Evolution of the brain and sensory structures in metatherians

Thomas E. Macrini, Michael Leary, Vera Weisbecker

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

1 Citation (Scopus)


The metatherians (crown-clade marsupial mammals and their fossil relatives) originated in the Late Jurassic or Early Cretaceous of Laurasia, and have since spread worldwide with diversification in South America and Australasia during the Cenozoic. Despite this long evolutionary history, paleoneurology is known for a few taxa from the Americas and Australia, with most work being published in the last 40+ years. Here, we contextualise research on metatherian paleoneurology with traditional tenets that marsupials are developmentally constrained in their brain size and advanced cognitive and sensorimotor capabilities. We summarize recent research on marsupial neuromorphology with a perspective on how these insights apply to extinct species. We describe a digital cranial endocast of the didelphid Caluromys philander to compare with endocasts of crown and stem marsupials. Although endocasts of basal metatherians morphologically resemble those of didelphids, there is significant variation in brain shape and cerebrum gyrification among marsupials, possibly due to differences in how neural tissue is distributed within limited braincase space. Lastly, we examined existing endocranial volume and body mass estimates for crown and stem marsupials. The earliest metatherians have substantially smaller relative brain sizes than recent species, although this may relate to errors in estimating metatherian mass and endocast volumes.

Original languageEnglish
Title of host publicationPaleoneurology of Amniotes
Subtitle of host publicationNew Directions in the Study of Fossil Endocasts
EditorsMaría Teresa Dozo, Ariana Paulina-Carabajal, Thomas E. Macrini, Stig Walsh
Place of PublicationSwitzerland
PublisherSpringer International Publishing
Number of pages34
ISBN (Electronic)9783031139833
ISBN (Print)9783031139826
Publication statusPublished - 2023


  • Brain evolution
  • Cranial endocast
  • Endocast
  • Marsupials
  • Metatheria
  • Stem marsupials


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