| Paludidraco | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Nothosauroidea |
| Family: | †Simosauridae |
| Genus: | †Paludidraco de Miguel Chaveset al., 2018 |
| Species: | †P. multidentatus |
| Binomial name | |
| †Paludidraco multidentatus de Miguel Chaveset al., 2018 | |
Paludidraco is anothosaur belonging to theSimosauridae from theLate Triassic ofSpain.[1] It includes one species,Paludidraco multidentatus.Paludidraco is thought to possibly have been afilter-feedingmarine reptile, and was about 2.5 metres (8.2 ft) long. The holotype, MUPA-ATZ0101, consists of one relatively completeskull and partial postcranialskeleton and one partial skull andmandibles, were found in the El Atance site inGuadalajara, Central Spain at theKeuper Facies horizon, the border of theCarnian andNorian periods of the Triassic.[1]
Paludidraco was similar to its close relativesSimosaurus,[2] but differed in several important respects. Theteeth werepleurodont and it had more than 15premaxillary teeth, hence the species namemultidentatus meaning 'many-toothed'. It had a relatively longsnout, but thenostrils were higher up on its head than those ofSimosaurus. The uppertemporal fenestra is narrow, and thepineal foramen is highly elongated. Thesupraoccipital is horizontally sutured with theparietal and exposed at the posterior end of the parietal table. The jaws are very slender and fragile, quite bowed, and with the teeth situated laterally. There are very many teeth, all small, recurved and flattened sideways. Thevertebral centra are amphicoelous and thezygapophyses arepachyostotic. Theribs are pachyostotic and strongly distally expanded.[1]
Paludidraco, like all nothosaurs, would have been mainly aquatic but able to come on land for short periods. It would not have been able to capture live prey, as its jaws were too fragile except for very small animals which could offer no resistance, and its robust pachyostotic postcranial skeleton would have made it unmanoeuvrable. Its many small teeth create acomb-like structure which would be suitable for filter-feeding, and its bowed jaws could have taken in large volumes of water for filtering, but it did not have an especially elongated rostrum or very large jaws, as modernbaleen whales do, suggesting that it would have been unable to 'suspension feed' in midwater with shoals ofcrustaceans orplankton.[1]
Paludidraco's small teeth and weak jaws would probably have also been inadequate for eating manymarine plants, but it might have been able to scrape off soft vegetable matter from plants on the sea floor. The pachyostotic skeleton, similar to that seen in modernsirenians, would have madePaludidraco slow and unmanoeuvrable, but would have given itneutral buoyancy and so enabled it to hover near thesea floor while expending very little energy. It has therefore been proposed thatPaludidraco swam slowly along the seabed, or possibly even walked along it, eating soft vegetable matter.[1] Alternatively, it could have taken mouthfuls ofsilt orsand from the seabed and shaken its head from side to side to filter out the small crustaceans orworms living in the sediment, in a similar way to moderngrey whales. This would explain its apparent ability to filter but not to 'suspension feed', while the pachyostotic skeleton would have made this a very low-energy lifestyle. It is also possible that it could have eaten both vegetable and animal matter in the ways proposed.
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