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Haestasaurus, new name for sauropod “Pelorosaurus” becklesii from Early Cretaceous of England

Ben Creisler

New in PLoS ONE:

Paul Upchurch, Philip D. Mannion & Michael P. Taylor (2015)
The Anatomy and Phylogenetic Relationships of “Pelorosaurus“ becklesii
(Neosauropoda, Macronaria) from the Early Cretaceous of England.
PLoS ONE 10(6): e0125819.

The sauropod dinosaur “Pelorosaurus” becklesii was named in 1852 on
the basis of an associated left humerus, ulna, radius and skin
impression from the Early Cretaceous (Berriasian-Valanginian) Hastings
Beds Group, near Hastings, East Sussex, southeast England, United
Kingdom. The taxonomy and nomenclature of this specimen have a complex
history, but most recent workers have agreed that “P.” becklesii
represents a distinct somphospondylan (or at least a titanosauriform)
and is potentially the earliest titanosaur body fossil from Europe or
even globally. The Hastings specimen is distinct from the
approximately contemporaneous Pelorosaurus conybeari from Tilgate
Forest, West Sussex. “P.” becklesii can be diagnosed on the basis of
five autapomorphies, such as: a prominent anteriorly directed process
projecting from the anteromedial corner of the distal humerus; the
proximal end of the radius is widest anteroposteriorly along its
lateral margin; and the unique combination of a robust ulna and
slender radius. The new generic name Haestasaurus is therefore erected
for “P.” becklesii. Three revised and six new fore limb characters
(e.g. the presence/absence of condyle-like projections on the
posterodistal margin of the radius) are discussed and added to three
cladistic data sets for Sauropoda. Phylogenetic analysis confirms that
Haestasaurus becklesii is a macronarian, but different data sets place
this species either as a non-titanosauriform macronarian, or within a
derived clade of titanosaurs that includes Malawisaurus and
Saltasauridae. This uncertainty is probably caused by several factors,
including the incompleteness of the Haestasaurus holotype and rampant
homoplasy in fore limb characters. Haestasaurus most probably
represents a basal macronarian that independently acquired the robust
ulna, enlarged olecranon, and other states that have previously been
regarded as synapomorphies of clades within Titanosauria. There is
growing evidence that basal macronarian taxa survived into the Early
Cretaceous of Europe and North America.