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Garjainia madiba, new erythrosuchid archosauriform species from South Africa



Ben Creisler
bcreisler@gmail.com

New in PLoS ONE:


(Named "madiba" in honor of Nelson Mandela (1918–2013))


David J. Gower, P. John Hancox, Jennifer Botha-Brink, Andrey G.
Sennikov & Richard J. Butler (2014)
A New Species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes:
Erythrosuchidae) from the Early Triassic of South Africa.
PLoS ONE 9(11): e111154.
doi:10.1371/journal.pone.0111154
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0111154





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).