A new ascarid species in cynodont coprolite dated of 240 million years

Abstract

Cynodonts represent the transition from reptiles to mammals. They are classified as synapsids, or tetrapod animals with mammalian characteristics. We present here the finding of helminth eggs in a coprolite identified as of cynodont origin dated of nearly 240 million years. Microscopy revealed the presence of very well preserved intestinal parasite eggs. Up to now we identified an ascarid egg by morphological characteristics. Based on a previous description of the new genus Ascarites Poinar Jr and Boucot 2006 in coprolites of iguanodons from Belgium, we propose a new species, Ascarites rufferi n.sp. in cynodonts, a host that inhabited the Southern Region of Brazil in the Triassic period.

The Geological Record of Parasitic Nematode Evolution

“…However, morphology and molecular methods do not always match. For instance, some molecular clock studies place the origin of ascarids in the Jurassic (Blaxter, 2009), but this is clearly incorrect since ascarid body fossils occur in the Triassic (Da Silva et al, 2014). Since most nematode families have multiple hosts, the earliest fossil of the most primitive host can be used to estimate the possible date of origin for various nematode groups (see Poinar (2011)).…”

“…Poinar and Boucot, 2006;Da Silva et al, 2014;Hugot et al, 2014) and desiccated dung of more recent ages (Poinar, 2014) can reveal the presence of vertebrateparasitic nematodes. Ancient dung samples also are one of the best resources for establishing early records of human nematode parasites (Gonçalves et al, 2003).…”

“…These include a 240 mya ascarid, Ascarites rufferi Da Silva et al (2014) and a 240 mya old oxyurid, Paleoxyuris cockburni Hugot et al (2014). The next oldest member of this group is the 130 mya mermithid, Cretacimermis libani Poinar et al (1994) from Early Cretaceous Lebanese amber.…”

“…However, the ascarid lineage may be just as ancient since the Triassic fossil, A. rufferi Da Silva et al (2014) dates from the same time period and same host as P. cockburni (Da Silva et al, 2014). The next oldest fossil ascarid parasites are the Early Cretaceous A. priscus and A. gerus recovered from an dinosaur coprolite (Poinar and Boucot, 2006).…”

First record of Acanthocephala parasites eggs in coprolites preliminary assigned to Crocodyliformes from the Adamantina Formation (Bauru Group, Upper Cretaceous), São Paulo, Brazil

“…In this context, coprolites are rich source of information, because they provide, besides possible presence of parasites, biological aspects of their hosts, just like food habits, but also paleoenviromental and paleoclimatic data, allowing better understanding of this complex inter specific relation, involving parasite, host, ecosystem (Silva et al 2014, Qvarnström et al 2016, Dentzien-Dias et al 2018. Additionally acquistion of this kind of fossilized material, associated to skeletons of extinct animals is common (Ferreira et al 2011), though they received few attention (Oliveira and Santucci 2017), and they are not much explored yet for paleoparasitological investigations.…”