A Technique for Salvaging Anatomical Material from Study Skins of Rare or Extinct Birds

Abstract

Nearly one-third of all species of birds are still represented in collections only by study ski•, with no skeletal or fluid-preserved material available (Zusi et al. 1982). The development of alternative techniques for preservation of other organ systems simultaneously with the integument (e.g. Norris 1961, Johnson et al. 1984) arrived too late for the species that are now extinct and for which only study skins exist. The lack of skeletal material of rare or extinct spedes can be a nearly i•urmountable impediment to systematic and paleontological investigations. Fortunately, most of the skull wing, and leg bones remain in the standard museum study skin, so skin collectio• are potential osteological repositories of species for which skeletons can no longer be obtained. We have developed a technique for the recovery of the bones and attached muscles from study skins that preserves the appearance and scientific usefulness of the skin. When series are available, it is of primary concern to select the specimen in which the bones are best preserved. This will vary according to the preparation technique of individual collectors. The skin may be felt to determine where the back of the skull has been cut or whether the mandibuiar articulation appears to be intact. Ideally, the specimen is x-rayed to determine exactly how much bone remains. There is a natural tendency to select a skin that appears poorly made, but this may be false economy because the better the initial appearance, the better the final result will be (Fig. 1). Once a specimen has been selected, detailed measurements should be made and recorded on a separate label, along with the date of repreparation and name of the preparator. The skin is then relaxed in a closed container above a layer of wet sand that has been laced with phenol (carbolic acid) to prevent mold. When the skin is supple, it is opened and the stuffed body removed. In most cases the skin will be too delicate to sustain the inversion of the skull through the neck, as in the usual skinning procedure, so incisions are made along the inside of the mandibular rami to produce a "ular flap" through which the skull is extracted. The skin is then teased away from the fore part of the skull and cut away from the base of the bill so the entire skull and bill can be removed. At this stage the remaining portions of the humeri can be extracted easily. Removal of the wing bones is facilitated by a longitudinal cut under the wing near the junction with the body. This is concealed by the wing in the finished specimen. It is also possible to skin the wing to retrieve the radius, ulna, and carpometacarpus, although if in poor condition the skin may be damaged when the remiges are separated from the underlying bone. The extracted wing bones are replaced with wire. The tibia and tarsometatarsus, even in small pas-setines, can be removed through a longitudinal slit in the podotheca and subsequent dissection of the bones, leaving the toes in place. This leaves the po-^ I Fig. 1. Harvard specimen of Ciridops anna (Dre-panidini) before (A) and after (B) repreparation. The bones from this specimen (C) were in excellent condition and perfectly suitable for comparative purposes. Only five specimens of this extinct species exist. 510