page_title: Alexander Kovalevsky
section_title: Discoveries
hierarchical_section_title: Alexander Kovalevsky / Discoveries
caption_attribution_description: Français&#160;: Antoine Fortuné Marion 1846-1900 et Alex Kowaleswsky 1840-1901
context_page_description: Alexander Onufrievich Kovalevsky, was a Russian embryologist, who studied medicine at the University of Heidelberg and became professor at the University of St Petersburg.
  He was the brother of paleontologist Vladimir Kovalevsky, and the brother-in-law of the mathematician Sofya Kovalevskaya.
context_section_description: Kowalevsky showed that all animals go through a period of gastrulation.
  Kovalevsky discovered that tunicates were not molluscs, but that their larval stage had a notochord and pharyngeal slits, like vertebrates. Further, these structures developed from the same germ layers in the embryo as the equivalent structures in vertebrates, so he argued that the tunicates should be grouped with the vertebrates as chordates. 19th century zoology thus converted embryology into an evolutionary science, connecting phylogeny with homologies between the germ layers of embryos, foreshadowing evolutionary developmental biology.
caption: Antoine Fortuné Marion and Alexander Kovalevsky, founder and collaborator of the Annals of Natural History Museum of Marseille
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