THE VALUE OF VOMIT: THE FOSSIL RECORD OF VERTEBRATE REGURGITALITES AND ITS SIGNIFICANCE

Vertebrate regurgitalites are rarely identified in the fossil record. One reason is that regurgitation is only common in a few discrete taxonomic groups. More important has been a lack of investigation and recognition. Regurgitalites can be identified by: (1) discrete accumulation of hard parts and other indigestible components such as fur; (2) paucity of groundmass; (3) corrosion of skeletal elements; (4) breakage of elements; (5) skeletal representation comparable to Recent regurgitalites; and (6) bite marks.

The majority of identified regurgitalites occur in four sedimentary environments: (1) shallow marine; (2) lacustrine; (3) fluvial; and (4) caves. Most of the reported regurgitalites from shallow marine environments are from the Pennsylvanian of the USA; they occur in the Desmoinesian Carbondale Formation (IN), Chesterian Tyler Formation (MT) and the Missourian Atrasado Formation (NM). Regurgitalites from these units include the ichnotaxa Ostracobromus snowyensis and Conchobromus kinneyensis. Other putative marine regurgitalites occur in the Late Cretaceous of Kansas, the Early Jurassic of Europe and the Pleistocene of Canada.

Lacustrine regurgitalites occur in shallow facies of multiple Eocene units of the western USA and British Columbia (e.g., Green River, Coldwater, Florissant formations). There are no convincing regurgitalites described from fluvial environments before the Tertiary. Strigilites (fossil owl pellets) occur in several localities in the Tertiary of the USA, including the Zia Sandstone (NM), the Chadron Formation (SD) and the White River Formation (WY), the latter within a purgolite (accumulation of regurgitalites). There are very few convincing examples of Tertiary paleontological microvertebrate accumulations that comprise bones derived from raptor regurgitations. However, some archeological sites and many cave deposits yield bone accumulations derived from raptor, notably owl, regurgitations.

The majority of identified vertebrate regurgitalites were produced by “fish” or birds and are preserved in limited environmental settings. Regurgitalites have diverse utility, including providing evidence of the evolution of predation and digestion, data for the analysis of taphonomy and sedimentary environments and acting as proxies for the presence of biotaxa.