title: Discovery of a 240 million year old nematode parasite egg in a cynodont coprolite sheds light on the early origin of pinworms in vertebrates.
abstract: BACKGROUND
  We report the discovery of a nematode parasite egg (Nemata: Oxyurida) from a coprolite closely associated with the remains of several species of Cynodontia, dated to 240 million years old. This finding is particularly significant because this is the oldest record of an oxyurid nematode yet discovered, and because the cynodonts are considered a stem-group of the mammals.
  
  
  METHODS
  We extracted material from a fully mineralized coprolite by both scraping the surface, and removing fragments from its interior with clean dental instruments used a single time. A single drop of glycerol from a new vial was added as a clearing reagent. Each slide was sealed with wax and examined with an optical microscope at 100× to 400× magnification.
  
  
  RESULTS
  From one coprolite, 550 slides were examined; from 275 of these slides, sediment was examined that was scraped from the surface of the coprolite, and from the other 275 slides, material was examined that was extracted from the interior of the coprolite. All microscopic structures encountered were photographed, measured, and identified when possible.
  
  
  CONCLUSIONS
  From the coprolite examined, we discovered an egg representing a new species of pinworm that, based on the egg structure, clearly places it in the family Heteroxynematidae. Nematodes of the order Oxyurida have very constrained life-histories, occurring only in animals that are not strictly carnivorous and also ingest large amounts of plant material. This fact enabled us to determine which species of cynodont, from several collected at the site in Brazil, are most likely the depositors of the coprolite, and therefore were the putative host of the parasite.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hugot
authors.affiliation: Harold W Manter Laboratory of Parasitology, University of Nebraska State Museum and School of Biological Sciences, University of Nebraska-Lincoln, W529 Nebraska Hall, Lincoln 685880514, NB, USA. slg@unl.edu.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Gardner
authors.forename: Victor
authors.initials: V
authors.lastname: Borba
authors.forename: Priscilla
authors.initials: P
authors.lastname: Araujo
authors.forename: Daniela
authors.initials: D
authors.lastname: Leles
authors.forename: Átila Augusto
authors.initials: ÁA
authors.lastname: Stock Da-Rosa
authors.forename: Juliana
authors.initials: J
authors.lastname: Dutra
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: Ferreira
authors.forename: Adauto
authors.initials: A
authors.lastname: Araújo
mesh_terms: D000818:Animals; D001938:Brazil; D005243:Feces / Q000469:parasitology; D005580:Fossils; D049690:History, Ancient; D008322:Mammals; D017167:Oxyurida / Q000145:classification / Q000302:isolation & purification*; D017194:Oxyurida Infections / Q000266:history*; D010164:Paleopathology; D010802:Phylogeny