Orstentype

Orstentype is a term used in paleontology to denote fossils associated with Orsten-type preservation, a distinctive mode of fossilization that captures soft tissues in three dimensions. Orsten-type preservation results from early diagenetic phosphatization, forming minute, three-dimensionally preserved remains that range from tens to hundreds of micrometres in size. The fossils often represent soft-bodied organisms and early metazoans, including small crustaceans and other minute forms whose exterior structures and appendages can be seen in detail. The deposits bearing this preservation are primarily known from Cambrian and early Paleozoic strata, with the mechanism first described at sites in Europe and subsequently recognized in other regions.

In practice, the term Orstentype is used to describe specimens recovered through Orsten-type processes or to refer to a subcategory within discussions of Orsten-type preservation. It is not a taxon or lineage, but a descriptor of preservation style with implications for morphological interpretation and phylogeny. The significance lies in its ability to reveal soft-tissue anatomy that is normally lost in conventional fossils, enabling more accurate reconstructions of early animal evolution, limb morphology, and functional anatomy. Researchers use Orstentype materials to study morphological variation across taxa and to inform developmental inferences drawn from the fossil record.

Limitations include the rarity of such preservation, restricted stratigraphic distribution, and the specialized preparation required to study the microfossils. While the term is common in some paleontological literature, many researchers prefer the broader phrase Orsten-type fossil or Orsten-type preservation. Orstentype keeps attention on the preservation context, which is essential for interpreting the anatomy and evolution of small, ancient organisms.