Resumen

GRIGORESCU, Dan. The "Tustea Puzzle": hadrosaurid (Dinosauria, Ornithopoda) hatchlings associated with Megaloolithidae eggs in the Maastrichtian of the Hateg Basin (Romania). Ameghiniana [online]. 2010, vol.47, n.1, pp.89-97. ISSN 1851-8044.

Since 1991 when the coinciding occurrence of megaloolithid eggs and hatchlings of the hadrosaurid Telmatosaurus transsylvanicus was suggested by few limb bone remains found close to the first discovered eggs in the Hateg Basin, tens of eggs grouped in clutches together with neonate bones were unearthed within the place that become "Tustea nesting site". In the meantime the original vertical escarpment near the village of Tustea was leveled and converted into a horizontal platform. By their external characters and eggshell microstructure all the eggs belong to the Megaloolithus oogenus, closer to M. siruguei; similarly, all the baby remains whose state of preservation allows their taxonomic assignment belong to Telmatosaurus transsylvanicus, one of the common dinosaur species from the rich Maastrichtian faunal assemblage of the Hateg Basin (Romania), and the basalmost hadrosaurid. Most of the baby remains consist of isolated bones and teeth, but partial skeletons with articulated elements were also found. The preliminary ontogenetic study reveals a rapid growth of the hatchlings, a fact also supported by the discovery of most of the skeletal remains outside the egg clutches, but in their close vicinity. In few cases bones were found within the egg clutches and even inside the egg. It is worth to mention that no sauropod remains were found within the nesting horizon from Tustea.

Palabras clave : Dinosaur eggs; Megaloolithidae; Hatchlings; Hadrosaurids; Telmatosaurus; Maastrichtian; Hateg Basin; Romania.