Ectenosaurus

Ectenosaurus is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Plioplatecarpinae subfamily alongside genera like Angolasaurus and Platecarpus. Ectenosaurus is known from the Santonian and Campanian of Kansas, Alabama, and Texas. The generic name means "drawn-out lizard", from Greek ectenes ("drawn-out") and Greek sauros ("lizard") referencing the elongated muzzle. With the preserved skull about long and the dorsal vertebrae about , Ectenosaurus is estimated to have reached in length and in body mass. It was a rare genus of mosasaur with several unique characteristics that clearly separate it from other mosasaur genera. The most prominent of these features is its elongated jaws, elongated in a similar vein to other mosasaurs with elongated jaws, such as Plotosaurus and Pluridens. Russell (1967) considered the form of the teeth, the shape of the frontal and the large suprastapedial process of the quadrate as evidence of a close relation between Ectenosaurus and Platecarpus. He separated Ectenosaurus from Platecarpus based on the elongated snout, the exclusion of the prefrontals from the narial borders and the fusion of the supra- and infrastepedial processes. The specimen FHSM VP-401 preserve significantly comprehensive skin impressions from Ectenosaurus, which makes it possible to draw conclusions not only about mosasaur integument at large but also about mosasaur movement and propulsion. The scales are considerably smaller in size (2.7×2.0 mm) than those found in the famed LACM 128319 specimen of Platecarpus (3.8×4.4 mm), despite the animals being of similar sizes. The combination of small and firmly anchored body scales as well as a complex meshwork of alternating crossed-helical and longitudinal fiber bundles suggest that the anterior torso of Ectenosaurus was reasonably stiff. This also suggests that this section of the body was quite rigid during locomotion, and that the main form of propulsion would have to have been done by the tail (likely possessing a tail fin like other mosasaur species), and that it could not move by undulating its entire body like snakes do, a previously popular view of mosasaur locomotion.