The Use of Acids in the Preparation of Vertebrate Fossils

A synopsis is given of work already published on the removal of vertebrate fossils from their rock matrix with acetic acid, and several new developments are described. The basic method depends on the solubility of the calcium carbonate of calcareous rocks in acetic acid, and the insolubility of the bone phosphate in the same acid. Methods of dealing with large specimens which need a partial temporary king for support are given. The transfer method is useful for fragile or unusual specimens; the fossil is embedded in cold-setting polyester resin (Marco Resin S.B. 26C) and the resin is cut away from the back of the specimen and the rock dissolved in the usual way. Formic acid may also be used. Specimens in siliceous rocks can be dissolved away with hydrochloric acid leaving a natural mold of the fossil in the rock.