Fig. 1: Some adult Europasaurus animals watch over the newly hatched Europasaurus chicks, which leave the nest to follow the herd. (C: Davide Bonadonn)A long-necked dinosaur from northern Germany was a so-called nest fledger
Europasaurus was a long-necked, herbivorous dinosaur on four legs. The dinosaur lived in the late Jurassic period about 154 million years ago on a small island in what is now northern Germany. Researchers from the Universities of Vienna and Greifswald have now examined fossil skull remains of Europasaurus using computer tomography. An analysis of the dinosaur’s inner ear gave the scientists new insights, not only into the hearing ability of the dinosaur species, but also into how Europasaurus lived and grew up. The study was published in the journal eLife.
Like its world-famous relative Brachiosaurus, Europasaurus is counted among the sauropod group, which includes the largest terrestrial vertebrates that have ever lived on Earth. Some sauropods grew to be around 40 meters long and possibly weighed 80 tons. Europasaurus holgeri, however, was a comparatively small species with a height of about three meters.
Europasaurus lived in the late Jurassic about 154 million years ago on an island in what is now northern Germany and is considered the first dinosaur in which the so-called island dwarfing has been demonstrated. Island dwarfing is an evolutionary biological phenomenon: animals that live on a smaller island without predators sometimes decrease their body size significantly. Thus, Europasaurus may represent the extinct counterpart to present-day island animals such as the Sumatran tiger or Sumatran rhinoceros, which are relatively small compared to their closest relatives on the mainland.
Fossil skull remains from small to adult animals examined
For the study now published, researchers from the Universities of Greifswald and Vienna examined fossil skull remains of Europasaurus , which were found near Goslar in northern Germany. To learn more about the life of this extinct dinosaur, the scientists analyzed the cavities in the skull, which once housed the brain and inner ears, using high-resolution computer tomography. The researchers examined fossils ranging from very young and small to adult animals.
The part of the inner ear responsible for hearing, the lagena or cochlea, is relatively long in Europasaurus. This fact suggests that the animals could hear quite well and lived in herds, which made intraspecific communication significant.
Europasaurus was probably a nest fledger
Another part of the inner ear is the organ of balance, which consists of three small arcades. The researchers* found housings of these balance organs in very small individuals that closely resemble those of adult animals in shape and size. "This shows that even very young individuals of Europasaurus relied heavily on their sense of balance. Some of the skull remains examined are so tiny (~2 cm) in the process that they may have come from hatchlings. This suggests that Europasaurus was probably a so-called nest fledger," explains Sebastian Stumpf of the University of Vienna. Nest fledglings are animals in which even the youngest members of the species move comparatively independently. They do not "squat in the nest", but leave it early. Since other sauropods were several tens of tons heavier than their freshly hatched offspring and thus posed a life-threatening threat, the Europasaurus hatchlings may have migrated right along with the group.
Original publication:
Schade, M., Knötschke, N., Hörnig, M.K., Paetzel, C., & Stumpf, S. 2022. neurovascular anatomy of dwarfed dinosaur implies precociality in sauropods. eLife.
elifesciences.org/articles/82190
Illustrations:
Fig. 1: Some adult Europasaurus animals watch over the newly hatched Europasaurus chicks, which leave the nest to follow the herd. (C: Davide Bonadonna)
