[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Tetanurae (Dinosauria: Theropoda).phylogeny

From: Ben Creisler

A paper in the new issue of Journal of Systematic Palaeontology:

Matthew T. Carrano, Roger B. J. Benson & Scott D. Sampson (2012)
The phylogeny of Tetanurae (Dinosauria: Theropoda).
Journal of Systematic Palaeontology 10(2): 211-300

Tetanuran theropods represent the majority of Mesozoic predatory
dinosaur diversity and the lineage leading to extant Aves. Thus their
history is relevant to understanding the evolution of dinosaur
diversity, Mesozoic terrestrial ecosystems, and modern birds.
Previously, the fragmentary and poorly sampled fossil record of basal
(non-coelurosaur) tetanurans led to uncertainties regarding their
basic interrelationships. This in turn prevented determining the
relationships of many incompletely known taxa that nonetheless
document a global radiation spanning more than 120 million years. We
undertook an exhaustive examination of all basal tetanurans and all
existing character data, taking advantage of recent discoveries and
adding new morphological, temporal and geographic data. Our cladistic
analysis of 61 taxa achieved significantly improved phylogenetic
resolution. These results position several ‘stem’ taxa basal to a
succession of monophyletic clades (Megalosauroidea, Allosauroidea and
Coelurosauria). Megalosauroids include nearly 20 taxa arrayed amongst
a basalmost clade (Piatnitzkysauridae, fam. nov.) and the sister taxa
Spinosauridae and Megalosauridae; the latter includes two subfamilies,
Megalosaurinae and Afrovenatorinae subfam. nov. Allosauroidea contains
a diverse Metriacanthosauridae (= Sinraptoridae), Neovenatoridae,
Carcharodontosauridae and a reduced Allosauridae. Finally, we assessed
more than 40 fragmentary forms and hundreds of additional reported
tetanuran occurrences. Tetanuran evolution was characterized by
repeated acquisitions of giant body size and at least two general
skull forms, but few variations in locomotor morphology. Despite
parallel diversification of multiple lineages, there is evidence for a
succession of ‘dominant’ clades. Tetanurae first appeared by the Early
Jurassic and was globally distributed by the Middle Jurassic. Several
major clades appeared prior to the breakup of Pangaea; as such their
absence in specific regions, and at later times, must be due to poor
sampling, dispersal failure and/or regional extinction. Finally, we
outline a general perspective on Mesozoic terrestrial biogeography
that should apply to most clades that appeared before the Late