Polyptychodon

Abstract: A partial pliosaur skull reveals anatomical features poorly known for Plesiosauria. The specimen lacks recorded contextual information, however preservational character and nannofossil analysis (earliest Turonian) suggests origination from the upper Greenhorn Limestone. The vomers bifurcate near their posterior termination, and are overlapped by long, slender extensions of the anterior pterygoids. The latter character has only recently been noted and may be variously developed in many if not all plesiosaurs. Large foramina commonly referred to as the ‘internal nares’ are formed at the juncture of the palatines, vomers, and maxillae. Configuration of the palatal elements differs in several ways from the only well established pliosaurid taxon of the North American Cretaceous, Brachauchenius. Particular differences include a more visibly elongate and lanceolate shape of the vomers, palatines which do not project as far anteriorly (similarly for the ‘internal nares’), and a squared posterior terminat...

Abstract: The first discovery of a Cretaceous pliosaurid tooth in Italy is reported. It comes from the Cenomanian-lower Campanian Argille Varicolori Formation near Castelvecchio di Prignano (Modena Province, northern Italy). Excepting this new specimen, Italy's only reported pliosaurid is a humerus from the Upper Cretaceous of Zavattarello near Pavia. The tooth morphology allows it to be ascribed to Polyptychodon interruptus Owen, 1841, a species only reported thus far from northern-central Europe (England, Germany, and the Czech Republic). This suggests the presence of marine reptile remains in the northern Apennines may have been underestimated.

Abstract: Referring to the genus of Saurians which he had founded, in 1841, on certain large detached teeth from the Cretaceous beds of Kent and Sussex, and which genus, in reference to the many-ridged or folded character of the enamel of those teeth, he had proposed to call Polyptychodon , Professor Owen noticed the successive discoveries of portions of jaws, one showing the thecodont implantation of those teeth, which, with the shape and proportions of the teeth, led him to suspect the crocodilian affinities of Polyptychodon ; and the subsequent discovery of bones in a Lower Greensand quarry at Hythe, which, on the hypothesis of their having belonged to Polyptychodon , had led him to suspect that the genus conformed to the plesiosauroid type. The fossils now exhibited by Mr. G. Cubitt consisted of part of the cranium, with fragments of the upper and lower jaws and teeth of the Polyptychodon interruptus , from the Lower Chalk at Dorking, and afforded further evidence of the plesiosauroid affinities of the genus. The cranial fragment included the frontal, parietal, and mastoid bones; and at the overlapping suture between the frontal and parietal was situated a large oblique ‘foramen parietale’—a part not present in the order Crocodilia , but characterizing the corresponding region of the cranium in the Plesiosauroids,—the ‘foramen parietale’ being likewise present in many Lacertians, in the Dicynodonts, the Ichthyosaurs, and Labyrinthodonts. The temporal fossae were large, and met upon the upper part of the parietal, with the intervention of a sharp and high ridge. The nasal

Abstract: In 1840 Mr. H. B. Mackeson discovered a group of bones of a large reptile in the Lower Greensand near Hythe, Kent; and in the following year the specimen was briefly noticed by Professor (Sir Richard) Owen, who provisionally referred it to the genus Polyptychodon. The fossil was presented by Mr. Mackeson to the British Museum, and ten years later the bones were described in detail by Owen, who recognised that they agreed most closely with those of the Jurassic Cetiosaurus, but still thought they might belong to the ‘crocodile’ whose teeth were known as Polyptychodon. Subsequent discoveries proved that Polyptychodon was a Pliosaurian, with limb-bones quite different from those of the Hythe fossil reptile, and Owen eventually realised that the specimen represented a species of Dinosaur, to which he gave the undefined name Dinodocus Mackesoni. Without adding to our knowledge of Dinodocus Lydekker placed it in the family Cetiosauridae, while Marsh agreed that it was truly a Sauropodous Dinosaur, though of uncertain affinity.