Temporal range: Middle Triassic, 240Ma
Cheng et al., 2014
Cheng et al., 2014
Atopodentatus is an extinct genus of marine reptile, possibly basal sauropterygian, known from the early Middle Triassic (Pelsonian substage, Anisian stage) of Luoping County, Yunnan Province, southwestern China. It contains a single species, Atopodentatus unicus. It is thought to have lived between 247 and 242 million years ago.
A near complete skeleton along with a left lateral fossil of the skull were discovered near Daaozi village, Yunnan, China. The scientific name derives from the peculiar zipper-shaped morphology of its jaws and unique dentition.
The genus has been named Atopodentatus from Ancient Greek atopos (άτοπος), signifying "unplaceable, strange, extravagant, absurd, eccentric, disturbing", combined with Latin dentatus, "toothed", referring to the unusual form of arrangement and shape of the teeth. The specific name "unicus" reinforces the uniqueness of the reptile's morphology.
Atopodentatus is 3 metres (9.8 ft) long. The geological strata in which the fossil was found, the elongated body, reduced neck, robust appendages and hips of Atopodentatus all suggest that the reptile was probably semi-aquatic in nature.
The most bizarre feature of Atopodentatus is its upper mandible which has the teeth run along the jawline and then up along a vertical split in the middle of its jaw. This gives the upper jaw the appearance of a "zipper smile of little teeth". The upper jaw hooked downwards. The needle-like teeth of Atopodentatus are covered in enamel and are not fixed in sockets but instead are fused to the sides of the jaw. There are 35 small teeth in the front of the upper jaw on each side of which around 35 are placed in the vertical stretch of the "zipper" while a hundred or so teeth are lined along the horizontal stretch of jawline. The lower jaw is shovel-shaped and hooked downwards and has over 190 small teeth along the horizontal jawline.
The bizarre dentition of Atopodentatus suggest that it was not a predator but probably a filter feeder which fed on invertebrates along the sea-bottom. The shape of the beak resembles that of extant flamingos. The authors suggest that the morphology made Atopodentatus "capable of walking on land or tidal flats and sandy islands in the intertidal zone".
- Cheng, L.; Chen, X. H.; Shang, Q. H.; Wu, X. C. (2014). "A new marine reptile from the Triassic of China, with a highly specialized feeding adaptation". Naturwissenschaften. doi:10.1007/s00114-014-1148-4.
- Prostak, Sergio (17 February 2014). "Atopodentatus unicus: Bizarre New Fossil Reptile Discovered in China". Sci-News.com. Retrieved 2 March 2014.
- Compare "atopic".
- Switek, Brian (5 February 2014). "Atopodentatus Will Blow Your Mind". Laelaps (blog). National Geographic Society. Retrieved 2 March 2014.