon helps fill a gap in the early fossil record of the group by showing that kannemeyeriiforms diversified right after the Permian-Triassic extinction event.

Classification

Four families have been included in the group: Kannemeyeriidae, Shansiodontidae, Stahleckeriidae, and Dinodontosauridae. Occasionally some of these families are not recognized, with most kannemeyeriiforms being placed in Kannemeyeriidae. Recent phylogenetic analyses suggest that these families represent similar body plans or morphotypes rather than true evolutionary groupings.

Phylogeny

Below is a cladogram from Kammerer et al. :