INVESTIGADORES
LECUONA Agustina
congresos y reuniones científicas
Título:
Major issues in notosuchian phylogeny: taxon and character sampling
Autor/es:
POL, D.; LEARDI, J. M.; LECUONA, A.; NASCIMENTO, P ; ZAHER, H.
Lugar:
San Juan
Reunión:
Congreso; IV Congreso Latinoamericano de Paleontología de Vertebrados; 2011
Institución organizadora:
Instituto y Museo de Cencias Naturales, Universidad Nacional de San Juan
Resumen:
The taxonomic
diversity of Cretaceous crocodyliforms from Gondwana has notably increased
during the last decade. Most of these taxa have been related to Notosuchia
Gasparini 1971, a large clade of basal mesoeucrocodylians that includes
small-bodied taxa as well as baurusuchids, and according to some authors Araripesuchus
Price, 1959, and sebecids (e.g., Pol and Apesteguía, 2005). Other
authors, however, consider either of the latter two taxa as more closely
related to peirosaurids and/or neosuchians (e.g., Ortega et al.,
2000; Larsson and Sues, 2007). In this contribution we present a phylogenetic
analysis that expands the taxon and character sampling from previous studies,
gathering characters stemming from previously published studies but most
importantly adding 92 new characters relevant to the relationships of
Cretaceous crocodyliforms from Gondwana. The new characters include 52
postcranial characters and 40 cranial characters. The incorporation of
postcranial characters to the phylogenetic analysis is critical to produce a
novel arrangement of the basal mesoeucrocodylians recorded in the
Cretaceous?Cenozoic of Gondwana, clustering Araripesuchus and
peirosaurids as sister taxa and this clade as the sister group of all other notosuchians.
A large clade of basal mesoeucrocodylians with similar taxonomic content (i.e.,
peirosaurids, Araripesuchus, and notosuchians, including sebecosuchians)
has been previously referred as Gondwanasuchia (Carvalho et al., 2004)
as it clusters most of the Cretaceous crocodyliform diversity from Gondwana.The
new skull and mandibular data provides high character support for the monophyly
of advanced notosuchians, a clade formed by taxa found in the Late Cretaceous
of South America, excluding all other notosuchians recorded in other regions of
Gondwana (Africa, Madagascar). The new postcranial characters (e.g.,
dorsally projected and strongly curved prezygapophysis of anterior cervicals,
deep circular depression on the proximal humerus for the M. scapulohumeralis
caudalis, subrectangular posterior end of postacetabular process of the
ilium with ventral margin horizontally directed ventrally to acetabular roof,
trapezoidal fibular facet on the astragalus) incorporated in the cladistic
analysis provide decisive support for monophyly of Gondwanasuchia and
strengthen the affinities of Sebecidae with Baurusuchidae (sebecosuchian
monophyly), as deeply nested within Notosuchia.