Fossil basicranium clarifies the origin of the avian central nervous system and inner ear

Among terrestrial vertebrates, only crown birds (Neornithes) rival mammals in terms of relative brain size and behavioural complexity. Relatedly, the anatomy of the avian central nervous system and associated sensory structures, such as the vestibular system of the inner ear, are highly modified with respect to those of other extant reptile lineages. However, a dearth of three-dimensional Mesozoic fossils has limited our knowledge of the origins of the distinctive endocranial structures of crown birds. Traits such as an expanded, flexed brain, a ventral connection between the brain and spinal column, and a modified vestibular system have been regarded as exclusive to Neornithes. Here, we demonstrate all of these 'advanced' traits in an undistorted braincase from an Upper Cretaceous enantiornithine bonebed in southeastern Brazil. Our discovery suggests that these crown bird-like endocranial traits may have originated prior to the split between Enantiornithes and the more crownward portion of avian phylogeny over 140 Ma, while coexisting with a remarkably plesiomorphic cranial base and posterior palate region. Altogether, our results support the interpretation that the distinctive endocranial morphologies of crown birds and their Mesozoic relatives are affected by complex trade-offs between spatial constraints during development.

Medienart:

E-Artikel

Erscheinungsjahr:

2022

Erschienen:

2022

Enthalten in:

Zur Gesamtaufnahme - volume:289

Enthalten in:

Proceedings. Biological sciences - 289(2022), 1983 vom: 28. Sept., Seite 20221398

Sprache:

Englisch

Beteiligte Personen:

Navalón, Guillermo [VerfasserIn]
Chiappe, Luis M [VerfasserIn]
Martinelli, Agustín G [VerfasserIn]
Nava, William [VerfasserIn]
Field, Daniel J [VerfasserIn]

Links:

Volltext

Themen:

Birds
Brains
Dinosaurs
Ear
Endocranium
Journal Article
Labyrinth
Research Support, Non-U.S. Gov't

Anmerkungen:

Date Completed 29.09.2022

Date Revised 11.10.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1098/rspb.2022.1398

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM346843669