A New Species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes: Erythrosuchidae) From the Early Triassic of South Africa

PLoS One. 2014 Nov 11;9(11):e111154. doi: 10.1371/journal.pone.0111154. eCollection 2014.

Abstract

A new species of the erythrosuchid archosauriform reptile Garjainia Ochev, 1958 is described on the basis of disarticulated but abundant and well-preserved cranial and postcranial material from the late Early Triassic (late Olenekian) Subzone A of the Cynognathus Assemblage Zone of the Burgersdorp Formation (Beaufort Group) of the Karoo Basin of South Africa. The new species, G. madiba, differs from its unique congener, G. prima from the late Olenekian of European Russia, most notably in having large bony bosses on the lateral surfaces of the jugals and postorbitals. The new species also has more teeth and a proportionately longer postacetabular process of the ilium than G. prima. Analysis of G. madiba bone histology reveals thick compact cortices comprised of highly vascularized, rapidly forming fibro-lamellar bone tissue, similar to Erythrosuchus africanus from Subzone B of the Cynognathus Assemblage Zone. The most notable differences between the two taxa are the predominance of a radiating vascular network and presence of annuli in the limb bones of G. madiba. These features indicate rapid growth rates, consistent with data for many other Triassic archosauriforms, but also a high degree of developmental plasticity as growth remained flexible. The diagnoses of Garjainia and of Erythrosuchidae are addressed and revised. Garjainia madiba is the geologically oldest erythrosuchid known from the Southern Hemisphere, and demonstrates that erythrosuchids achieved a cosmopolitan biogeographical distribution by the end of the Early Triassic, within five million years of the end-Permian mass extinction event. It provides new insights into the diversity of the Subzone A vertebrate assemblage, which partially fills a major gap between classic 'faunal' assemblages from the older Lystrosaurus Assemblage Zone (earliest Triassic) and the younger Subzone B of the Cynognathus Assemblage Zone (early Middle Triassic).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone and Bones / anatomy & histology*
  • Bone and Bones / blood supply*
  • Fossils / anatomy & histology*
  • Paleontology
  • Reptiles / anatomy & histology*
  • Reptiles / classification*
  • South Africa
  • Tooth

Grant support

DJG carried out much of the comparative work for this project during tenure of a NERC PhD studentship at the University of Bristol (1990-1994), supervised by Mike Benton. PJH was supported by the NRF African Origins Platform and the DST/NRF Centre of Excellence for Palaeosciences. JBB is supported by the National Research Foundation (UID 80587) and the Palaeontological Scientific Trust. AGS was supported by the Russian Foundation for Basic Research (projects 13-05-00274, 14-04-00185 and 14-05-93964), the Program of Basic Research of the Presidium of the Russian Academy of Sciences no. 28, and the Russian Government funded Program of Competitive Growth of Kazan Federal University. RJB is supported by a Marie Curie Career Integration Grant (PCIG-GA-2013-630123 ARCHOSAUR RISE) and an Emmy Noether Programme Award from the DFG (BU 2587/3-1), which also supported visits to Munich and Moscow by DJG as part of the completion of this project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.