Preparation of a Fossil Mosasaur (Squamata: Mosasauridae) from Hokkaido, Northern Japan

Abstract

By Ashley Hopkins, Biology

Advisor: Takuya Konishi

Presentation ID: PM_ATRIUM04

Abstract: Presented here are the steps taken to carefully prepare a mosasaur fossil found in Hokkaido, northern Japan. Entombed inside a hard calcareous nodule, this specimen requires both mechanical and chemical preparations to be removed from the rock-matrix encasing the specimen. Mechanical preparation included chipping and grinding away at the rock using a high-pressured air tool called an Airscribe and a high-speed Dremel tool. This mechanical preparation constituted the initial stage of the specimen preparation, where the bulk of the nodule has been removed. The next stage of the preparation will constitute chemical preparation, which is to be initiated in the near future. In this latter stage, Paraloid adhesive will be used to protect the exposed bone surface while an acid bath is used to dissolve the rock-matrix at the same time. These techniques are commonly practiced and proven effective at various museums. In addition to the technical aspect of fossil preparation, thorough understanding of the mosasaur skull anatomy is as essential to properly preparing the fossil without damaging the fragile, only partially exposed bones. Understanding where structures begin and end is an important part of properly preparing a specimen and exposing all its related features properly. One must also be aware that structures can shift during fossilization and that the fossil may not follow schematic drawings exactly. So far, my preparation revealed all the upper-tooth-bearing bones in original articulation with teeth in place, except one tooth that was found outside the tooth socket.