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Alexander Onufrievich Kovalevsky (Russian: Алекса́ндр Ону́фриевич Ковале́вский, Polish: Aleksander Kowalewski, 7 November 1840 in Vorkovo, Vitebsk Governorate, Russian Empire – 1901, St. Petersburg, Russian Empire), also written Alexander Kowalevsky, was a Russian embryologist of Polish descent, who studied medicine at the University of Heidelberg and became professor at the University of St Petersburg.[1][2][3][4] He was the brother of paleontologist Vladimir Kovalevsky.

Alexander Kovalevsky
Alexander Kovalevsky
Born7 November 1840
Alma materUniversity of Heidelberg
Known forGastrulation
Scientific career


A. Lancelet (a chordate), B. Larval tunicate, C. Adult tunicate. Kovalevsky saw that the notochord (1) and gill slit (5) are features shared by tunicates and vertebrates.

Kowalevsky showed that all animals go through a period of gastrulation.[1][2][3][4]

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.[5]

Antoine Fortuné Marion and Alexander Kovalevsky, founder and collaborator of the Annals of Natural History Museum of Marseille


  • Kowalevsky, A (1901). "Les Hedylidés, étude anatomique". Zapiski Imperatorskoi Akademii Nauk. 12: 1–32.


  1. ^ a b Ereskovsky, Alexander (2012). "Introduction to the Kowalevsky medal issue". Evolution & Development. 14 (1): 1–2. doi:10.1111/j.1525-142X.2011.00516.x.
  2. ^ a b Fokin, Sergei I. (2012). "Life of Alexander Onufrievich Kowalevsky (1840–1901)". Evolution & Development. 14 (1): 3–8. doi:10.1111/j.1525-142X.2011.00517.x.
  3. ^ a b Haas, L F (May 1999). "Alexander Onufrievich Kovalevsky (1840-1901)". J. Neurol. Neurosurg. Psychiatry. 66 (5): 680. doi:10.1136/jnnp.66.5.680. PMC 1736354. PMID 10209188.
  4. ^ a b Kyle, R A; Shampo M A (Sep 1982). "Alexander O. Kovalevsky". JAMA. 248 (11): 1336. doi:10.1001/jama.248.11.1336. PMID 7050433.
  5. ^ Gilbert, Scott F. (2003). "The morphogenesis of evolutionary developmental biology" (PDF). International Journal of Developmental Biology. 47: 467–477.