Paleontologists have, for the first time, described the neuroanatomy of Europasaurus holgeri, a remarkable macronarian dinosaur from the Jurassic period of Germany.
Europasaurus holgeri is one of the most peculiar and best-studied sauropods worldwide.
This dinosaur lived in what is now northern Germany during the Late Jurassic epoch, some 154 million years ago.
It belonged to Macronaria, a group of mostly colossal sauropods, comprised the largest terrestrial vertebrates of Earth’s history.
However, Europasaurus holgeri was a comparatively small macronarian species with a body height of up to 3 m (10 feet).
It owed its reduced size to having become isolated on an island, where it became smaller after many generations.
“Dinosaurs, like all animals with spines, had their main sensory organs — the organs that allowed them to listen, taste, see, smell, think and even keep their balance — on their heads,” said University of Greifswald paleontologist Marco Schade and colleagues.
“This means that studying their fossilized skulls can provide a wealth of information about how these animals perceived their environment through so-called ‘endocasts’ — digital models of the cavities within the skull.”
In the new study, the authors studied the braincases of both very young and mature Europasaurus holgeri individuals using a technique called micro-computed tomography.
“The part of the inner ear being responsible for hearing, the lagena or cochlea, turns out to be relatively long in Europasaurus holgeri,” they said.
“This suggests that these animals had a good sense of hearing, rendering intraspecific communication crucial and gregarious behavior likely.”
“Another part of the inner ear is relevant for the sense of equilibrium and consists of three tiny arches.”
“We found that the inner ear cavities within very small specimens resemble the respective cavities of adults in form and size.”
“This supposes that very young individuals of Europasaurus holgeri strongly relied on the ability to equilibrate already.”
“Some considered skull remains were so tiny (about 2 cm, or 0.8 inches) that they may belong to hatchlings, which renders the species precocial.”
“Whereas some sauropods weighed several tens of tons more than their newly-hatched offspring, the hatchlings of Europasaurus holgeri may have immediately followed the herd in some approximation.”
The results appear in the journal eLife.
Marco Schade et al. 2022. Neurovascular anatomy of dwarf dinosaur implies precociality in sauropods. eLife 11: e82190; doi: 10.7554/eLife.82190
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