A Redescription of Aigialosaurus (= Opetiosaurus) Bucchichi (Kornhuber, 1901) (Squamata: Aigialosauridae) with Comments on Mosasauroid Systematics

ABSTRACT Previous works discussing interrelationships of squamates, mosasauroids, and aigialosaurs have alternately suggested Opetiosaurus bucchichi and Aigialosaurus dalmaticus to be accurately diagnosed, congeneric, and in some cases, conspecific taxa. Recent systematic work has shown that these two species, as basal mosasauroids, are critical to understanding the evolutionary history of mosasaurs. Because earlier attempts at descriptions of O. bucchichi have proven insufficient for systematic purposes, the specimen is redescribed here based on the counterpart skull to the holotype part specimen, revealing new anatomical details unavailable to previous workers. This comparison of O. bucchichi and A. dalmaticus reveals no morphological differences that support a generic differentiation of the two specimens assigned to these monospecific genera. The genus Opetiosaurus is therefore a junior synonym of Aigialosaurus and O. bucchichi is re-diagnosed as A. bucchichi; the species A. bucchichi is retained because some minor differences are present between the individual specimens assigned to the respective species. Incorporation of new anatomical information into a phylogenetic analysis lends support to suggestions from previous workers that the paddle-shaped limb evolved more than once within Mosasauroidea; however, the tree topologies are not robust. The results of this study indicate that the systematic relationships of halisaurine mosasaurs are of primary importance in the study of mosasauroid interrelationships.

[1]  A. Palci,et al.  A NEW BASAL MOSASAUROID FROM THE CENOMANIAN (U. CRETACEOUS) OF SLOVENIA WITH A REVIEW OF MOSASAUROID PHYLOGENY AND EVOLUTION , 2007 .

[2]  M. Caldwell,et al.  Redescription of Aigialosaurus dalmaticus Kramberger, 1892, a Cenomanian mosasauroid lizard from Hvar Island, Croatia , 2006 .

[3]  M. Polcyn,et al.  Dallasaurus turneri, a new primitive mosasauroid from the Middle Turonian of Texas and comments on the phylogeny of Mosasauridae (Squamata) , 2005, Netherlands Journal of Geosciences.

[4]  Michael P. Cummings,et al.  PAUP* [Phylogenetic Analysis Using Parsimony (and Other Methods)] , 2004 .

[5]  N. Jalil,et al.  A new mosasauroid (Squamata) from the Late Cretaceous (Turonian) of Morocco , 2003 .

[6]  M. Caldwell.  ON THE AQUATIC SQUAMATE DOLICHOSAURUS LONGICOLLIS Owen, 1850 (CENOMANIAN, UPPER CRETACEOUS), AND THE EVOLUTION OF ELONGATE NECKS IN SQUAMATES , 2001 .

[7]  Michael S. Y. Lee,et al.  ADRIOSAURUS AND THE AFFINITIES OF MOSASAURS, DOLICHOSAURS, AND SNAKES , 2000 .

[8]  L. Jacobs,et al.  THE CRETACEOUS BIOGEOGRAPHY OF THE EASTERN MEDITERRANEAN WITH A DESCRIPTION OF A NEW BASAL MOSASAUROID FROM 'EIN YABRUD, ISRAEL , 1999 .

[9]  M. Caldwell.  Squamate phylogeny and the relationships of snakes and mosasauroids , 1999 .

[10]  Michael S. Y. Lee.  Convergent evolution and character correlation in burrowing reptiles: towards a resolution of squamate relationships , 1998 .

[11]  Michael S. Y. Lee.  The phylogeny of varanoid lizards and the affinities of snakes , 1997 .

[12]  G. L. Bell.  A Phylogenetic Revision of North American and Adriatic Mosasauroidea , 1997 .

[13]  M. Caldwell.  Ontogeny and phylogeny of the mesopodial skeleton in mosasauroid reptiles , 1996 .

[14]  R. Carroll,et al.  The pectoral girdle and forelimb of Carsosaurus marchesetti (Aigialosauridae), with a preliminary phylogenetic analysis of mosasauroids and varanoids , 1995 .

[15]  I. Gušić,et al.  Upper Cenomanian-lower Turonian sea-level rise and its consequences on the Adriatic-Dinaric carbonate platform , 1993 .

[16]  R. Carroll,et al.  The Origin of Mosasaurs As a Model of Macroevolutionary Patterns and Processes , 1993 .

[17]  R. Carroll,et al.  Aigialosaurs: mid-Cretaceous varanoid lizards , 1992 .

[18]  K. Queiroz**,et al.  Phylogenetic relationships within squamata , 1988 .

[19]  E. Cope.  On the reptilian orders, Pythonomorpha and Streptosauria , 1869 .

[20]  M. Oppel.  Die ordnungen, familien und gattungen der reptilien als prodrom einer naturgeschichte derselben. Von Michael Oppel. , 1811 .