Tuesday, March 19, 2013

New Phylogeny for South American Cretaceous Endemic Mammals (or Meridiolestida finds a new home)

A new phylogeny for basal Trechnotheria and Cladotheria and affinities of South American endemic Late Cretaceous mammals


1. Alexander O. Averianov (a,b)
2. Thomas Martin (c)
3. Alexey V. Lopatin (d)


a. Zoological Institute of the Russian Academy of Sciences, Universitetskaya nab. 1, 199034, Saint Petersburg, Russia

b. Department of Paleontology, Geological Faculty, Saint Petersburg State University, 16 Liniya VO 29, 199178, Saint Petersburg, Russia

c. Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Nussallee 8, 53115, Bonn, Germany

d. Borissiak Paleontological Institute of the Russian Academy of Sciences, Profsouznaya str. 123, 117997, Moscow, Russia


The endemic South American mammals Meridiolestida, considered previously as dryolestoid cladotherians, are found to be non-cladotherian trechnotherians related to spalacotheriid symmetrodontans based on a parsimony analysis of 137 morphological characters among 44 taxa. Spalacotheriidae is the sister taxon to Meridiolestida, and the latter clade is derived from a primitive spalacolestine that migrated to South America from North America at the beginning of the Late Cretaceous. Meridiolestida survived until the early Paleocene (Peligrotherium) and early Miocene (Necrolestes) in South America, and their extinction is probably linked to the increasing competition with metatherian and eutherian tribosphenic mammals. The clade Meridiolestida plus Spalacotheriidae is the sister taxon to Cladotheria and forms a new clade Alethinotheria. Alethinotheria and its sister taxon Zhangheotheria, new clade (Zhangheotheriidae plus basal taxa), comprise Trechnotheria. Cladotheria is divided into Zatheria (plus stem taxa, including Amphitherium) and Dryolestida, including Dryolestidae and a paraphyletic array of basal dryolestidans (formerly classified as “Paurodontidae”). The South American Vincelestes and Groebertherium are basal dryolestidans.

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