Navaornis hestiae

Reconstruction of Navaornis hestiae（image source：TotalDino，採用 CC BY 4.0 授權）

Age

Cretaceous（Late Cretaceous）

85 - 75 Ma

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Taxonomy

Kingdom：Animalia

Phylum：Chordata

Class：Sauropsida

Order：Saurischia

Genus：Navaornis

Species：Navaornis hestiae

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Morphological description

Navaornis hestiae possesses a toothless skull in which the premaxillae are fully fused into a single element with a convex dorsorostral surface. The jugal is strongly curved, while the quadratojugal is small and comma-shaped. The lacrimal is extremely reduced and does not separate the orbit from the antorbital fenestra. The parasphenoidal rostrum bears a large, oval opening.

Holotype specimen of Navaornis hestiae（image source：Chiappe, L. M et al. (2024).，採用 CC BY 4.0 授權）

Based on the well-preserved cranial material, the brain of Navaornis hestiae can be reconstructed as heart-shaped in dorsal view. It exhibits a flexed configuration, with the brainstem projecting ventrally to a degree previously observed only in modern birds. Because only the left frontal is well preserved, the extent of separation between the telencephalic hemispheres remains uncertain. In dorsal view, the hemispheres are pear-shaped and show pronounced mediolateral expansion, exceeding that seen in Archaeopteryx and all known non-avian pennaraptoran dinosaurs.

The cerebellum is relatively small and even less developed than that of Archaeopteryx and some non-avian dinosaurs, with no clearly defined foliation visible on its surface.

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Etymology

The generic name Navaornis honors both the holotype specimen and William Nava, the discoverer of the fossil locality, who first identified the site in 2004 and later discovered the holotype in 2016.

The species name hestiae refers to the Greek goddess Hestia, the eldest of the Olympian gods yet ranked last, alluding to the combination of a relatively derived skull with a basal phylogenetic position.

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Biological interpretation

MPM-200: the white elements represent the holotype of Navaornis hestiae; the light grey elements correspond to its postcranial skeleton; the dark grey elements represent bones from other enantiornithine individuals（image source：Chiappe, L. M et al. (2024).，採用 CC BY 4.0 授權）

The holotype of Navaornis hestiae was discovered in the Adamantina Formation in São Paulo State, southeastern Brazil. The holotype specimen (MPM-200-1) consists of a well-preserved skull and originates from the larger specimen MPM-200, which contains a mixture of avian bones, including postcranial elements of Navaornis hestiae and other enantiornithines. An additional referred specimen, MPM-334-1, consists of an isolated basicranium that closely matches that of the holotype.

Phylogenetic analyses place Navaornis within Enantiornithes, forming a clade with toothless enantiornithines such as Gobipteryx and Yuornis, although support for this grouping is weak and may not be robust.

discovery of this species indicates that both toothed and toothless enantiornithines coexisted in the same region, suggesting a degree of ecological differentiation among bird communities during the Cretaceous.

（Author: Bai Leng）

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Reference

Chiappe, L. M., Navalón, G., Martinelli, A. G., Carvalho, I. d. S., Miloni Santucci, R., Wu, Yun-Hsin., Field, D. J. (2024). Cretaceous bird from Brazil informs the evolution of the avian skull and brain. Nature.

-21.6, -50.1

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