Talenkauen

MEANING: Small skull

PERIOD: Late Cretaceous

CONTINENT: South America

Talenkauen is a basal iguanodont with teeth in the tip of its beak, unlike more derived iguanodontians. It was around 4.5 m in length, and weighed about 300 kg. Similarities with other South American ornithopods suggest there was a distinct Southern Hemisphere group. Specimens include the first hatchling ornithopod discovered in the Southern Hemisphere.

Talenkauen is from the Late Cretaceous. The Cretaceous is the third and final geological period of the Mesozoic Era, with the Late Cretaceous making up roughly the second half of it, lasting from about 100 to 66 million years ago. It was a time of significant evolutionary change, with dinosaurs reaching their greatest diversity before the mass extinction at the end of the Cretaceous.

The Cretaceous was a period with a relatively warm climate, though the Late Cretaceous experienced a global cooling trend, caused by falling levels of carbon dioxide in the atmosphere. The continents were nearing their present positions, but high sea levels flooded low-lying regions, turning Europe into an archipelago, and forming the Western Interior Seaway in North America. These seas were home to a variety of marine reptiles, including mosasaurs and plesiosaurs, while pterosaurs and birds shared the skies.

On land, dinosaurs continued to thrive and diversify during the Late Cretaceous, producing many of the most well-known goups, including tyrannosaurs, hadrosaurs, and pachycephalosaurs. Established Cretaceous dinosaur clades like the ceratopsians, ankylosaurs, and dromaeosaurs continued to flourish. Sauropod species consisted almost exclusively of titanosaurs, which seemed to be confined to the Southern Hemisphere for much of the Late Cretaceous. Flowering plants and grasses diversified and spread, becoming the dominant flora similar to what we see today.

The Cretaceous (along with the Mesozoic) ended with the Cretaceous-Paleogene (K-Pg) extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. This event, likely triggered by an asteroid impact, is marked by the abrupt K-Pg boundary, a distinct geologic layer separating the Mesozoic and Cenozoic Eras. In its aftermath, mammals and avian dinosaurs rapidly diversified, becoming the dominant land animals of the Cenozoic Era.

Talenkauen is an elasmarian. Elasmaria is a group of basal ornithopod dinosaurs primarily known from the Cretaceous of the Southern Hemisphere, especially South America, Australia, and Antarctica. These dinosaurs were small to medium-sized herbivores that retained primitive features compared to their more derived relatives, like the hadrosaurs. Typically, elasmarian ornithopods were lightly built and bipedal, with slender limbs and long tails, adaptations that likely helped them maneuver quickly through their environments to escape predators.

Fossil evidence shows that elasmarians thrived in high-latitude regions during the Cretaceous, suggesting they were adaptable to a range of climates, including cooler polar conditions. Unlike the later, larger ornithopods, they did not develop complex tooth batteries but instead retained simpler dentitions suited for processing softer vegetation. This group highlights the regional diversification of basal ornithopods in Gondwana and offers important clues about how these dinosaurs evolved and adapted away from their Northern Hemisphere relatives.