Sunday, May 8, 2016

[Paleontology • 2016] Atopodentatus unicus • The Earliest Herbivorous Marine Reptile and Its Remarkable Jaw Apparatus


Newly discovered fossils of the Middle Triassic reptile Atopodentatus unicus call for a radical reassessment of its feeding behavior. The skull displays a pronounced hammerhead shape that was hitherto unknown. The long, straight anterior edges of both upper and lower jaws were lined with batteries of chisel-shaped teeth, whereas the remaining parts of the jaw rami supported densely packed needle-shaped teeth forming a mesh. The evidence indicates a novel feeding mechanism wherein the chisel-shaped teeth were used to scrape algae off the substrate, and the plant matter that was loosened was filtered from the water column through the more posteriorly positioned tooth mesh. This is the oldest record of herbivory within marine reptiles.

Keywords: paleontology, marine reptiles, Atopodentatus unicus, Middle Triassic

A model reconstruction of  Atopodentatus unicus with the real fossil
Image: Nick Fraser, National Museums Scotland

Fig. 3 Artist’s restoration of Atopodentatus unicus depicting it as a herbivore grazing on marine plants growing on a hard substrate in the eastern Tethyan Sea during Middle Triassic times.
 Using batteries of spatulate teeth lining the hammerhead expansions of both the upper and lower jaws, it would have been able to scrape off numerous pieces of plant matter into suspension in the water. This could then be sucked in and filtered by the long, thin, and closely packed needle-shaped teeth lining the main jaw rami. [Illustration: Y. Chen, Institute of Vertebrate Paleontology and Paleoanthropology]

Li Chun, Olivier Rieppel, Cheng Long and Nicholas C. Fraser. 2016. The Earliest Herbivorous Marine Reptile and Its Remarkable Jaw Apparatus. Science Advances. 2(5) e1501659. DOI:  10.1126/sciadv.1501659

Oldest Known Plant-Eating Marine Reptile Had A Bizarre 'Hammerhead' Mouth via @forbes
Earliest Plant-Eating Marine Reptile Had A Hammerhead via @OceanLeadership