A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods

Abstract

BackgroundSecondary adaptation to aquatic life occurred independently in several amniote lineages, including reptiles during the Mesozoic and mammals during the Cenozoic. These evolutionary shifts to aquatic environments imply major morphological modifications, especially of the feeding apparatus. Mesozoic (250–65 Myr) marine reptiles, such as ichthyosaurs, plesiosaurs, mosasaurid squamates, crocodiles, and turtles, exhibit a wide range of adaptations to aquatic feeding and a broad overlap of their tooth morphospaces with those of Cenozoic marine mammals. However, despite these multiple feeding behavior convergences, suction feeding, though being a common feeding strategy in aquatic vertebrates and in marine mammals in particular, has been extremely rarely reported for Mesozoic marine reptiles.Principal FindingsA relative of fossil protostegid and dermochelyoid sea turtles, Ocepechelon bouyai gen. et sp. nov. is a new giant chelonioid from the Late Maastrichtian (67 Myr) of Morocco exhibiting remarkable adaptations to marine life (among others, very dorsally and posteriorly located nostrils). The 70-cm-long skull of Ocepechelon not only makes it one of the largest marine turtles ever described, but also deviates significantly from typical turtle cranial morphology. It shares unique convergences with both syngnathid fishes (unique long tubular bony snout ending in a rounded and anteriorly directed mouth) and beaked whales (large size and elongated edentulous jaws). This striking anatomy suggests extreme adaptation for suction feeding unmatched among known turtles.Conclusion/SignificanceThe feeding apparatus of Ocepechelon, a bony pipette-like snout, is unique among tetrapods. This new taxon exemplifies the successful systematic and ecological diversification of chelonioid turtles during the Late Cretaceous. This new evidence for a unique trophic specialization in turtles, along with the abundant marine vertebrate faunas associated to Ocepechelon in the Late Maastrichtian phosphatic beds of Morocco, further supports the hypothesis that marine life was, at least locally, very diversified just prior to the Cretaceous/Palaeogene (K/Pg) biotic crisis.

The turtles from the upper Eocene, Osona County (Ebro Basin, Catalonia, Spain): new material and its faunistic and environmental context

“…Eochelone brabantica and other related Cheloniidae were previously examined first hand for comparison with Osonachelus (Lapparent de Broin et al, 2014b), the other marine cheloniid turtle from the same latest Eocene (Priabonian) localities of Santa Cecília de Voltregà and Múnter. As it was previously demonstrated (see Bardet et al, 2013Bardet et al, , 2017Hay, 1908; Pérez-García and Lapparent de Broin, 2013; Lapparent de Broin et al, 2014a), many of the features classically identified as present in the Cheloniidae are also present in dermochelyoids (in Dermochelyidae, Protostegidae, and in a still undefined new family including Ocepechelon Bardet et al, 2013 and Alienochelys Lapparent de Broin et al, 2014a). These characteristics correspond to both plesiomorphies and/or homoplasies, often linked to the environment in which these forms lived to a feeding pattern and to the strategies of adaptation to an aquatic locomotion.…”

Comparative analysis of the shape and size of the middle ear cavity of turtles reveals no correlation with habitat ecology

“…We used an updated version of the informal supertree of Foth & Joyce (2016) as the phylogenetic backbone for various statistical analyses, which differs from the published version in the position of some extinct marine turtles. In particular, pan-chelonioids were resolved according to Weems & Brown (2017) and protostegid turtles, including the 'dermochelyoids' of Bardet et al (2013) and Lapparent de Broin et al (2014), were placed as sister to thalassochelydians, as originally proposed by Joyce (2007) (but see Raselli, 2018 and for alternative phylogenetic placements for protostegids). The tree was time-calibrated in R using the package paleotree (Bapst, 2012) using information from the ages of fossils and from molecular clock studies.…”

The shell bone histology of fossil and extant marine turtles revisited

“…(including Ctenochelys and Toxochelys ), and dermochelyoid turtles (e.g. Ocepechelon ; Bardet et al ., ). Some Palaeogene taxa (e.g.…”