The first
Mycterosaurus skull ever discovered was that of
Mycterosaurus longiceps. The holotype (FMNH-UC 692) was discovered by Mr. Herman Douthitt in 1915 at a deposit of the
Samuel Wendell Williston analyzed the holotype, describing the skull and other fragmented portions of the skeleton in his publication
A New Genus and Species of American Theromorpha. In 1930, R Broom identified an unstudied fossil collected by
Jacob Boll at the
American Museum that he believed had been wrongly labeled by collectors as a small
labyrinthodont. The fossil, AMNH 7002, consisted of a fragmentary skull and partially crushed skeleton. Broom named the fossil Eumatthevia Bolli after the late American paleontologist Professor
W.D. Matthew. Broom noted that the skull of the fossil appeared similar to that of other primitive theromorphs such as
Glaucosaurus and
Mycterosaurus, but that it appeared more slenderly built and presented a flatter skull compared to
Mycterosaurus. Despite this difference, an independent junior author's restoration differed in no aspects from
Mycterosaurus except that the skull was lower, a difference attributed to crushing. As such, Romer concluded that
Eumatthevia bolli was surely a synonym of
Mycterosaurus longiceps. In 1940, Romer and Price reviewed both aforementioned fossil records in their review of
pelycosaurs. The authors note both specimens were affected by different types of crushing, making it difficult to accurately assess the true nature of the skull. However, Romer and Price estimate the true proportions were likely an intermediate between the narrow shape Williston observed and the broad low type restored by Broom. The authors failed to observe contacts between the lacrimal and jugal, ventral of the orbit, as described by Williston and Broom. Additionally, the authors believe defining features of height, pineal size, and teeth differentiated "
Eumatthevia" and "
Mycterosaurus" were inaccurate. Instead, these differences were likely due to crushing and inaccuracies of measurement by Williston. There is, however, agreement on the large size of the quadratojugal and orbits through all reports. In 1957, Peter Paul Vaughn published a paper describing the features of a
pelycosaur named
Basicranodon fortsillensis that he believed carried very similar features to the Caseidae. However, Romer had previously established that
Mycterosaurus should be classified as an edaphosaur. In 1966, the US Geographic Survey published a paper stating that
Basicranodon fortsillensis could well belong to
Mycterosaurus if better preserved specimens were ever discovered. In 1953, a new fossil (MCZ 2985), was discovered in
Colorado and in 1964 named by Lewis and Vaughn as a new species that they called
Mycterosaurus smithae, after Mrs Stockton Smith. Features on MCZ 2985 such as the measurements of the orbit, temporal region, interorbital width, parietal region, and posteroventral corner of the cheek that matched that of
Mycterosaurus longiceps led Lewis and Vaughn to their designation of a new
Mycterosaurus species. However, a reexamination conducted by Brocklehurst et al (2016) using synchrotron radiation micro-
computed tomography revealed observations that prompted the authors to reclassify
Mycterosaurus smithae into genus Vaughnictis. The additional preparation and synchrotron scanning showed a lack of slender femur, serrated lateral dentition, teeth present on the coronoid, or a lateral boss on the postorbital, these being the most unambiguous varanopid and
Mycterosaurine synapomorphies. == Classification ==