INVESTIGADORES
LECUONA Agustina
congresos y reuniones científicas
Título:
New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation
Autor/es:
BUTLER, R.J.; SULLIVAN, C.; EZCURRA, M.D.; LIU, J.; LECUONA, A.; SOOKIAS, R.B.
Lugar:
Berlin
Reunión:
Congreso; Annual Meeting of the Society of Vertebrate Paleontology; 2014
Resumen:
The
origin and early evolutionary radiation of archosaurs and their close relatives
(Archosauriformes) during the Triassic was a critical event that led to the
dinosaurdominated ecosystems of the Jurassic and Cretaceous. The timing and
dynamics of this evolutionary radiation are currently obscured by the poorly
constrained phylogenetic positions of several key early archosauriform taxa,
including several species from the Middle Triassic of Argentina (Gracilisuchus
stipanicicorum) and China (Turfanosuchus dabanensis, Yonghesuchus
sangbiensis). Morphological phylogenetic analyses of early archosaurs have
identified these species as unstable 'wildcards' that reduce phylogenetic resolution.
We present new anatomical data for the type specimens of Gracilisuchus, Turfanosuchus,
and Yonghesuchus, and incorporate these data into a revised phylogenetic
analysis. Our results indicate that these three previously enigmatic taxa form
a wellsupported clade of Middle Triassic archosaurs that we refer to as
Gracilisuchidae, which is placed basally among suchian archosaurs. The
approximately contemporaneous and morphologically similar Gracilisuchus and
Yonghesuchus may be sister taxa within Gracilisuchidae. Our results
provide increased resolution of the interrelationships of early archosaurs,
with increased levels of phylogenetic support for several key early pseudosuchian
clades. Moreover, they falsify previous hypotheses suggesting that Turfanosuchus
and Yonghesuchus are not members of the archosaur crown group. The recognition
of Gracilisuchidae provides further support for a rapid phylogenetic diversification
of crown archosaurs by the Middle Triassic. The disjunct distribution of the
gracilisuchid clade in China and Argentina supports the hypothesis that early archosaurs
were distributed over much or all of Pangea, although they may have initially been
relatively rare members of faunal assemblages.