First discovered in 2001, a 122 million year old species of dinosaur from China named Liaoningosaurus paradoxus is causing quite a stir among the palaeontological community.
Until very recently, Liaoningosaurus was considered to be something of a footnote among its family, the ankylosaurs, which were famous for their thick armour and bony tail clubs. At about 13 inches in length and lacking the fused vertebrae typically associated with adult dinosaurs, Liaoningosaurus was widely believed to be a juvenile and therefore not indicative of a mature specimen.
However, a study of another Liaoningosaurus paradoxus specimen published in the Journal of Geology by a team of Chinese palaeontologists has interpreted the tiny dinosaur in a very different light. Far from being a juvenile member of a much larger species, their research suggests that Liaoningosaurus may well have been the finished article. Not only that though, but their analysis suggests that Liaoningosaurus may have been a thoroughly unique dinosaur quite unlike anything which has been described before.
A one-of-a-kind dinosaur?
The paper deduces that Liaoningosaurus might in fact have been an aquatic, or at least semi-aquatic fish-eater; the first and only known ornitischian (the order of dinosaurs which includes most plant-eaters including Stegosaurus, Triceratops and Iguanodon) to live such a lifestyle. The paper’s authors point to the creature’s long back legs and toes as being suitable for swimming, while fork-shaped teeth and sharp claws could have been used for grasping a slippery fish supper. In terms of a “smoking gun”, fish bones have been found in Liaoningosaurus‘ stomach, although it is not fully clear whether the dinosaur actually ate them or if they merely got jumbled up with the skeleton at a later time. The team has also interpreted the lack of fusion in key areas of Liaoningosaurus‘ skeleton as further adaptations toward a water-based lifestyle.
However, not all palaeontologists agree with this new interpretation of Liaoningosaurus. Commenting on a post on The Prehistoric Times’ Facebook page, Thomas R. Holtz reminded people to err on the side of caution in relation to the paper and stressed that more evidence was needed before any concrete conclusions could be made:
Take this with a big-ass chunk of salt for now. The so-called aquatic features and predator features are not clearly so; their argument that it is an adult is very very weak (i.e., wrong); and it is not at all clear that the fish are actual gut contents. (After all, Euhelopus and some hadrosaurs are found with fish in them, but they are likely postmortem).
That is not to say that the idea is crazy; just that they do not actually have the evidence to support it yet.
If Liaoningosaurus paradoxus does truly turn out to be a fish-eating member of the ankylosaur family, it will be the first of its kind. While certain dinosaurs such as Baryonyx, Spinosaurus and Deinocheirus are all noted fish-eaters, they are members of the theropod dinosaur family and directly evolved from meat-eating ancestors. Never before has a herbivorous branch of dinosaurs been observed to have evolved toward flesh-eating, although the opposite has been seen in the likes of Therizinosaurus and Chilesaurus.
Until this new fishy hypothesis can be proven either way, Liaoningosaurus paradoxus shall remain something of a mystery for palaeontologists.