Talenkauen was rather like Dryosaurus in shape and build, but with a proportionally longer neck. The full length of the body is estimated at no more than. Unlike more derived iguanodontians, it still had teeth in the tip of the beak, and a first toe. More derived iguanodonts lose this toe, retaining only the three middle toes. The humerus has reduced areas for muscle attachment, a featured shared with other South American ornithopods like Notohypsilophodon and Anabisetia. This and other similarities to South American ornithopods suggests that there may have been a distinct Southern Hemisphere ornithopod group, but at the time the authors cautioned that such an interpretation was not entirely justified. In 2015, the describers of Morrosaurus found that such a clade did indeed exist.
Talenkauen's most distinct feature is a set of smooth, ovoid plates found along the side of the rib cage. These plates can be long, but are very thin. They were present with at least the first eight ribs, attaching along the middle portion of a rib and lying flat. Several other dinosaurs are known to have had similar plates, including Hypsilophodon, Othnielosaurus, Parksosaurus, Thescelosaurus, and Macrogryphosaurus, which may have been related. Because of the fragility of the plates, and the fact that they may not have alwaysturned to bone in the living animal, they may have been more widespread than currently known. Novas and colleagues suggested that the plates may be homologous to uncinate processes, strip-like bony projections found on the ribs of a variety of animals including the tuatara, crocodiles, birds, and some maniraptoran theropod dinosaurs. In birds, uncinate processes help to ventilate the lungs, working with rib cage muscles, and Novas and colleagues proposed a similar function for the plates of Talenkauen. This homology was rejected in a more recent study by Richard Butler and Peter Galton because of the plates' form. The plates were too thin and limited in location to have been very useful as defensive devices.
Classification
Through cladistic analysis, it was found to be more basal than Dryosaurus and Anabisetia, but more derived than Tenontosaurus and Gasparinisaura. More recently, the describers of Macrogryphosaurus found their genus and Talenkauen to be related, and coined the clade Elasmaria for the two genera. In 2015, several other Patagonian and Antarctic ornithopods were also found to be related. Cladogram based in the phylogenetic analysis of Rozadilla et al., 2015:
Palaeoecology
Talenkauen, as a basal iguanodont, would have been a small, bipedalherbivore. Other dinosaurs from the Pari Aike Formation include the giant titanosauridPuertasaurus and the predatory neovenatoridOrkoraptor.
