The skull of the Upper Cretaceous snake Dinilysia patagonica Smith-Woodward, 1901, and its phylogenetic position revisited
Article first published online: 18 NOV 2011
© 2011 The Linnean Society of London
Zoological Journal of the Linnean Society
Volume 164, Issue 1, pages 194–238, January 2012
How to Cite
ZAHER, H. and SCANFERLA, C. A. (2012), The skull of the Upper Cretaceous snake Dinilysia patagonica Smith-Woodward, 1901, and its phylogenetic position revisited. Zoological Journal of the Linnean Society, 164: 194–238. doi: 10.1111/j.1096-3642.2011.00755.x
- Issue published online: 17 JAN 2012
- Article first published online: 18 NOV 2011
- Received 23 April 2010; revised 5 April 2011; accepted for publication 18 April 2011
- cranial anatomy;
The cranial anatomy of Dinilysia patagonica, a terrestrial snake from the Upper Cretaceous of Argentina, is redescribed and illustrated, based on high-resolution X-ray computed tomography and better preparations made on previously known specimens, including the holotype. Previously unreported characters reinforce the intriguing mosaic nature of the skull of Dinilysia, with a suite of plesiomorphic and apomorphic characters with respect to extant snakes. Newly recognized plesiomorphies are the absence of the medial vertical flange of the nasal, lateral position of the prefrontal, lizard-like contact between vomer and palatine, floor of the recessus scalae tympani formed by the basioccipital, posterolateral corners of the basisphenoid strongly ventrolaterally projected, and absence of a medial parietal pillar separating the telencephalon and mesencephalon, amongst others. We also reinterpreted the structures forming the otic region of Dinilysia, confirming the presence of a crista circumfenestralis, which represents an important derived ophidian synapomorphy. Both plesiomorphic and apomorphic traits of Dinilysia are treated in detail and illustrated accordingly. Results of a phylogenetic analysis support a basal position of Dinilysia, as the sister-taxon to all extant snakes. The fossil taxa Yurlunggur, Haasiophis, Eupodophis, Pachyrhachis, and Wonambi appear as derived snakes nested within the extant clade Alethinophidia, as stem-taxa to the crown-clade Macrostomata. The hypothesis of a sister-group relationship between Dinilysia and Najash rionegrina, as suggested by some authors, is rejected by the results of our analysis.
© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164, 194–238.