The emergence of predation and associated complex behaviors in jawed vertebrates (gnathostomes) were major driving forces in brain evolution. To gain insight into the neuronal complexity of the last common gnathostome ancestor, we studied the development of the shark telencephalon by combining single-cell and spatial transcriptomics. Our findings suggest an ancient origin of pallial neurogenesis, including basal progenitors, which were previously only identified in tetrapods. We find evidence for migrating gabaergic neurons populating the dorsal pallium, where we observe incipient layering. Finally, we provide evidence for the existence of Cajal-Retzius cells in the developing shark telencephalon, with a conserved molecular profile and tissue localization relative to mammals. Our analyses revealed that major features of the vertebrate pallium arose much earlier than previously thought, in the gnathostome lineage. ### Competing Interest Statement The authors have declared no competing interest.

Birds have evolved a unique sex chromosome dosage compensation mechanism involving the male-biased microRNA (miR-2954), which is essential for male survival by regulating the expression of dosage-sens...

In chelicerates whole genome duplications (WGDs) were identified in distinct groups. While there is evidence that Xiphosurans/horseshoe crabs had three rounds of WGD and arachnopulmonates (e.g. spide...

Come join our EU cephalopod consortium to discover how octopuses and other coleoids developed their large nervous system. Postdoc position available in the Seuntjens Lab in Leuven, Belgium.

Here they generate a cell type atlas of the colonial cnidarian Hydractinia symbiolongicarpus, which reveals that distinct colony parts are mostly made from unique combinations of shared cell types, an...

Extreme morphological disparity within Mollusca has long confounded efforts to reconstruct a stable backbone phylogeny for the phylum. Familiar molluscan groups—gastropods, bivalves, and cephalopods—e...

Neural development and brain circuit evolution converged in birds and mammals

Neural development and brain circuit evolution converged in birds and mammals

Innovations in the pallium likely facilitated the evolution of advanced cognitive abilities in birds. We therefore scrutinized its cellular composition and evolution using cell type atlases from chick...

Analysing wing shapes within and across distantly related dipteran lineages, the authors show that intrapopulation variation reflecting microevolutionary change can predict deep divergence at macroevo...