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RE: Ichthyovenator



I have not read the paper yet, but I wonder if a sinusoidal sail might actually 
be characteristic of female spinosaurids.  Having a gap in the sail above the 
pelvis might make it easier for the male to get his leg over the female when 
mounting her (picture spinosaurids in this position: 
http://www.luisrey.ndtilda.co.uk/html/carnsex.htm).  A somewhat similar 
condition is also seen in the type specimen of Concavenator, maybe a solution 
to the same problem.  





> Date: Sun, 22 Apr 2012 15:24:14 -0700
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Ichthyovenator, new spinosaurid from Early Cretaceous of Laos
> 
> From: Ben Creisler
> bcreisler@gmail.com
> 
> A new online paper:
> 
> Ronan Allain, Tiengkham Xaisanavong, Philippe Richir and Bounsou
> Khentavong (2012)
> The first definitive Asian spinosaurid (Dinosauria: Theropoda) from
> the Early Cretaceous of Laos.
> Naturwissenschaften (advance online publication)
> 2012, DOI: 10.1007/s00114-012-0911-7
> http://www.springerlink.com/content/r5x213648388tt23/
> 
> 
> Spinosaurids are among the largest and most specialized carnivorous
> dinosaurs. The morphology of their crocodile-like skull, stomach
> contents, and oxygen isotopic composition of the bones suggest they
> had a predominantly piscivorous diet. Even if close relationships
> between spinosaurids and Middle Jurassic megalosaurs seem well
> established, very little is known about the transition from a
> generalized large basal tetanuran to the specialized morphology of
> spinosaurids. Spinosaurid remains were previously known from the Early
> to Late Cretaceous of North Africa, Europe, and South America. Here,
> we report the discovery of a new spinosaurid theropod from the late
> Early Cretaceous Savannakhet Basin in Laos, which is distinguished by
> an autapomorphic sinusoidal dorsosacral sail. This new taxon,
> Ichthyovenator laosensis gen. et sp. nov., includes well-preserved and
> partially articulated postcranial remains. Although possible
> spinosaurid teeth have been reported from various Early Cretaceous
> localities in Asia, the new taxon I. laosensis is the first definite
> record of Spinosauridae from Asia. Cladistic analysis identifies
> Ichthyovenator as a member of the sub-clade Baryonychinae and suggests
> a widespread distribution of this clade at the end of the Early
> Cretaceous. Chilantaisaurus tashouikensis from the Cretaceous of Inner
> Mongolia, and an ungual phalanx from the Upper Jurassic of Colorado
> are also referred to spinosaurids, extending both the stratigraphical
> and geographical range of this clade.