A new species of the archaic “turtle barnacle” genus Protochelonibia (Coronuloidea, Chelonibiidae) from the upper Rupelian Chickasawhay Formation of Mississippi (U.S.A.)

Turtle barnacles have been turtle riders for more than 30 million years

“…In the light of the above considerations, we assign these barnacle shells to the extinct chelonibiid species Protochelonibia melleni, a Rupelian form that has been recently reported from the Rauenberg fossil-lagerstätte based on two clustered shells (Collareta et al 2022a). Protochelonibia melleni is the earliest member of the monotypic subfamily Protochelonibiinae, which is currently known from fossils ranging chronostratigraphically from the lower Oligocene to the ?upper Pliocene (Harzhauser et al 2011;Collareta et al 2022a;Perreault et al 2022).…”

“…Note that all the C. testudinaria shells have their rostral end facing anteriorly, as also observed in the fossil Protochelonibia melleni shell depicted in Fig. 3C: this may be somewhat significant as living C. testudinaria individuals are believed to be able to reorient themselves and even move on turtle shells to achieve dispositions that maximize the nutrient flow (Moriarty et al 2008;Chan et al 2021) which likely lived on cheloniid sea turtles (Harzhauser et al 2011), P. melleni is a member of the extinct subfamily Protochelonibiinae, which coexisted with members of the extant genus Chelonibia (the only known genus of Chelonibiinae) throughout most of the Neogene (Collareta et al 2022a, c, and references therein;Perreault et al 2022). The present paper unambiguously demonstrates that chelonibiids have been turtle-dwelling organisms for more than 30 million years, as well as that the extinct protochelonibiines have been chelonophilic epizoic organisms since at least Rupelian times.…”

A forgotten cirripedological gem: a new species of whale barnacle of the genus Cetopirus from the Pleistocene of the United States West Coast

“…The coasts of North America represent a privileged location for investigating the evolutionary history of the coronuloid barnacles, not least because they are home to the earliest members of this superfamily (Ross & Newman 1967; Zullo 1982; Collareta & Newman 2020; Perreault et al . 2022). Furthermore, the Pliocene and Pleistocene deposits of the Pacific coast of North America have yielded a rather idiosyncratic fossil coronulid fauna.…”

Ghosts of the Holobiont: Borings on a Miocene Turtle Carapace from the Pisco Formation (Peru) as Witnesses of Ancient Symbiosis

“…Occurrences of barnacle remains associated with those of the putative host organism(s) are exceedingly rare [25,[126][127][128]. Although morphofunctional considerations can provide some hints of what sort of host the extinct turtle barnacles might have been on [129][130][131], body fossils alone cannot disclose much information on the ancient basibionts of chelonibiids and platylepadids, nor on the nature of the intercurrent symbiotic association. Furthermore, as a likely consequence of the tiny and fragile shells they secrete [22], platylepadids are particularly rare as fossils, their fossil record being limited to a handful of Pleistocene occurrences of the extant genus Platylepas [132][133][134][135].…”